Article

The purpose of the present study was to investigate whether altered longitudinal
bending stiffness (LBS) levels of the midsole of a running shoe lead to a
systematic change in lower extremity joint lever arms of the ground reaction
force (GRF). Joint moments and GRF lever arms in the sagittal plane were
determined from 19 male subjects running at 3.5 m/s using inverse dynamics
procedures. LBS was manipulated using carbon fiber insoles of 1.9 mm and 3.2 mm
thickness. Increasing LBS led to a significant shift of joint lever arms to a
more anterior position. Effects were more pronounced at distal joints. Ankle
joint moments were not significantly increased in the presence of higher GRF
lever arms when averaged over all subjects. Still, two individual strategies (1:
increase ankle joint moments while keeping push-off times almost constant, 2:
decrease ankle joint moments and increase push-off times) could be identified in
response to increased ankle joint lever arms that might reflect individual
differences between subjects with respect to strength capacities or
anthropometric characteristics. The results of the present study indicate that
LBS systematically influences GRF lever arms of lower extremity joints during the
push-off phase in running. Further, individual responses to altered LBS levels
could be identified that could aid in finding optimum LBS values for a given
individual.
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Langue : ANGLAIS