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Canter lead change kinematics of superior olympic dressage horses
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CANTER LEADCHANGEKINEMATICSOF SUPERIOROLYMPICDRESSAGEHORSES N. R. Deuel, ~PhD; J. Park,2 PhD
study provided the first objective documentation of the canter limb contact patterns ofworld-class dressage horses. SUMMARY
Limb contact variables of the gaits of superior dressage horses were determined for competitors at the 1988 Seoul Summer Olympic Games in the finals of the Individual Dressage competition. Two 16-mm motion picture cameras were aimed perpendicular to the plane of motion along the HXF and KXM diagonals of the standard dressage arena, and filmed at 100 fps. Nineteen of the horses selected as finalists for individual dressage medals were filmed during the Grand Prix Special test executing one-stride canter lead changes, two-stride canter lead changes and the left lead extended canter. Velocities, stride lengths and stride durations were 7.03+.07 m/s, 4.15+.05 m and .592+.004 s for the extended canter. Across all stride frequencies, score was optimized with extended canter slrides of the greatest length, with no upper limit detected to optimal stride length. Canter strides with lead changes had lower velocities, shorter strides and longer durations than strides without a lead change, with velocities, stride lengths and stride durations, respectively, of 3.36+.05 m/s, 2.08+.04 m and .617+.003 s for one-stride canter lead change strides; 3.65+.07 m/s, 2.21+.04 m and .605+.003 s for pre-change canter two-stride lead change strides; and 3.95+.07 m/s, 2.44+.04 m and .621+.004 s for post-change canter two-stride lead change strides. This Authors' addresses. 1Department of Animal Nutritional Sciences, Kendall Hall, University of New Hampshire, Durham, NH 03824 USA; 2Department of Physical Education, Pusan Sanub University, Taeyun-dong, Nam-gu, Pusan, Korea 608. Acknowledgements:The authors would like to express their appreciation to Dr. Inseong Hwang of Yonsei University, Seoul, Korea, for coordinating this project, which was sponsored by the Medical Commission of the International Olympic Committee, and received corporate sponsorship from Eastman Kodak Company and Redlake Corporation. Thanks are also extended to the staffs of the Federation Equestre Intemationaleand the Seoul Equestrian Park for their cooperation. We are grateful to Ms. Vinsel, Mr. Lee, Mr. Kim and the many other individuals that provided on-site assistance with filming and videotaping. The first author would also like to thank Dr. W. Condon and Dr. R. Strout for their support of this project.
Volume 10, Number 4 1990
INTRODUCTION
Many excellent texts have discussed the practical aspects of gait characteristics desirable in a dressage horse.13,1~ However, there has been little scientific documentation of the gait characteristics of successful dressage horses, and particularly little objective study of the kinematics of world-class dressage competitors. The biomechanics of the locomotion of competitive athletic horses have been studied most extensively in the Standardbred racehorse ~11 and to a much lesser extent in Thoroughbred racehorses TMand jumpers.~SHowever, there have been few other objective studies of the gait kinematics of riding horses. Dressage horses receive the most lengthy training of any type of riding horse; typically a minimum of seven years of training before entering toplevel competition. Because of these extensive training procedures, Olympic dressage individual medal finalists have motion patterns that are the most highly developed of all riding horses. There is a paucity of research literature pertaining to the kinematics of the equine canter 2 and none of that concerns the canter of world-class dressage horses. Furthermore, little is known about the complex motion patterns that occur as a horse executing the transverse canter or gallop changes from one lead to the other) 4 The purposes of this study were to document the kinematics of the limb contact phases of the canter exhibited by superior dressage horses competing at the 1988 Seoul Summer Olympics Games, and to determine the limb contact patterns typical of their canter lead changes. A final objective was to associate alterations in certain limb contact variables of each gait pattern with dressage scores in
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Table 1. Canter stride limb contact variables of superior Olympic dressage horses. 1 Score
Horse
Nation
Variable
2-Stride lead changes Pre-change Post-change mean mean
1-Stride Changes mean
Extended mean
1521
Rembrandt 24
FRG
Vel (m/s) SL (m) Freq (s~)
3.9 2.3 1.7
4.0 2.6 1.6
3.5 2.2 1.6
8.9 5.2 1.7
1462
Corlandus
FRA
Vel (m/s) SL (m) Freq (s-~)
4.0 2.6 1.6
4.2 2.7 1.5
3.1 2.0 1.6
6.8 4.3 1.6
1417
Gaugin de Lully
SUI
Vel (m/s) SL (m) Freq (s ~)
----
----
3.5 2.2 1.6
---
3.1 1.8 1.7
3.4 2.1 1.6
3.2 2.0 1.6
6.4 3.9 1.6
3.5 2.2 1.6
--
1401
Dynasty
CAN
Vel (m/s) SL (m) Freq (st)
1393
Matador
FIN
Vel (m/s) SL (m) Freq (s -1)
--
--
-
-
-
-
-
-
-
-
--
-
1385
Ganimedes
FRG
Vel (m/s) SL (m) Freq (s-1)
3.7 2.4 1.6
4.3 2.6 1.6
3.7 2.2 1.7
6.6 4.2 1.6
1383
Andiamo
SUI
Vel (m/s) SL (m) Freq (s1)
3.5 2.1 1.6
3.8 2.2 1.7
3.3 2.0 1.7
6.1 3.5 1.7
1374
Courage 10
FRG
Vel (m/s) SL (m) Freq (s"1)
----
----
3.5 2.1 1.6
m
1354
Dixon
URS
Vel (m/s) SL (m) Freq (s-1)
4.1 2.3 1.8
4.6 2.5 1.8
----
7ol 3.9 1.8
1349
Pascal
KOR
Vel (m/s) SL (m) Freq (s-~)
3.4 2.0 1.7
3.9 2.2 1.7
3.4 1.9 1.7
7.2 4.1 1.7
1330
Random
SUI
Vel (m/s) SL (m) Freq (s1)
3.3 2.2 1.5
3.6 2.4 1.5
3.4 2.2 1,5
6.7 4.1 1.6
1326
Malte
CAN
Vel (m/s) SL (m) Freq (s ~)
3.4 2.1 1.6
3.8 2.3 1.6
----
6.7 4.2 1.6
1320
Federleicht
USA
Vel (m/s) SL (m) Freq (s1)
3.9 2.5 1.6
4.3 2.8 1.6
3.6 2.3 1.5
6.9 4.2 1.7
1304
Dutch Gold
GBR
Vel (m/s) SL (m) Freq (s1)
3.8 2.2 1.7
3.9 2.4 1.7
----
7,2 4.0
288
1.8
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Table 1 (continued) Score
Horse
Nation
Variable
2-Stride lead changes
Pre-change mean
Post-change mean
1-Stride
Changes mean
Extended mean
1297
Petit Prince
HOL
Vel (m/s) SL (m) Freq (s~)
3.8 2.1 1.8
4.0 2.5 1.6
3.2 1.9 1.7
7.0 4.0 1.7
1296
Reipo
CAN
Vel (m/s) SL (m) Freq (s 1)
3.8 2.3 1.7
4.1 2.6 1.6
3.2 2.1 1.6
6.9 4.3 1.6
1282
Orpheus
USA
Vel (m/s) SL (m) Freq (s~)
3.5 2,1 1.7
3.7 2.3 1.6
----
7.2 4.2 1.7
1280
Cantat
DEN
Vel (m/s) SL (m) Freq (s~)
3.7 2.3 1.6
4.1 2.6 1.6
----
7.0 4.3 1.6
1267
Amen 5
HOL
Vel (m/s) SL (m) Freq (s-~)
3,2 2.0 1.6
3.4 2.1 1.6
----
6.6 3.9 1.7
• ~Values are mean velocities (Vel) measured for 2 to 3 strides in m/s (SE range .02 to .29; LSD=.29), stride lengths (SL) in m (SE range .01 to .14; LSD=.16) and stride frequencies (Freq) in strides/s (SE range .01 to .06; LSD=.05). Missing data are signified by --.
world-class dressage competition. This study of equine gaits will be confined to velocities, stride lengths, Step lengths and temporal variables delimited by limb impacts and liftoffs, since these represent the summary result of all rotational and translational motions of body limb segments through the stride cycle.
MATERIALS
AND METHODS
Measurements of limb contact variables were made for the canter of dressage horses competing at the 1988 Seoul Summer Olympic Games. All horses were filmed while executing prescribed movements with a 16-mm high-speed motion picture careers (100 fps), aimedperpendicular to the plane of horse motion along the F I X and KXM diagonals of a standard 20m x 60m dressage arena (Figure 1). Nineteen horses selected as contenders for individual dressage medals (finalists) were filmed during completion of the 7.5rain Grand Prix Special dressage test on September 27, 1988 while executing movement 19, two-stride canter lead changes; movement 20, one-stride canter lead changes, and movement 21, extended canter (left lead). The cameras" field of view was 14 to 15 m. Some of the film sequence data were missed (Table 1) due to camera operator error and in Volume 10, Number 4 1990
one case, failure of the horse to execute the prescribed lead changes. The centermost strides in the film frame were analyzed per sequence. It should be noted that the horse and rider always compete as a team in Olympic equestrian events and it was therefore impossible to differentiate the effects of specific riders on horse performance in this study. Limb contact timing variables were measured from frame-by-frame analysis of projected film images of limb impacts and liftoffs, utilizing previously established methods and nomenclatureY Linear distances were calculated from conversions of projected image distances utilizing a reference meterstick filmed in the plane of motion. Frame rates were determined from marks on film made at 10 msec intervals by the cameras' internal timing light generators. Stride lengths were determined by fdm image linear measurements between successive impact locations of the toe of the hind trailing limb, and step lengths between toe locations at successive hoof impacts. Interrelationships between scores, velocity, stride length and stride frequency were examined for each gait pattern by means of linear regression analysis. Limb contact data were subjected to multiple linear regression analyses of variance 17 to determine the effect of the individual horse on stride limb contact timing patterns. Total Grand Prix Special dressage test score was also included in multiple linear regression analy289
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DRESSAGE ARENA EXTENDED CANTER OLYMPIC DRESSAGE FINALISTS
A
TOTAL SCORE
1.80"
F-i 1412. F_
1.75"
I~
126114t2
>0
1,o,-
g ,to.
~1
<1'09
~W 1.65,
1261
R2 = .71
bJ
P <.0001
Ito
~ 1.60' I.$5'
p. Figure 2. Contour plot of the response surface relating extended canter stride frequency (s-l) and stride length (m)
B_
"E 6 0 m J f
M.
C <
20m
>
Figure 1. Standard dressage arena utilized for Olympic competition, with locations of cameras 1 and 2 depicted with focal axes perpendicular to planes of equestrian motion. The center of the arena is designated location X, so motion along the diagonals is described as along FXH or HXF (illmed by camera1 ) or along MXK or KXM (filmed by cam era 2).
290
ses to determine possible relationships between canter stride variables and score (total of five judges' subjective marks). 8 It should be noted that all comparisons of stride limb contact temporal and linear measurements were made on the basis of standardized (average) stride frequencies, stride lengths and scores. If the relationship between a stride variable and score was significant in the multiple linear regression model (on a standard-velocity basis), simple linear regression was employed to determine the equation relating the two variables for each movement (which may incorporate velocity effects). For the extended canter, linear and quadratic functions of stride length and stride frequency were associated with score as a response surface (RSREG procedure) ~7 to identify optimal combinations of those stride variables. It is important to point out that the horses involved in this study belonged to a relatively homogeneous group of superior athletes selected in world-class competition. The discriminations determined in dressage scores are between the world' s best and the nearly-best. The relationships documented for this group may not hold for horses of lesser abilities. The R z values represent the proportion of variability in one characteristic that can be associated with variability in another, with no cause-and-effect relationship necessarily implied. Due to the homogeneity of the population, statistically significant relationships found in this study should be considered meaningful for world-class competitors, even though some R z values may appear low at first inspection. One might expect higher R z values from a more heterogeneous population that included horses of all ability
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Table
2.
Limb contact linear variables of canter strides of superior Olympic dressage horses.
Variable
N strides Velocity (m/s) Stride length (m)
2-Stride lead changes Pre-change Post-change
1-Stride Changes
Extended
SD
32 3.65" 2.21"
31 3.95b 2.44b
51 3.36¢ 2.08=
40 7.03d 4.15d
.36 .24
Hindstep HT-->HL (m) (%)
.87" 40.7'b
.88" 37.4 ~
.94" 49.7"
1.13b 28.1b
.15 33.2
Midstep HL-->FT (m) (%)
.97'~ 45.7"
.93" 39.7b
.97= 47.6"
1.00b 24.7=
.11 11.6
Forestep FT-->FL (m) (%)
.79" 37.1"
.89 b 37.9"
.80" 39.6"
1.13= 28.1 b
.07 11.
-.33b
-.53° -26.1,
Hoof impact distances~,z
Airbome ste~ FL-->HT(m) (%)
-.47" -22.7 a
-14.7 ab
.78d 19.1=
.11 7.6
'Arithmeticmeans. 2Abbreviationsare H=hind,F=fore, L=lead,T=trail. 3Positivevalues indicate that the hind trailing limb impact overstepped the fore leading limb impact of the previous stride in the plane of motion.
levels. Combinations of temporal and linear variables associated with high scores for the canter were also determined by stepwise multiple regression, using the maximum R z improvement method with a P<.15 level for inclusion in the model and P>. 15 level for deletion. 15,17Models selected and presented herein are those in which the number of variables most closely approaches the Cp statistic. 17 Judges' scores for the individual dressage movements were requested but unfortunately unavailable. In the Grand Prix Special Test, the percentage of the total score related to the judges' subjective impressions of the walk is 7.3%; trot, 45.1%; canter, 28.1%; collective marks on paces, impulsion and submission, 14.6%; and rider position and use of aids, 4.9%? For canter movements, the percentage accorded in the total score for the extended canter is 2.4%; for singlestride lead changes, 4.9 %, and for double-stride lead changes, 2.4%. s Therefore any statistically significant R 2 value exceeding .05 may indicate akinematic variable more strongly associated with judges" scores than one might anticipate by the scoresheet values accorded to that movement.
RESULTS AND DISCUSSION
Total score for Grand Prix Special dressage tests averages 1354+11 points, out of a theoretical perfect score of Volume 10, Number 4 1990
2050 points. The top scoring horse-rider team was Rembrandt 24 ridden by Nicole Uphoff of the Federal Republic of Germany, receiving 1521 points. Every canter stride variable measured was found to differ (P<.05) between horses, and therefore the limb contact characteristics were highly individualized features of the canter stride, just as they are in the gallop gait. 6 For each horse, velocities, stride lengths and stride frequencies for each canter movement (extended, onestride lead changes, two-stride lead change pre-change, two-stride lead change post-change) are provided in Table 1. Overall, higher scores were associated with higher velocities (P<.004), longer stride lengths (P<.0001), but had no significant relationship with stride frequency. This may be interpreted to mean that in canter work of superior dressage horses, high velocities and long strides are judged favorably while stride frequencies have relatively little effect on the score. Most notable were stride lengths as long as 5.2 m (17 feet) demonstrated by the gold medalist Rembrandt 24 in the extended canter, while in executing the same movement four of the finalists had stride lengths of 3.9 m (13 feet) or less. Linear measurements for each canter movement are provided in Table 2, while temporal measurements are presented in Table 3. In Table 4, simple linear regression equations are presented relating total Grand Prix Special dressage score with stride variables for each canter movement.
291
,:~;~.
~ EquineNutritionandPhysiologySociety
EXTENDED CANTER STRIDE
ONE-STRIDE CANTER LEAD CHANGE HL+FT+FL
HL+FL
.101=16.8 %
.014 =2.41% IlL+ FT + FL • FL . , , , ~ ~ . 0 4 1 =6.9 % .120 20.2 % y ~ HL+ FT 76=12.7%
FT+FL ~
~
.006"1.2~
.I27-=21.5r*/~"/
HL+FT
~ 6 = 2 . 6
%
HT+HL+FT I I3 =18.9%
"~
HT+HL+FT
.046= 7.8 %
I
HT+FT .010 = 1.7% AIRBORNE .098:16.4%
.117=19.6 %
~ \ \ \ \ ~ . _ HT+HL 7-.027=4.4%
~
HT .111-|8.5%
Figure 3. Pie gait diagrams of cyclic limb contact phases of the exte~Ided canter stride and one-stride canter lead change stride of superior Olympic dressage horses, standardized to similar stride durations. Label values indicate for each limb contact phase the duration of the phase (s) and the proportion of the entire stride (%). Limb contacts, depicted counter-clockwise in time: H=hind, F--fore, L=lead, T=trail. Shaded segments represent canter stride phases that differ significantly between movements. CANTER
LEAD
CHANGE
PRE-CHANGESTRIDE HL+FT+FL HL+FL ~
.,o5-,.4~
.102:16.8% HL÷FT /~o9 • 3.,'/,
FL i111111/~\
//
POST-CHANGE STRIDE HL+FT+FL HL+FL .095-.15.7 % .022=5.6~ ~ - ' - " " . ~
HL~F2"r "
3.7"/.
\ HT÷HL÷FT .138=22.7~.
yt.ff,/.~JJJJJ.~jI AIRBORNE, ¢ ' ~ J / / ~
1o,.1,,,,
'"¢~\\~L HT+ FT " ~ .019=3.1%
/
A ~"
;',":;B 5,,
112-18.4%
~JJJZT~J
A,R8ORNE
.095 • 15.6%
~,~F,~ HT+ HL
/
O,B-2,,,
.106-17.5 %
Figure 4. Pie gait diagrams of limb contact phases of two-stride canter lead change strides for pre-change and post-change canter strides of superior Olympic dressage horses, standardized to similar stride durations. Label values indicate for each limb contact phase the duration of the phase (s) and the proportion of the entire stride (%). Limb contacts, depicted counterclockwise in time: H=hind, F=fore, L--lead, T=trail. Shaded segments represent canter stride phases that differ significantly between movements. It should be noted that all canter lead changes filmed were executed first by the hindlimbs and then by the forelimbs. All strides observed were those of the transverse canter,2,s although horses are capable of switching leads only in the forelimbs, and thereby executing rotary canter strides. 12 Over all canter strides, statistically significant but weak relationships were detected between score and stride kinematic variables (Table 4). Score was positively related to midstep length, hind lead unipedal contact, fore trail unipedal contact, hind trail-hind lead bipedal contact, and 292
quadrupedal contact. The extended canter stride
Velocities of the extended canter averages 7.03+0.7 m/ s (mean~.+SE)or 422 m/min, with stride lengths averaging 4.15+.05 m and stride durations of .592+.004 s. The extended canter had a tempo of 101 strides/min, slightly faster than the 96 strides/min cited for dressage canter work. 1 Velocities of the extended canter were higher than when lead changes were executed, resulting from both longer strides and higher stride frequencies. For the extended EQUINE VETERINARY SCIENCE
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canter, (velocity) =1.42 + 1.34 (stride length) (R~.63,P<.0001). The creation of a response surface from the effects of extended canter stride frequency and stride length yielded an optimization contour plot (Figure 2). Score was optimized with the longest stride lengths, in the scoring range of the three individual medalists. There was no upper limit detected for optimal stride length, across all stride frequencies. The lowest scoring horses had stride frequencies above 1.58 s-I and the shortest strides. The longer stride of the extended canter in comparison with lead change strides was due primarily to greater distances between hindlimb impacts and between forelimb impacts, and also the result of the hind trailing limb impact overstepping the location of the previous fore leading limb impact. This made each step length of the extended canter a smaller proportion of total stride length than in lead change strides, although each distance between successive limb impacts was greater in absolute magnitude. The most common support sequence for extended canter strides (48% of strides) was 1) hind trail unipedal, 2) hind trail-fore trail bipedal, 3) hind trail-hind lead-fore trail tripedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) hind lead-fore lead bipedal, 7) fore lead unipedal, and 8) airborne phase. ~ On the average, impacts of the hind leading limb and fore trailing limb were nearly simultaneous in the extended canter. Fewer than 5% of extended canter strides had limb contact sequences typical of the gallop gait, that is, with a hind trail-hind lead bipedal contact, a unipedal hind lead contact, a unipedal fore trail contact and a fore trail-fore lead contact.8 Therefore, virtually all strides filmed were those of a true extended canter. For step lengths of the extended canter, forestep length had the strongest positive relationship with score, while hindstep length and midstep length were also both positively related to score. Other single extended canter stride variables with significant relationships with higher scores were longer hind lead unipedal contacts, longer fore trail unipedal contacts and shorter fore tripedal contacts. Stepwise multiple regression (R~.90,P<.0001) revealed a combination of 11 stride temporal ariables associated with higher scores: longer hind lead limb contacts, shorter fore lead limb contacts, shorter hind trail non-contact durations, longer intervals between impacts of hind lead and fore trail limbs, smaller ratios of hind lead contact to total hind contacts, greater ratios of fore lead contact to total fore
Volume 10, Number 4 1990
contacts, greater ratios of fore contacts to hind contacts, longer unipedal contacts of the hind lead limb, shorter fore tripedal contacts, shorter simultaneous support by the hind trail and hind lead, and longer airborne durations. Stepwise multiple regression of linear measurements revealed a combination of five variables associated (P<.0001; RL--.56) with higher scores: increased midstep and airborne step lengths, decreased forestep lengths, decreased proportions of midsteps, and increased proportions of foresteps in the total stride. The practical interpretation of these findings in that the higher-seoring horses demonstrated extended canter strides with relatively high velocities and long strides while maintaining a nearly constant tempo, decreasing the time in which the limbs were in ground contact, utilizing their limbs more asynchronously in support, increasing the time and distance between hindlimb and forelimb contacts, and increasing the airborne time and distance.
Extended canter st rides versus canter lead change strides In comparison with extended canter strides, strides of horses executing lead changes, had on the average velocities 52% as fast (averaging approximately 3.65 m/s or 219 m/min), with stride lengths 54% as long, while maintaining stride frequencies at 96% of extended canter levels (Tables 2 and 3). The difference in the stride lengths was the result of shorter steps between the hindlimbs (79% of extended canter hindstep), shorter steps between the forelimbs (73% of extended canter forestep), and also the hind trail limb impact failing to overstep the imprint of the fore leading limb from the previous stride. On the average, during lead change strides the impact of the hind trailing limb fell .44 m short of the imprint of the fore leading limb, while in the extended canter the impact of the hind trailing limb overstepped the imprint of the fore leading limb by .78 m. Lead change canter strides also had longer limb contact durations and shorter limb non-contact durations for all four limbs than in the extended canter stride. In addition, there were longer total contact durations and shorter airborne phases in lead change canter strides. Total bipedal contact durations, total quadrupedal contact durations, total hind contact durations and total fore contact durations were all greater in lead change canter strides than in extended canter strides. On the average, impacts of the hind leading limb and fore trailing limb were nearly simultaneous in the extended canter, but were separated by 14 to 24 msec in lead change strides.
293
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T a b l e 3 . L i m b c o n t a c t t e m p o r a l v a r i a b l e s of c a n t e r s t r i d e s of s u p e r i o r O l y m p i c d r e s s a g e h o r s e s . 2-Stride lead changes Pre-change Post-change
Variable
1-Stride Changes
Extended
SD
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L i m b c o n t a c t d u r a t i o n s (s) ~ Hind trail Hind lead Fore trail Fore lead
;: ::::;: ::::: :::::i:::
:::::;:::::::::::::
:::i::::i
.240' .242" .246a .247"
i : : : ::: : : : : : : : : : : : : : : : : : : :
.240 = .2670 .232 ~ .2570
::: :::::::
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.253 ~ .258 ~ .241" .249 ~
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.182 = .1870 .180 = .181 =
.017 .020 .017 .017
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Bipedal c o n t a c t d u r a t i o n s (s) ~,= HT +HL HT + FT HT + FL HL + FT HL + FL FT + FL Total
.004 ~ .019"
.018 ~ .003 ~
.027 ° .002 ~
.009 = .010 b
.000
.000
,000
.000
.019" .015 ~ .005' .061'
.022 a .022 a .O01a .067"
.015 ~ .0070 .014 b .066"
.076 b .014 "b .006 ~ .115 b
.016 .014 .018 .015 .010 .032
:iiiiii~iiiii:: ~i:i :~i~!:i~;~iit~iEi~iii~iii!~i ~N~ii:~i:~i~:ii~iiiii?:i~i~i~i:i:i~i'!:!:i:i:i:i~i:i'i:i:i'i:! :i :i~ITi~i:i~i~i:i:i'i:i?':ii~'i~'i':i'i~'~ii'i'i'i~'J~ii::'i'i::i'i:':iii!'ii:~i':i~~Ii~:ii~i':!::~ii~:~::J:i::!ii:: i::~i'i:'i~i'i'i:i:i~'i'i'::!i:~'i::i:~li:i:i ~i:i 'i:i:i::::::i~i:=ii :;::i::::ii:i:i:::::ii::::::i:i::'i::i:ii' ::i:ii:~i:iili~i::i i'i :i :i i::i::i:i::i:i ii:::ii::i::::::::::::::::::::::::: i:::i i:i:i::iii;i:i::i::?J:i::i:i::i:i'::i::iii:i::::::::::ii:J::::: :i :ii::::::::~ i:i:i :i i :i:~i:i:i i i :i:i:i ~ii!l!~i;~i~iiiiilJi::i i !i iiiiiii i i~i::ii:~i i:~ii;i:~i::ii!i i i!i!!~~ii:i!i~;i~i~! ;~ .:..ii i i !i~i i i~iiiiiijiiiii ili~!ii;i~iiii::i!i~ i~::ili :i:i::ii!!iii i!:~:::i:~::::::::::::::::::::::::::::: : ::: :: ::: : ~':':"'.',:" :::::::::::::::::::::::
::::::::::::::::::::::::::::::::::::::::::::::
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:::::::::"
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Total quadrupedal contact durations (s) ~,~ HT + HL + FT + FL
.003 =
.003 =
.004 =
<.001 ~
.006
~i~i::~::i:~i~i::i~i::?~i:=~iii::i~:=~::i:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::~::::::ii~::i::::::;::i::~:::::~:::::::=i~i::::::::::::::::::::::::::i~:~i::i::ii?~i::;::?:ii;~::?:?:i::i~;~ N o n - c o n t a c t d u r a t i o n s (s) Hind trail Hind lead Fore trail Fore lead Airborne phase
.371 ~ .369' .365" .364" .107"
.371" .344 ~ .379 ~ .354 ~ .094 ~
.358 ~ .352 ~ .370" .362" .098 '~
.428 ¢ .424 ¢ .431 ° .430 ° .170 ¢
.017 .020 .017 .018 .021
:~i~i:i ~i ~i:i~i~:~i~i~:~:~ii~i~:~i~:~ii~:~i~i~:~:~i~i ~i~::~:~:~::~i~i`;~;~i ~:i:~i~~:ii~i:i~:~ii ~i%~ ~i~:i:i:::%::~%~i~!~:::::::~i~;~:~:::::i::::::i ~i~!~:::~i i:::;:::::i~i:MJ~::i::i:::::::::i :i:::iii:~i:::iii::::::iii:~iiii!:ii!?:iiiiiii!i i::, .i:~ii!;iiiii;i:iiiiiiii .i.i i.i.i.i.i;;`~.;.ii;i~`;.;.ii;~!i.i.i ;i~i .i.i`i;;i~.i.i.;~;i~.i.i.;~;.~`~.i~;`;`i.~.~!.;~::;.i1.i.:i:~::::~:.:m:i:::ii:i i:::~::iii:::~ii ~ : : i i i ::~::::i~:
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::::iiiii iii~:iiiiii::iiiiii ::iii:::ji ::iiiiiii i iiiiiiiii::i!::iii::iiiiiii::::iiiiiii~~~iiiiiiiiiiiiiiiiiiiiiii ii~ ~1~iiiiiii i::!iiiiiiiii ::iiiiiiiiiii::iii~::~iiiii!::ii!iiiii!ii ii::iiiii iiiiiiiiiiiii!iiiiiiiiiii::ii!iiiiiii!ii!i~i~i.2:i!..::::~iiiiii::i::i::iiiii!::i::iiii!ii!::iiiiiiii::!iiiiiiiiii!ii!ii::iiiiii::: : ~ i :.
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::::::::::::::::::::::::::::::::::::::::::::::::
-
:' :~
Contact ratios (s:s) Hind lead: total hind Fore lead: total fore Total fore: total hind
.648" .641 • 1,040 ~
.708 ~ .655 "~ 1.045"
.695 ~ .664 b 1.014 ~
.595 ° .575 ~ 1.005 ~
.048 .037 .063
~Leastsquare means standardized according to the average stride frequency (1.64 s-l), lead and score. Values without common superscripts within a row are different (P<.05). 2Abbreviations are H=hind, F=fore, L=lead, T=trail.
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Equine Nutrition and Physiology Society REFEREEDPAPERSFROMTHE 11THSYMPOSIUM
Table 4 , S i m p l e linear regression e q u a t i o n s relating total d r e s s a g e score with canter stride variables? : : :: : : : :[: :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: :: : :: : ::: : :: : : : : : : :: : : : ::: :; ; :: : : : : :.:.:.: :.:: : :: :.:.:.:.:.:.:.:,:.:.:.:. ~:.'.:.:.:~" :.:.:.:.:.:.:.:~:,:.:...:.:.:.:.:.:.,..:..:+:.:
..........
: ......................................
...., .......
...................,...................................
iii~iiiiii~iiiiiiiiiii!i~ii~ii~iiiiiiiiiiii~iii~i~i~i~i~i~i~i~i~i~iiiiiiiiiii!!iiiiiiiiiiiiiiiiiiiiiiiiii;iiiiiii~iiii~ii~iii~iiiiiiiiiiii~i~i~i~h~iiiiiiiii~i~i~i~iiiiiiii~i~i~iiiiii~iiiiiiii~ii~iii~i~!~iiiiii~i~!i~iiiii ~i~;i~;~;i;;~;~;~;~i~iiiiii;~iiiiii~iil;iii!iiiiiiiiiii~ii;ziiii!!i;iiiiiiiiiiiiii;!;~iiiiii ::i::il;i;ii:::::::::::iii::::::::::::iii::::::::i:::::::::::::::::::::::::::::: i::i::i::::i:::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::: ::i::::::::::::::::::::::::::::::::::::::::::: All canter strides Score = 1221 + 143 Score = 1354 + 16684 Score = 1354 + 9998 Score = 1341 + 959
~Midstep (m) HL unipedal contact (s) "FT unipedal contact (s) "HT + HL bipedal contact (s)
.07 .08 .07 .08
iii:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: iiiiiiiii ii i ii ii ! i iii ii ii!iiiiiiiiiiiiii i i i i i iiiiiiiii;i i i i i ii ii iiii!i i i ii ! ii i T TiiT i iii iii ii iiiiii i i i iiiiii i i iii i i iiiiiii;i :::: iiii iiiii! !iiii ii i i !i i i iiiiiiiiii ii!!ii !!i!i!i!!!i i i i!i iiiiiiiiiiiiiiiiiiii!iiiiiiiiiiiii!i!! !iiiiiiiiiii!! !ii Two-stride canter lead change post-change strides Score = 1107 + Score = 1401 +
257 167
:Midstep (m) Airborne step (m)
.14 .13
:::::::::::::::::::::::: ::~ ~i~::ii :::::tiL~i i~:::::::::::::::: i11::~§:::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::::::::: i::::::i::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: :::::: :::::::::::::::::::::::::: i::!ii::;::i i?::i::i::i::)::i ::i::ii::i:i:iii::i::iNi ::i::i:: ~N ~~ ~::)~N ~::::i ~i i}::i::i::!::iiiii::i::ii!::)!i!!:~ilil i::ii ::):: ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: i':ii?i::?:}i :: iiii)::i::i::iiii ilil;iN?:}i?ii::)ii::iii!ii!! iiii iii::)i)::iiiiil i::ii) Extended canter strides Score = 1051 + 42.1 Score = 966 + 91.4 Score = 1000 + 304 Score = 1190 + 154 Score = 797 + 485 Score = 1326 + 19486 Score = 1327 + 11636 Score = 1414 - 2004
~Velocity (m/s) Stride length (m) ~Hindstep (m) Midstep (m) ~Forestep (m) H L unipedal contact (s) FT unipedal contact (s) "HL+FT+FL tripedal contact (s)
.13 .20 .14 .11 .36 .42 .37 .18
1All equations listedare significantat P<.05. Abbreviations are H=hind, F=fore, L=lead, T=trail.
For all strides involving lead changes, velocities, stride lengths and stride frequencies were not significantly related to scores. T w o - s t r i d e canter lead c h a n g e s : strides versus post-change strides
pre-change
In comparison with canter strides following a lead change, canter strides preceding a lead change had velocities 8% slower, stride lengths 9% shorter and stride durations 3% shorter (even though ranges of stride durations were similar). The difference in stride lengths were due to 10 cm shorter step between the forelimbs and advancing forward 14 cm less in the airborne step in strides preceding a lead change than in strides following a lead change. For two-stride lead change sequences, slride length and velocity were related such that, for the pre-change stride, (velocity)=.525 + 1.38 (stride length) (RZ=.68,P<.0001); and for Volume 10, Number 4 1990
the post-change stride (velocity)=.525 + 1.40 (slride length) (RZ=.70,P<.0001). Stride durations were similar for post-change twostride lead change strides and one-stride canter lead change strides, each with a tempo of 97 strides/min, but pre-change two-stride lead change strides were of a shorter (P<.05) duration with a tempo of 99 strides/min. These values are similar to the tempo of 96 strides/rain cited for dressage canter work? S iridespreceding a lead change displayed shorter limb contact durations for the hind lead limb, fore vail limb and fore lead hmb. They also had longer non-contact durations for the hind lead limb and the fore lead limb, but shorter contact durations for the fore traillimb. In addition, strides preceding a lead change had shorter fore lead unipedal con tacts, shorter hind trail -hind lead bipedal contacts, longer hind trail-fore trail bipedal contacts, shorter total contact 295
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durations and longer airborne durations, as well as longer intervals between impacts of the hindlimbs and lower ratios of hind lead contact to total hind contacts. The most common support sequence for canter strides immediately preceding a lead change (31% of strides) was the same as reported for the extended canter, s The most common support sequence for canter strides immediately following a lead change (48% of strides) was 1) hind trail unipedal, 2) hind trail-hind lead bipedal, 3) hind trail-hind lead-fore trail tripedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) hind lead-fore lead bipedal, 7) fore lead unipedal, and 8) airborne phase, s The most pronounced difference between the limb contact patterns was that strides preceding lead changes predominantly had the impact of the fore wail limb occur before the impact of the hind lead limb, but in strides following lead changes the hind lead limb impacted before the fore trail limb. Canter strides preceding lead changes had a wide variety of limb contact patterns toward the end of the contact phase, with 31% of strides having a fore trailfore lead bipedal contact phase, 19% of strides having simultaneous litioff of the hind lead limb and fore trail limb, and 50% of strides having a hind lead-fore trail contact phase, s On the other hand, strides following lead changes showed almost an exclusive reliance upon lateral support by the hind lead and fore lead legs towards the end of the contact phase. Single variables of the pre-change canter stride that were significantly related to higher scores were longer midstep lengths, shorter fore trail unipedal contact, longer hind wail-hind lead bipedal contact, and longer fore trail non-contact durations. Stepwise multiple regression (RZ=A4, P<.05) revealed a combination of 7 temporal variables of the pre-change canter stride that was associated with the highest scores: shorter fore trail contacts, shorter impact intervals between fore lead and hind trail limbs, longer hind trail unipedal contacts, longer bipedal contacts of the hind wail and hind lead, longer bipedal contacts of the hind lead and fore lead, longer hind tripedal contacts, and shorter quadrupedal contacts. Stepwise multiple regression of linear measurements revealed a combination of five variables associated (P<.004; R2=.44) with higher scores: increased midstep and airborne step lengths, decreased forestep lengths, and decreased proportions ofmidsteps and airborne steps in the total stride. This may be interpreted to mean that preceding a lead change, the higher-scoring horses increased their contact durations of the hindlimbs and decreased the length of step and time between forelimb 296
impacts to prepare to execute the lead change in the succeeding airbome phase. Single variables of the post-change canter stride that were significantly related to higher scores were increased midstep length and increased airborne step length. Stepwise multiple regression (RZ=.38,P<.05) revealed a combination of 5 temporal variables of the post-change canter stride that was associated with the highest scores: longer impact intervals between hindlimbs, shorter impact intervals between forelimbs, longer bipedal contacts of the fore trail and fore lead, longer quadrupedal contacts and longer total tripedal contacts. Stepwise multiple regression of linear measurements revealed a combination of seven variables associated (P<.007; RZ=.52) with higher scores: decreased stride lengths and forestep lengths, increased hindstep and midstep lengths, and decreased proportions of hindsteps and foresteps in the total stride. These findings may be interpreted to mean that higher-scoring horses demonstrated a greater degree of collection as they recovered from the lead change, with shortened strides and relatively greater tripedal contacts and quadrupedal contacts.
One-stride lead change canter strides versus twostride lead change canter strides In comparison with strides of horses executing twostride lead changes, strides completed while executing onestride lead changes had velocities 12% slower, stride lengths 7% shorter, but stride durations similar to post-change twostride canter lead change strides. The difference in stride length was accounted for primarily by a forward advancement during the airborne phase averaging 13 cm less in single stride lead changes. For one-stride canter lead changes, stride length and velocity were related such that (velocity)=l.29 + 1.00 (stride length) (RZ=-.53, P<.0001), and (stride duration)=.380 + .115 (stride length) (RZ=.31,P<.0001). Single lead change strides in comparison with twostride lead change strides had shorter hind trail limb contact durations, and longer hind trail limb non-contact durations. In addition, one-stride lead changes involved longer hind trail-hind lead bipedal contact durations, shorter hind leadfore lead bipedal contact durations, longer fore trail-fore lead bipedal contact durations, and shorter intervals between forelimb impacts than did strides involving twostride lead changes. The limb support sequences of single-stride changes showed a fair degree of variability in technique. The most common support sequence for one-stride lead change canEQUINE VETERINARY SCIENCE
EquineNutritionandPhysiology Society~ ~~~~ ter strides (29% of strides) was 1) hind trail unipedal, 2) hind trail-hind lead bipedal, 3) hind trail-hind lead-fore trail tripedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) fore trail-fore lead bipedal, 7) fore lead unipedal and 8) airborne phase, s The second most common support sequence for one-stride lead change canter strides (24% of strides) was 1) hind trail unipedal, 2) hind trail-hind lead bipedal, 3) hind trail-hind lead-fore trail nipedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) hind lead-fore lead bipedal, 7) fore lead unipedal and 8) airborne phase. 8 One stride canter lead changes showed a pronounced reliance upon simultaneous contact by the two hindlimbs at the initiation of support and a simultaneous contact by the two forelimbs near the termination of support. Thus, the contact phases of the strides were initiated quite similar to strides following a two-stride lead change, but the strides were terminated with the most pronouned emphasis on bipedal forelimb contact of any of the canter strides filmed, similar to the limb contact pattern at the completion of gallop strides. Several kinematic variables of single lead change strides had significant relationships with score. Higher scores were associated with shorter fore trail contacts, shorter hind tripedal contacts, shorter total fore contacts, longer fore trail non-contact durations and longer airborne phase durations. Stepwise multiple regression (RZ=.61,P<.0001) revealed a combination of 7 temporal variables of one-snide canter lead changes associated with higher scores: lower fore trail contact durations, lower fore lead contact durations, longer intervals between impacts of the fore lead limb and hind trail limb, longer total hindlimb contacts, longer bipedal contacts of the hind lead and fore trail, shorter bipedal contacts of the hind lead and fore lead, and longer quadrupedal contacts. Stepwise multiple regression of linear measurements revealed a combination of five variables weakly associated (P<.05; RZ=.19) with higher scores: decreased forestep lengths, increased midstep and airborne step lengths, decreased proportions of midsteps and increased proportions of foresteps in the total stride. While executing singlesnide lead changes, higher-scoring horses demonstrated a greater degree of collection and impulsion from the hindquarters with a greater time in hindlimb support and a shorter time in forelimb support in preparing for a longer time in the air executing the lead change. In future studies it would be advantageous to compare a slower collected canter (rather than the extended canter) with canter strides involving lead changes, to determine Volume 10, Number 4 1990
more subtle alterations in gait patterns associated with lead changes. It would also be valuable to perform kinematic analyses of other precision motions of world-class dressage horses, such as the piaffe, passage and piroutte.
CONCLUSIONS
1. High speed cinematography utilizedat 100 frames per sec was able to detect individualized features of canter motion in horses moving at velocities from 3 to 9 m/s. 2. This study provided the first reference documentation of the canter stride characteristics of world-class dressage horses during execution of the Grand Prix Special test in the Olympic Games. 3. Kinematics of the canter determined from film analysis can be accurately associated with dressage judges' subjective scores. 4. Differences in velocity between 3 and 9 m/s of the canter of world-class dressage horses were primarily the result of differences in stride length. For all canter movements, stride length and velocity were closely related, but stride duration and stride length tended to be unrelated. Stride duration and velocity were not significantly related for any canter movement, in contrast to the gallop. 4 5. Score was optimized with the greatest length of extended canter strides. There was no upper limit detected for optimal snide length, across all stride frequencies. The lowest scoring horses had extended canter stride frequencies above 1.58 s-1 and the shortest strides. 6. Lead changes of the canter stride were performed at 52% of the velocity, 54% of the stride length and 96% of the stride frequency of the extended canter. 7. Canter strides preceding a lead change were slower in velocity, stride lengths shorter, and stride durations briefer than strides following a lead change. 8. Kinematic analysis of canter snides of higher-scoring horses showed a greater degree of coUection and impulsion from the hindquarters during lead changes and higher velocities and longer strides at the extended canter.
REFERENCES 1. Cohen S: Tempo and the development of the paces. Dressage & C T 32(197):19-23,1989. 2. DeuelNR, Lawrence LM: Cinematographic methodology for the kinematic analysis of the canter. Proc Equine Nutr Physl Syrup 9:254-259,1983.
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3. Deuel NR, Lawrence LM: Computer-drawn gaitdiagrams. J Equine Vet Sci 4(5):228-229,1984. 4. Deuel NR, Lawrence LM: Gallop velocity and limb contact variables of Quarter Horses. JEquine VetSci 6(3):143-147,1986. 5. Deuel NR, Lawrence LM: Kinematics of the equine transverse gallop. J Equine Vet Sci 7(6):375-382,1987. 6. Deuel NR, Lawrence LM: Individual variation in the Quarter Horse gallop. Equine Exer Physio/, ICEEP Publications, Edwards Brothers, Inc., Ann Arbor MI, 2:567-574,1987. 7. Deuel NR, Lawrence LM: Laterality in the gallop gait of horses. J Biomech 20(6):645-649,1987. 8. Deuel NR, Park J: The gait patterns of Olympic dressage horses./ntl J Spts Biomech 6(2):198-226,1990. 9. Drevemo S, Dalin G, Fredricson I, Hjerten G: The analysis of linear and temporal stride characteristics of trotting Standardbreds. Equine Vet J 12(2):60-65,1980. 10. Drevemo S, Fredricson I, Dalin G, Bjome K: The analysis of coordination between limbs of trotting Standardbreds. Equine Vet
J 12(2):66-70,1980. 11. Drevemo S, Dalin G, Fredrioson I, Bjorne K: The reproducibilityof gait in Standardbred trotters. Equine VetJ 12(2)71-73,1980. 12. Hildebrand M: Analysis of asymmetrical gaits. Am Zoo/ 20:131-156,1977. 13. Jackson N: Effective Horsemanship. p 328,1967. Arco Publ. Co., NY. 14. Leach DH, Dagg AI: A review of research on equine locomotion and biomechanics. Equine Vet J 15(2):93-102,1983. 15. Leach DH, Ormrod K, Clayton HM: Stride characteristics of horses competing in Grand Prixjumping. Am J VetRes 45(5):888892,1984. 16. Podhajsky A: The Complete Training of Horse and Rider, Doubleday and Co., Inc., Garden City, NY, p 287,1967. 17. SAS: SAS User's Guide: Statistics, Version 5 Edition. Cary, NC, SAS Institute Inc., pp.763-774,1985.
EFFECT OF INSEMINATION VOLUME ON EMBRYO RECOVERY IN MARES H. S. Rowley, MS; E. L. Squires, PhD; B. W. Pickett, PhD
SUMMARY
The objective of this study was to determine the effect of insemination volumes on embryo recovery in mares. Sixty-twolight-horse mares were randomly assigned to 1 of 3 insemination treatments as they exhibited estrus. Mares were artificially inseminated with 100 x l& progressively motile spermatozoa (pms) extended in 10, 100 or200 ml of dried skim milk extender (E-Z Mixin). Embryo-recovery attempts were performed 6 or 7 days post-ovulation. 6 Due Authors'address:AnimalReproductionLaboratory,ColoradoStateUniversity, Fort Collins,CO 80523. Supported in part by the AmericanQuarter Horse Associationand Abney Foundation.
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to recovery of a low number of embryos, a second experiment was conducted with the same mares using a greater number of progressively motile spermatozoa (250 x 106 pms) suspended in either 10 or 100 ml of E-Z Mixin extender. In Experiment 1, there was no difference(P>0.05) in numbers of embryos recovered between mares inseminated with 10 (40%) and 100 ml (10.0%) of extender, nor was there a difference (1:'>0.05) between mares inseminated with 100 (10.0%) and 200 ml (0.0%). However, there was a significant difference in embryos recovered between mares inseminated with 10 (40.0%) and 200 ml (0.0%) (P<0.001). In Experiment 2, there was a highly significant difference between mares inseminated with 10 ml (70.6%) compared to 100 ml (13.0%) of extender (P<0.0005). Itwas concluded that insemination volumes of 100 ml or 200 ml were associated with lower fertility than with a 10 mI
EQUINE VETERINARY SCIENCE
CANTER LEADCHANGEKINEMATICSOF SUPERIOROLYMPICDRESSAGEHORSES N. R. Deuel, ~PhD; J. Park,2 PhD
study provided the first objective documentation of the canter limb contact patterns ofworld-class dressage horses. SUMMARY
Limb contact variables of the gaits of superior dressage horses were determined for competitors at the 1988 Seoul Summer Olympic Games in the finals of the Individual Dressage competition. Two 16-mm motion picture cameras were aimed perpendicular to the plane of motion along the HXF and KXM diagonals of the standard dressage arena, and filmed at 100 fps. Nineteen of the horses selected as finalists for individual dressage medals were filmed during the Grand Prix Special test executing one-stride canter lead changes, two-stride canter lead changes and the left lead extended canter. Velocities, stride lengths and stride durations were 7.03+.07 m/s, 4.15+.05 m and .592+.004 s for the extended canter. Across all stride frequencies, score was optimized with extended canter slrides of the greatest length, with no upper limit detected to optimal stride length. Canter strides with lead changes had lower velocities, shorter strides and longer durations than strides without a lead change, with velocities, stride lengths and stride durations, respectively, of 3.36+.05 m/s, 2.08+.04 m and .617+.003 s for one-stride canter lead change strides; 3.65+.07 m/s, 2.21+.04 m and .605+.003 s for pre-change canter two-stride lead change strides; and 3.95+.07 m/s, 2.44+.04 m and .621+.004 s for post-change canter two-stride lead change strides. This Authors' addresses. 1Department of Animal Nutritional Sciences, Kendall Hall, University of New Hampshire, Durham, NH 03824 USA; 2Department of Physical Education, Pusan Sanub University, Taeyun-dong, Nam-gu, Pusan, Korea 608. Acknowledgements:The authors would like to express their appreciation to Dr. Inseong Hwang of Yonsei University, Seoul, Korea, for coordinating this project, which was sponsored by the Medical Commission of the International Olympic Committee, and received corporate sponsorship from Eastman Kodak Company and Redlake Corporation. Thanks are also extended to the staffs of the Federation Equestre Intemationaleand the Seoul Equestrian Park for their cooperation. We are grateful to Ms. Vinsel, Mr. Lee, Mr. Kim and the many other individuals that provided on-site assistance with filming and videotaping. The first author would also like to thank Dr. W. Condon and Dr. R. Strout for their support of this project.
Volume 10, Number 4 1990
INTRODUCTION
Many excellent texts have discussed the practical aspects of gait characteristics desirable in a dressage horse.13,1~ However, there has been little scientific documentation of the gait characteristics of successful dressage horses, and particularly little objective study of the kinematics of world-class dressage competitors. The biomechanics of the locomotion of competitive athletic horses have been studied most extensively in the Standardbred racehorse ~11 and to a much lesser extent in Thoroughbred racehorses TMand jumpers.~SHowever, there have been few other objective studies of the gait kinematics of riding horses. Dressage horses receive the most lengthy training of any type of riding horse; typically a minimum of seven years of training before entering toplevel competition. Because of these extensive training procedures, Olympic dressage individual medal finalists have motion patterns that are the most highly developed of all riding horses. There is a paucity of research literature pertaining to the kinematics of the equine canter 2 and none of that concerns the canter of world-class dressage horses. Furthermore, little is known about the complex motion patterns that occur as a horse executing the transverse canter or gallop changes from one lead to the other) 4 The purposes of this study were to document the kinematics of the limb contact phases of the canter exhibited by superior dressage horses competing at the 1988 Seoul Summer Olympics Games, and to determine the limb contact patterns typical of their canter lead changes. A final objective was to associate alterations in certain limb contact variables of each gait pattern with dressage scores in
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Table 1. Canter stride limb contact variables of superior Olympic dressage horses. 1 Score
Horse
Nation
Variable
2-Stride lead changes Pre-change Post-change mean mean
1-Stride Changes mean
Extended mean
1521
Rembrandt 24
FRG
Vel (m/s) SL (m) Freq (s~)
3.9 2.3 1.7
4.0 2.6 1.6
3.5 2.2 1.6
8.9 5.2 1.7
1462
Corlandus
FRA
Vel (m/s) SL (m) Freq (s-~)
4.0 2.6 1.6
4.2 2.7 1.5
3.1 2.0 1.6
6.8 4.3 1.6
1417
Gaugin de Lully
SUI
Vel (m/s) SL (m) Freq (s ~)
----
----
3.5 2.2 1.6
---
3.1 1.8 1.7
3.4 2.1 1.6
3.2 2.0 1.6
6.4 3.9 1.6
3.5 2.2 1.6
--
1401
Dynasty
CAN
Vel (m/s) SL (m) Freq (st)
1393
Matador
FIN
Vel (m/s) SL (m) Freq (s -1)
--
--
-
-
-
-
-
-
-
-
--
-
1385
Ganimedes
FRG
Vel (m/s) SL (m) Freq (s-1)
3.7 2.4 1.6
4.3 2.6 1.6
3.7 2.2 1.7
6.6 4.2 1.6
1383
Andiamo
SUI
Vel (m/s) SL (m) Freq (s1)
3.5 2.1 1.6
3.8 2.2 1.7
3.3 2.0 1.7
6.1 3.5 1.7
1374
Courage 10
FRG
Vel (m/s) SL (m) Freq (s"1)
----
----
3.5 2.1 1.6
m
1354
Dixon
URS
Vel (m/s) SL (m) Freq (s-1)
4.1 2.3 1.8
4.6 2.5 1.8
----
7ol 3.9 1.8
1349
Pascal
KOR
Vel (m/s) SL (m) Freq (s-~)
3.4 2.0 1.7
3.9 2.2 1.7
3.4 1.9 1.7
7.2 4.1 1.7
1330
Random
SUI
Vel (m/s) SL (m) Freq (s1)
3.3 2.2 1.5
3.6 2.4 1.5
3.4 2.2 1,5
6.7 4.1 1.6
1326
Malte
CAN
Vel (m/s) SL (m) Freq (s ~)
3.4 2.1 1.6
3.8 2.3 1.6
----
6.7 4.2 1.6
1320
Federleicht
USA
Vel (m/s) SL (m) Freq (s1)
3.9 2.5 1.6
4.3 2.8 1.6
3.6 2.3 1.5
6.9 4.2 1.7
1304
Dutch Gold
GBR
Vel (m/s) SL (m) Freq (s1)
3.8 2.2 1.7
3.9 2.4 1.7
----
7,2 4.0
288
1.8
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Table 1 (continued) Score
Horse
Nation
Variable
2-Stride lead changes
Pre-change mean
Post-change mean
1-Stride
Changes mean
Extended mean
1297
Petit Prince
HOL
Vel (m/s) SL (m) Freq (s~)
3.8 2.1 1.8
4.0 2.5 1.6
3.2 1.9 1.7
7.0 4.0 1.7
1296
Reipo
CAN
Vel (m/s) SL (m) Freq (s 1)
3.8 2.3 1.7
4.1 2.6 1.6
3.2 2.1 1.6
6.9 4.3 1.6
1282
Orpheus
USA
Vel (m/s) SL (m) Freq (s~)
3.5 2,1 1.7
3.7 2.3 1.6
----
7.2 4.2 1.7
1280
Cantat
DEN
Vel (m/s) SL (m) Freq (s~)
3.7 2.3 1.6
4.1 2.6 1.6
----
7.0 4.3 1.6
1267
Amen 5
HOL
Vel (m/s) SL (m) Freq (s-~)
3,2 2.0 1.6
3.4 2.1 1.6
----
6.6 3.9 1.7
• ~Values are mean velocities (Vel) measured for 2 to 3 strides in m/s (SE range .02 to .29; LSD=.29), stride lengths (SL) in m (SE range .01 to .14; LSD=.16) and stride frequencies (Freq) in strides/s (SE range .01 to .06; LSD=.05). Missing data are signified by --.
world-class dressage competition. This study of equine gaits will be confined to velocities, stride lengths, Step lengths and temporal variables delimited by limb impacts and liftoffs, since these represent the summary result of all rotational and translational motions of body limb segments through the stride cycle.
MATERIALS
AND METHODS
Measurements of limb contact variables were made for the canter of dressage horses competing at the 1988 Seoul Summer Olympic Games. All horses were filmed while executing prescribed movements with a 16-mm high-speed motion picture careers (100 fps), aimedperpendicular to the plane of horse motion along the F I X and KXM diagonals of a standard 20m x 60m dressage arena (Figure 1). Nineteen horses selected as contenders for individual dressage medals (finalists) were filmed during completion of the 7.5rain Grand Prix Special dressage test on September 27, 1988 while executing movement 19, two-stride canter lead changes; movement 20, one-stride canter lead changes, and movement 21, extended canter (left lead). The cameras" field of view was 14 to 15 m. Some of the film sequence data were missed (Table 1) due to camera operator error and in Volume 10, Number 4 1990
one case, failure of the horse to execute the prescribed lead changes. The centermost strides in the film frame were analyzed per sequence. It should be noted that the horse and rider always compete as a team in Olympic equestrian events and it was therefore impossible to differentiate the effects of specific riders on horse performance in this study. Limb contact timing variables were measured from frame-by-frame analysis of projected film images of limb impacts and liftoffs, utilizing previously established methods and nomenclatureY Linear distances were calculated from conversions of projected image distances utilizing a reference meterstick filmed in the plane of motion. Frame rates were determined from marks on film made at 10 msec intervals by the cameras' internal timing light generators. Stride lengths were determined by fdm image linear measurements between successive impact locations of the toe of the hind trailing limb, and step lengths between toe locations at successive hoof impacts. Interrelationships between scores, velocity, stride length and stride frequency were examined for each gait pattern by means of linear regression analysis. Limb contact data were subjected to multiple linear regression analyses of variance 17 to determine the effect of the individual horse on stride limb contact timing patterns. Total Grand Prix Special dressage test score was also included in multiple linear regression analy289
~~~ ~ ~ '
EquineNutritionandPhysiologySociety ~
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DRESSAGE ARENA EXTENDED CANTER OLYMPIC DRESSAGE FINALISTS
A
TOTAL SCORE
1.80"
F-i 1412. F_
1.75"
I~
126114t2
>0
1,o,-
g ,to.
~1
<1'09
~W 1.65,
1261
R2 = .71
bJ
P <.0001
Ito
~ 1.60' I.$5'
p. Figure 2. Contour plot of the response surface relating extended canter stride frequency (s-l) and stride length (m)
B_
"E 6 0 m J f
M.
C <
20m
>
Figure 1. Standard dressage arena utilized for Olympic competition, with locations of cameras 1 and 2 depicted with focal axes perpendicular to planes of equestrian motion. The center of the arena is designated location X, so motion along the diagonals is described as along FXH or HXF (illmed by camera1 ) or along MXK or KXM (filmed by cam era 2).
290
ses to determine possible relationships between canter stride variables and score (total of five judges' subjective marks). 8 It should be noted that all comparisons of stride limb contact temporal and linear measurements were made on the basis of standardized (average) stride frequencies, stride lengths and scores. If the relationship between a stride variable and score was significant in the multiple linear regression model (on a standard-velocity basis), simple linear regression was employed to determine the equation relating the two variables for each movement (which may incorporate velocity effects). For the extended canter, linear and quadratic functions of stride length and stride frequency were associated with score as a response surface (RSREG procedure) ~7 to identify optimal combinations of those stride variables. It is important to point out that the horses involved in this study belonged to a relatively homogeneous group of superior athletes selected in world-class competition. The discriminations determined in dressage scores are between the world' s best and the nearly-best. The relationships documented for this group may not hold for horses of lesser abilities. The R z values represent the proportion of variability in one characteristic that can be associated with variability in another, with no cause-and-effect relationship necessarily implied. Due to the homogeneity of the population, statistically significant relationships found in this study should be considered meaningful for world-class competitors, even though some R z values may appear low at first inspection. One might expect higher R z values from a more heterogeneous population that included horses of all ability
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Table
2.
Limb contact linear variables of canter strides of superior Olympic dressage horses.
Variable
N strides Velocity (m/s) Stride length (m)
2-Stride lead changes Pre-change Post-change
1-Stride Changes
Extended
SD
32 3.65" 2.21"
31 3.95b 2.44b
51 3.36¢ 2.08=
40 7.03d 4.15d
.36 .24
Hindstep HT-->HL (m) (%)
.87" 40.7'b
.88" 37.4 ~
.94" 49.7"
1.13b 28.1b
.15 33.2
Midstep HL-->FT (m) (%)
.97'~ 45.7"
.93" 39.7b
.97= 47.6"
1.00b 24.7=
.11 11.6
Forestep FT-->FL (m) (%)
.79" 37.1"
.89 b 37.9"
.80" 39.6"
1.13= 28.1 b
.07 11.
-.33b
-.53° -26.1,
Hoof impact distances~,z
Airbome ste~ FL-->HT(m) (%)
-.47" -22.7 a
-14.7 ab
.78d 19.1=
.11 7.6
'Arithmeticmeans. 2Abbreviationsare H=hind,F=fore, L=lead,T=trail. 3Positivevalues indicate that the hind trailing limb impact overstepped the fore leading limb impact of the previous stride in the plane of motion.
levels. Combinations of temporal and linear variables associated with high scores for the canter were also determined by stepwise multiple regression, using the maximum R z improvement method with a P<.15 level for inclusion in the model and P>. 15 level for deletion. 15,17Models selected and presented herein are those in which the number of variables most closely approaches the Cp statistic. 17 Judges' scores for the individual dressage movements were requested but unfortunately unavailable. In the Grand Prix Special Test, the percentage of the total score related to the judges' subjective impressions of the walk is 7.3%; trot, 45.1%; canter, 28.1%; collective marks on paces, impulsion and submission, 14.6%; and rider position and use of aids, 4.9%? For canter movements, the percentage accorded in the total score for the extended canter is 2.4%; for singlestride lead changes, 4.9 %, and for double-stride lead changes, 2.4%. s Therefore any statistically significant R 2 value exceeding .05 may indicate akinematic variable more strongly associated with judges" scores than one might anticipate by the scoresheet values accorded to that movement.
RESULTS AND DISCUSSION
Total score for Grand Prix Special dressage tests averages 1354+11 points, out of a theoretical perfect score of Volume 10, Number 4 1990
2050 points. The top scoring horse-rider team was Rembrandt 24 ridden by Nicole Uphoff of the Federal Republic of Germany, receiving 1521 points. Every canter stride variable measured was found to differ (P<.05) between horses, and therefore the limb contact characteristics were highly individualized features of the canter stride, just as they are in the gallop gait. 6 For each horse, velocities, stride lengths and stride frequencies for each canter movement (extended, onestride lead changes, two-stride lead change pre-change, two-stride lead change post-change) are provided in Table 1. Overall, higher scores were associated with higher velocities (P<.004), longer stride lengths (P<.0001), but had no significant relationship with stride frequency. This may be interpreted to mean that in canter work of superior dressage horses, high velocities and long strides are judged favorably while stride frequencies have relatively little effect on the score. Most notable were stride lengths as long as 5.2 m (17 feet) demonstrated by the gold medalist Rembrandt 24 in the extended canter, while in executing the same movement four of the finalists had stride lengths of 3.9 m (13 feet) or less. Linear measurements for each canter movement are provided in Table 2, while temporal measurements are presented in Table 3. In Table 4, simple linear regression equations are presented relating total Grand Prix Special dressage score with stride variables for each canter movement.
291
,:~;~.
~ EquineNutritionandPhysiologySociety
EXTENDED CANTER STRIDE
ONE-STRIDE CANTER LEAD CHANGE HL+FT+FL
HL+FL
.101=16.8 %
.014 =2.41% IlL+ FT + FL • FL . , , , ~ ~ . 0 4 1 =6.9 % .120 20.2 % y ~ HL+ FT 76=12.7%
FT+FL ~
~
.006"1.2~
.I27-=21.5r*/~"/
HL+FT
~ 6 = 2 . 6
%
HT+HL+FT I I3 =18.9%
"~
HT+HL+FT
.046= 7.8 %
I
HT+FT .010 = 1.7% AIRBORNE .098:16.4%
.117=19.6 %
~ \ \ \ \ ~ . _ HT+HL 7-.027=4.4%
~
HT .111-|8.5%
Figure 3. Pie gait diagrams of cyclic limb contact phases of the exte~Ided canter stride and one-stride canter lead change stride of superior Olympic dressage horses, standardized to similar stride durations. Label values indicate for each limb contact phase the duration of the phase (s) and the proportion of the entire stride (%). Limb contacts, depicted counter-clockwise in time: H=hind, F--fore, L=lead, T=trail. Shaded segments represent canter stride phases that differ significantly between movements. CANTER
LEAD
CHANGE
PRE-CHANGESTRIDE HL+FT+FL HL+FL ~
.,o5-,.4~
.102:16.8% HL÷FT /~o9 • 3.,'/,
FL i111111/~\
//
POST-CHANGE STRIDE HL+FT+FL HL+FL .095-.15.7 % .022=5.6~ ~ - ' - " " . ~
HL~F2"r "
3.7"/.
\ HT÷HL÷FT .138=22.7~.
yt.ff,/.~JJJJJ.~jI AIRBORNE, ¢ ' ~ J / / ~
1o,.1,,,,
'"¢~\\~L HT+ FT " ~ .019=3.1%
/
A ~"
;',":;B 5,,
112-18.4%
~JJJZT~J
A,R8ORNE
.095 • 15.6%
~,~F,~ HT+ HL
/
O,B-2,,,
.106-17.5 %
Figure 4. Pie gait diagrams of limb contact phases of two-stride canter lead change strides for pre-change and post-change canter strides of superior Olympic dressage horses, standardized to similar stride durations. Label values indicate for each limb contact phase the duration of the phase (s) and the proportion of the entire stride (%). Limb contacts, depicted counterclockwise in time: H=hind, F=fore, L--lead, T=trail. Shaded segments represent canter stride phases that differ significantly between movements. It should be noted that all canter lead changes filmed were executed first by the hindlimbs and then by the forelimbs. All strides observed were those of the transverse canter,2,s although horses are capable of switching leads only in the forelimbs, and thereby executing rotary canter strides. 12 Over all canter strides, statistically significant but weak relationships were detected between score and stride kinematic variables (Table 4). Score was positively related to midstep length, hind lead unipedal contact, fore trail unipedal contact, hind trail-hind lead bipedal contact, and 292
quadrupedal contact. The extended canter stride
Velocities of the extended canter averages 7.03+0.7 m/ s (mean~.+SE)or 422 m/min, with stride lengths averaging 4.15+.05 m and stride durations of .592+.004 s. The extended canter had a tempo of 101 strides/min, slightly faster than the 96 strides/min cited for dressage canter work. 1 Velocities of the extended canter were higher than when lead changes were executed, resulting from both longer strides and higher stride frequencies. For the extended EQUINE VETERINARY SCIENCE
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canter, (velocity) =1.42 + 1.34 (stride length) (R~.63,P<.0001). The creation of a response surface from the effects of extended canter stride frequency and stride length yielded an optimization contour plot (Figure 2). Score was optimized with the longest stride lengths, in the scoring range of the three individual medalists. There was no upper limit detected for optimal stride length, across all stride frequencies. The lowest scoring horses had stride frequencies above 1.58 s-I and the shortest strides. The longer stride of the extended canter in comparison with lead change strides was due primarily to greater distances between hindlimb impacts and between forelimb impacts, and also the result of the hind trailing limb impact overstepping the location of the previous fore leading limb impact. This made each step length of the extended canter a smaller proportion of total stride length than in lead change strides, although each distance between successive limb impacts was greater in absolute magnitude. The most common support sequence for extended canter strides (48% of strides) was 1) hind trail unipedal, 2) hind trail-fore trail bipedal, 3) hind trail-hind lead-fore trail tripedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) hind lead-fore lead bipedal, 7) fore lead unipedal, and 8) airborne phase. ~ On the average, impacts of the hind leading limb and fore trailing limb were nearly simultaneous in the extended canter. Fewer than 5% of extended canter strides had limb contact sequences typical of the gallop gait, that is, with a hind trail-hind lead bipedal contact, a unipedal hind lead contact, a unipedal fore trail contact and a fore trail-fore lead contact.8 Therefore, virtually all strides filmed were those of a true extended canter. For step lengths of the extended canter, forestep length had the strongest positive relationship with score, while hindstep length and midstep length were also both positively related to score. Other single extended canter stride variables with significant relationships with higher scores were longer hind lead unipedal contacts, longer fore trail unipedal contacts and shorter fore tripedal contacts. Stepwise multiple regression (R~.90,P<.0001) revealed a combination of 11 stride temporal ariables associated with higher scores: longer hind lead limb contacts, shorter fore lead limb contacts, shorter hind trail non-contact durations, longer intervals between impacts of hind lead and fore trail limbs, smaller ratios of hind lead contact to total hind contacts, greater ratios of fore lead contact to total fore
Volume 10, Number 4 1990
contacts, greater ratios of fore contacts to hind contacts, longer unipedal contacts of the hind lead limb, shorter fore tripedal contacts, shorter simultaneous support by the hind trail and hind lead, and longer airborne durations. Stepwise multiple regression of linear measurements revealed a combination of five variables associated (P<.0001; RL--.56) with higher scores: increased midstep and airborne step lengths, decreased forestep lengths, decreased proportions of midsteps, and increased proportions of foresteps in the total stride. The practical interpretation of these findings in that the higher-seoring horses demonstrated extended canter strides with relatively high velocities and long strides while maintaining a nearly constant tempo, decreasing the time in which the limbs were in ground contact, utilizing their limbs more asynchronously in support, increasing the time and distance between hindlimb and forelimb contacts, and increasing the airborne time and distance.
Extended canter st rides versus canter lead change strides In comparison with extended canter strides, strides of horses executing lead changes, had on the average velocities 52% as fast (averaging approximately 3.65 m/s or 219 m/min), with stride lengths 54% as long, while maintaining stride frequencies at 96% of extended canter levels (Tables 2 and 3). The difference in the stride lengths was the result of shorter steps between the hindlimbs (79% of extended canter hindstep), shorter steps between the forelimbs (73% of extended canter forestep), and also the hind trail limb impact failing to overstep the imprint of the fore leading limb from the previous stride. On the average, during lead change strides the impact of the hind trailing limb fell .44 m short of the imprint of the fore leading limb, while in the extended canter the impact of the hind trailing limb overstepped the imprint of the fore leading limb by .78 m. Lead change canter strides also had longer limb contact durations and shorter limb non-contact durations for all four limbs than in the extended canter stride. In addition, there were longer total contact durations and shorter airborne phases in lead change canter strides. Total bipedal contact durations, total quadrupedal contact durations, total hind contact durations and total fore contact durations were all greater in lead change canter strides than in extended canter strides. On the average, impacts of the hind leading limb and fore trailing limb were nearly simultaneous in the extended canter, but were separated by 14 to 24 msec in lead change strides.
293
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T a b l e 3 . L i m b c o n t a c t t e m p o r a l v a r i a b l e s of c a n t e r s t r i d e s of s u p e r i o r O l y m p i c d r e s s a g e h o r s e s . 2-Stride lead changes Pre-change Post-change
Variable
1-Stride Changes
Extended
SD
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!:ii~:~:;:ii i;!~!~!:~. : :::::::::::::::::::::::::
:::::::::
::::::::::::::::;:
::::::: ::::::::::::::
L i m b c o n t a c t d u r a t i o n s (s) ~ Hind trail Hind lead Fore trail Fore lead
;: ::::;: ::::: :::::i:::
:::::;:::::::::::::
:::i::::i
.240' .242" .246a .247"
i : : : ::: : : : : : : : : : : : : : : : : : : :
.240 = .2670 .232 ~ .2570
::: :::::::
:::::::::::::::
::::::::
::::::::::::::::::::::::
.253 ~ .258 ~ .241" .249 ~
:::::::::::::
::;:::::::::::
i!!!!i
:: :::: :: !:i::: i:!:!:!:i:!:::
.182 = .1870 .180 = .181 =
.017 .020 .017 .017
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i;!iiiii iii!!ii iii!iii ii!iiii~iiiiiii~iiiii ?:ii i?~i l ::i~!::ii i !::ii i ~i~i~i~i~!~:,i~i ;~i~i:~i:~i:i~::ii:?~!:::i::i::ii:~::i::i~!~::~i~ i i!~!~::i::i?:: i~ ::i::i::i::::!::i:~iiiii:,i::~!~i~i~i:: :: :::::::::::::::::::::: i ::i::iiii::iii ::iiiiiiiiiii::i:: ii i~i~i! i iii iiiii ?: i i i:: ii?:i:: i~i::::::ii~:::::~:::::i~ ::
Bipedal c o n t a c t d u r a t i o n s (s) ~,= HT +HL HT + FT HT + FL HL + FT HL + FL FT + FL Total
.004 ~ .019"
.018 ~ .003 ~
.027 ° .002 ~
.009 = .010 b
.000
.000
,000
.000
.019" .015 ~ .005' .061'
.022 a .022 a .O01a .067"
.015 ~ .0070 .014 b .066"
.076 b .014 "b .006 ~ .115 b
.016 .014 .018 .015 .010 .032
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:i:;:!:!:i:;:i:~:!:;:~i~!:i:i:i:!:i:;:i:i:~:!:;:i:i:;:i:;:;:!:!~i:i:;~!~;ii:;:;~;:~i;:i:i~;:!;iii:i:i:i;!~i:i:;:i:i:;:;:;:;:!:;:i:i:;:;:;:;:i:;:;:i:!~:::i:;~!:;:i:i:;:!:i:i:i:i:;:i~i:;:;~:~:i:i:;:!~!~i:!:i:;:i:i:;:i:i:i
Total quadrupedal contact durations (s) ~,~ HT + HL + FT + FL
.003 =
.003 =
.004 =
<.001 ~
.006
~i~i::~::i:~i~i::i~i::?~i:=~iii::i~:=~::i:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::~::::::ii~::i::::::;::i::~:::::~:::::::=i~i::::::::::::::::::::::::::i~:~i::i::ii?~i::;::?:ii;~::?:?:i::i~;~ N o n - c o n t a c t d u r a t i o n s (s) Hind trail Hind lead Fore trail Fore lead Airborne phase
.371 ~ .369' .365" .364" .107"
.371" .344 ~ .379 ~ .354 ~ .094 ~
.358 ~ .352 ~ .370" .362" .098 '~
.428 ¢ .424 ¢ .431 ° .430 ° .170 ¢
.017 .020 .017 .018 .021
:~i~i:i ~i ~i:i~i~:~i~i~:~:~ii~i~:~i~:~ii~:~i~i~:~:~i~i ~i~::~:~:~::~i~i`;~;~i ~:i:~i~~:ii~i:i~:~ii ~i%~ ~i~:i:i:::%::~%~i~!~:::::::~i~;~:~:::::i::::::i ~i~!~:::~i i:::;:::::i~i:MJ~::i::i:::::::::i :i:::iii:~i:::iii::::::iii:~iiii!:ii!?:iiiiiii!i i::, .i:~ii!;iiiii;i:iiiiiiii .i.i i.i.i.i.i;;`~.;.ii;i~`;.;.ii;~!i.i.i ;i~i .i.i`i;;i~.i.i.;~;i~.i.i.;~;.~`~.i~;`;`i.~.~!.;~::;.i1.i.:i:~::::~:.:m:i:::ii:i i:::~::iii:::~ii ~ : : i i i ::~::::i~:
.. :~':':
::::iiiii iii~:iiiiii::iiiiii ::iii:::ji ::iiiiiii i iiiiiiiii::i!::iii::iiiiiii::::iiiiiii~~~iiiiiiiiiiiiiiiiiiiiiii ii~ ~1~iiiiiii i::!iiiiiiiii ::iiiiiiiiiii::iii~::~iiiii!::ii!iiiii!ii ii::iiiii iiiiiiiiiiiii!iiiiiiiiiii::ii!iiiiiii!ii!i~i~i.2:i!..::::~iiiiii::i::i::iiiii!::i::iiii!ii!::iiiiiiii::!iiiiiiiiii!ii!ii::iiiiii::: : ~ i :.
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:
:::::::::::::::::::::::::::::::
:" :.. " : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : :
"
::::::::::::::::::::::::::::::::::::::::::::::::
-
:' :~
Contact ratios (s:s) Hind lead: total hind Fore lead: total fore Total fore: total hind
.648" .641 • 1,040 ~
.708 ~ .655 "~ 1.045"
.695 ~ .664 b 1.014 ~
.595 ° .575 ~ 1.005 ~
.048 .037 .063
~Leastsquare means standardized according to the average stride frequency (1.64 s-l), lead and score. Values without common superscripts within a row are different (P<.05). 2Abbreviations are H=hind, F=fore, L=lead, T=trail.
294
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Equine Nutrition and Physiology Society REFEREEDPAPERSFROMTHE 11THSYMPOSIUM
Table 4 , S i m p l e linear regression e q u a t i o n s relating total d r e s s a g e score with canter stride variables? : : :: : : : :[: :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: :: : :: : ::: : :: : : : : : : :: : : : ::: :; ; :: : : : : :.:.:.: :.:: : :: :.:.:.:.:.:.:.:,:.:.:.:. ~:.'.:.:.:~" :.:.:.:.:.:.:.:~:,:.:...:.:.:.:.:.:.,..:..:+:.:
..........
: ......................................
...., .......
...................,...................................
iii~iiiiii~iiiiiiiiiii!i~ii~ii~iiiiiiiiiiii~iii~i~i~i~i~i~i~i~i~i~iiiiiiiiiii!!iiiiiiiiiiiiiiiiiiiiiiiiii;iiiiiii~iiii~ii~iii~iiiiiiiiiiii~i~i~i~h~iiiiiiiii~i~i~i~iiiiiiii~i~i~iiiiii~iiiiiiii~ii~iii~i~!~iiiiii~i~!i~iiiii ~i~;i~;~;i;;~;~;~;~i~iiiiii;~iiiiii~iil;iii!iiiiiiiiiii~ii;ziiii!!i;iiiiiiiiiiiiii;!;~iiiiii ::i::il;i;ii:::::::::::iii::::::::::::iii::::::::i:::::::::::::::::::::::::::::: i::i::i::::i:::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::: ::i::::::::::::::::::::::::::::::::::::::::::: All canter strides Score = 1221 + 143 Score = 1354 + 16684 Score = 1354 + 9998 Score = 1341 + 959
~Midstep (m) HL unipedal contact (s) "FT unipedal contact (s) "HT + HL bipedal contact (s)
.07 .08 .07 .08
iii:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: iiiiiiiii ii i ii ii ! i iii ii ii!iiiiiiiiiiiiii i i i i i iiiiiiiii;i i i i i ii ii iiii!i i i ii ! ii i T TiiT i iii iii ii iiiiii i i i iiiiii i i iii i i iiiiiii;i :::: iiii iiiii! !iiii ii i i !i i i iiiiiiiiii ii!!ii !!i!i!i!!!i i i i!i iiiiiiiiiiiiiiiiiiii!iiiiiiiiiiiii!i!! !iiiiiiiiiii!! !ii Two-stride canter lead change post-change strides Score = 1107 + Score = 1401 +
257 167
:Midstep (m) Airborne step (m)
.14 .13
:::::::::::::::::::::::: ::~ ~i~::ii :::::tiL~i i~:::::::::::::::: i11::~§:::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::::::::: i::::::i::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: :::::: :::::::::::::::::::::::::: i::!ii::;::i i?::i::i::i::)::i ::i::ii::i:i:iii::i::iNi ::i::i:: ~N ~~ ~::)~N ~::::i ~i i}::i::i::!::iiiii::i::ii!::)!i!!:~ilil i::ii ::):: ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: i':ii?i::?:}i :: iiii)::i::i::iiii ilil;iN?:}i?ii::)ii::iii!ii!! iiii iii::)i)::iiiiil i::ii) Extended canter strides Score = 1051 + 42.1 Score = 966 + 91.4 Score = 1000 + 304 Score = 1190 + 154 Score = 797 + 485 Score = 1326 + 19486 Score = 1327 + 11636 Score = 1414 - 2004
~Velocity (m/s) Stride length (m) ~Hindstep (m) Midstep (m) ~Forestep (m) H L unipedal contact (s) FT unipedal contact (s) "HL+FT+FL tripedal contact (s)
.13 .20 .14 .11 .36 .42 .37 .18
1All equations listedare significantat P<.05. Abbreviations are H=hind, F=fore, L=lead, T=trail.
For all strides involving lead changes, velocities, stride lengths and stride frequencies were not significantly related to scores. T w o - s t r i d e canter lead c h a n g e s : strides versus post-change strides
pre-change
In comparison with canter strides following a lead change, canter strides preceding a lead change had velocities 8% slower, stride lengths 9% shorter and stride durations 3% shorter (even though ranges of stride durations were similar). The difference in stride lengths were due to 10 cm shorter step between the forelimbs and advancing forward 14 cm less in the airborne step in strides preceding a lead change than in strides following a lead change. For two-stride lead change sequences, slride length and velocity were related such that, for the pre-change stride, (velocity)=.525 + 1.38 (stride length) (RZ=.68,P<.0001); and for Volume 10, Number 4 1990
the post-change stride (velocity)=.525 + 1.40 (slride length) (RZ=.70,P<.0001). Stride durations were similar for post-change twostride lead change strides and one-stride canter lead change strides, each with a tempo of 97 strides/min, but pre-change two-stride lead change strides were of a shorter (P<.05) duration with a tempo of 99 strides/min. These values are similar to the tempo of 96 strides/rain cited for dressage canter work? S iridespreceding a lead change displayed shorter limb contact durations for the hind lead limb, fore vail limb and fore lead hmb. They also had longer non-contact durations for the hind lead limb and the fore lead limb, but shorter contact durations for the fore traillimb. In addition, strides preceding a lead change had shorter fore lead unipedal con tacts, shorter hind trail -hind lead bipedal contacts, longer hind trail-fore trail bipedal contacts, shorter total contact 295
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REFEREEDPAPERS FROMTHE 11TH SYMPOSIUM
durations and longer airborne durations, as well as longer intervals between impacts of the hindlimbs and lower ratios of hind lead contact to total hind contacts. The most common support sequence for canter strides immediately preceding a lead change (31% of strides) was the same as reported for the extended canter, s The most common support sequence for canter strides immediately following a lead change (48% of strides) was 1) hind trail unipedal, 2) hind trail-hind lead bipedal, 3) hind trail-hind lead-fore trail tripedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) hind lead-fore lead bipedal, 7) fore lead unipedal, and 8) airborne phase, s The most pronounced difference between the limb contact patterns was that strides preceding lead changes predominantly had the impact of the fore wail limb occur before the impact of the hind lead limb, but in strides following lead changes the hind lead limb impacted before the fore trail limb. Canter strides preceding lead changes had a wide variety of limb contact patterns toward the end of the contact phase, with 31% of strides having a fore trailfore lead bipedal contact phase, 19% of strides having simultaneous litioff of the hind lead limb and fore trail limb, and 50% of strides having a hind lead-fore trail contact phase, s On the other hand, strides following lead changes showed almost an exclusive reliance upon lateral support by the hind lead and fore lead legs towards the end of the contact phase. Single variables of the pre-change canter stride that were significantly related to higher scores were longer midstep lengths, shorter fore trail unipedal contact, longer hind wail-hind lead bipedal contact, and longer fore trail non-contact durations. Stepwise multiple regression (RZ=A4, P<.05) revealed a combination of 7 temporal variables of the pre-change canter stride that was associated with the highest scores: shorter fore trail contacts, shorter impact intervals between fore lead and hind trail limbs, longer hind trail unipedal contacts, longer bipedal contacts of the hind wail and hind lead, longer bipedal contacts of the hind lead and fore lead, longer hind tripedal contacts, and shorter quadrupedal contacts. Stepwise multiple regression of linear measurements revealed a combination of five variables associated (P<.004; R2=.44) with higher scores: increased midstep and airborne step lengths, decreased forestep lengths, and decreased proportions ofmidsteps and airborne steps in the total stride. This may be interpreted to mean that preceding a lead change, the higher-scoring horses increased their contact durations of the hindlimbs and decreased the length of step and time between forelimb 296
impacts to prepare to execute the lead change in the succeeding airbome phase. Single variables of the post-change canter stride that were significantly related to higher scores were increased midstep length and increased airborne step length. Stepwise multiple regression (RZ=.38,P<.05) revealed a combination of 5 temporal variables of the post-change canter stride that was associated with the highest scores: longer impact intervals between hindlimbs, shorter impact intervals between forelimbs, longer bipedal contacts of the fore trail and fore lead, longer quadrupedal contacts and longer total tripedal contacts. Stepwise multiple regression of linear measurements revealed a combination of seven variables associated (P<.007; RZ=.52) with higher scores: decreased stride lengths and forestep lengths, increased hindstep and midstep lengths, and decreased proportions of hindsteps and foresteps in the total stride. These findings may be interpreted to mean that higher-scoring horses demonstrated a greater degree of collection as they recovered from the lead change, with shortened strides and relatively greater tripedal contacts and quadrupedal contacts.
One-stride lead change canter strides versus twostride lead change canter strides In comparison with strides of horses executing twostride lead changes, strides completed while executing onestride lead changes had velocities 12% slower, stride lengths 7% shorter, but stride durations similar to post-change twostride canter lead change strides. The difference in stride length was accounted for primarily by a forward advancement during the airborne phase averaging 13 cm less in single stride lead changes. For one-stride canter lead changes, stride length and velocity were related such that (velocity)=l.29 + 1.00 (stride length) (RZ=-.53, P<.0001), and (stride duration)=.380 + .115 (stride length) (RZ=.31,P<.0001). Single lead change strides in comparison with twostride lead change strides had shorter hind trail limb contact durations, and longer hind trail limb non-contact durations. In addition, one-stride lead changes involved longer hind trail-hind lead bipedal contact durations, shorter hind leadfore lead bipedal contact durations, longer fore trail-fore lead bipedal contact durations, and shorter intervals between forelimb impacts than did strides involving twostride lead changes. The limb support sequences of single-stride changes showed a fair degree of variability in technique. The most common support sequence for one-stride lead change canEQUINE VETERINARY SCIENCE
EquineNutritionandPhysiology Society~ ~~~~ ter strides (29% of strides) was 1) hind trail unipedal, 2) hind trail-hind lead bipedal, 3) hind trail-hind lead-fore trail tripedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) fore trail-fore lead bipedal, 7) fore lead unipedal and 8) airborne phase, s The second most common support sequence for one-stride lead change canter strides (24% of strides) was 1) hind trail unipedal, 2) hind trail-hind lead bipedal, 3) hind trail-hind lead-fore trail nipedal, 4) hind lead-fore trail bipedal, 5) hind lead-fore trail-fore lead tripedal, 6) hind lead-fore lead bipedal, 7) fore lead unipedal and 8) airborne phase. 8 One stride canter lead changes showed a pronounced reliance upon simultaneous contact by the two hindlimbs at the initiation of support and a simultaneous contact by the two forelimbs near the termination of support. Thus, the contact phases of the strides were initiated quite similar to strides following a two-stride lead change, but the strides were terminated with the most pronouned emphasis on bipedal forelimb contact of any of the canter strides filmed, similar to the limb contact pattern at the completion of gallop strides. Several kinematic variables of single lead change strides had significant relationships with score. Higher scores were associated with shorter fore trail contacts, shorter hind tripedal contacts, shorter total fore contacts, longer fore trail non-contact durations and longer airborne phase durations. Stepwise multiple regression (RZ=.61,P<.0001) revealed a combination of 7 temporal variables of one-snide canter lead changes associated with higher scores: lower fore trail contact durations, lower fore lead contact durations, longer intervals between impacts of the fore lead limb and hind trail limb, longer total hindlimb contacts, longer bipedal contacts of the hind lead and fore trail, shorter bipedal contacts of the hind lead and fore lead, and longer quadrupedal contacts. Stepwise multiple regression of linear measurements revealed a combination of five variables weakly associated (P<.05; RZ=.19) with higher scores: decreased forestep lengths, increased midstep and airborne step lengths, decreased proportions of midsteps and increased proportions of foresteps in the total stride. While executing singlesnide lead changes, higher-scoring horses demonstrated a greater degree of collection and impulsion from the hindquarters with a greater time in hindlimb support and a shorter time in forelimb support in preparing for a longer time in the air executing the lead change. In future studies it would be advantageous to compare a slower collected canter (rather than the extended canter) with canter strides involving lead changes, to determine Volume 10, Number 4 1990
more subtle alterations in gait patterns associated with lead changes. It would also be valuable to perform kinematic analyses of other precision motions of world-class dressage horses, such as the piaffe, passage and piroutte.
CONCLUSIONS
1. High speed cinematography utilizedat 100 frames per sec was able to detect individualized features of canter motion in horses moving at velocities from 3 to 9 m/s. 2. This study provided the first reference documentation of the canter stride characteristics of world-class dressage horses during execution of the Grand Prix Special test in the Olympic Games. 3. Kinematics of the canter determined from film analysis can be accurately associated with dressage judges' subjective scores. 4. Differences in velocity between 3 and 9 m/s of the canter of world-class dressage horses were primarily the result of differences in stride length. For all canter movements, stride length and velocity were closely related, but stride duration and stride length tended to be unrelated. Stride duration and velocity were not significantly related for any canter movement, in contrast to the gallop. 4 5. Score was optimized with the greatest length of extended canter strides. There was no upper limit detected for optimal snide length, across all stride frequencies. The lowest scoring horses had extended canter stride frequencies above 1.58 s-1 and the shortest strides. 6. Lead changes of the canter stride were performed at 52% of the velocity, 54% of the stride length and 96% of the stride frequency of the extended canter. 7. Canter strides preceding a lead change were slower in velocity, stride lengths shorter, and stride durations briefer than strides following a lead change. 8. Kinematic analysis of canter snides of higher-scoring horses showed a greater degree of coUection and impulsion from the hindquarters during lead changes and higher velocities and longer strides at the extended canter.
REFERENCES 1. Cohen S: Tempo and the development of the paces. Dressage & C T 32(197):19-23,1989. 2. DeuelNR, Lawrence LM: Cinematographic methodology for the kinematic analysis of the canter. Proc Equine Nutr Physl Syrup 9:254-259,1983.
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3. Deuel NR, Lawrence LM: Computer-drawn gaitdiagrams. J Equine Vet Sci 4(5):228-229,1984. 4. Deuel NR, Lawrence LM: Gallop velocity and limb contact variables of Quarter Horses. JEquine VetSci 6(3):143-147,1986. 5. Deuel NR, Lawrence LM: Kinematics of the equine transverse gallop. J Equine Vet Sci 7(6):375-382,1987. 6. Deuel NR, Lawrence LM: Individual variation in the Quarter Horse gallop. Equine Exer Physio/, ICEEP Publications, Edwards Brothers, Inc., Ann Arbor MI, 2:567-574,1987. 7. Deuel NR, Lawrence LM: Laterality in the gallop gait of horses. J Biomech 20(6):645-649,1987. 8. Deuel NR, Park J: The gait patterns of Olympic dressage horses./ntl J Spts Biomech 6(2):198-226,1990. 9. Drevemo S, Dalin G, Fredricson I, Hjerten G: The analysis of linear and temporal stride characteristics of trotting Standardbreds. Equine Vet J 12(2):60-65,1980. 10. Drevemo S, Fredricson I, Dalin G, Bjome K: The analysis of coordination between limbs of trotting Standardbreds. Equine Vet
J 12(2):66-70,1980. 11. Drevemo S, Dalin G, Fredrioson I, Bjorne K: The reproducibilityof gait in Standardbred trotters. Equine VetJ 12(2)71-73,1980. 12. Hildebrand M: Analysis of asymmetrical gaits. Am Zoo/ 20:131-156,1977. 13. Jackson N: Effective Horsemanship. p 328,1967. Arco Publ. Co., NY. 14. Leach DH, Dagg AI: A review of research on equine locomotion and biomechanics. Equine Vet J 15(2):93-102,1983. 15. Leach DH, Ormrod K, Clayton HM: Stride characteristics of horses competing in Grand Prixjumping. Am J VetRes 45(5):888892,1984. 16. Podhajsky A: The Complete Training of Horse and Rider, Doubleday and Co., Inc., Garden City, NY, p 287,1967. 17. SAS: SAS User's Guide: Statistics, Version 5 Edition. Cary, NC, SAS Institute Inc., pp.763-774,1985.
EFFECT OF INSEMINATION VOLUME ON EMBRYO RECOVERY IN MARES H. S. Rowley, MS; E. L. Squires, PhD; B. W. Pickett, PhD
SUMMARY
The objective of this study was to determine the effect of insemination volumes on embryo recovery in mares. Sixty-twolight-horse mares were randomly assigned to 1 of 3 insemination treatments as they exhibited estrus. Mares were artificially inseminated with 100 x l& progressively motile spermatozoa (pms) extended in 10, 100 or200 ml of dried skim milk extender (E-Z Mixin). Embryo-recovery attempts were performed 6 or 7 days post-ovulation. 6 Due Authors'address:AnimalReproductionLaboratory,ColoradoStateUniversity, Fort Collins,CO 80523. Supported in part by the AmericanQuarter Horse Associationand Abney Foundation.
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to recovery of a low number of embryos, a second experiment was conducted with the same mares using a greater number of progressively motile spermatozoa (250 x 106 pms) suspended in either 10 or 100 ml of E-Z Mixin extender. In Experiment 1, there was no difference(P>0.05) in numbers of embryos recovered between mares inseminated with 10 (40%) and 100 ml (10.0%) of extender, nor was there a difference (1:'>0.05) between mares inseminated with 100 (10.0%) and 200 ml (0.0%). However, there was a significant difference in embryos recovered between mares inseminated with 10 (40.0%) and 200 ml (0.0%) (P<0.001). In Experiment 2, there was a highly significant difference between mares inseminated with 10 ml (70.6%) compared to 100 ml (13.0%) of extender (P<0.0005). Itwas concluded that insemination volumes of 100 ml or 200 ml were associated with lower fertility than with a 10 mI
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