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Journal of Experimental Biology partnership with Dryad

Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance
Tim W. Dorn, Anthony G. Schache, Marcus G. Pandy

SUMMARY

Humans run faster by increasing a combination of stride length and stride frequency. In slow and medium-paced running, stride length is increased by exerting larger support forces during ground contact, whereas in fast running and sprinting, stride frequency is increased by swinging the legs more rapidly through the air. Many studies have investigated the mechanics of human running, yet little is known about how the individual leg muscles accelerate the joints and centre of mass during this task. The aim of this study was to describe and explain the synergistic actions of the individual leg muscles over a wide range of running speeds, from slow running to maximal sprinting. Experimental gait data from nine subjects were combined with a detailed computer model of the musculoskeletal system to determine the forces developed by the leg muscles at different running speeds. For speeds up to 7 m s–1, the ankle plantarflexors, soleus and gastrocnemius, contributed most significantly to vertical support forces and hence increases in stride length. At speeds greater than 7 m s–1, these muscles shortened at relatively high velocities and had less time to generate the forces needed for support. Thus, above 7 m s–1, the strategy used to increase running speed shifted to the goal of increasing stride frequency. The hip muscles, primarily the iliopsoas, gluteus maximus and hamstrings, achieved this goal by accelerating the hip and knee joints more vigorously during swing. These findings provide insight into the strategies used by the leg muscles to maximise running performance and have implications for the design of athletic training programs.

FOOTNOTES

  • Supplementary material available online at http://jeb.biologists.org/cgi/content/full/215/11/1944/DC1

  • FUNDING

    This work was supported by a Victorian Endowment for Science Knowledge and Innovation Fellowship to M.G.P., Australian Research Council Discovery Project Grants [DP0772838 and DP0878705] to M.G.P. and an Australian Research Council Linkage Project Grant [LP110100262] to A.G.S. and M.G.P.

  • LIST OF ABBREVIATIONS

    BW
    body weight
    cFO
    contralateral foot-off
    cFS
    contralateral foot-strike
    EMG
    electromyography
    GAS
    medial and lateral gastrocnemius combined
    GMAX
    superior, middle and inferior gluteus maximus combined
    GMED
    anterior, middle and posterior gluteus medius combined
    HAMS
    biceps femoris long head, semimembranosus and semitendinosus combined
    iFO
    ipsilateral foot-off iFS ipsilateral foot-strike
    ILPSO
    iliacus and psoas combined
    RF
    rectus femoris
    SOL
    soleus
    TIBANT
    tibialis anterior
    TKE
    Teager–Kaiser energy
    VAS
    vastus medialis, vastus intermedius and vastus lateralis combined
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