American Football Position Does Not Influence Symmetry in Joint Power During High-Speed Running Original Research
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Keywords
biomechanics, gait, inverse dynamics
Abstract
Introduction: The distinct physical and tactical roles of American football positions may influence interlimb symmetry of ankle, knee, and hip power distribution during high-speed running. This study examined differences in joint power distribution symmetry between position groups and joints using inverse dynamics.
Methods: Sixty-eight draft-eligible American football players (Big n=18; Big-skill n=24; Skill n=26) completed a single high-speed running trial (6.4 m/s) on an instrumented treadmill synchronized with a motion capture system. Joint powers were computed via inverse dynamics and expressed as positive (generation) and negative (absorption) percent contributions to total limb power. Interlimb differences were quantified using the Asymmetry Index (AI = |left−right|/[(left+right)/2] ×100%). Group differences were analyzed using Kruskal-Wallis tests with Bonferroni-adjusted post hoc comparisons (α = .017).
Results: No significant differences in AI were found among position groups for positive ankle (p = .868), knee (p = .082), or hip power (p = .846), nor for negative ankle (p = .222), knee (p = .181), or hip power (p = .496). AI differed significantly among joints for both positive (F(2,134)=33.4, p<.001, η²=0.332) and negative power (F(2,134)=15.7, p<.001, η²=0.19). Knee AI was highest for positive power (31.9 ± 24.5%), followed by hip (18.1 ± 28.9%) and ankle (9.6 ± 6.9%). Negative AI was lowest at the ankle (11.9 ± 14.1%) compared to knee (22.4 ± 16.6%) and hip (22.8 ± 19.5%).
Conclusions: Player position does not influence the symmetry of joint power contributions during high-speed running. The ankle demonstrates the greatest symmetry, whereas the knee shows the largest asymmetry.
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This work is licensed under a Creative Commons Attribution 4.0 International License.
Copyright, 2026 by the authors. This work is licensed under the Creative Commons Attribution 4.0 International License.
Antonio Crisanti, Nova Southeastern University
Health and Human Performance
Graduate Student
Pete Bommarito, Nova Southeastern University
Owner, Bommarito Performance Systems
Instructor, Health and Human Performance