Individual effects of stride length and frequency on shock attenuation during running.
Shock attenuation during running is the process of absorbing impact energy due to the foot-ground collision, reducing shock wave amplitude between the foot and head. Shock attenuation is affected by changes in stride length and stride frequency, but it is not clear whether either parameter individually affects shock attenuation.


OBJECTIVE
To identify the independent affects of stride length (SL) and stride frequency (SF) on shock attenuation.


METHODS
Subjects ( N = 10) completed three experiments consisting of SL and SF manipulations relative to preferred stride length (PSL) and frequency (PSF). During experiment 1, stride length was manipulated (+15% PSL, PSL, -15% PSL) while stride frequency was always set to PSF. During experiment 2, stride frequency was manipulated (+15% PSF, PSF, -15% PSF) while stride length was always set to PSL. During experiment 3, stride length and stride frequency were manipulated concurrently (+10% PSL/-10% PSF, PSL/PSF, and -10% PSL/+10% PSF). Running velocity was always the product of stride length and stride frequency. Transfer functions were calculated using tibial and forehead surface mounted accelerometer data to represent shock attenuation.


RESULTS
Shock attenuation changed only when stride length changed ( P < 0.05). Specifically, shock attenuation increased as stride length increased.


CONCLUSIONS
It was concluded that changes in stride length not stride frequency affected shock attenuation.
Mercer
John A
JA
Department of Kinesiology, University of Nevada, Las Vegas, Las Vegas, NV 89154-3034, USA. jmercer@nevada.edu
Devita
Paul
P
Derrick
Tim R
TR
Bates
Barry T
BT
D000042:Absorption; D000328:Adult; D001696:Biomechanical Phenomena; D005528:Foot; D005684:Gait; D006801:Humans; D008297:Male; D055585:Physical Phenomena; D010825:Physics; D012420:Running / Q000502:physiology*; D016474:Weight-Bearing