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Reliable passive ankle range of motion measures correlate to ankle motion achieved during ergometer rowing
Physical Therapy in Sport 5 (2004) 75–83 www.elsevier.com/locate/yptsp
Original research
Reliable passive ankle range of motion measures correlate to ankle motion achieved during ergometer rowing Clara Sopera,*, Duncan Reidb, Patria Anne Humea a
New Zealand Institute of Sport and Recreation Research, Faculty of Health, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand b Division of Rehabilitation and Occupational Studies, Faculty of Health, Auckland University of Technology, Auckland, New Zealand Received 6 July 2003; revised 18 November 2003; accepted 24 November 2003
Abstract Objectives. To determine whether ankle range of motion during ergometer rowing is best approximated by reliable active or passive plantarflexion and dorsiflexion tests. Design. Repeated measures and cross-sectional. Setting. In a laboratory setting, an electrogoniometer was attached to each subjects’ left ankle during active, passive and dynamic ankle range of motion tests. Participants. Three adult males and seven adult females participated in part A of the study. Ten junior male rowers took part in Part B of the study. Main outcome measures. Endpoint plantarflexion and dorsiflexion. Results. Mean active and passive endpoint plantarflexion were significantly greater than mean plantarflexion achieved during ergometer rowing. In comparison, endpoint dorsiflexion measured passively and during ergometer rowing were not significantly different ðP ¼ 0:40Þ; and moderately correlated (r ¼ 0:60; 95% CI ¼ 20.05 – 0.89). The active and passive ankle range of motion tests were reliable (r ¼ 0:90 – 0:95; highest SEM ¼ 2.88, 95% CI ¼ 1.9 – 5.18). The passive tests produced significantly greater mean endpoint ankle plantarflexion (7.48 ^ 3.78, 14.9%) and dorsiflexion (6.58 ^ 3.78, 28.2%) than the active tests. Conclusions. Compared to dynamic measurement, passive plantarflexion and dorsiflexion are the preferred tests to assess rowers’ ankle motion due to the high reliability, validity and easier measurement procedures. q 2004 Elsevier Ltd. All rights reserved. Keywords: Rowing; Ergometer; Dorsiflexion; Plantarflexion; reliability
1. Introduction The ability to measure endpoint ankle plantarflexion and dorsiflexion reliably and know their relationship to ankle range of motion during a rowing stroke cycle is important to physiotherapists and biomechanists working with rowers. Physiotherapists perform all musculoskeletal screening of rowers in the Rowing New Zealand High Performance Programme. Screening results are applicable to both injury prevention and performance enhancement strategies. Physiotherapists can utilise range of motion information for injury prevention (Pope, Herbert, & Kirwan, 1988; Tabrizi, McIntyre, Quesnel, & Howard, 2000) and rehabilitation programmes, whilst the biomechanist and rowing * Corresponding author. Tel.: 9-9179999. E-mail address: [email protected] (C. Soper). 1466-853X/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.ptsp.2003.11.006
coach require this information to monitor and ensure that changes to the set up of the boat are likely to be within the physical capabilities of the rower. The ability of the rower to plantarflex their ankles may increase stroke length at the end of drive phase and allow for a smooth withdrawal of the blades from the water. Similarly, the ability to achieve a ‘tight’ catch position with the shank vertical at the start of the drive phase is considered a positive attribute of the rowing stroke cycle. A tight catch allows a longer stroke length to be achieved (greater sternward position of oar handles) and the rower is placed in a powerful position (ankle, knee and hip flexion) to apply propulsive forces to the foot-stretcher and oar handle(s). The foot-stretcher is set at a fixed angle in a rowing boat, chosen for comfort rather than with regard to any mechanical advantage it may afford. It has previously
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been suggested (Hume, Soper, Joe, Williams, Aitchison, & Gunn, 2000) that a steeper (more vertical) foot-stretcher angle may allow the application of greater horizontal propulsive force to the boat. However, a rowers’ soleus muscle length will limit the shank and upper leg positions achievable at the catch, as a steeper foot-stretcher angle requires greater dorsiflexion for the same amount of knee flexion. Various protocols and equipment for testing ankle range of motion are currently used; however, determining the procedure that reliably approximates the range of motion used during rowing is essential. Before further foot-stretcher optimisation studies are completed, research indicating the most valid and reliable ankle range of motion test is necessary. During ergometer rowing, rowers sit on a sliding seat with their forefoot of secured via straps to the foot-stretcher. Forces are applied to the ergometer during the drive phase of the rowing stroke cycle via the hands on the oar(s) and the feet on the foot-stretcher as the ankle moves from dorsiflexion to plantarflexion. The drive phase is initiated in the ‘catch’ position and completed in the ‘finish’ position (see Fig. 1). At the catch position, the blade(s) catch or make contact with the water. The rower’s ankles, knees and hips are in a flexed position preparing for the drive phase. The drive phase is initiated as the legs extend moving the pelvis towards the bow of the boat. The finish position occurs when the ankles, knees, and trunk are extended and the blades are withdrawn from the water. Research (Halliday, Zavatsky, Andrews, & Hase, 2001; Hume et al., 2000) has reported ankle range of motion during ergometer rowing, however, it is not known which clinical-setting range of motion test best predicts ankle movement during rowing. Whether a rowers’ endpoint ankle plantarflexion or dorsiflexion should be measured passively or actively needs to be considered. Passive stretching refers to a stretch that requires no muscular contraction—rather an end range of motion is gained by an external force being applied to the limb. Active stretching is
achieved through the rower contracting appropriate muscles to produce a stretch. Previous research has reported that active range of motion tests generally produce smaller absolute ranges of motion, and that these are more closely correlated to sports movements than passive tests (Iashvili, 1983). Furthermore, Iashvili (1983) reported that active and passive ranges of motion tests were only moderately correlated at the shoulder, hip, knee and ankle ðr ¼ 0:61 – 0:73Þ: A rowers’ ankle range of motion is currently measured during regular musculoskeletal screening sessions to ensure that the desired range of movements during each stroke cycle can be achieved. No published research has shown whether ankle range of motion tests for rowers should be conducted under active or passive measurement conditions. In order to identify whether a rowers’ endpoint ankle motion should be measured actively or passively, analysis was required to establish the test procedure that best predicted ankle motion during ergometer rowing. Therefore, the aims of this study were to determine: (1) the reliability of an active and passive endpoint ankle plantarflexion and dorsiflexion test in a clinical setting; (2) the relationship between active and passive endpoint ankle plantarflexion and dorsiflexion; and (3) whether ankle range of ankle motion achieved during ergometer rowing was best approximated by a rowers’ active or passively measured plantarflexion and dorsiflexion.
2. Methods Reliability of a test refers to the ability of the subjects to reproduce the measure of performance when the test is repeatedly administered (Schabort, Hawley, Hopkins, & Blum, 1999). A reliable test is one that has small changes in the mean, small within-individual variation (Standard Error of the Mean, (SEM)) and a high test-retest correlation
Fig. 1. Catch and finish positions during rowing.
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between the repeated tests (Schabort et al., 1999). A reliable test is typically reported when the SEM is less than 2% or less than the smallest worthwhile detectable change (Hopkins, 2000a). Reliability of the passive and active ankle plantarflexion and dorsiflexion tests were determined in Part A of this investigation. Part B investigated the relationship between active, passive and dynamic (ergometer rowing) ankle motion. 2.1. Subjects A convenience sample of three male and seven female adults (26.0 ^ 4.7 years, 167.1 ^ 5.3 cm tall, 66.3 ^ 8.3 kg) completed Part A of the investigation. Ten injury-free junior male competitive junior rowers (16.0 ^ 0.0 years, 180.2 ^ 6.5 cm tall, 82.0 ^ 9.5 kg) completed Part B. Ethical approval was gained from the Auckland University of Technology Ethics Committee. All subjects were informed of the procedures and gave their written consent. The sample size was considered adequate to detect a small effect size for ankle range of motion.
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2.2. Equipment A registered physiotherapist with 22 years experience marked the proximal and distal end of a straight line between the lateral malleolus and the lateral epicondyle of the fibula. The wired end of a dual axis electrogoniometer (Applied Measurement Australia) was positioned horizontally directly below the lateral malleolus of the right leg. The arm of the electrogoniometer was aligned with the lateral epicondyle of the fibula (see Fig. 2A). The electrogoniometer was wired to enable real time data collection at 100 Hz via a custom designed LabVIEWe data collection system. The electrogoniometer was not removed from each subjects’ ankle until all plantarflexion and dorsiflexion measurements were recorded. All plantarflexion and dorsiflexion angles were represented with respect to the subjects’ ankle position during standing in the anatomical position (see Fig. 2A). Plantarflexion and dorsiflexion were classified as movements of the dorsal surface of the foot away from the shin (pointing) and towards the shin respectively (see Fig. 3). Prior to all data collection the electrogoniometer was calibrated using zero
Fig. 2. Data collection procedures for passive, active and dynamic plantarflexion and dorsiflexion.
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Fig. 3. Plantarflexion and dorsifexion calculation from the neutral ankle position.
and 458 on a plastic goniometer. Custom designed LabViewe analysis programmes provided endpoint angle data following data collection.
2.3.2. Passive ankle plantarflexion and dorsiflexion measurements Passive ankle plantarflexion (see Fig. 2D) was measured with the subject standing in a traditional quadriceps stretch position (right knee flexed with foot held by the right hand close to the buttock). The right knee was moved anteriorly to take tension off the hip flexors. The subjects applied selfinduced pressure to the dorsal surface of the foot by the hand, to induce maximum plantarflexion, then relaxed the pressure and repeated the sequence eight times. Passive ankle dorsiflexion (see Fig. 2E) was measured with the subject standing facing a wall with their feet parallel and shoulder-width apart. The subjects flexed their knees to as much as possible, aligning the kneecap directly over the first toes as far as possible while keeping the heels on the ground. The subjects then extended their knees and repeated the knee flexion exercise a further eight times. Gravity and body weight provided assistance during the dorsiflexion test.
2.3. Procedures The subjects in Part A were required to attend testing on two consecutive days at the same time of day for measurement of active then passive range of motion of the right ankle. The rowers in Part B completed active, passive and dynamic range of ankle motion testing on a single day (the same order of tests for each rower). During ergometer rowing the rowers rowed at their race pace. Range of motion during rowing was collected from the right ankle. Active then passive ankle ranges of motion were recorded to ensure that the passive tests did not affect active range of motion. The plantarflexion and dorsiflexion tests were completed in a random order for each type of test. Nine stretches for each test were completed to ensure maximal achievable range of motion was achieved in stretches 6 –9 (McNair and Stanley, 1996; Taylor, Dalton, & Seaber, 1990). In all tests, the subjects were asked to reach maximum endpoint range of motion as determined by reaching a maximum tolerable position for the active dorsiflexion test and the active and passive plantarflexion tests, and just prior to the heels lifting off the ground for the passive dorsiflexion test. During all dorsiflexion movements the knee was flexed in order to place the stretch on the soleus muscle as occurs during the rowing stroke cycle. 2.3.1. Active ankle plantarflexion and dorsiflexion measurements The subjects sat up-right in a stable chair while holding their flexed right leg behind the distal thigh, taking tension off the gastrocnemius muscle. Subjects then maximally plantarflexed and dorsiflexed their right ankle nine times (see Fig. 2B and C). During the active range of motion maximal effort contractions of the major plantarflexor (soleus) and dorsiflexor (tibialis anterior) muscles of the lower limb were required to achieve endpoint ankle positions.
2.3.3. Dynamic ankle plantarflexion and dorsiflexion measurements The additional dynamic endpoint plantarflexion and dorsiflexion tests in Part B recorded the ankle motion during 30 s of maximal effort race-pace rowing on a RowPerfecte ergometer (see Fig. 2F and G). Measures of endpoint ankle plantarflexion and dorsiflexion were an average of three stroke cycles in the final 10 s of dynamic range of motion for Part B. Analysis of ergometer rowing kinematics has shown no significant differences between examination of 3 – 8 strokes (Caldwell, McNair, & Williams, 2003). 2.4. Statistical analyses Descriptive statistics for angle measurements included the mean, standard deviation and mean difference for trials 6 – 8 during active and passive range of motion tests in Part A and B, and for three strokes in the final 10 s of dynamic range of motion for Part B. Reliability was established by determining the Pearson correlation coefficient and SEM (expressed in degrees) between days one and two (Hopkins, 2000b). The Pearson correlation coefficient established the relationship between endpoint plantarflexion and dorsiflexion when measured by active and passive ankle range of motion tests. The likely ranges of the true values were provided by 95% confidence limits (CL). Significant differences in the range of motion Table 1 Subject characteristics for Part A and Part B
Age (years) Weight (kg) Height (m)
Part A
Part B
26.8 ^ 4.5 66.3 ^ 8.3 166.9 ^ 5.3
16.1 ^ 0.6 82.3 ^ 9.2 181.4 ^ 6.9
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Table 2 Mean, standard deviation, confidence limits, percent changes, SEM and Pearson correlation coefficients for between-day endpoint active and passive ankle plantarflexion and dorsiflexion measures for 10 subjects (Part A) Ankle plantarflexion Active Day one
Ankle dorsiflexion Passive
Day two
Day one
Mean ^ SD: 42.98 ^ 9.08 41.48 ^ 8.68 49.58 ^ 6.18 Mean change: 21.58 ^ 3.98 20.18 ^ 2.18 Standard error of measurement (95% confidence limits): 2.88 1.58 (1.9–5.1) (1.0–2.7) Pearson correlation (95% confidence limits): 0.90 0.94 (0.62–0.98) (0.76–0.99)
Active
Passive
Day two
Day one
Day two
Day one
Day two
49.58 ^ 6.18
16.38 ^ 7.48 20.28 ^ 2.58
16.58 ^ 7.88
22.48 ^ 8.18 20.98 ^ 2.88
23.38 ^ 8.18
tests for Part B were determined using the t-test statistics ðP ¼ 0:05Þ:
3. Results The characteristics of the 10 adults and 10 male junior competitive rowers used in Part A and B, respectively, are presented in Table 1. The competitive rowers in Part B, although younger, were taller and heavier than the male and female adults who participated in Part A. 3.1. Reliability of active, passive and dynamic ankle plantarflexion and dorsiflexion The reliability of all endpoint plantarflexion and dorsiflexion test procedures were determined in the laboratory. Table 2 provides data specific to each range of motion test on day 1 and 2 for Part A. The mean changes between days 1 and 2 ranged from 2 0.18 ^ 2.18 to 2 1.58 ^ 3.98 for the active and passive plantarflexion and dorsiflexion tests, respectively. The highest SEM calculated when repeating these tests 1 day apart using the procedures and instrumentation outlined in the study was 2.88 (95% CL ¼ 1.9– 5.18). The test – retest correlation coefficients between day 1 and 2 were all greater than 0.90 (95% CL range ¼ 0.62 – 0.99). For ergometer rowing the SEM’s in endpoint plantarflexion and dorsiflexion over three rowing stroke cycles were 1.48 (95% CL ¼ 1.0 – 2.58) and 0.78 (95% CL ¼ 0.5 – 1.28), respectively.
1.88 (1.2 2 3.2)
2.08 (1.4 2 3.6)
0.95 (0.78 2 0.99)
0.94 (0.76 2 0.99)
in passive (22.98 ^ 7.9) than active (16.48 ^ 7.4) measures for the subjects by 28.2% or 6.58 ^ 3.48 (95% CL ¼ 4.98 –8.18) (see Fig. 4). Although passive ankle plantarflexion and dorsiflexion measurements were significantly greater than active measurements the two testing conditions were highly correlated. The Pearson correlation coefficients between active and passive endpoint plantarflexion and dorsiflexion were r ¼ 0:94 (95% CL ¼ 0.85 –0.98) and r ¼ 0:90 (95% CL ¼ 0.77 – 0.96), respectively. 3.3. The relationship between active, passive and dynamic endpoint plantarflexion and dorsiflexion Endpoint plantarflexion and dorsiflexion angles during the active, passive and dynamic (ergometer rowing) tests are provided in Table 4. Compared to ergometer rowing at 38 ^ 4 strokes per minute, significantly greater endpoint plantarflexion was achieved during the active (20.5%) and passive (33.8%) ankle range of motion tests (see Fig. 5). In contrast, significantly less endpoint dorsiflexion (28.6%) was achieved during the active range of motion test compared to rowing on the ergometer. No significant difference was found between the passive endpoint dorsiflexion and rowing on the ergometer ðP ¼ 0:40Þ: Ergometer rowing was not correlated to active endpoint plantarflexion ðr ¼ 0:26Þ or passive endpoint plantarflexion ðr ¼ 0:21Þ; Table 3 Mean difference and Pearson correlation coefficients for active versus passive endpoint plantarflexion and dorsiflexion tests for 10 subjects (Part A)
3.2. The relationship between active and passive endpoint ankle plantarflexion and dorsiflexion Comparisons of the active and passive tests are presented in Table 3. The endpoint plantarflexion was significantly greater ðP ¼ 0:001Þ in passive (49.58 ^ 5.9) than active (42.18 ^ 8.6) range of motion tests for the subjects by 14.9% or 7.48 ^ 3.78 (95% CL ¼ 5.78 –9.18). Similarly, endpoint dorsiflexion was significantly greater ðP ¼ 0:001Þ
Active to passive relative difference Active to passive percent difference Pearson correlation
Ankle plantarflexion
Ankle dorsiflexion
7.48 ^ 3.78
6.58 ^ 3.48
.14.9%
.28.2%
0.94 (0.85 –0.98)
0.90 (0.77–0.96)
. , Greater during passive than during active range of motion test (95% confidence limits).
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4.1. The relationships between active, passive and dynamic endpoint ankle plantarflexion and dorsiflexion
Fig. 4. Mean and standard deviation for endpoint active and passive plantarflexion and dorsiflexion angles for 10 subjects (Part A). *Significantly different to active tests.
but was moderately correlated to active endpoint dorsiflexion ðr ¼ 0:59Þ and passive endpoint dorsiflexion ðr ¼ 0:60Þ:
4. Discussion This study provides physiotherapists and biomechanists with a reliable and valid measure of endpoint ankle plantarflexion and dorsiflexion. The results showed that passive measures of dorsiflexion provided an indication of the range of motion achieved during ergometer rowing. However, this study did not allow a determination of whether a rowers’ maximal dorsiflexion measured passively limited dorsiflexion achievable during ergometer rowing. Reliability of endpoint ankle plantarflexion and dorsiflexion measured actively and passively was determined between days, whilst reliability of dynamic ankle motion during rowing was determined between stroke cycles. Correlation analysis provided an indication as to whether active or passively measured endpoint plantarflexion and dorsiflexion provided the strongest relationship to the ankle range of motion used during ergometer rowing.
Rowers did not use their full range of plantarflexion as indicated by the significantly smaller endpoint plantarflexion results during ergometer rowing with respect to the measures taken during the active and passive tests. On average, a rower used 71.8 ^ 13.7% of their total plantarflexion measured passively during ergometer rowing. Therefore, reduced plantarflexion should not be a limiting factor in rowing technique and may not disadvantage a rower. Increasing ankle plantarflexion at the finish may allow for a small increase in stroke length for any given stroke rate. It is, however, unclear what percent change in stroke length is required to have a real effect on ergometer or on-water rowing performance as force application near the catch and finish is inefficient due to blade angle (McBride, 1998). Alternatively, rowers may not utilise 100% of their available plantarflexion at the ankle in an effort to reduce intra-stroke fluctuations in boat velocity due to displacement of the seat, and therefore, the rower’s body weight. Previous researchers (Celentano, Cortili, di-Prampero, & Cerretelli, 1974; Martin and Bernfield, 1980; Zatsiorsky and Yakunin, 1991) have agreed that the displacement of the rower’s centre of mass may directly influence the intrastroke fluctuations in boat velocity. Reductions in average boat velocity will require greater force application at the catch to increase boat velocity during the drive phase. Maintenance of a constant boat velocity or reductions in the amplitude of intra-stroke fluctuations should improve performance. Endpoint dorsiflexion was significantly greater (mean difference ¼ 7.38 ^ 7.48) during ergometer rowing compared to the active test, indicating that the active test did not adequately assess if a rower had sufficient dorsiflexion to achieve the required ankle angle at the catch position during rowing. However, the mean difference between endpoint dorsiflexion measured passively and during ergometer rowing was 1.88 ^ 6.48 ðP ¼ 0:40Þ: The two tests’ methods
Table 4 Mean, standard deviation, percent difference and correlations for endpoint plantarflexion and dorsiflexion angles measured during active, passive, and dynamic range of motion tests for 10 rowers (Part B) Endpoint ankle angle
Mean difference from ergometer rowing
Correlationa with ergometer rowing
Plantarflexion Active Passive Ergometer rowing
34.38 ^ .38 38.08 ^ 5.38 28.48 ^ 3.48
* . 5.88 ^ 6.38 * . 11.38 ^ 7.38 –
0.26 (20.44–0.77) 0.21 (20.49–0.74) –
Dorsiflexion Active Passive Ergometer rowing
18.28 ^ 8.88 23.78 ^ 7.38 25.58 ^ 7.18
* , 7.38 ^ 7.38 ,1.88 ^ 6.48 –
0.59 (20.07–0.89) 0.60 (20.05–0.89) –
Mean ^ standard deviation; ., Greater than during ergometer rowing; ,, Less than during ergometer rowing; *, Significantly different to ergometer rowing ðP , 0:05Þ: a Pearson Correlation coefficient (95% confidence limits).
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Fig. 5. Mean and standard deviation for endpoint active, passive and dynamic plantarflexion and dorsiflexion angles for 10 rowers (Part B). *Significantly greater than during rowing, ^Significantly smaller than during rowing.
were moderately correlated ðr ¼ 0:60Þ indicating the strength of the relationship between passively and dynamically measured ankle dorsiflexion in rowers. During rowing the athlete returns to the catch position with momentum and leans the trunk forward. The forward trunk position assists in transferring the rowers’ centre of gravity closer to the stern of the boat, compacting the body, which contributes to the development of greater ankle dorsiflexion. The use of body weight and gravity during the passive range of motion test simulated rowing conditions closer than during the active tests when no external forces were applied. Of the tests investigated in the current study, the passive dorsiflexion test is the best indicator of ankle dorsiflexion angles that rowers achieve during ergometer rowing. The mean difference (1.88 ^ 6.48) between passive and dynamically measured dorsiflexion falls within the determined SEM making it unclear whether the difference is a result of the measurement method (passive or dynamic) or standard measurement error. The similarity in dorsiflexion results between the passive and dynamic protocols will allow the subsequent question of whether rowers with varying passive ankle motion ability perform (e.g. total force production) differently when the foot-stretcher is positioned steeper to be examined. It is not known if a rowers’ current passive endpoint dorsiflexion ability restricts the dorsiflexion achieved at the catch position during rowing. An increase in passive endpoint dorsiflexion, achieved by implementing a longterm stretching programme, could result in increased dorsiflexion at the catch position during rowing. Increased dorsiflexion may allow the foot-stretcher angle to be steeper in the boat optimising propulsive force capabilities. It is well documented that an increase in range of motion will occur following a specific stretching programme (Bandy and Irion, 1994; Willy, Kyle, Moore, & Chleboun, 2001). However, less is known of the ability of subjects to use any
new range of motion in dynamic movement. Schache, Blanch, and Murphy (2000) reported that due to the complex neuromotor patterns involved in dynamic movements, measures of static range of motion may not provide any valuable prediction of dynamic movement. In support of this notion, Reid (2002) reported that although hamstring range of motion improved from 16.18 ^ 7.1 to 6.08 ^ 6.88 (smaller angle equals greater range of motion) following a monitored 6-week hamstring stretching programme there was no change in pelvic angle during ergometer rowing. Should further research find additional ankle range of motion to be an advantage to rowers, the rowing sport science and sport medicine support team will need to monitor the development of this range of motion and ensure rowers utilise the additional motion in the rowing stroke cycle through technique coaching. A limitation of the current study was that active and passive measures of plantarflexion and dorsiflexion were compared to movements during ergometer rowing rather than during on-water rowing. The recording of reliable and valid kinematic data from on-water rowing is difficult, primarily due to the inability to adequately control for perspective error. Research by Weise (1997) has investigated the effectiveness of attaching a camera to the rowing boat directly and via a Mobile Video Platform. The Mobile Video Platform did not provide valid kinematic results for the investigation of on-water rowing kinematics, however, when the camera was mounted directly to the boat substantial reductions in camera movement relative to spatial coordinates were observed (Weise, 1997). Videoing from the shoreline whilst crews row back and forth parallel to the camera (Stuble, Erdman, & Stoner, 1980) or from a coach boat attempting to travel at the same speed as the rowing boat (Dawson, Lockwook, Wilson, & Freeman, 1998; Soper, Hume, Reid, & Tonks, 2002a,b) are other video-based methods. Stuble et al. (1980) panned a camera
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through a 208 angle from the shore-line and concluded that the error was relatively small and subsequently was ignored. One of the more difficult issues to solve is that the ankle is not always visible from the side as the feet are positioned below the top edge of the boat. Marking the ankle position on the boat does not allow accurate knowledge of total dorsiflexion or plantarflexion at the catch and finish, as ankle movement cannot be monitored. Using a telemetered electrogoniometer signal from the ankle may be a more valid and reliable method of recording on-water ankle and whole body kinematics.
and dorsiflexion tests to assess rowers’ ankle motion due to the high reliability, validity and easier measurement procedures compared with dynamic measurement.
4.2. Reliability of active, passive and dynamic ankle plantarflexion and dorsiflexion
References
The instrumentation and procedures used to determine endpoint active and passive plantarflexion and dorsiflexion in this study were highly reliable and provide physiotherapists and biomechanists with reliable protocols to monitor and detect change in ankle range of motion with knee joint flexion (i.e. soleus flexibility). The within-subject variation between day one and day two, expressed as the SEM, ranged from 1.5 to 2.88. The SEM in endpoint plantarflexion and dorsiflexion for three rowing stroke cycles was also very small indicating high reliability in dynamic endpoint plantarflexion and dorsiflexion. Endpoint dorsiflexion occurred near the ‘catch’, or start position of the power phase of the rowing stroke when the ankles, knees and hips were in maximal flexion, placing maximal stretch on the soleus muscle. The finish position completes the drive phase where endpoint plantarflexion at the ankle occurs as the knees and hip reach their peak extension. Although not expected, the active range of motion tests completed prior to the passive range of motion tests may have influenced the results. Future research might consider using a balanced cross-over design to remove the effect of test order.
5. Conclusions The protocols used in this study provided reliable assessment of endpoint plantarflexion and dorsiflexion measured passively, actively and dynamically. Passive and active tests of endpoint plantarflexion and dorsiflexion were highly correlated, and passive tests produced the greatest endpoint positions. Dorsiflexion measured passively appeared to be the most valid measure of dorsiflexion achieved dynamically during ergometer rowing. The methods appeared to be sensitive enough to use passively measured dorsiflexion as a potential covariate in future foot-stretcher optimisation studies. Further research is needed to determine endpoint plantarflexion and dorsiflexion used during on-water rowing. Physiotherapists should use passive plantarflexion
Acknowledgements Thanks are given to the subjects in the study. Sport Science New Zealand and the Auckland University of Technology funded this study.
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C. Soper et al. / Physical Therapy in Sport 5 (2004) 75–83 Soper, C., Hume, P. A., Reid, D., & Tonks, R (2002a). The effectiveness of the Goggle Training System and verbal feedback in changing on-water rowing technique, submitted for publication. Soper, C., Hume, P. A. Reid, D. Tonks, R (2002). The effectiveness of the Goggles Training System as a coaching tool in changing pelvis angle at the catch during on-water rowing. Paper presented at the XXth International Symposium on Biomechanics in Sports, Caceres, Spain. Stuble, K. R., Erdman, A. G., Stoner, L. J (1980). Kinematic analysis of rowing and rowing simulators. Paper presented at the International Conference on Medical Devices and Sports Equipment, San Francisco, CA. Tabrizi, P., McIntyre, W. M., Quesnel, M. B., & Howard, A. W. (2000). Limited dorsiflexion predisposes to injuries of the ankle in children. Journal of Bone and Joint Surgery (Br), 82B, 1103–1106.
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Taylor, D. C., Dalton, J. D., Seaber, A. V., & Garrett, W. E. (1990). Viscoelastic properties of muscle-tendon units. The biomechanical effects of stretching. American Journal of Sports Medicine, 18, 300– 309. Weise, M. J (1997). Accuracy assessment of a mobile video plateform used for kinematic analysis of rowing. Unpublished Master of Science Thesis, Michigan State University, Michigan. Willy, R. W., Kyle, B. A., Moore, S. A., & Chleboun, G. S. (2001). Effect of cessation and resumption of static hamstring muscle stretching on joint range of motion. Journal of Orthopaedic and Sports Physical Therapy, 31, 138–144. Zatsiorsky, V. M., & Yakunin, N. (1991). Mechanics and biomechanics of rowing: a review. International Journal of Sport Biomechanics, 7, 229– 281.
Original research
Reliable passive ankle range of motion measures correlate to ankle motion achieved during ergometer rowing Clara Sopera,*, Duncan Reidb, Patria Anne Humea a
New Zealand Institute of Sport and Recreation Research, Faculty of Health, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand b Division of Rehabilitation and Occupational Studies, Faculty of Health, Auckland University of Technology, Auckland, New Zealand Received 6 July 2003; revised 18 November 2003; accepted 24 November 2003
Abstract Objectives. To determine whether ankle range of motion during ergometer rowing is best approximated by reliable active or passive plantarflexion and dorsiflexion tests. Design. Repeated measures and cross-sectional. Setting. In a laboratory setting, an electrogoniometer was attached to each subjects’ left ankle during active, passive and dynamic ankle range of motion tests. Participants. Three adult males and seven adult females participated in part A of the study. Ten junior male rowers took part in Part B of the study. Main outcome measures. Endpoint plantarflexion and dorsiflexion. Results. Mean active and passive endpoint plantarflexion were significantly greater than mean plantarflexion achieved during ergometer rowing. In comparison, endpoint dorsiflexion measured passively and during ergometer rowing were not significantly different ðP ¼ 0:40Þ; and moderately correlated (r ¼ 0:60; 95% CI ¼ 20.05 – 0.89). The active and passive ankle range of motion tests were reliable (r ¼ 0:90 – 0:95; highest SEM ¼ 2.88, 95% CI ¼ 1.9 – 5.18). The passive tests produced significantly greater mean endpoint ankle plantarflexion (7.48 ^ 3.78, 14.9%) and dorsiflexion (6.58 ^ 3.78, 28.2%) than the active tests. Conclusions. Compared to dynamic measurement, passive plantarflexion and dorsiflexion are the preferred tests to assess rowers’ ankle motion due to the high reliability, validity and easier measurement procedures. q 2004 Elsevier Ltd. All rights reserved. Keywords: Rowing; Ergometer; Dorsiflexion; Plantarflexion; reliability
1. Introduction The ability to measure endpoint ankle plantarflexion and dorsiflexion reliably and know their relationship to ankle range of motion during a rowing stroke cycle is important to physiotherapists and biomechanists working with rowers. Physiotherapists perform all musculoskeletal screening of rowers in the Rowing New Zealand High Performance Programme. Screening results are applicable to both injury prevention and performance enhancement strategies. Physiotherapists can utilise range of motion information for injury prevention (Pope, Herbert, & Kirwan, 1988; Tabrizi, McIntyre, Quesnel, & Howard, 2000) and rehabilitation programmes, whilst the biomechanist and rowing * Corresponding author. Tel.: 9-9179999. E-mail address: [email protected] (C. Soper). 1466-853X/$ - see front matter q 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.ptsp.2003.11.006
coach require this information to monitor and ensure that changes to the set up of the boat are likely to be within the physical capabilities of the rower. The ability of the rower to plantarflex their ankles may increase stroke length at the end of drive phase and allow for a smooth withdrawal of the blades from the water. Similarly, the ability to achieve a ‘tight’ catch position with the shank vertical at the start of the drive phase is considered a positive attribute of the rowing stroke cycle. A tight catch allows a longer stroke length to be achieved (greater sternward position of oar handles) and the rower is placed in a powerful position (ankle, knee and hip flexion) to apply propulsive forces to the foot-stretcher and oar handle(s). The foot-stretcher is set at a fixed angle in a rowing boat, chosen for comfort rather than with regard to any mechanical advantage it may afford. It has previously
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been suggested (Hume, Soper, Joe, Williams, Aitchison, & Gunn, 2000) that a steeper (more vertical) foot-stretcher angle may allow the application of greater horizontal propulsive force to the boat. However, a rowers’ soleus muscle length will limit the shank and upper leg positions achievable at the catch, as a steeper foot-stretcher angle requires greater dorsiflexion for the same amount of knee flexion. Various protocols and equipment for testing ankle range of motion are currently used; however, determining the procedure that reliably approximates the range of motion used during rowing is essential. Before further foot-stretcher optimisation studies are completed, research indicating the most valid and reliable ankle range of motion test is necessary. During ergometer rowing, rowers sit on a sliding seat with their forefoot of secured via straps to the foot-stretcher. Forces are applied to the ergometer during the drive phase of the rowing stroke cycle via the hands on the oar(s) and the feet on the foot-stretcher as the ankle moves from dorsiflexion to plantarflexion. The drive phase is initiated in the ‘catch’ position and completed in the ‘finish’ position (see Fig. 1). At the catch position, the blade(s) catch or make contact with the water. The rower’s ankles, knees and hips are in a flexed position preparing for the drive phase. The drive phase is initiated as the legs extend moving the pelvis towards the bow of the boat. The finish position occurs when the ankles, knees, and trunk are extended and the blades are withdrawn from the water. Research (Halliday, Zavatsky, Andrews, & Hase, 2001; Hume et al., 2000) has reported ankle range of motion during ergometer rowing, however, it is not known which clinical-setting range of motion test best predicts ankle movement during rowing. Whether a rowers’ endpoint ankle plantarflexion or dorsiflexion should be measured passively or actively needs to be considered. Passive stretching refers to a stretch that requires no muscular contraction—rather an end range of motion is gained by an external force being applied to the limb. Active stretching is
achieved through the rower contracting appropriate muscles to produce a stretch. Previous research has reported that active range of motion tests generally produce smaller absolute ranges of motion, and that these are more closely correlated to sports movements than passive tests (Iashvili, 1983). Furthermore, Iashvili (1983) reported that active and passive ranges of motion tests were only moderately correlated at the shoulder, hip, knee and ankle ðr ¼ 0:61 – 0:73Þ: A rowers’ ankle range of motion is currently measured during regular musculoskeletal screening sessions to ensure that the desired range of movements during each stroke cycle can be achieved. No published research has shown whether ankle range of motion tests for rowers should be conducted under active or passive measurement conditions. In order to identify whether a rowers’ endpoint ankle motion should be measured actively or passively, analysis was required to establish the test procedure that best predicted ankle motion during ergometer rowing. Therefore, the aims of this study were to determine: (1) the reliability of an active and passive endpoint ankle plantarflexion and dorsiflexion test in a clinical setting; (2) the relationship between active and passive endpoint ankle plantarflexion and dorsiflexion; and (3) whether ankle range of ankle motion achieved during ergometer rowing was best approximated by a rowers’ active or passively measured plantarflexion and dorsiflexion.
2. Methods Reliability of a test refers to the ability of the subjects to reproduce the measure of performance when the test is repeatedly administered (Schabort, Hawley, Hopkins, & Blum, 1999). A reliable test is one that has small changes in the mean, small within-individual variation (Standard Error of the Mean, (SEM)) and a high test-retest correlation
Fig. 1. Catch and finish positions during rowing.
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between the repeated tests (Schabort et al., 1999). A reliable test is typically reported when the SEM is less than 2% or less than the smallest worthwhile detectable change (Hopkins, 2000a). Reliability of the passive and active ankle plantarflexion and dorsiflexion tests were determined in Part A of this investigation. Part B investigated the relationship between active, passive and dynamic (ergometer rowing) ankle motion. 2.1. Subjects A convenience sample of three male and seven female adults (26.0 ^ 4.7 years, 167.1 ^ 5.3 cm tall, 66.3 ^ 8.3 kg) completed Part A of the investigation. Ten injury-free junior male competitive junior rowers (16.0 ^ 0.0 years, 180.2 ^ 6.5 cm tall, 82.0 ^ 9.5 kg) completed Part B. Ethical approval was gained from the Auckland University of Technology Ethics Committee. All subjects were informed of the procedures and gave their written consent. The sample size was considered adequate to detect a small effect size for ankle range of motion.
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2.2. Equipment A registered physiotherapist with 22 years experience marked the proximal and distal end of a straight line between the lateral malleolus and the lateral epicondyle of the fibula. The wired end of a dual axis electrogoniometer (Applied Measurement Australia) was positioned horizontally directly below the lateral malleolus of the right leg. The arm of the electrogoniometer was aligned with the lateral epicondyle of the fibula (see Fig. 2A). The electrogoniometer was wired to enable real time data collection at 100 Hz via a custom designed LabVIEWe data collection system. The electrogoniometer was not removed from each subjects’ ankle until all plantarflexion and dorsiflexion measurements were recorded. All plantarflexion and dorsiflexion angles were represented with respect to the subjects’ ankle position during standing in the anatomical position (see Fig. 2A). Plantarflexion and dorsiflexion were classified as movements of the dorsal surface of the foot away from the shin (pointing) and towards the shin respectively (see Fig. 3). Prior to all data collection the electrogoniometer was calibrated using zero
Fig. 2. Data collection procedures for passive, active and dynamic plantarflexion and dorsiflexion.
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Fig. 3. Plantarflexion and dorsifexion calculation from the neutral ankle position.
and 458 on a plastic goniometer. Custom designed LabViewe analysis programmes provided endpoint angle data following data collection.
2.3.2. Passive ankle plantarflexion and dorsiflexion measurements Passive ankle plantarflexion (see Fig. 2D) was measured with the subject standing in a traditional quadriceps stretch position (right knee flexed with foot held by the right hand close to the buttock). The right knee was moved anteriorly to take tension off the hip flexors. The subjects applied selfinduced pressure to the dorsal surface of the foot by the hand, to induce maximum plantarflexion, then relaxed the pressure and repeated the sequence eight times. Passive ankle dorsiflexion (see Fig. 2E) was measured with the subject standing facing a wall with their feet parallel and shoulder-width apart. The subjects flexed their knees to as much as possible, aligning the kneecap directly over the first toes as far as possible while keeping the heels on the ground. The subjects then extended their knees and repeated the knee flexion exercise a further eight times. Gravity and body weight provided assistance during the dorsiflexion test.
2.3. Procedures The subjects in Part A were required to attend testing on two consecutive days at the same time of day for measurement of active then passive range of motion of the right ankle. The rowers in Part B completed active, passive and dynamic range of ankle motion testing on a single day (the same order of tests for each rower). During ergometer rowing the rowers rowed at their race pace. Range of motion during rowing was collected from the right ankle. Active then passive ankle ranges of motion were recorded to ensure that the passive tests did not affect active range of motion. The plantarflexion and dorsiflexion tests were completed in a random order for each type of test. Nine stretches for each test were completed to ensure maximal achievable range of motion was achieved in stretches 6 –9 (McNair and Stanley, 1996; Taylor, Dalton, & Seaber, 1990). In all tests, the subjects were asked to reach maximum endpoint range of motion as determined by reaching a maximum tolerable position for the active dorsiflexion test and the active and passive plantarflexion tests, and just prior to the heels lifting off the ground for the passive dorsiflexion test. During all dorsiflexion movements the knee was flexed in order to place the stretch on the soleus muscle as occurs during the rowing stroke cycle. 2.3.1. Active ankle plantarflexion and dorsiflexion measurements The subjects sat up-right in a stable chair while holding their flexed right leg behind the distal thigh, taking tension off the gastrocnemius muscle. Subjects then maximally plantarflexed and dorsiflexed their right ankle nine times (see Fig. 2B and C). During the active range of motion maximal effort contractions of the major plantarflexor (soleus) and dorsiflexor (tibialis anterior) muscles of the lower limb were required to achieve endpoint ankle positions.
2.3.3. Dynamic ankle plantarflexion and dorsiflexion measurements The additional dynamic endpoint plantarflexion and dorsiflexion tests in Part B recorded the ankle motion during 30 s of maximal effort race-pace rowing on a RowPerfecte ergometer (see Fig. 2F and G). Measures of endpoint ankle plantarflexion and dorsiflexion were an average of three stroke cycles in the final 10 s of dynamic range of motion for Part B. Analysis of ergometer rowing kinematics has shown no significant differences between examination of 3 – 8 strokes (Caldwell, McNair, & Williams, 2003). 2.4. Statistical analyses Descriptive statistics for angle measurements included the mean, standard deviation and mean difference for trials 6 – 8 during active and passive range of motion tests in Part A and B, and for three strokes in the final 10 s of dynamic range of motion for Part B. Reliability was established by determining the Pearson correlation coefficient and SEM (expressed in degrees) between days one and two (Hopkins, 2000b). The Pearson correlation coefficient established the relationship between endpoint plantarflexion and dorsiflexion when measured by active and passive ankle range of motion tests. The likely ranges of the true values were provided by 95% confidence limits (CL). Significant differences in the range of motion Table 1 Subject characteristics for Part A and Part B
Age (years) Weight (kg) Height (m)
Part A
Part B
26.8 ^ 4.5 66.3 ^ 8.3 166.9 ^ 5.3
16.1 ^ 0.6 82.3 ^ 9.2 181.4 ^ 6.9
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Table 2 Mean, standard deviation, confidence limits, percent changes, SEM and Pearson correlation coefficients for between-day endpoint active and passive ankle plantarflexion and dorsiflexion measures for 10 subjects (Part A) Ankle plantarflexion Active Day one
Ankle dorsiflexion Passive
Day two
Day one
Mean ^ SD: 42.98 ^ 9.08 41.48 ^ 8.68 49.58 ^ 6.18 Mean change: 21.58 ^ 3.98 20.18 ^ 2.18 Standard error of measurement (95% confidence limits): 2.88 1.58 (1.9–5.1) (1.0–2.7) Pearson correlation (95% confidence limits): 0.90 0.94 (0.62–0.98) (0.76–0.99)
Active
Passive
Day two
Day one
Day two
Day one
Day two
49.58 ^ 6.18
16.38 ^ 7.48 20.28 ^ 2.58
16.58 ^ 7.88
22.48 ^ 8.18 20.98 ^ 2.88
23.38 ^ 8.18
tests for Part B were determined using the t-test statistics ðP ¼ 0:05Þ:
3. Results The characteristics of the 10 adults and 10 male junior competitive rowers used in Part A and B, respectively, are presented in Table 1. The competitive rowers in Part B, although younger, were taller and heavier than the male and female adults who participated in Part A. 3.1. Reliability of active, passive and dynamic ankle plantarflexion and dorsiflexion The reliability of all endpoint plantarflexion and dorsiflexion test procedures were determined in the laboratory. Table 2 provides data specific to each range of motion test on day 1 and 2 for Part A. The mean changes between days 1 and 2 ranged from 2 0.18 ^ 2.18 to 2 1.58 ^ 3.98 for the active and passive plantarflexion and dorsiflexion tests, respectively. The highest SEM calculated when repeating these tests 1 day apart using the procedures and instrumentation outlined in the study was 2.88 (95% CL ¼ 1.9– 5.18). The test – retest correlation coefficients between day 1 and 2 were all greater than 0.90 (95% CL range ¼ 0.62 – 0.99). For ergometer rowing the SEM’s in endpoint plantarflexion and dorsiflexion over three rowing stroke cycles were 1.48 (95% CL ¼ 1.0 – 2.58) and 0.78 (95% CL ¼ 0.5 – 1.28), respectively.
1.88 (1.2 2 3.2)
2.08 (1.4 2 3.6)
0.95 (0.78 2 0.99)
0.94 (0.76 2 0.99)
in passive (22.98 ^ 7.9) than active (16.48 ^ 7.4) measures for the subjects by 28.2% or 6.58 ^ 3.48 (95% CL ¼ 4.98 –8.18) (see Fig. 4). Although passive ankle plantarflexion and dorsiflexion measurements were significantly greater than active measurements the two testing conditions were highly correlated. The Pearson correlation coefficients between active and passive endpoint plantarflexion and dorsiflexion were r ¼ 0:94 (95% CL ¼ 0.85 –0.98) and r ¼ 0:90 (95% CL ¼ 0.77 – 0.96), respectively. 3.3. The relationship between active, passive and dynamic endpoint plantarflexion and dorsiflexion Endpoint plantarflexion and dorsiflexion angles during the active, passive and dynamic (ergometer rowing) tests are provided in Table 4. Compared to ergometer rowing at 38 ^ 4 strokes per minute, significantly greater endpoint plantarflexion was achieved during the active (20.5%) and passive (33.8%) ankle range of motion tests (see Fig. 5). In contrast, significantly less endpoint dorsiflexion (28.6%) was achieved during the active range of motion test compared to rowing on the ergometer. No significant difference was found between the passive endpoint dorsiflexion and rowing on the ergometer ðP ¼ 0:40Þ: Ergometer rowing was not correlated to active endpoint plantarflexion ðr ¼ 0:26Þ or passive endpoint plantarflexion ðr ¼ 0:21Þ; Table 3 Mean difference and Pearson correlation coefficients for active versus passive endpoint plantarflexion and dorsiflexion tests for 10 subjects (Part A)
3.2. The relationship between active and passive endpoint ankle plantarflexion and dorsiflexion Comparisons of the active and passive tests are presented in Table 3. The endpoint plantarflexion was significantly greater ðP ¼ 0:001Þ in passive (49.58 ^ 5.9) than active (42.18 ^ 8.6) range of motion tests for the subjects by 14.9% or 7.48 ^ 3.78 (95% CL ¼ 5.78 –9.18). Similarly, endpoint dorsiflexion was significantly greater ðP ¼ 0:001Þ
Active to passive relative difference Active to passive percent difference Pearson correlation
Ankle plantarflexion
Ankle dorsiflexion
7.48 ^ 3.78
6.58 ^ 3.48
.14.9%
.28.2%
0.94 (0.85 –0.98)
0.90 (0.77–0.96)
. , Greater during passive than during active range of motion test (95% confidence limits).
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4.1. The relationships between active, passive and dynamic endpoint ankle plantarflexion and dorsiflexion
Fig. 4. Mean and standard deviation for endpoint active and passive plantarflexion and dorsiflexion angles for 10 subjects (Part A). *Significantly different to active tests.
but was moderately correlated to active endpoint dorsiflexion ðr ¼ 0:59Þ and passive endpoint dorsiflexion ðr ¼ 0:60Þ:
4. Discussion This study provides physiotherapists and biomechanists with a reliable and valid measure of endpoint ankle plantarflexion and dorsiflexion. The results showed that passive measures of dorsiflexion provided an indication of the range of motion achieved during ergometer rowing. However, this study did not allow a determination of whether a rowers’ maximal dorsiflexion measured passively limited dorsiflexion achievable during ergometer rowing. Reliability of endpoint ankle plantarflexion and dorsiflexion measured actively and passively was determined between days, whilst reliability of dynamic ankle motion during rowing was determined between stroke cycles. Correlation analysis provided an indication as to whether active or passively measured endpoint plantarflexion and dorsiflexion provided the strongest relationship to the ankle range of motion used during ergometer rowing.
Rowers did not use their full range of plantarflexion as indicated by the significantly smaller endpoint plantarflexion results during ergometer rowing with respect to the measures taken during the active and passive tests. On average, a rower used 71.8 ^ 13.7% of their total plantarflexion measured passively during ergometer rowing. Therefore, reduced plantarflexion should not be a limiting factor in rowing technique and may not disadvantage a rower. Increasing ankle plantarflexion at the finish may allow for a small increase in stroke length for any given stroke rate. It is, however, unclear what percent change in stroke length is required to have a real effect on ergometer or on-water rowing performance as force application near the catch and finish is inefficient due to blade angle (McBride, 1998). Alternatively, rowers may not utilise 100% of their available plantarflexion at the ankle in an effort to reduce intra-stroke fluctuations in boat velocity due to displacement of the seat, and therefore, the rower’s body weight. Previous researchers (Celentano, Cortili, di-Prampero, & Cerretelli, 1974; Martin and Bernfield, 1980; Zatsiorsky and Yakunin, 1991) have agreed that the displacement of the rower’s centre of mass may directly influence the intrastroke fluctuations in boat velocity. Reductions in average boat velocity will require greater force application at the catch to increase boat velocity during the drive phase. Maintenance of a constant boat velocity or reductions in the amplitude of intra-stroke fluctuations should improve performance. Endpoint dorsiflexion was significantly greater (mean difference ¼ 7.38 ^ 7.48) during ergometer rowing compared to the active test, indicating that the active test did not adequately assess if a rower had sufficient dorsiflexion to achieve the required ankle angle at the catch position during rowing. However, the mean difference between endpoint dorsiflexion measured passively and during ergometer rowing was 1.88 ^ 6.48 ðP ¼ 0:40Þ: The two tests’ methods
Table 4 Mean, standard deviation, percent difference and correlations for endpoint plantarflexion and dorsiflexion angles measured during active, passive, and dynamic range of motion tests for 10 rowers (Part B) Endpoint ankle angle
Mean difference from ergometer rowing
Correlationa with ergometer rowing
Plantarflexion Active Passive Ergometer rowing
34.38 ^ .38 38.08 ^ 5.38 28.48 ^ 3.48
* . 5.88 ^ 6.38 * . 11.38 ^ 7.38 –
0.26 (20.44–0.77) 0.21 (20.49–0.74) –
Dorsiflexion Active Passive Ergometer rowing
18.28 ^ 8.88 23.78 ^ 7.38 25.58 ^ 7.18
* , 7.38 ^ 7.38 ,1.88 ^ 6.48 –
0.59 (20.07–0.89) 0.60 (20.05–0.89) –
Mean ^ standard deviation; ., Greater than during ergometer rowing; ,, Less than during ergometer rowing; *, Significantly different to ergometer rowing ðP , 0:05Þ: a Pearson Correlation coefficient (95% confidence limits).
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Fig. 5. Mean and standard deviation for endpoint active, passive and dynamic plantarflexion and dorsiflexion angles for 10 rowers (Part B). *Significantly greater than during rowing, ^Significantly smaller than during rowing.
were moderately correlated ðr ¼ 0:60Þ indicating the strength of the relationship between passively and dynamically measured ankle dorsiflexion in rowers. During rowing the athlete returns to the catch position with momentum and leans the trunk forward. The forward trunk position assists in transferring the rowers’ centre of gravity closer to the stern of the boat, compacting the body, which contributes to the development of greater ankle dorsiflexion. The use of body weight and gravity during the passive range of motion test simulated rowing conditions closer than during the active tests when no external forces were applied. Of the tests investigated in the current study, the passive dorsiflexion test is the best indicator of ankle dorsiflexion angles that rowers achieve during ergometer rowing. The mean difference (1.88 ^ 6.48) between passive and dynamically measured dorsiflexion falls within the determined SEM making it unclear whether the difference is a result of the measurement method (passive or dynamic) or standard measurement error. The similarity in dorsiflexion results between the passive and dynamic protocols will allow the subsequent question of whether rowers with varying passive ankle motion ability perform (e.g. total force production) differently when the foot-stretcher is positioned steeper to be examined. It is not known if a rowers’ current passive endpoint dorsiflexion ability restricts the dorsiflexion achieved at the catch position during rowing. An increase in passive endpoint dorsiflexion, achieved by implementing a longterm stretching programme, could result in increased dorsiflexion at the catch position during rowing. Increased dorsiflexion may allow the foot-stretcher angle to be steeper in the boat optimising propulsive force capabilities. It is well documented that an increase in range of motion will occur following a specific stretching programme (Bandy and Irion, 1994; Willy, Kyle, Moore, & Chleboun, 2001). However, less is known of the ability of subjects to use any
new range of motion in dynamic movement. Schache, Blanch, and Murphy (2000) reported that due to the complex neuromotor patterns involved in dynamic movements, measures of static range of motion may not provide any valuable prediction of dynamic movement. In support of this notion, Reid (2002) reported that although hamstring range of motion improved from 16.18 ^ 7.1 to 6.08 ^ 6.88 (smaller angle equals greater range of motion) following a monitored 6-week hamstring stretching programme there was no change in pelvic angle during ergometer rowing. Should further research find additional ankle range of motion to be an advantage to rowers, the rowing sport science and sport medicine support team will need to monitor the development of this range of motion and ensure rowers utilise the additional motion in the rowing stroke cycle through technique coaching. A limitation of the current study was that active and passive measures of plantarflexion and dorsiflexion were compared to movements during ergometer rowing rather than during on-water rowing. The recording of reliable and valid kinematic data from on-water rowing is difficult, primarily due to the inability to adequately control for perspective error. Research by Weise (1997) has investigated the effectiveness of attaching a camera to the rowing boat directly and via a Mobile Video Platform. The Mobile Video Platform did not provide valid kinematic results for the investigation of on-water rowing kinematics, however, when the camera was mounted directly to the boat substantial reductions in camera movement relative to spatial coordinates were observed (Weise, 1997). Videoing from the shoreline whilst crews row back and forth parallel to the camera (Stuble, Erdman, & Stoner, 1980) or from a coach boat attempting to travel at the same speed as the rowing boat (Dawson, Lockwook, Wilson, & Freeman, 1998; Soper, Hume, Reid, & Tonks, 2002a,b) are other video-based methods. Stuble et al. (1980) panned a camera
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through a 208 angle from the shore-line and concluded that the error was relatively small and subsequently was ignored. One of the more difficult issues to solve is that the ankle is not always visible from the side as the feet are positioned below the top edge of the boat. Marking the ankle position on the boat does not allow accurate knowledge of total dorsiflexion or plantarflexion at the catch and finish, as ankle movement cannot be monitored. Using a telemetered electrogoniometer signal from the ankle may be a more valid and reliable method of recording on-water ankle and whole body kinematics.
and dorsiflexion tests to assess rowers’ ankle motion due to the high reliability, validity and easier measurement procedures compared with dynamic measurement.
4.2. Reliability of active, passive and dynamic ankle plantarflexion and dorsiflexion
References
The instrumentation and procedures used to determine endpoint active and passive plantarflexion and dorsiflexion in this study were highly reliable and provide physiotherapists and biomechanists with reliable protocols to monitor and detect change in ankle range of motion with knee joint flexion (i.e. soleus flexibility). The within-subject variation between day one and day two, expressed as the SEM, ranged from 1.5 to 2.88. The SEM in endpoint plantarflexion and dorsiflexion for three rowing stroke cycles was also very small indicating high reliability in dynamic endpoint plantarflexion and dorsiflexion. Endpoint dorsiflexion occurred near the ‘catch’, or start position of the power phase of the rowing stroke when the ankles, knees and hips were in maximal flexion, placing maximal stretch on the soleus muscle. The finish position completes the drive phase where endpoint plantarflexion at the ankle occurs as the knees and hip reach their peak extension. Although not expected, the active range of motion tests completed prior to the passive range of motion tests may have influenced the results. Future research might consider using a balanced cross-over design to remove the effect of test order.
5. Conclusions The protocols used in this study provided reliable assessment of endpoint plantarflexion and dorsiflexion measured passively, actively and dynamically. Passive and active tests of endpoint plantarflexion and dorsiflexion were highly correlated, and passive tests produced the greatest endpoint positions. Dorsiflexion measured passively appeared to be the most valid measure of dorsiflexion achieved dynamically during ergometer rowing. The methods appeared to be sensitive enough to use passively measured dorsiflexion as a potential covariate in future foot-stretcher optimisation studies. Further research is needed to determine endpoint plantarflexion and dorsiflexion used during on-water rowing. Physiotherapists should use passive plantarflexion
Acknowledgements Thanks are given to the subjects in the study. Sport Science New Zealand and the Auckland University of Technology funded this study.
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