14, 15, 18, 19, 26, 48 and 49 Some of these kinematic features have been observed previously with RF compared with FF running.23

Therefore, the joint geometry characteristics of RF running at foot-ground collision result in greater peak tibial acceleration magnitude in the time domain and greater tibial acceleration signal power in the frequency domain compared with FF running. Joint and segment configurations at terminal swing will influence the velocity of the foot and leg just prior to impact and thus the force and rate of deceleration required to terminate foot and leg movement at initial contact. As a result, impact shock magnitude and the frequency that peak power occurs will also be affected. In the

higher frequency range, peak power of the tibial acceleration signal occurred at a lower frequency during FF running this website compared with CP-673451 ic50 RF running. This finding may indicate that FF running results in a lower rate of tibial acceleration in the time domain at initial contact compared with RF running. Greater ankle compliance during FF running23 and 50 may contribute to a lower rate of tibial deceleration after ground contact compared with RF running and may also delay the time that the vertical impact peak GRF occurs in FF running. A first delay in the timing of the impact peak may explain why it is not visible in the time domain vertical GRF during FF running.51 Tibial acceleration signal power in the lower frequency range, representing the vertical GRF active peak and active movement of the leg and foot and whole body COM during stance,13 and 17 was hypothesized to be greater during FF running than RF running because previous studies observed greater vertical GRF active peak magnitude in the time domain with FF running.23 and 24 Contrary to this hypothesis, RF running resulted in greater tibial acceleration

power magnitude in the lower range compared with FF running. Previous observations that RF running results in greater knee flexion excursion and velocity,23 a greater stride length, and a greater contact time52 may explain these results because these kinematics result in greater tibial signal power magnitude of frequencies below 10 Hz.14, 17 and 22 However, the frequency that peak tibial acceleration signal power occurred in the lower range was similar between footfall patterns indicating a similar rate of tibial acceleration during stance after initial contact. This result suggests that the dominant frequency component contributing to the overall tibial acceleration waveform in the lower frequency range is similar between footfall patterns.