Built for speed: musculoskeletal structure and sprinting ability

NewsBot · Nov 2, 2009

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Built for speed: musculoskeletal structure and sprinting ability
Sabrina S. M. Lee and Stephen J. Piazza
Journal of Experimental Biology 212, 3700-3707 (2009)

The musculoskeletal structure of the foot and ankle has the potential to influence human sprinting performance in complex ways. A large Achilles' tendon moment arm improves the mechanical advantage of the triceps surae but also produces larger shortening velocity during rapid plantarflexion, which detracts from the force-generating capacity of the plantarflexors. The lever arm of the ground reaction force that resists the muscular plantarflexor moment during propulsive push-off is constrained in part by the skeletal structure of the foot. In this study, we measured the plantarflexion moment arms of the Achilles' tendon, lateral gastrocnemius fascicle lengths and pennation angles, and anthropometric characteristics of the foot and lower leg in collegiate sprinters and height-matched non-sprinters. The Achilles' tendon moment arms of the sprinters were 25% smaller on average in sprinters than in non-sprinters (P<0.001) whereas the sprinters' fascicles were 11% longer on average (P=0.024). The ratio of fascicle length to moment arm was 50% larger in sprinters (P<0.001). Sprinters were found to have longer toes (P=0.032) and shorter lower legs (P=0.026) than non sprinters. A simple computer simulation of the sprint push-off demonstrated that shorter plantarflexor moment arms and longer toes, like those measured in sprinters, permit greater generation of forward impulse. Simulated propulsion was enhanced in both cases by increasing the `gear ratio' of the foot, thus maintaining plantarflexor fibre length and reducing peak fibre shortening velocity. Longer toes especially prolonged the time of contact, giving greater time for forward acceleration by propulsive ground reaction force.
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Admin2 · Nov 2, 2009

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NewsBot · May 27, 2019

Horizontal force production and multi‐segment foot kinematics during the acceleration phase of bend sprinting
Laura J. Judson Sarah M. Churchill Andrew Barnes Joseph A. Stone Ian G. A Brookes Jon Wheat
Scand J: 27 May 2019

This paper investigated horizontal force production, foot kinematics and metatarsophalangeal (MTP) joint push‐off axis use during acceleration in bend (anti‐clockwise) and straight‐line sprinting. It was hypothesised that bend sprinting would cause the left step push‐off to occur about the oblique axis, resulting in a decrease in propulsive force. Three‐dimensional kinematic and ground reaction force data were collected from nine participants during sprinting on the bend (36.5 m radius) and straight. Anteroposterior force was reduced at 38‐44% of stance during bend sprinting compared with the straight. This coincided with an increase in mediolateral force for the majority of the stance phase (3‐96%) on the bend compared with the straight. In addition, a lower propulsive impulse was reported on the bend compared with the straight. Analysis of multi‐segment foot kinematics provides insight into the possible mechanisms behind these changes in force production. Mean mediolateral centre of pressure position was more lateral in relation to the second metatarsal head in the left step on the bend compared with the straight, indicating the oblique axis was used for push‐off at the MTP joint. Greater peak joint angles of the left foot were also reported, in particular, an increase in left step midfoot eversion and internal ankle rotation. It is possible these changes in joint kinematics are associated with the observed decrease in propulsive force. Therefore, practitioners should seek to strengthen muscles such as tibialis posterior in frontal and sagittal planes and ensure specificity of training which may aid in addressing these force reductions.
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NewsBot · Jun 14, 2021

Medial gastrocnemius muscle fascicles shorten throughout stance during sprint acceleration
Amelie Werkhausen, Steffen Willwacher, Kirsten Albracht
22 March 2021 https://doi.org/10.1111/sms.13956

The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.
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NewsBot · Oct 3, 2022

The Muscle Morphology of Elite Female Sprint Running
Miller, Robert et al
Medicine & Science in Sports & Exercise: September 27, 2022 - Volume - Issue - 10.1249/MSS.0000000000002999

Introduction
A paucity of research exists examining the importance of muscle morphological and functional characteristics for elite female sprint performance.

Purpose
This study aimed to compare lower body muscle volumes and vertical jumping power between elite vs. sub-elite female sprinters; and assess the relationships of these characteristics with sprint race and acceleration performance.

Methods
Five elite (100 m seasons best [SBE100]: 11.16 ± 0.06 s) and 17 sub-elite (SBE100 11.84 ± 0.42 s) female sprinters underwent: 3 T magnetic resonance imaging to determine the volume of 23 individual leg muscles/compartments and five functional muscle groups; countermovement jump (CMJ) and 30 m acceleration tests.

Results
Total absolute lower body muscle volume was higher in elite vs. sub-elite sprinters (+15%). Elite females exhibited greater muscle volume of the hip flexors (absolute +28%, relative [to body mass] +19%), hip extensors (absolute +22%, relative +14%), and knee extensors (absolute +21%), demonstrating pronounced anatomically specific muscularity, with relative hip flexor volume alone explaining 48% of sprint performance variability. The relative volume of five individual muscles (sartorius, gluteus maximus, adductor magnus, vastus lateralis, illiopsoas) were both distinct between groups (elite > sub-elite) and related to SBE100 (r = 0.553-0.639), with the combination of the sartorius (41%) and the adductor magnus (17%) explaining 58% of the variance in SBE100. Elite female sprinters demonstrated greater absolute CMJ power vs. sub-elite, and absolute and relative power were related to both SBE100 (r = -0.520 to -0.741) and acceleration performance (r = 0.569 to 0.808).

Conclusions
This investigation illustrates the distinctive, anatomically specific muscle volume distribution that facilitates elite sprint running in females, and emphasises the importance of hip flexor and extensor relative muscle volume.
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Built for speed: musculoskeletal structure and sprinting ability

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Built for speed: musculoskeletal structure and sprinting ability

NewsBot The Admin that posts the news.

Admin2 Administrator Staff Member

NewsBot The Admin that posts the news.

NewsBot The Admin that posts the news.

NewsBot The Admin that posts the news.

Fully supported in a purpose built clinic - Taupo

Full time ... Full scope ... One purpose built location

How to sleep w/ boot. Rebuilt arch.

Can foot soles/fat pads be built up?

Wolfs law our inbuilt force plate

Optimal Shear Cushion Stiffness at Different Gait Speeds

Gait speed,walking, relates to ageing process

Share This Page

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