The Effects of Fatigue on Rear Foot Angle in Normal and Pronate Individuals

The purpose of this study was to identify the effects of fatigue caused by exercise on rear foot angle (RFA) in normal and pronate subjects during the stance phase of running.
Twenty-four male students from Birjand University (13 with normal foot, 11 with pronate foot) were selected based on navicular drop index. After the measuring RFA (according to Nigg (1986), each subject ran on the treadmill at the speed of 3/5 m/s for 15 minutes without shoes. In addition, the RFA were measured after fatigue situation which determined according to the scale rating of perceived exertion (RPE) during running.
Dependent t-test showed no significant difference in RFA between normal foot before fatigue (at the initial of the protocol) and during fatigue (at the end of the protocol) in all phases of stance phase, except in the heel contact (p=0.001). However, there was a significant difference between the RFA of pronate foot before and after fatigue in all phases of stance phase (p≤0.05), where the RFA showed significant increase after fatigue.
Based on the present results, fatigue can be considered as an important factor in increasing RFA in people with pronate foot. Therefore, it can be considered for runners, especially with pronate foot for prevention of injuries during running.