Background:The ankle and foot together contribute to over half of the positive and negative work performed by the lower limbs during running.Yet,little is known about how foot kinetics change throughout a run.The amount of negative foot work may decrease as tibialis anterior(TA)electromyography(EMG)changes throughout longer-duration runs.Therefore,we examined ankle and foot work as well as TA EMG changes throughout a changing-speed run.Methods:Fourteen heel-striking subjects ran on a treadmill for 58 min.We collected ground reaction forces,motion capture,and EMG.Subjects ran at 110％,100％,and 90％of their 10-km running speed and 2.8 m/s multiple times throughout the run.Foot work was evaluated using the dis-tal rearfoot work,which provides a net estimate of all work contributors within the foot.Results:Positive foot work increased and positive ankle work decreased throughout the run at all speeds.At the 110％10-km running speed,neg-ative foot work decreased and TA EMG frequency shifted lower throughout the run.The increase in positive foot work may be attributed to increased foot joint work performed by intrinsic foot muscles.Changes in negative foot work and TA EMG frequency may indicate that the TA plays a role in negative foot work in the early stance of a run.Conclusion:This study is the first to examine how the kinetic contributions of the foot change throughout a run.Future studies should investigate how increases in foot work affect running performance.

Eric C.Honert;Florian Ostermair;Vinzenz von Tscharner;Benno M.Nigg

Human Performance Laboratory,Faculty of Kinesiology,University of Calgary,Calgary,AB T2N 1N4,Canada;Institute of Sports and Sports Science,Karlsruhe Institute of Technology,Karlsruhe 76131,Germany;Department of Sports Science and Sports,Friedrich Alexander University Erlangen-Nuremberg,Erlangen 91058,Germany

运动与健康科学（英文）

[1]Eric C.Honert;Florian Ostermair;Vinzenz von Tscharner;Benno M.Nigg-.Changes in ankle work,foot work,and tibialis anterior activation throughout a long run)[J].运动与健康科学（英文）,2022(03):330-338

rearfoot

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