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Lower leg musculoskeletal geometry and sprint performance
Gait & Posture 34 (2011) 138–141
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Short communication
Lower leg musculoskeletal geometry and sprint performance Kiros Karamanidis a,*, Kirsten Albracht a, Bjoern Braunstein a,b, Maria Moreno Catala a, Jan-Peter Goldmann a,b, Gert-Peter Bru¨ggemann a a b
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Am Sportpark Mu¨ngersdorf 6, 50933 Cologne, Germany German Research Centre of Elite Sport Cologne, Germany
A R T I C L E I N F O
A B S T R A C T
Article history: Received 7 July 2010 Received in revised form 2 March 2011 Accepted 7 March 2011
The purpose of this study was to investigate whether sprint performance is related to lower leg musculoskeletal geometry within a homogeneous group of highly trained 100-m sprinters. Using a cluster analysis, eighteen male sprinters were divided into two groups based on their personal best (fast: N = 11, 10.30 0.07 s; slow: N = 7, 10.70 0.08 s). Calf muscular fascicle arrangement and Achilles tendon moment arms (calculated by the gradient of tendon excursion versus ankle joint angle) were analyzed for each athlete using ultrasonography. Achilles tendon moment arm, foot and ankle skeletal geometry, fascicle arrangement as well as the ratio of fascicle length to Achilles tendon moment arm showed no significant (p > 0.05) correlation with sprint performance, nor were there any differences in the analyzed musculoskeletal parameters between the fast and slow sprinter group. Our findings provide evidence that differences in sprint ability in world-class athletes are not a result of differences in the geometrical design of the lower leg even when considering both skeletal and muscular components. ß 2011 Elsevier B.V. All rights reserved.
Keywords: Achilles tendon moment arm Fascicle length Foot geometry Sprinting
1. Introduction In sprinting, it is essential for the calf musculature to generate high shortening velocities in order to accelerate rapidly during the first strides and to achieve high locomotor velocities [1–3]. It is suggested that longer fascicles are preferable for sprinters because of their greater number of sarcomeres in series [1]. This is because for a given muscle-tendon unit shortening velocity, such as during sprinting, each individual sarcomere can shorten more slowly, thereby increasing overall muscle force generation capacity [4]. In addition, longer fascicles will produce more power, and at a higher shortening velocity increase the rates at which force can be applied to the ground, thereby contributing to better sprinting ability. Although longer muscle fascicles have been observed in the calf musculature of human sprinters when compared to distance runners [5] triceps surae muscle fascicle length is not [6] or only moderately [1,2] linked to sprint performance. The amount of change in muscle fascicle length that occurs as a joint rotates depends on the muscle moment arm [4] and, therefore, it is also important to consider muscle fascicle length in relation to tendon moment arm. Lee and Piazza [3] recently showed that sprinters have smaller Achilles tendon moment arms and longer fascicles of the gastrocnemius lateralis muscle (GL) than non-sprinters, consequently leading to a greater fascicle length to moment
* Corresponding author. Tel.: +49 221 4982 5680; fax: +49 221 4973454. E-mail addresses: [email protected], [email protected] (K. Karamanidis). 0966-6362/$ – see front matter ß 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2011.03.009
arm ratio for sprinters. Using a model of the lower leg, they reported that these properties could enhance sprint performance by allowing the calf musculature to operate at a more favorable force–length–velocity-relationship during ground contact, thereby increasing sprint ability [3]. The simulations showed that as Achilles tendon moment arm decreased by 10 mm, horizontal acceleration impulse increased by about 6 Ns [3]. Although the influence of tendon moment arm on forward impulse decreases with increasing sprint velocity [3], thus making a clear statement about the expected overall improvement in 100-m sprint time that might result from such changes in moment arm difficult, the above findings provide strong evidence of the importance of Achilles tendon moment arm for sprint performance, in particular for the acceleration phase. However, the effect of Achilles tendon moment arm on sprinting has not yet been experimentally investigated and an analysis of lower leg musculoskeletal geometry in a group of highly trained 100-m sprint specialists is missing. Such information is necessary to increase our understanding of musculoskeletal function in elite athletes. Thus, the purpose of this study was to investigate whether sprint performance is related to lower leg musculoskeletal geometry within a homogeneous group of elite male 100-m sprinters. 2. Method Eighteen 100-m male sprinters (height: 182 5 cm; body mass: 77 5 kg; age: 21 4 yrs) with a personal best ranging from 10.14 to 10.76 s (10.42 0.21 s) participated in this study. Approval was obtained from the university’s committee for the protection of human subjects and informed consent was given by all subjects.
K. Karamanidis et al. / Gait & Posture 34 (2011) 138–141
Slow sprinters (N = 7)
4.2 0.6 7.6 3.3 14.3 2.3 6.0 0.9 22.9 2.7 1.84 0.91
4.2 0.8p: 0.88 7.6 1.6p: 0.98 15.0 2.3p: 0.54 6.0 0.9p: 0.97 22.2 4.4p: 0.69 1.88 0.60p: 0.91
1.43 0.27
1.49 0.48p:
26.7 1.6 21.2 1.3
27.3 0.9p: 21.7 0.9p:
39.9 2.1
4.5 4.0 3.5 3.0 2.5
0.73
0.26 0.33
p: 0.26
7.6 0.2 10.1 0.5p: 0.12 5.34 1.02p: 0.57 p: 0.09
41.2 1.2
GL: musculus gastrocnemius lateralis; GM: musculus gastrocnemius medialis; 1st MTH: first metatarsal head; DP: distal to proximal. DP distance heel to toe: distance between the most posterior and most anterior boundary of the foot, i.e., maximal distance where the point of force application can be moved under the foot in the sagittal plane. The midpoint of the malleolii was defined as the midpoint of the line connecting malleolus lateralis and medialis using the individual sketches of the foot (the vertical projection of both bony landmarks was drawn).
The moment arm of the Achilles tendon was obtained for each athlete by using the tendon excursion method [7] under in vivo conditions [8,9]. The method implies that the moment arm can be obtained from the slope of the tendon excursion versus joint angle [7]. For this reason, the athletes were seated on a dynamometer (Biodex Medical Systems, USA) with the knee fully extended (1808) while a passive ankle joint motion from 808 to 1108 (908: shank perpendicular to the foot) was performed by the dynamometer. Ankle joint angles and displacement of the gastrocnemius medialis (GM) myotendinous junction were determined by a motion capturing system (Vicon, Oxford, UK) and by ultrasonography (Aloka SSD 4000, Tokyo, JP), respectively. The ultrasound images taken during the passive joint motion were digitized frame by frame from 858 to 1058 ankle joint angle. In order to register any motion of the probe relative to the skin during the passive ankle joint motion, a marker was placed between skin and ultrasound probe [6]. Subjects had to remain passive while the measurements were taken because any active muscular force production would affect the slope of the tendon excursion versus ankle joint angle and hence the calculated moment arms. Passive condition was monitored by an online expectation of the GM fascicle and myotendinous junction behavior, and by the ankle joint moment over the time for each athlete. Ultrasonography was also used to determine GL and GM muscle architecture using the method described previously [10]. Briefly, the pennation angles of the GM and GL were measured as the angle of insertion of the muscle fascicles into the distal aponeurosis. Fascicle length was defined as the length of the fascicle between the insertions of the fascicle into the proximal and distal aponeurosis. Skeletal geometry of the foot and ankle were determined by making individual sketches of the foot [3] and by using a millimeter-graded tape (analyzed parameters are described in Table 1). All sketches and distance measurements were conducted by the same examiner and a post examination of this method revealed that the average difference between measurements was 3 mm or less. On the following test day, the athletes were asked to perform sprints over different distances (10 m, 25 m and 40 m) in order to determine acceleration performance. These tests were conducted as it has been shown by previous model calculations [3] that a smaller Achilles tendon moment arm can increase horizontal acceleration impulse during sprinting, potentially improving sprinters’ acceleration performance. For this reason, two double photocell barriers were placed 4 m from each other at the 10 m, 25 m and 40 m mark. The athletes always used a starting block and performed two sprints for each condition. Only the fastest trials were considered in our analysis. Six athletes refused to participate in these sprints because the measurements were taken during the pre indoor season and those athletes did not want to risk any injuries. Relationships between sprint performance (100-m personal best, sprinting velocity determined during the acceleration tests) and lower leg musculoskeletal geometry have been examined using Pearson correlation coefficients. Using a cluster analysis (single linkage algorithm) with Euclidean distance measure, the sprinters were divided into two groups based on their personal best: fast sprinters: N = 11, 10.27 0.07 s; slow sprinters: N = 7, 10.67 0.08 s. A t-test for independent samples
r = 0.04 (NS)
3.0
Fascicle LengthGL / Moment Arm
7.3 0.7 9.6 0.6 5.10 0.79
r = 0.12 (NS)
5.0
2.7 2.4 2.1 1.8 1.5 1.2 0.9 3.0
Fascicle LengthGM / Moment Arm
Achilles tendon moment arm [cm] GL fascicle length [cm] GL pennation angle [deg.] GM fascicle length [cm] GM pennation angle [deg.] GL fascicle length/Achilles tendon moment arm GM fascicle length/Achilles tendon moment arm DP distance heel to toe [cm] DP distance midpoint malleolii to toe [cm] DP distance 1st MTH to toe [cm] Maximum foot width [cm] Distance midpoint malleolii to toe/ Achilles tendon moment arm Distance fibular head to lat malleolus [cm]
Fast sprinters (N = 11)
5.5
Moment Arm [cm]
Table 1 Musculoskeletal geometrical parameters at the lower leg for the fast and slow sprinters group (mean SD). Fascicle arrangement was analyzed at an inactive condition (relaxed muscles) with the shank perpendicular to the foot and the knee fully extended. Skeletal geometry of the foot and ankle were determined by making individual sketches of the foot and by using a millimeter-graded tape.
139
2.7
r = 0.05 (NS)
Fast sprinters Slow sprinters
2.4 2.1 1.8 1.5 1.2 0.9 0.6 10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
100 m personal best [s] Fig. 1. Relationship between 100-m personal best and Achilles tendon moment arm, ratio of the gastrocnemius lateralis (GL) and medialis (GM) fascicle length to Achilles tendon moment arm in elite male sprinters. The closed circles and open triangles represent the fast (N = 11) and slow (N = 7) sprinters, respectively.
was used in order to check for differences in the analyzed musculoskeletal variables between fast and slow sprinters.
3. Results There were no differences (p > 0.05) between the fast and slow sprinters in Achilles tendon moment arm, GM and GL muscle architecture or skeletal characteristics of the foot and ankle (Table 1). In the same manner, we did not find any differences (p > 0.05) in the ratio of muscle fascicle length to Achilles tendon moment arm or in the ratio of foot skeletal geometry (distance midpoint malleolii to toe) to Achilles tendon moment arm between the fast and slow sprinter group (Table 1). Body height and mass was not different (p > 0.05) between fast (181 5 cm; 78 6 kg) and slow sprinters (182 5 cm; 76 4 kg). Further, none of the examined muscular or skeletal geometrical parameters of the lower leg showed
140
K. Karamanidis et al. / Gait & Posture 34 (2011) 138–141
Table 2 Relationship between sprint performance (100-m personal best, sprinting velocity at 10 m, 25 m and 40 m) and musculoskeletal geometrical parameters at the lower leg in elite male sprinters (values represent Pearson correlation coefficient). Skeletal geometry of the foot and ankle were determined by making individual sketches of the foot and by using a millimeter-graded tape. Sprinting velocity (Vmax) analyzed at 10 m, 25 m and 40 m were 8.40 0.32 m/s, 9.87 0.25 m/s and 10.31 0.23 m/s, respectively (six athletes did not agree to participate in those sprints).
Achilles tendon moment arm GL fascicle length GL pennation angle GM fascicle length GM pennation angle GL fascicle length/Achilles tendon moment arm GM fascicle length/Achilles tendon moment arm DP distance heel to toe DP distance midpoint malleolii to toe DP distance 1st MTH to toe Maximum foot width Distance midpoint malleolii to toe/Achilles tendon moment arm Distance fibular head to lat malleolus
Personal best (N = 18)
Vmax at 10 m (N = 12)
Vmax at 25 m (N = 12)
Vmax at 40 m (N = 12)
0.12p: 0.63 0.07p: 0.78 0.06p: 0.81 0.13p: 0.62 0.06p: 0.82 0.04p: 0.88 0.05p: 0.86 0.36p: 0.15 0.39p: 0.10 0.36p: 0.15 0.32p: 0.19 0.02p: 0.94 0.47p: 0.04
0.04p: 0.91 0.21p: 0.54 0.19p: 0.59 0.24p: 0.48 0.13p: 0.71 0.19p: 0.58 0.10p: 0.78 0.01p: 0.99 0.20p: 0.60 0.28p: 0.40 0.60p: 0.53 0.17p: 0.62 0.20p: 0.57
0.06p: 0.86 0.31p: 0.33 0.02p: 0.95 0.12p: 0.70 0.42p: 0.18 0.26p: 0.42 0.16p: 0.62 0.15p: 0.63 0.32p: 0.30 0.27p: 0.40 0.26p: 0.41 0.23p: 0.47 0.16p: 0.61
0.12p: 0.71 0.19p: 0.55 0.19p: 0.56 0.11p: 0.73 0.42p: 0.17 0.15p: 0.65 0.14p: 0.67 0.18p: 0.58 0.03p: 0.94 0.53p: 0.08 0.25p: 0.43 0.18p: 0.58 0.18p: 0.58
GL: musculus gastrocnemius lateralis; GM: musculus gastrocnemius medialis; 1st MTH: first metatarsal head; DP: distal to proximal. DP distance heel to toe: distance between the most posterior and most anterior boundary of the foot i.e., maximal distance where the point of force application can be moved under the foot in the sagittal plane. The midpoint of the malleolii was defined as the midpoint of the line connecting malleolus lateralis and medialis using the individual sketches of the foot (the vertical projection of both bony landmarks was drawn).
a significant (p > 0.05) correlation with the personal best of the athletes (Fig. 1) or the sprinting velocity determined at 10 m (mean value and standard deviation: 8.40 0.32 m/s), 25 m (9.87 0.25 m/ s) and 40 m (10.31 0.23 m/s; see Table 2). Only for the shank length (i.e., distance of the fibular head to malleolus lateralis) did we find a significant (p = 0.04) but moderate relationship (r = 0.47) with the 100-m personal best (Table 2) and a slight tendency (p = 0.09) towards lower values for the fast compared to the slow sprinters (Table 1). On average, however, the differences were less than 3.5% (about 1.3 cm). 4. Discussion The main results of the present study were that none of the examined muscular (fascicle length, pennation angle) or skeletal (e.g. Achilles tendon moment arm) geometrical parameters of the lower leg showed a clear significant correlation with sprint performance. Further, we did not detect any significant differences between the fast and slow sprinter groups in the investigated parameters to describe the geometrical design of the lower leg. Therefore, the differences in sprint ability between the fast and slow sprinter groups were likely not the result of differences in lower leg musculoskeletal geometry. Investigations of lower limb musculoskeletal design in sprinters [3] as well as in fast-running animals such as the racing greyhound [11] revealed a large muscle fiber length to moment arm ratio. Short moment arms reduce the mechanical advantage for joint moment development, but in combination with long fascicles they can also enhance the range of motion for active force generation during contractions performed at high joint angular velocities [3,4]. Given that maximal angular velocity at the ankle joint during the push-off phase while sprinting can reach values close to 10008/s [12] we expected that the ratio of fascicle length to moment arm at the ankle joint would significantly influence sprint performance. However, the current study shows that the fascicle length to Achilles tendon moment ratio cannot be used to differentiate the sprint ability of an elite group of male sprinters. One might argue that our results (e.g. no significant correlation between GM or GL fascicle length and sprint performance) contradict the existing literature [1–3,5]. However, some of those studies compared sprinters with non-sprinters [3,5] and the range of 100-m personal bests investigated was clearly wider (Abe et al. [1]: 11.04–13.42 s; Kumagai et al. [2]: 10.00–11.70 s) than in the present study (10.14–10.76 s). Although the absolute personal
bests of the highly trained sprinters in our present study were slower than those of the world’s top athletes, our examined range in 100-m sprint times was similar to that of previous World Championship finalist (e.g. 2009: 9.58–10.34 s), suggesting that differences in 100-m sprint times in world-class athletes are likewise not a result of differences in the geometrical design of the lower leg. Using our methodological approach we cannot exclude differences between athletes based on their current training or performance status which might affect our findings in the acceleration test. However, because all of the athletes were in the regular pre-indoor season, none had any serious injury within the previous two years, and we found a significant correlation (r = 0.87, p < 0.001) between personal best and seasonal best performed during the outdoor season (i.e., confirming the relationship between current performance and their best sprint performance), this drawback may not have influenced our findings. We used the sprinters’ personal bests rather than their seasonal bests because we believe that this procedure is more appropriate, representing as it does the best sprint performance of the athletes. However, when using the sprinters’ seasonal bests the results did not change significantly (data not presented in this article). Conflict of interest statement The authors disclose any financial and personal relationships with other people or organisations that could inappropriately influence (bias) their work. References [1] Abe T, Fukashiro S, Harada Y, Kawamoto K. Relationship between sprint performance and muscle fascicle length in female sprinters. J Physiol Anthropol Appl Human Sci 2001;20(2):141–7. [2] Kumagai K, Abe T, Brechue WF, Ryushi T, Takano S, Mizuno M. Sprint performance is related to muscle fascicle length in male 100-m sprinters. J Appl Physiol 2000;88(3):811–6. [3] Lee SS, Piazza SJ. Built for speed: musculoskeletal structure and sprinting ability. J Exp Biol 2009;212:3700–7. [4] Lieber RL, Fride´n J. Functional and clinical significance of skeletal muscle architecture. Muscle Nerve 2000;23(11):1647–66. [5] Abe T, Kumagai K, Brechue WF. Fascicle length of leg muscles is greater in sprinters than distance runners. Med Sci Sports Exerc 2000;32(6):1125–9. [6] Stafilidis S, Arampatzis A. Muscle-tendon unit mechanical and morphological properties and sprint performance. J Sports Sci 2007;25(9):1035–46. [7] An KN, Ueba Y, Chao EY, Cooney WP, Linscheid RL. Tendon excursion and moment arm of index finger muscles. J Biomech 1983;16(6):419–25.
K. Karamanidis et al. / Gait & Posture 34 (2011) 138–141 [8] Ito M, Akima H, Fukunaga T. In vivo moment arm determination using B-mode ultrasonography. J Biomech 2000;33(2):215–8. [9] Maganaris CN. In vivo measurement-based estimations of the moment arm in the human tibialis anterior muscle-tendon unit. J Biomech 2000;33(3):375–9. [10] Karamanidis K, Stafilidis S, DeMonte G, Morey-Klapsing G, Bru¨ggemann GP, Arampatzis A. Inevitable joint angular rotation affects muscle architecture during isometric contraction. J Electromyogr Kinesiol 2005;15(6):608–16.
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[11] Williams SB, Wilson AM, Daynes J, Peckham K, Payne RC. Functional anatomy and muscle moment arms of the thoracic limb of an elite sprinting athlete: the racing greyhound (Canis familiaris). J Anat 2008;213(4): 373–82. [12] Jacobs R, Bobbert MF, van Ingen Schenau GJ. Mechanical output from individual muscles during explosive leg extensions: the role of biarticular muscles. J Biomech 1996;29(4):513–23.
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Short communication
Lower leg musculoskeletal geometry and sprint performance Kiros Karamanidis a,*, Kirsten Albracht a, Bjoern Braunstein a,b, Maria Moreno Catala a, Jan-Peter Goldmann a,b, Gert-Peter Bru¨ggemann a a b
Institute of Biomechanics and Orthopaedics, German Sport University Cologne, Am Sportpark Mu¨ngersdorf 6, 50933 Cologne, Germany German Research Centre of Elite Sport Cologne, Germany
A R T I C L E I N F O
A B S T R A C T
Article history: Received 7 July 2010 Received in revised form 2 March 2011 Accepted 7 March 2011
The purpose of this study was to investigate whether sprint performance is related to lower leg musculoskeletal geometry within a homogeneous group of highly trained 100-m sprinters. Using a cluster analysis, eighteen male sprinters were divided into two groups based on their personal best (fast: N = 11, 10.30 0.07 s; slow: N = 7, 10.70 0.08 s). Calf muscular fascicle arrangement and Achilles tendon moment arms (calculated by the gradient of tendon excursion versus ankle joint angle) were analyzed for each athlete using ultrasonography. Achilles tendon moment arm, foot and ankle skeletal geometry, fascicle arrangement as well as the ratio of fascicle length to Achilles tendon moment arm showed no significant (p > 0.05) correlation with sprint performance, nor were there any differences in the analyzed musculoskeletal parameters between the fast and slow sprinter group. Our findings provide evidence that differences in sprint ability in world-class athletes are not a result of differences in the geometrical design of the lower leg even when considering both skeletal and muscular components. ß 2011 Elsevier B.V. All rights reserved.
Keywords: Achilles tendon moment arm Fascicle length Foot geometry Sprinting
1. Introduction In sprinting, it is essential for the calf musculature to generate high shortening velocities in order to accelerate rapidly during the first strides and to achieve high locomotor velocities [1–3]. It is suggested that longer fascicles are preferable for sprinters because of their greater number of sarcomeres in series [1]. This is because for a given muscle-tendon unit shortening velocity, such as during sprinting, each individual sarcomere can shorten more slowly, thereby increasing overall muscle force generation capacity [4]. In addition, longer fascicles will produce more power, and at a higher shortening velocity increase the rates at which force can be applied to the ground, thereby contributing to better sprinting ability. Although longer muscle fascicles have been observed in the calf musculature of human sprinters when compared to distance runners [5] triceps surae muscle fascicle length is not [6] or only moderately [1,2] linked to sprint performance. The amount of change in muscle fascicle length that occurs as a joint rotates depends on the muscle moment arm [4] and, therefore, it is also important to consider muscle fascicle length in relation to tendon moment arm. Lee and Piazza [3] recently showed that sprinters have smaller Achilles tendon moment arms and longer fascicles of the gastrocnemius lateralis muscle (GL) than non-sprinters, consequently leading to a greater fascicle length to moment
* Corresponding author. Tel.: +49 221 4982 5680; fax: +49 221 4973454. E-mail addresses: [email protected], [email protected] (K. Karamanidis). 0966-6362/$ – see front matter ß 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2011.03.009
arm ratio for sprinters. Using a model of the lower leg, they reported that these properties could enhance sprint performance by allowing the calf musculature to operate at a more favorable force–length–velocity-relationship during ground contact, thereby increasing sprint ability [3]. The simulations showed that as Achilles tendon moment arm decreased by 10 mm, horizontal acceleration impulse increased by about 6 Ns [3]. Although the influence of tendon moment arm on forward impulse decreases with increasing sprint velocity [3], thus making a clear statement about the expected overall improvement in 100-m sprint time that might result from such changes in moment arm difficult, the above findings provide strong evidence of the importance of Achilles tendon moment arm for sprint performance, in particular for the acceleration phase. However, the effect of Achilles tendon moment arm on sprinting has not yet been experimentally investigated and an analysis of lower leg musculoskeletal geometry in a group of highly trained 100-m sprint specialists is missing. Such information is necessary to increase our understanding of musculoskeletal function in elite athletes. Thus, the purpose of this study was to investigate whether sprint performance is related to lower leg musculoskeletal geometry within a homogeneous group of elite male 100-m sprinters. 2. Method Eighteen 100-m male sprinters (height: 182 5 cm; body mass: 77 5 kg; age: 21 4 yrs) with a personal best ranging from 10.14 to 10.76 s (10.42 0.21 s) participated in this study. Approval was obtained from the university’s committee for the protection of human subjects and informed consent was given by all subjects.
K. Karamanidis et al. / Gait & Posture 34 (2011) 138–141
Slow sprinters (N = 7)
4.2 0.6 7.6 3.3 14.3 2.3 6.0 0.9 22.9 2.7 1.84 0.91
4.2 0.8p: 0.88 7.6 1.6p: 0.98 15.0 2.3p: 0.54 6.0 0.9p: 0.97 22.2 4.4p: 0.69 1.88 0.60p: 0.91
1.43 0.27
1.49 0.48p:
26.7 1.6 21.2 1.3
27.3 0.9p: 21.7 0.9p:
39.9 2.1
4.5 4.0 3.5 3.0 2.5
0.73
0.26 0.33
p: 0.26
7.6 0.2 10.1 0.5p: 0.12 5.34 1.02p: 0.57 p: 0.09
41.2 1.2
GL: musculus gastrocnemius lateralis; GM: musculus gastrocnemius medialis; 1st MTH: first metatarsal head; DP: distal to proximal. DP distance heel to toe: distance between the most posterior and most anterior boundary of the foot, i.e., maximal distance where the point of force application can be moved under the foot in the sagittal plane. The midpoint of the malleolii was defined as the midpoint of the line connecting malleolus lateralis and medialis using the individual sketches of the foot (the vertical projection of both bony landmarks was drawn).
The moment arm of the Achilles tendon was obtained for each athlete by using the tendon excursion method [7] under in vivo conditions [8,9]. The method implies that the moment arm can be obtained from the slope of the tendon excursion versus joint angle [7]. For this reason, the athletes were seated on a dynamometer (Biodex Medical Systems, USA) with the knee fully extended (1808) while a passive ankle joint motion from 808 to 1108 (908: shank perpendicular to the foot) was performed by the dynamometer. Ankle joint angles and displacement of the gastrocnemius medialis (GM) myotendinous junction were determined by a motion capturing system (Vicon, Oxford, UK) and by ultrasonography (Aloka SSD 4000, Tokyo, JP), respectively. The ultrasound images taken during the passive joint motion were digitized frame by frame from 858 to 1058 ankle joint angle. In order to register any motion of the probe relative to the skin during the passive ankle joint motion, a marker was placed between skin and ultrasound probe [6]. Subjects had to remain passive while the measurements were taken because any active muscular force production would affect the slope of the tendon excursion versus ankle joint angle and hence the calculated moment arms. Passive condition was monitored by an online expectation of the GM fascicle and myotendinous junction behavior, and by the ankle joint moment over the time for each athlete. Ultrasonography was also used to determine GL and GM muscle architecture using the method described previously [10]. Briefly, the pennation angles of the GM and GL were measured as the angle of insertion of the muscle fascicles into the distal aponeurosis. Fascicle length was defined as the length of the fascicle between the insertions of the fascicle into the proximal and distal aponeurosis. Skeletal geometry of the foot and ankle were determined by making individual sketches of the foot [3] and by using a millimeter-graded tape (analyzed parameters are described in Table 1). All sketches and distance measurements were conducted by the same examiner and a post examination of this method revealed that the average difference between measurements was 3 mm or less. On the following test day, the athletes were asked to perform sprints over different distances (10 m, 25 m and 40 m) in order to determine acceleration performance. These tests were conducted as it has been shown by previous model calculations [3] that a smaller Achilles tendon moment arm can increase horizontal acceleration impulse during sprinting, potentially improving sprinters’ acceleration performance. For this reason, two double photocell barriers were placed 4 m from each other at the 10 m, 25 m and 40 m mark. The athletes always used a starting block and performed two sprints for each condition. Only the fastest trials were considered in our analysis. Six athletes refused to participate in these sprints because the measurements were taken during the pre indoor season and those athletes did not want to risk any injuries. Relationships between sprint performance (100-m personal best, sprinting velocity determined during the acceleration tests) and lower leg musculoskeletal geometry have been examined using Pearson correlation coefficients. Using a cluster analysis (single linkage algorithm) with Euclidean distance measure, the sprinters were divided into two groups based on their personal best: fast sprinters: N = 11, 10.27 0.07 s; slow sprinters: N = 7, 10.67 0.08 s. A t-test for independent samples
r = 0.04 (NS)
3.0
Fascicle LengthGL / Moment Arm
7.3 0.7 9.6 0.6 5.10 0.79
r = 0.12 (NS)
5.0
2.7 2.4 2.1 1.8 1.5 1.2 0.9 3.0
Fascicle LengthGM / Moment Arm
Achilles tendon moment arm [cm] GL fascicle length [cm] GL pennation angle [deg.] GM fascicle length [cm] GM pennation angle [deg.] GL fascicle length/Achilles tendon moment arm GM fascicle length/Achilles tendon moment arm DP distance heel to toe [cm] DP distance midpoint malleolii to toe [cm] DP distance 1st MTH to toe [cm] Maximum foot width [cm] Distance midpoint malleolii to toe/ Achilles tendon moment arm Distance fibular head to lat malleolus [cm]
Fast sprinters (N = 11)
5.5
Moment Arm [cm]
Table 1 Musculoskeletal geometrical parameters at the lower leg for the fast and slow sprinters group (mean SD). Fascicle arrangement was analyzed at an inactive condition (relaxed muscles) with the shank perpendicular to the foot and the knee fully extended. Skeletal geometry of the foot and ankle were determined by making individual sketches of the foot and by using a millimeter-graded tape.
139
2.7
r = 0.05 (NS)
Fast sprinters Slow sprinters
2.4 2.1 1.8 1.5 1.2 0.9 0.6 10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
100 m personal best [s] Fig. 1. Relationship between 100-m personal best and Achilles tendon moment arm, ratio of the gastrocnemius lateralis (GL) and medialis (GM) fascicle length to Achilles tendon moment arm in elite male sprinters. The closed circles and open triangles represent the fast (N = 11) and slow (N = 7) sprinters, respectively.
was used in order to check for differences in the analyzed musculoskeletal variables between fast and slow sprinters.
3. Results There were no differences (p > 0.05) between the fast and slow sprinters in Achilles tendon moment arm, GM and GL muscle architecture or skeletal characteristics of the foot and ankle (Table 1). In the same manner, we did not find any differences (p > 0.05) in the ratio of muscle fascicle length to Achilles tendon moment arm or in the ratio of foot skeletal geometry (distance midpoint malleolii to toe) to Achilles tendon moment arm between the fast and slow sprinter group (Table 1). Body height and mass was not different (p > 0.05) between fast (181 5 cm; 78 6 kg) and slow sprinters (182 5 cm; 76 4 kg). Further, none of the examined muscular or skeletal geometrical parameters of the lower leg showed
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Table 2 Relationship between sprint performance (100-m personal best, sprinting velocity at 10 m, 25 m and 40 m) and musculoskeletal geometrical parameters at the lower leg in elite male sprinters (values represent Pearson correlation coefficient). Skeletal geometry of the foot and ankle were determined by making individual sketches of the foot and by using a millimeter-graded tape. Sprinting velocity (Vmax) analyzed at 10 m, 25 m and 40 m were 8.40 0.32 m/s, 9.87 0.25 m/s and 10.31 0.23 m/s, respectively (six athletes did not agree to participate in those sprints).
Achilles tendon moment arm GL fascicle length GL pennation angle GM fascicle length GM pennation angle GL fascicle length/Achilles tendon moment arm GM fascicle length/Achilles tendon moment arm DP distance heel to toe DP distance midpoint malleolii to toe DP distance 1st MTH to toe Maximum foot width Distance midpoint malleolii to toe/Achilles tendon moment arm Distance fibular head to lat malleolus
Personal best (N = 18)
Vmax at 10 m (N = 12)
Vmax at 25 m (N = 12)
Vmax at 40 m (N = 12)
0.12p: 0.63 0.07p: 0.78 0.06p: 0.81 0.13p: 0.62 0.06p: 0.82 0.04p: 0.88 0.05p: 0.86 0.36p: 0.15 0.39p: 0.10 0.36p: 0.15 0.32p: 0.19 0.02p: 0.94 0.47p: 0.04
0.04p: 0.91 0.21p: 0.54 0.19p: 0.59 0.24p: 0.48 0.13p: 0.71 0.19p: 0.58 0.10p: 0.78 0.01p: 0.99 0.20p: 0.60 0.28p: 0.40 0.60p: 0.53 0.17p: 0.62 0.20p: 0.57
0.06p: 0.86 0.31p: 0.33 0.02p: 0.95 0.12p: 0.70 0.42p: 0.18 0.26p: 0.42 0.16p: 0.62 0.15p: 0.63 0.32p: 0.30 0.27p: 0.40 0.26p: 0.41 0.23p: 0.47 0.16p: 0.61
0.12p: 0.71 0.19p: 0.55 0.19p: 0.56 0.11p: 0.73 0.42p: 0.17 0.15p: 0.65 0.14p: 0.67 0.18p: 0.58 0.03p: 0.94 0.53p: 0.08 0.25p: 0.43 0.18p: 0.58 0.18p: 0.58
GL: musculus gastrocnemius lateralis; GM: musculus gastrocnemius medialis; 1st MTH: first metatarsal head; DP: distal to proximal. DP distance heel to toe: distance between the most posterior and most anterior boundary of the foot i.e., maximal distance where the point of force application can be moved under the foot in the sagittal plane. The midpoint of the malleolii was defined as the midpoint of the line connecting malleolus lateralis and medialis using the individual sketches of the foot (the vertical projection of both bony landmarks was drawn).
a significant (p > 0.05) correlation with the personal best of the athletes (Fig. 1) or the sprinting velocity determined at 10 m (mean value and standard deviation: 8.40 0.32 m/s), 25 m (9.87 0.25 m/ s) and 40 m (10.31 0.23 m/s; see Table 2). Only for the shank length (i.e., distance of the fibular head to malleolus lateralis) did we find a significant (p = 0.04) but moderate relationship (r = 0.47) with the 100-m personal best (Table 2) and a slight tendency (p = 0.09) towards lower values for the fast compared to the slow sprinters (Table 1). On average, however, the differences were less than 3.5% (about 1.3 cm). 4. Discussion The main results of the present study were that none of the examined muscular (fascicle length, pennation angle) or skeletal (e.g. Achilles tendon moment arm) geometrical parameters of the lower leg showed a clear significant correlation with sprint performance. Further, we did not detect any significant differences between the fast and slow sprinter groups in the investigated parameters to describe the geometrical design of the lower leg. Therefore, the differences in sprint ability between the fast and slow sprinter groups were likely not the result of differences in lower leg musculoskeletal geometry. Investigations of lower limb musculoskeletal design in sprinters [3] as well as in fast-running animals such as the racing greyhound [11] revealed a large muscle fiber length to moment arm ratio. Short moment arms reduce the mechanical advantage for joint moment development, but in combination with long fascicles they can also enhance the range of motion for active force generation during contractions performed at high joint angular velocities [3,4]. Given that maximal angular velocity at the ankle joint during the push-off phase while sprinting can reach values close to 10008/s [12] we expected that the ratio of fascicle length to moment arm at the ankle joint would significantly influence sprint performance. However, the current study shows that the fascicle length to Achilles tendon moment ratio cannot be used to differentiate the sprint ability of an elite group of male sprinters. One might argue that our results (e.g. no significant correlation between GM or GL fascicle length and sprint performance) contradict the existing literature [1–3,5]. However, some of those studies compared sprinters with non-sprinters [3,5] and the range of 100-m personal bests investigated was clearly wider (Abe et al. [1]: 11.04–13.42 s; Kumagai et al. [2]: 10.00–11.70 s) than in the present study (10.14–10.76 s). Although the absolute personal
bests of the highly trained sprinters in our present study were slower than those of the world’s top athletes, our examined range in 100-m sprint times was similar to that of previous World Championship finalist (e.g. 2009: 9.58–10.34 s), suggesting that differences in 100-m sprint times in world-class athletes are likewise not a result of differences in the geometrical design of the lower leg. Using our methodological approach we cannot exclude differences between athletes based on their current training or performance status which might affect our findings in the acceleration test. However, because all of the athletes were in the regular pre-indoor season, none had any serious injury within the previous two years, and we found a significant correlation (r = 0.87, p < 0.001) between personal best and seasonal best performed during the outdoor season (i.e., confirming the relationship between current performance and their best sprint performance), this drawback may not have influenced our findings. We used the sprinters’ personal bests rather than their seasonal bests because we believe that this procedure is more appropriate, representing as it does the best sprint performance of the athletes. However, when using the sprinters’ seasonal bests the results did not change significantly (data not presented in this article). Conflict of interest statement The authors disclose any financial and personal relationships with other people or organisations that could inappropriately influence (bias) their work. References [1] Abe T, Fukashiro S, Harada Y, Kawamoto K. Relationship between sprint performance and muscle fascicle length in female sprinters. J Physiol Anthropol Appl Human Sci 2001;20(2):141–7. [2] Kumagai K, Abe T, Brechue WF, Ryushi T, Takano S, Mizuno M. Sprint performance is related to muscle fascicle length in male 100-m sprinters. J Appl Physiol 2000;88(3):811–6. [3] Lee SS, Piazza SJ. Built for speed: musculoskeletal structure and sprinting ability. J Exp Biol 2009;212:3700–7. [4] Lieber RL, Fride´n J. Functional and clinical significance of skeletal muscle architecture. Muscle Nerve 2000;23(11):1647–66. [5] Abe T, Kumagai K, Brechue WF. Fascicle length of leg muscles is greater in sprinters than distance runners. Med Sci Sports Exerc 2000;32(6):1125–9. [6] Stafilidis S, Arampatzis A. Muscle-tendon unit mechanical and morphological properties and sprint performance. J Sports Sci 2007;25(9):1035–46. [7] An KN, Ueba Y, Chao EY, Cooney WP, Linscheid RL. Tendon excursion and moment arm of index finger muscles. J Biomech 1983;16(6):419–25.
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