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Profile and Surface Conditions of New Zealand Thoroughbred Racetracks
Journal of Equine Veterinary Science 34 (2014) 1105–1109
Contents lists available at ScienceDirect
Journal of Equine Veterinary Science journal homepage: www.j-evs.com
Original Research
Profile and Surface Conditions of New Zealand Thoroughbred Racetracks Chris W. Rogers MAgriSci, PhD a, *, Charlotte F. Bolwell PhD a, Erica K. Gee BVSc, PhD a, Michael L. Peterson PhD b, C. Wayne McIlwraith BVSC, PhD, DSc c a b c
Massey Equine, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand Department of Mechanical Engineering, University of Maine, Orono, ME Orthopedic Research Center, Colorado State University, Fort Collins, CO
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 March 2014 Received in revised form 12 June 2014 Accepted 18 June 2014 Available online 25 June 2014
There are no published data on racetrack configuration or the surface conditions of racing in New Zealand. Data on the physical shape and dimensions of racetracks were obtained from Google Earth and an online database (www.nzracing.co.nz). An electronic extract of all race records (horse and track condition details) covering the 7-year period from 2005/ 2006 to 2011/2012 were obtained from New Zealand Thoroughbred Racing Inc. Track data were examined in relation with the following categories: oval track, egg shaped, and other. Track condition data were described as official penetrometer or going data. Physical descriptions were obtained of the 49 official racetracks used in the 2011/2012 season. There were 27 oval-shaped, 16 egg-shaped, and five other-shaped tracks with most racing occurring in a counter clockwise direction (39 of 49). The median racetrack circumference was 1,800 m (interquartlie range, 1,600–1,800 m). There was no significant effect of track shape on the physical dimensions of the turns (home straight or back straight turn) or of the estimated centrifugal force. There were few fast tracks (penetrometer, 2.0–2.5) reported (8 of 1,093 races) and an even distribution of races among good (393 of 1,093), dead (204 of 1,093), slow (261 of 1,093), and heavy (227 of 1,093) tracks. Tracks were significantly heavier in winter (P ¼ .001). Change in going during a race meeting was limited, with a median of one-point change (interquartlie range, 1–2) on the going scale. The consistency of the racing direction, track circumferences, and turn dimensions in association with a consistent pattern of track going during a season implies a relatively consistent racing surface is available for horse racing in New Zealand. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Racetrack Track condition Horse racing Racing surface
1. Introduction Musculoskeletal injury and race day fracture are complex multifactorial events [1], and a number of studies have identified racecourse-related risk factors, such as racetrack, racetrack surface, and geometry [2–5]. Within some racing
* Corresponding author at: Chris W. Rogers, MAgriSci, PhD, Massey Equine, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 11222, New Zealand. E-mail address: [email protected] (C.W. Rogers). 0737-0806/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jevs.2014.06.017
jurisdictions, such as California, aggressive programs of change have been implemented to improve surface conditions with the transition from dirt to synthetic all weather racing surfaces, in an attempt to reduce the rate of musculoskeletal injury and fracture [6]. These changes and assumptions of the effect of racetrack surface largely ignore track shape, which may be a confounding factor. The radius of the turns and the level of banking alter the loading pattern of the distal limb [7]. However, within the literature, there are limited data on optimal racetrack shape and the interaction of track design (configuration) on race day injury, with much of the
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C.W. Rogers et al. / Journal of Equine Veterinary Science 34 (2014) 1105–1109
published data focusing on harness racing as opposed to Thoroughbred flat racing [4,8]. Surface maintenance, irrespective of surface composition or type, is of importance in attenuating injury, and track going is largely modified by the moisture content of the surface and its subsequent ability to retain moisture [9,10]. In a wet temperate climate, such as New Zealand, it is management of excess moisture and its effect on racetrack surfaces that often becomes an issue. Within New Zealand, most fast work (gallops during training and/or breezing) and racing are conducted on turf tracks [11,12] and most horses race counter clockwise [11]. It is believed that most tracks within New Zealand are of an oval shape and approximately 1 mile (1,600 m) in circumference. However, there are limited data published on the variation in track shape, dimensions, or racetrack surfaces within New Zealand [13]. Variations in racetrack design may exist because of local environmental and/or geographical constraints [14]. Within New Zealand, there is an opportunity for rationalization of racetracks and associated greater economies of scale, as there are a large number of racetracks in relation to the number of race meetings and race starters. Fewer racetracks may mean less variation in racing surface and environment and, hence, possibly less environmental contribution to race day injury. It is therefore important to quantify current racetrack design and variation in track surface for a comparison against other racing jurisdictions and to provide a reference point against which one could quantify the impact of any change. This article reports on the track shape and variation in track surface during seven Thoroughbred flat racing seasons within New Zealand. These data provide a baseline for further investigation into track-based risk factors and association with injury within New Zealand flat racing.
Fig. 1. Calculation of aspect ratio for racetrack turns.
calculated using the formula provided by Fredricson et al [8] and an average racehorse mass of 440 kg. 2.1. Racetrack Composition and Variation Data on the official penetrometer and “going” for all races and race meetings in New Zealand in the 7-year period covering the 2005/2006 to 2011/2012 racing seasons were obtained. The initial penetrometer value reported for a race meeting was an average of 30 readings from around the track taken between 6 and 7 AM of the race meeting. During the period of data capture, there was a change in the official measurement of track surface conditions from penetrometer readings to a “going scale,” based on that used in Australia, which uses both the penetrometer data and objective assessment of the track (Table 1). This new system came into effect on June 22, 2008. The number of tracks for which going data were available was greater than that reported for track dimensions as three tracks used during this 6-year period were no longer used for official race meetings in the 2011/ 2012 racing season. 2.2. Statistical Analysis
2. Materials and Methods A complete list of all racetracks that held at least one official race meeting in the 2011/2012 racing season were obtained from the official website of New Zealand Thoroughbred Racing Inc (www.nzracing.co.nz). Data on the physical shape and the physical dimensions of each racetrack were calculated by using known global Positioning Satellites coordinate data within Google Earth (earth. google.com). The data derived consisted of the circumference, radius of turns, length of straights, and changes in altitude throughout the track. Additional data on racing direction and track dimensions were obtained from the official New Zealand Thoroughbred Racing Inc website and used to validate data obtained via Google Earth. Track shape was described using common racing descriptors of oval (two straights and two turns of equal radius), egg (two straights and two turns, one of which was larger [by 10%]), or other. To describe the flattened arc of the turns, an aspect ratio for each turn was calculated. The aspect ratio was the ratio of the true radius of the turn divided by half the distance between the two straight sections of track (Fig. 1). Changes in elevation of the back straight and home straight were obtained from a profile plot of the tracks altitude. The estimated centrifugal force throughout the turn was
The data extracts were imported and sorted within a customized database (MS Access, Microsoft Corporation, Redmond, WA) before export for statistical analysis. Data were screened and described using simple descriptive statistics to identify coding errors and outliers. Graphical
Table 1 The official 11-scale “going” track grading system used in New Zealand Scale
Rating
Penetrometer Band
Comment
1 2 3 4
Fast Good Good Dead
0.5–1.9 2.0–2.2 2.3–2.5 2.6–2.8
5 6
Dead Dead
2.9–3.2 3.3–3.5
7
Slow
3.6–3.8
8 9
Slow Slow
3.9–4.2 4.3–4.5
Heavy Heavy
4.6–5.5 5.6þ
A dry hard track A firm track Ideal track with some give Track with give better side of Genuine Dead Genuine Dead Significant amount of give, worse side of Genuine Dead A mildly rain-affected track, better side of Genuine Slow Genuine Slow Rain affected, worse side of Genuine Slow Genuine Heavy Very soft and wet, heaviest category
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C.W. Rogers et al. / Journal of Equine Veterinary Science 34 (2014) 1105–1109
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significant differences in the distribution of going during the 7-year period with few meetings reporting fast tracks (n ¼ 8) and even distribution among good (n ¼ 393), dead (n ¼ 204), slow (n ¼ 261), and heavy (n ¼ 227) (Table 3). There was a significant difference between the seasons for penetrometer and going score with summer clustered toward better going, a larger spread in spring and autumn, and winter skewed toward heavy going (P ¼ .0001). If change in going was reported, the pattern was of tracks getting heavier during a race meeting. However, the median range of change reported was low, usually within one point of the going scale. There was limited change in the penetrometer measures reported during the race meetings.
presentation of the data and tests of normality were used to identify appropriate parametric or nonparametric tests. Differences among groups (track configuration, location, and season) were tested using a Kruskal–Wallis nonparametric analysis of variance, and differences in paired data were tested using the Wilcoxon pair signed rank test. Differences in distributions of track shape and going by season were tested using Fisher Exact test. All statistical analyses were performed using STATA 12 (StataCorp LP, College Station, TX).
3. Results Physical description of racetrack shape and dimensions were obtained on the 49 racetracks that held 350 race meetings and had 32,425 starters in the 2011/2012 racing season. The most common shape was oval (27 of 49) followed by egg (16 of 49). The remaining tracks were described as other (5 of 49), which included one of an isosceles triangle shape and four approximating a rectangular shape. Most of the tracks were raced in a counter clockwise direction (39 of 49) and were 1,800 m (interquartlie range, 1,600–1,800 m) in circumference. Despite the obvious differences in track shape, there was limited variation in the specific measurements for the different track shapes (Table 2). There were 29 tracks in the North Island and 20 in the South Island. There was a significant difference in the distribution of track shape between islands, as the South Island had most of the other shapes (P ¼ .014), but not in track circumference (P ¼ .2). There were no significant differences between the oval- and the egg-shaped tracks for the turn radius, aspect ratio of the turn, or estimated centrifugal force (all P > .6). There were no significant differences within the oval- or the egg-shaped tracks for the turn radius, aspect ratio of the turn, or estimated centrifugal force between the two turns. There was a seasonal pattern to racetrack use with a moderate restriction of racing to fewer tracks (n ¼ 25–30 of 49) during winter. The penetrometer reading taken between 6 and 7 AM on race day was consistent across all seasons with the exception of winter (P < .001). There were
4. Discussion Thoroughbred racing within New Zealand is under the control of a single regulatory authority, and this provides relative ease in the extraction of data relating to racing across a number of seasons and locations within the country. The relatively small number of official racetracks and a single regulatory authority may assist in providing a relatively homogeneous racing product across the country. Despite only a small difference in number of racetracks between the North and South Islands, there is a significantly greater concentration of Thoroughbred racing in the North Island of New Zealand, approximately 75% of all races and starters [15], which was reflected in the number of starters for the respective tracks in the North Island. Horses in training within the northern region of the North Island were also more likely to race, which may in part be because of clustering of the more successful trainers in this region [16,17]. Starters and number of race meetings were also stratified according to regional or premier tracks within the different racing regions, with more race meetings, at a higher frequency, at premier tracks. These premier tracks and meetings also attract horses from a greater catchment area [15,18]. In contrast to many international racing jurisdictions Thoroughbred racing in New Zealand is conducted solely on grass and/or turf tracks. Sand and all weather surfaces are used extensively for training, but none of these surfaces
Table 2 Physical description of Thoroughbred racetracks operational in New Zealand during the 2011/2012 racing season Variable
Oval
Egg
Number of tracks (n ¼ 49) Median circumference (m)a Median back straight length (m)a Median home straight length (m) No. of tracks with the home straight uphill No. of tracks with the home straight downhill No. of tracks with the back straight uphill No. of tracks with the back straight downhill Median variation in elevation of back straight (m)a Median variation in elevation of home straight (m) Median aspect ratio of turn into home straighta Median aspect ratio of turn into back straighta Estimated median centrifugal forces of turn into home straighta Estimated median centrifugal forces of turn into back straighta
27 1,800 400 363 13 7 12 7 1 1 1.19 1.17 771 798
16 1,800 350 350 5 7 9 4 1 2 1.22 1.36 662 979
a
Data are represented as medians (interquartile range).
(1,600–1,800) (350–450) (350–425)
(0–3) (0–3) (1.13–2.24) (1.12–1.29) (695–908) (695–908)
Other (1,600–1,876) (250–350) (300–400)
(1–4) (1–5) (1.15–1.3) (1.06–1.54) (557–893) (586–1,224)
5 1,600 300 300 1 4 3 2 2 1.5 1.18 1.21 816 838
(1,445–1,775) (250–350) (263–333)
(0.5–3) (1–5) (1.12–1.22) (1.20–1.22) (686–946) (662–1,014)
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Table 3 Track use and “going” parameters for all tracks used for official race meetings in New Zealand during the 2005/2006 to 2011/2012 racing seasons Variable
Spring
Summer
Autumn
Winter
Median penetrometer rating Median track condition scalea No. of race meetings fast in going No. of race meetings good in going No. of race meetings dead in going No. of race meetings slow in going No. of race meetings heavy in going No. of race meetings with a change in going No. of race meetings with improvement >1 in going No. of race meetings with worsening >1 in going Median improvement in goinga Median worsening in goinga
2.7 (23–2.9) 5 (3–8)a 4 118 62 74 48 81/306 22 59 1 (1–2) 1 (1–2)
2.3 (2.2–2.6) 3 (2–4)a 4 185 57 64 36 58/271 9 49 2 (1–3) 1 (1–2)
2.7 (2.3–3.6) 5 (3–8)a 0 84 57 64 36 58/241 13 45 2 (1–2) 1 (1–2)
4.3 (3.5–5.1) 10 (7–10)b 0 6 38 90 141 49/275 11 38 1 (1–1) 1 (1–1)
Different superscripts represent P < .05. a Data are represented as medians (interquartile range).
are used for racing [11,12]. Most of the racing tracks were approximately 1,800 m in circumferences and would have been laid out initially to provide a 1 mile circumference, as this reflects the common racing distances of horses in New Zealand at 1,400 m (interquartile range, 1,200–1,670 m) and the reference of race distances as units of mile or one eighth of a mile (a furlong) [15]. Most tracks were counter clockwise (“left handed”), and this direction of racing may reflect the observation that many horses find it easier to work this way and may be “left handed” [19–21]. Training, both pace and gallop work, in New Zealand is also predominantly counter clockwise, and this may represent specificity of the training program [11,12,22,23]. Significant adaptive responses of the third metacarpal bone have been documented with horses training counter clockwise with greater bone mineral density medial on the inside foreleg and lateral on the outside foreleg [24]. The similarity in track size, shape, and going throughout a season may mean that race horses within New Zealand are exposed to similar strains during racing throughout the season or a preparation. In many racing jurisdictions, the move toward all weather tracks has been driven by the desire to provide a consistent racing surface, as variation in racetrack surface has been implicated as a risk factor for musculoskeletal injury and fracture [5,25]. Despite the seasonal variability in weather and the geographical variation in the location of racetracks throughout New Zealand, the data collected in this study indicate that the turf racing surfaces are relatively homogeneous and have limited across race meeting variation in going. There also appears to be a focus of track managers to present tracks as “good” (penetrometer range, 2–2.5) for race meetings. This consistency may reflect the drainage and sand slotting program implemented on heavy tracks and the irrigation of dry tracks during summer. During late autumn, winter, and early spring, race meetings are also scheduled at racetracks which are known to be free draining, and thus, avoid extremes of going during these traditionally wet periods. These industry-level and tracklevel management approaches indicate the possibility of intuitive management [26], based on observation rather than empirical data, to provide a consistent racing surface. Optimization of racing surfaces may even be possible but must depend on the ability to link these measured data to
the epidemiologic outcomes to reduce the risk to riders and horses. There has been an association of going with an increased risk of fracture [5,25]. The provision of good going may be a balancing act by the track managers to provide an optimal track surface for racing while attenuating one of the variables associated with race day musculoskeletal injury. Initial examination of failure to finish as an indicator of musculoskeletal injury within New Zealand has identified a low failure to finish rate (2.8 of 1,000 starts; unpublished data). This value includes loss of rider and horse falls, pulled up horses, and horses that suffer a musculoskeletal injury during racing. The low failure to finish rate, which is lower than the fracture rate reported in a number of racing jurisdictions (range, 3.1–4.4 of 1,000), is an interesting phenomena [27,28]. By international comparison, there is also a low rate of jockey falls in New Zealand [29], which may also be because of the predictability or uniformity of the racing track dimensions and surface qualities. Both the lack of fast tracks and the uniformity of the racing surfaces within a meeting and within a season may contribute to the low rate of failure to finish observed in New Zealand. 5. Conclusions Despite the geographical spread of racetracks and the use of grass and/or turf surfaces, there appears to be relatively homogeneity of the racing surface parameters within a meeting and within a season. New Zealand tracks cluster toward good going with minimal changes within a meeting. Winter racing is clustered around heavy tracks but with minimal drift of variation in the definition of going within meetings and within the winter racing season providing a predictable racing surface.
Acknowledgments The authors gratefully acknowledge funding support from the Equine Trust as part of the Partnership for Excellence. The authors thank New Zealand Thoroughbred Racing for provision of the data.
C.W. Rogers et al. / Journal of Equine Veterinary Science 34 (2014) 1105–1109
References [1] Parkin TDH. Epidemiology of racetrack injuries in racehorses. Vet Clin North Am Equine Pract 2008;24:1–19. [2] Boden LA, Anderson GA, Charles JA, Morgan KL, Morton JM, Parkin TDH, et al. Risk factors for Thoroughbred racehorse fatality in flat starts in Victoria, Australia (1989-2004. Equine Vet J 2007;39: 430–7. [3] Parkin TDH, Clegg PD, French NP, Proudman CJ, Riggs CM, Singer ER, et al. Race- and course-level risk factors for fatal distal limb fracture in racing Thoroughbreds. Equine Vet J 2004;36:521–6. [4] Evans DL, Walsh JS. Effect of increasing the banking of a racetrack on the occurrence of injury and lameness in Standardbred horses. Aust Vet J 1997;75:751–2. [5] Oikawa M, Kusunose R. Fractures sustained by racehorses in Japan during flat racing with special reference to track condition and racing time. Vet J 2005;170:369–74. [6] Peterson ML, Reiser RF, Kuo PH, Radford DW, McIlwraith CW. Effect of temperature on race times on a synthetic surface. Equine Vet J 2010;42:351–7. [7] Peterson ML, Roepstorff L, Thomason JJ, Mahaffey CA, McIlwraith CW. Racing surfaces. White paper. 2012. p. 34. [8] Fredricson I, Dalin G, Drevemo S, Hjerten G, Alm LOA. Biotechnical approach to the geometric design of racetracks. Equine Vet J 1975;7: 91–5. [9] Ratzlaff MH, Hyde ML, Hutton DV, Rathgeber RA, Balch OK. Interrelationships between moisture content of the track, dynamic properties of the track and the locomotor forces exerted by galloping horses. J Equine Vet Sci 1997;17:35–42. [10] Peterson ML, McIlwraith CW. Effect of track maintenance on mechanical properties of a dirt racetrack: a preliminary study. Equine Vet J 2008;40:602–5. [11] Rogers CW, Firth EC. Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 2. Measurement error and effect of training stage on the relationship between objective and subjective criteria of training workload. N Z Vet J 2004;52:272–9. [12] Rogers CW, Firth EC, McIlwraith CW, Barneveld A, Goodship AE, Kawcak CE, et al. Evaluation of a new strategy to modulate skeletal development in racehorses by imposing track-based exercise during growth: the effects on 2-and 3-year-old racing careers. Equine Vet J 2008;40:119–27. [13] Murphy JW, Field TRO, Thomas VJ. Racetrack assessment by penetrometer. Part II. Application of the model. J Turf Manag 1996:1. [14] Mahaffey CA, Peterson ML, McIlwraith CW. Archetypes in Thoroughbred dirt racetracks regarding track design, clay mineralogy, and climate. Sports Eng 2012;15:21–7.
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[15] Bolwell CF, Rogers CW, Gee EK, Rosanowski SM. Descriptive statistics and the pattern of horse racing in New Zealand: Part 1 Thoroughbred racing. An Prod Sci 2014. In Press. [16] Perkins NR, Reid SWJ, Morris RS. Effect of training location and time period on racehorse performance in New Zealand. 2. Multivariable analysis. N Z Vet J 2004;52:243–9. [17] Bolwell CF, Russell LJ, Rogers CW, Firth EC. A cross-sectional survey of training practices of 2-year-old racehorses in the North Island of New Zealand. Comp Ex Phys 2010;7:37–42. [18] Rosanowski SM, Rogers CW, Cogger N. The movement pattern of horses around race meetings in New Zealand. An Prod Sci 2014. In Press. [19] Meij HS, Meij JCP. Functional asymmetry in the motor system of the horse. S Afr J Sci 1980;76:552–6. [20] Rogers CW, Davies AS, Pfeiffer DU, Davie PS. Linear and temporal stride characteristics of 3-day event horses at a CCl***3-day event horse inspection. N Z Vet J 1999;47:193–7. [21] Heaps LA, Franklin SH, Colborne GR. Horizontal moment around the hoof centre of pressure during walking on right and left circles. Equine Vet J 2011;43:190–5. [22] Rogers CW, Firth EC, Anderson B. Musculoskeletal responses of 2year-old Thoroughbred horses to early training. 5 Kinematic Effects. N Z Vet J 2005;53:95–100. [23] Rogers CW, Kidd L, Firth EC. Linear and temporal changes in the trot of 2-year-old Thoroughbred racehorses in relation to early exercise and race training. Equine Comp Ex Phys 2010;7:65–71. [24] Firth EC, Rogers CW, Doube M, Jopson NB. Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 6. Bone parameters in the third metacarpal and third metatarsal bones. N Z Vet J 2005;53:101–12. [25] Bailey CJ, Reid SWJ, Hodgson DR, Bourke JM, Rose RJ. Flat, hurdle and steeple racing: risk factors for musculoskeletal injury. Equine Vet J 1998;30:498–503. [26] Mahaffey CA, Peterson ML, Roepstorff L. The effects of varying cushion depth on dynamic loading in shallow sand thoroughbred horse dirt racetracks. Biosys Eng 2013;114:178–86. [27] Cohen ND, Mundy GD, Peloso JG, Carey VJ, Amend NK. Results of physical inspection before races and race-related characteristics and their association with musculoskeletal injuries in Thoroughbreds during races. J Am Vet Med Assoc 1999;215:654–61. [28] Williams RB, Harkins LS, Hammond CJ, Wood JLN. Racehorse injuries, clinical problems and fatalities recorded on British racecourses from flat racing and National Hunt racing during 1996, 1997 and 1998. Equine Vet J 2001;33:478–86. [29] Bolwell C, Rogers C, Gee E. Descriptive epidemiology of race-day jockey falls and injuries in New Zealand. Comp Ex Phys 2014;10: 49–55.
Contents lists available at ScienceDirect
Journal of Equine Veterinary Science journal homepage: www.j-evs.com
Original Research
Profile and Surface Conditions of New Zealand Thoroughbred Racetracks Chris W. Rogers MAgriSci, PhD a, *, Charlotte F. Bolwell PhD a, Erica K. Gee BVSc, PhD a, Michael L. Peterson PhD b, C. Wayne McIlwraith BVSC, PhD, DSc c a b c
Massey Equine, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand Department of Mechanical Engineering, University of Maine, Orono, ME Orthopedic Research Center, Colorado State University, Fort Collins, CO
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 March 2014 Received in revised form 12 June 2014 Accepted 18 June 2014 Available online 25 June 2014
There are no published data on racetrack configuration or the surface conditions of racing in New Zealand. Data on the physical shape and dimensions of racetracks were obtained from Google Earth and an online database (www.nzracing.co.nz). An electronic extract of all race records (horse and track condition details) covering the 7-year period from 2005/ 2006 to 2011/2012 were obtained from New Zealand Thoroughbred Racing Inc. Track data were examined in relation with the following categories: oval track, egg shaped, and other. Track condition data were described as official penetrometer or going data. Physical descriptions were obtained of the 49 official racetracks used in the 2011/2012 season. There were 27 oval-shaped, 16 egg-shaped, and five other-shaped tracks with most racing occurring in a counter clockwise direction (39 of 49). The median racetrack circumference was 1,800 m (interquartlie range, 1,600–1,800 m). There was no significant effect of track shape on the physical dimensions of the turns (home straight or back straight turn) or of the estimated centrifugal force. There were few fast tracks (penetrometer, 2.0–2.5) reported (8 of 1,093 races) and an even distribution of races among good (393 of 1,093), dead (204 of 1,093), slow (261 of 1,093), and heavy (227 of 1,093) tracks. Tracks were significantly heavier in winter (P ¼ .001). Change in going during a race meeting was limited, with a median of one-point change (interquartlie range, 1–2) on the going scale. The consistency of the racing direction, track circumferences, and turn dimensions in association with a consistent pattern of track going during a season implies a relatively consistent racing surface is available for horse racing in New Zealand. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Racetrack Track condition Horse racing Racing surface
1. Introduction Musculoskeletal injury and race day fracture are complex multifactorial events [1], and a number of studies have identified racecourse-related risk factors, such as racetrack, racetrack surface, and geometry [2–5]. Within some racing
* Corresponding author at: Chris W. Rogers, MAgriSci, PhD, Massey Equine, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 11222, New Zealand. E-mail address: [email protected] (C.W. Rogers). 0737-0806/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jevs.2014.06.017
jurisdictions, such as California, aggressive programs of change have been implemented to improve surface conditions with the transition from dirt to synthetic all weather racing surfaces, in an attempt to reduce the rate of musculoskeletal injury and fracture [6]. These changes and assumptions of the effect of racetrack surface largely ignore track shape, which may be a confounding factor. The radius of the turns and the level of banking alter the loading pattern of the distal limb [7]. However, within the literature, there are limited data on optimal racetrack shape and the interaction of track design (configuration) on race day injury, with much of the
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C.W. Rogers et al. / Journal of Equine Veterinary Science 34 (2014) 1105–1109
published data focusing on harness racing as opposed to Thoroughbred flat racing [4,8]. Surface maintenance, irrespective of surface composition or type, is of importance in attenuating injury, and track going is largely modified by the moisture content of the surface and its subsequent ability to retain moisture [9,10]. In a wet temperate climate, such as New Zealand, it is management of excess moisture and its effect on racetrack surfaces that often becomes an issue. Within New Zealand, most fast work (gallops during training and/or breezing) and racing are conducted on turf tracks [11,12] and most horses race counter clockwise [11]. It is believed that most tracks within New Zealand are of an oval shape and approximately 1 mile (1,600 m) in circumference. However, there are limited data published on the variation in track shape, dimensions, or racetrack surfaces within New Zealand [13]. Variations in racetrack design may exist because of local environmental and/or geographical constraints [14]. Within New Zealand, there is an opportunity for rationalization of racetracks and associated greater economies of scale, as there are a large number of racetracks in relation to the number of race meetings and race starters. Fewer racetracks may mean less variation in racing surface and environment and, hence, possibly less environmental contribution to race day injury. It is therefore important to quantify current racetrack design and variation in track surface for a comparison against other racing jurisdictions and to provide a reference point against which one could quantify the impact of any change. This article reports on the track shape and variation in track surface during seven Thoroughbred flat racing seasons within New Zealand. These data provide a baseline for further investigation into track-based risk factors and association with injury within New Zealand flat racing.
Fig. 1. Calculation of aspect ratio for racetrack turns.
calculated using the formula provided by Fredricson et al [8] and an average racehorse mass of 440 kg. 2.1. Racetrack Composition and Variation Data on the official penetrometer and “going” for all races and race meetings in New Zealand in the 7-year period covering the 2005/2006 to 2011/2012 racing seasons were obtained. The initial penetrometer value reported for a race meeting was an average of 30 readings from around the track taken between 6 and 7 AM of the race meeting. During the period of data capture, there was a change in the official measurement of track surface conditions from penetrometer readings to a “going scale,” based on that used in Australia, which uses both the penetrometer data and objective assessment of the track (Table 1). This new system came into effect on June 22, 2008. The number of tracks for which going data were available was greater than that reported for track dimensions as three tracks used during this 6-year period were no longer used for official race meetings in the 2011/ 2012 racing season. 2.2. Statistical Analysis
2. Materials and Methods A complete list of all racetracks that held at least one official race meeting in the 2011/2012 racing season were obtained from the official website of New Zealand Thoroughbred Racing Inc (www.nzracing.co.nz). Data on the physical shape and the physical dimensions of each racetrack were calculated by using known global Positioning Satellites coordinate data within Google Earth (earth. google.com). The data derived consisted of the circumference, radius of turns, length of straights, and changes in altitude throughout the track. Additional data on racing direction and track dimensions were obtained from the official New Zealand Thoroughbred Racing Inc website and used to validate data obtained via Google Earth. Track shape was described using common racing descriptors of oval (two straights and two turns of equal radius), egg (two straights and two turns, one of which was larger [by 10%]), or other. To describe the flattened arc of the turns, an aspect ratio for each turn was calculated. The aspect ratio was the ratio of the true radius of the turn divided by half the distance between the two straight sections of track (Fig. 1). Changes in elevation of the back straight and home straight were obtained from a profile plot of the tracks altitude. The estimated centrifugal force throughout the turn was
The data extracts were imported and sorted within a customized database (MS Access, Microsoft Corporation, Redmond, WA) before export for statistical analysis. Data were screened and described using simple descriptive statistics to identify coding errors and outliers. Graphical
Table 1 The official 11-scale “going” track grading system used in New Zealand Scale
Rating
Penetrometer Band
Comment
1 2 3 4
Fast Good Good Dead
0.5–1.9 2.0–2.2 2.3–2.5 2.6–2.8
5 6
Dead Dead
2.9–3.2 3.3–3.5
7
Slow
3.6–3.8
8 9
Slow Slow
3.9–4.2 4.3–4.5
Heavy Heavy
4.6–5.5 5.6þ
A dry hard track A firm track Ideal track with some give Track with give better side of Genuine Dead Genuine Dead Significant amount of give, worse side of Genuine Dead A mildly rain-affected track, better side of Genuine Slow Genuine Slow Rain affected, worse side of Genuine Slow Genuine Heavy Very soft and wet, heaviest category
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significant differences in the distribution of going during the 7-year period with few meetings reporting fast tracks (n ¼ 8) and even distribution among good (n ¼ 393), dead (n ¼ 204), slow (n ¼ 261), and heavy (n ¼ 227) (Table 3). There was a significant difference between the seasons for penetrometer and going score with summer clustered toward better going, a larger spread in spring and autumn, and winter skewed toward heavy going (P ¼ .0001). If change in going was reported, the pattern was of tracks getting heavier during a race meeting. However, the median range of change reported was low, usually within one point of the going scale. There was limited change in the penetrometer measures reported during the race meetings.
presentation of the data and tests of normality were used to identify appropriate parametric or nonparametric tests. Differences among groups (track configuration, location, and season) were tested using a Kruskal–Wallis nonparametric analysis of variance, and differences in paired data were tested using the Wilcoxon pair signed rank test. Differences in distributions of track shape and going by season were tested using Fisher Exact test. All statistical analyses were performed using STATA 12 (StataCorp LP, College Station, TX).
3. Results Physical description of racetrack shape and dimensions were obtained on the 49 racetracks that held 350 race meetings and had 32,425 starters in the 2011/2012 racing season. The most common shape was oval (27 of 49) followed by egg (16 of 49). The remaining tracks were described as other (5 of 49), which included one of an isosceles triangle shape and four approximating a rectangular shape. Most of the tracks were raced in a counter clockwise direction (39 of 49) and were 1,800 m (interquartlie range, 1,600–1,800 m) in circumference. Despite the obvious differences in track shape, there was limited variation in the specific measurements for the different track shapes (Table 2). There were 29 tracks in the North Island and 20 in the South Island. There was a significant difference in the distribution of track shape between islands, as the South Island had most of the other shapes (P ¼ .014), but not in track circumference (P ¼ .2). There were no significant differences between the oval- and the egg-shaped tracks for the turn radius, aspect ratio of the turn, or estimated centrifugal force (all P > .6). There were no significant differences within the oval- or the egg-shaped tracks for the turn radius, aspect ratio of the turn, or estimated centrifugal force between the two turns. There was a seasonal pattern to racetrack use with a moderate restriction of racing to fewer tracks (n ¼ 25–30 of 49) during winter. The penetrometer reading taken between 6 and 7 AM on race day was consistent across all seasons with the exception of winter (P < .001). There were
4. Discussion Thoroughbred racing within New Zealand is under the control of a single regulatory authority, and this provides relative ease in the extraction of data relating to racing across a number of seasons and locations within the country. The relatively small number of official racetracks and a single regulatory authority may assist in providing a relatively homogeneous racing product across the country. Despite only a small difference in number of racetracks between the North and South Islands, there is a significantly greater concentration of Thoroughbred racing in the North Island of New Zealand, approximately 75% of all races and starters [15], which was reflected in the number of starters for the respective tracks in the North Island. Horses in training within the northern region of the North Island were also more likely to race, which may in part be because of clustering of the more successful trainers in this region [16,17]. Starters and number of race meetings were also stratified according to regional or premier tracks within the different racing regions, with more race meetings, at a higher frequency, at premier tracks. These premier tracks and meetings also attract horses from a greater catchment area [15,18]. In contrast to many international racing jurisdictions Thoroughbred racing in New Zealand is conducted solely on grass and/or turf tracks. Sand and all weather surfaces are used extensively for training, but none of these surfaces
Table 2 Physical description of Thoroughbred racetracks operational in New Zealand during the 2011/2012 racing season Variable
Oval
Egg
Number of tracks (n ¼ 49) Median circumference (m)a Median back straight length (m)a Median home straight length (m) No. of tracks with the home straight uphill No. of tracks with the home straight downhill No. of tracks with the back straight uphill No. of tracks with the back straight downhill Median variation in elevation of back straight (m)a Median variation in elevation of home straight (m) Median aspect ratio of turn into home straighta Median aspect ratio of turn into back straighta Estimated median centrifugal forces of turn into home straighta Estimated median centrifugal forces of turn into back straighta
27 1,800 400 363 13 7 12 7 1 1 1.19 1.17 771 798
16 1,800 350 350 5 7 9 4 1 2 1.22 1.36 662 979
a
Data are represented as medians (interquartile range).
(1,600–1,800) (350–450) (350–425)
(0–3) (0–3) (1.13–2.24) (1.12–1.29) (695–908) (695–908)
Other (1,600–1,876) (250–350) (300–400)
(1–4) (1–5) (1.15–1.3) (1.06–1.54) (557–893) (586–1,224)
5 1,600 300 300 1 4 3 2 2 1.5 1.18 1.21 816 838
(1,445–1,775) (250–350) (263–333)
(0.5–3) (1–5) (1.12–1.22) (1.20–1.22) (686–946) (662–1,014)
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Table 3 Track use and “going” parameters for all tracks used for official race meetings in New Zealand during the 2005/2006 to 2011/2012 racing seasons Variable
Spring
Summer
Autumn
Winter
Median penetrometer rating Median track condition scalea No. of race meetings fast in going No. of race meetings good in going No. of race meetings dead in going No. of race meetings slow in going No. of race meetings heavy in going No. of race meetings with a change in going No. of race meetings with improvement >1 in going No. of race meetings with worsening >1 in going Median improvement in goinga Median worsening in goinga
2.7 (23–2.9) 5 (3–8)a 4 118 62 74 48 81/306 22 59 1 (1–2) 1 (1–2)
2.3 (2.2–2.6) 3 (2–4)a 4 185 57 64 36 58/271 9 49 2 (1–3) 1 (1–2)
2.7 (2.3–3.6) 5 (3–8)a 0 84 57 64 36 58/241 13 45 2 (1–2) 1 (1–2)
4.3 (3.5–5.1) 10 (7–10)b 0 6 38 90 141 49/275 11 38 1 (1–1) 1 (1–1)
Different superscripts represent P < .05. a Data are represented as medians (interquartile range).
are used for racing [11,12]. Most of the racing tracks were approximately 1,800 m in circumferences and would have been laid out initially to provide a 1 mile circumference, as this reflects the common racing distances of horses in New Zealand at 1,400 m (interquartile range, 1,200–1,670 m) and the reference of race distances as units of mile or one eighth of a mile (a furlong) [15]. Most tracks were counter clockwise (“left handed”), and this direction of racing may reflect the observation that many horses find it easier to work this way and may be “left handed” [19–21]. Training, both pace and gallop work, in New Zealand is also predominantly counter clockwise, and this may represent specificity of the training program [11,12,22,23]. Significant adaptive responses of the third metacarpal bone have been documented with horses training counter clockwise with greater bone mineral density medial on the inside foreleg and lateral on the outside foreleg [24]. The similarity in track size, shape, and going throughout a season may mean that race horses within New Zealand are exposed to similar strains during racing throughout the season or a preparation. In many racing jurisdictions, the move toward all weather tracks has been driven by the desire to provide a consistent racing surface, as variation in racetrack surface has been implicated as a risk factor for musculoskeletal injury and fracture [5,25]. Despite the seasonal variability in weather and the geographical variation in the location of racetracks throughout New Zealand, the data collected in this study indicate that the turf racing surfaces are relatively homogeneous and have limited across race meeting variation in going. There also appears to be a focus of track managers to present tracks as “good” (penetrometer range, 2–2.5) for race meetings. This consistency may reflect the drainage and sand slotting program implemented on heavy tracks and the irrigation of dry tracks during summer. During late autumn, winter, and early spring, race meetings are also scheduled at racetracks which are known to be free draining, and thus, avoid extremes of going during these traditionally wet periods. These industry-level and tracklevel management approaches indicate the possibility of intuitive management [26], based on observation rather than empirical data, to provide a consistent racing surface. Optimization of racing surfaces may even be possible but must depend on the ability to link these measured data to
the epidemiologic outcomes to reduce the risk to riders and horses. There has been an association of going with an increased risk of fracture [5,25]. The provision of good going may be a balancing act by the track managers to provide an optimal track surface for racing while attenuating one of the variables associated with race day musculoskeletal injury. Initial examination of failure to finish as an indicator of musculoskeletal injury within New Zealand has identified a low failure to finish rate (2.8 of 1,000 starts; unpublished data). This value includes loss of rider and horse falls, pulled up horses, and horses that suffer a musculoskeletal injury during racing. The low failure to finish rate, which is lower than the fracture rate reported in a number of racing jurisdictions (range, 3.1–4.4 of 1,000), is an interesting phenomena [27,28]. By international comparison, there is also a low rate of jockey falls in New Zealand [29], which may also be because of the predictability or uniformity of the racing track dimensions and surface qualities. Both the lack of fast tracks and the uniformity of the racing surfaces within a meeting and within a season may contribute to the low rate of failure to finish observed in New Zealand. 5. Conclusions Despite the geographical spread of racetracks and the use of grass and/or turf surfaces, there appears to be relatively homogeneity of the racing surface parameters within a meeting and within a season. New Zealand tracks cluster toward good going with minimal changes within a meeting. Winter racing is clustered around heavy tracks but with minimal drift of variation in the definition of going within meetings and within the winter racing season providing a predictable racing surface.
Acknowledgments The authors gratefully acknowledge funding support from the Equine Trust as part of the Partnership for Excellence. The authors thank New Zealand Thoroughbred Racing for provision of the data.
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References [1] Parkin TDH. Epidemiology of racetrack injuries in racehorses. Vet Clin North Am Equine Pract 2008;24:1–19. [2] Boden LA, Anderson GA, Charles JA, Morgan KL, Morton JM, Parkin TDH, et al. Risk factors for Thoroughbred racehorse fatality in flat starts in Victoria, Australia (1989-2004. Equine Vet J 2007;39: 430–7. [3] Parkin TDH, Clegg PD, French NP, Proudman CJ, Riggs CM, Singer ER, et al. Race- and course-level risk factors for fatal distal limb fracture in racing Thoroughbreds. Equine Vet J 2004;36:521–6. [4] Evans DL, Walsh JS. Effect of increasing the banking of a racetrack on the occurrence of injury and lameness in Standardbred horses. Aust Vet J 1997;75:751–2. [5] Oikawa M, Kusunose R. Fractures sustained by racehorses in Japan during flat racing with special reference to track condition and racing time. Vet J 2005;170:369–74. [6] Peterson ML, Reiser RF, Kuo PH, Radford DW, McIlwraith CW. Effect of temperature on race times on a synthetic surface. Equine Vet J 2010;42:351–7. [7] Peterson ML, Roepstorff L, Thomason JJ, Mahaffey CA, McIlwraith CW. Racing surfaces. White paper. 2012. p. 34. [8] Fredricson I, Dalin G, Drevemo S, Hjerten G, Alm LOA. Biotechnical approach to the geometric design of racetracks. Equine Vet J 1975;7: 91–5. [9] Ratzlaff MH, Hyde ML, Hutton DV, Rathgeber RA, Balch OK. Interrelationships between moisture content of the track, dynamic properties of the track and the locomotor forces exerted by galloping horses. J Equine Vet Sci 1997;17:35–42. [10] Peterson ML, McIlwraith CW. Effect of track maintenance on mechanical properties of a dirt racetrack: a preliminary study. Equine Vet J 2008;40:602–5. [11] Rogers CW, Firth EC. Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 2. Measurement error and effect of training stage on the relationship between objective and subjective criteria of training workload. N Z Vet J 2004;52:272–9. [12] Rogers CW, Firth EC, McIlwraith CW, Barneveld A, Goodship AE, Kawcak CE, et al. Evaluation of a new strategy to modulate skeletal development in racehorses by imposing track-based exercise during growth: the effects on 2-and 3-year-old racing careers. Equine Vet J 2008;40:119–27. [13] Murphy JW, Field TRO, Thomas VJ. Racetrack assessment by penetrometer. Part II. Application of the model. J Turf Manag 1996:1. [14] Mahaffey CA, Peterson ML, McIlwraith CW. Archetypes in Thoroughbred dirt racetracks regarding track design, clay mineralogy, and climate. Sports Eng 2012;15:21–7.
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[15] Bolwell CF, Rogers CW, Gee EK, Rosanowski SM. Descriptive statistics and the pattern of horse racing in New Zealand: Part 1 Thoroughbred racing. An Prod Sci 2014. In Press. [16] Perkins NR, Reid SWJ, Morris RS. Effect of training location and time period on racehorse performance in New Zealand. 2. Multivariable analysis. N Z Vet J 2004;52:243–9. [17] Bolwell CF, Russell LJ, Rogers CW, Firth EC. A cross-sectional survey of training practices of 2-year-old racehorses in the North Island of New Zealand. Comp Ex Phys 2010;7:37–42. [18] Rosanowski SM, Rogers CW, Cogger N. The movement pattern of horses around race meetings in New Zealand. An Prod Sci 2014. In Press. [19] Meij HS, Meij JCP. Functional asymmetry in the motor system of the horse. S Afr J Sci 1980;76:552–6. [20] Rogers CW, Davies AS, Pfeiffer DU, Davie PS. Linear and temporal stride characteristics of 3-day event horses at a CCl***3-day event horse inspection. N Z Vet J 1999;47:193–7. [21] Heaps LA, Franklin SH, Colborne GR. Horizontal moment around the hoof centre of pressure during walking on right and left circles. Equine Vet J 2011;43:190–5. [22] Rogers CW, Firth EC, Anderson B. Musculoskeletal responses of 2year-old Thoroughbred horses to early training. 5 Kinematic Effects. N Z Vet J 2005;53:95–100. [23] Rogers CW, Kidd L, Firth EC. Linear and temporal changes in the trot of 2-year-old Thoroughbred racehorses in relation to early exercise and race training. Equine Comp Ex Phys 2010;7:65–71. [24] Firth EC, Rogers CW, Doube M, Jopson NB. Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 6. Bone parameters in the third metacarpal and third metatarsal bones. N Z Vet J 2005;53:101–12. [25] Bailey CJ, Reid SWJ, Hodgson DR, Bourke JM, Rose RJ. Flat, hurdle and steeple racing: risk factors for musculoskeletal injury. Equine Vet J 1998;30:498–503. [26] Mahaffey CA, Peterson ML, Roepstorff L. The effects of varying cushion depth on dynamic loading in shallow sand thoroughbred horse dirt racetracks. Biosys Eng 2013;114:178–86. [27] Cohen ND, Mundy GD, Peloso JG, Carey VJ, Amend NK. Results of physical inspection before races and race-related characteristics and their association with musculoskeletal injuries in Thoroughbreds during races. J Am Vet Med Assoc 1999;215:654–61. [28] Williams RB, Harkins LS, Hammond CJ, Wood JLN. Racehorse injuries, clinical problems and fatalities recorded on British racecourses from flat racing and National Hunt racing during 1996, 1997 and 1998. Equine Vet J 2001;33:478–86. [29] Bolwell C, Rogers C, Gee E. Descriptive epidemiology of race-day jockey falls and injuries in New Zealand. Comp Ex Phys 2014;10: 49–55.