PNF and Movement 2019; 17(3): 481-486
Effect of Calf Muscle Fatigue on Postural Sway According to Foot Posture
Myoung-Hee Lee, P.T., Ph.D⋅Jong-Sung Chang, P.T., Ph.D1†
Department of Physical Therapy, Uiduk University
1Department of Physical Therapy, Yeungnam University College
Correspondence to: Jong-Sung Chang (
Received: December 9, 2019; Revised: December 9, 2019; Accepted: December 11, 2019; Published online: December 31, 2019.
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Purpose: This study examined the effect of calf muscle fatigue on postural sway according to foot posture (a pes cavus, a normal foot, and a pes planus).
Methods: The subjects of this study were 12, 11, and 9 students of U University with a pes cavus, a normal foot, and a pes planus, respectively, according to a Navicular Drop Test. Postural sway was measured with a balance instrument (BioRescue, RM Ingenierie, France) while the subjects stood static on two legs as well as during one-leg standing using the dominant leg in two conditions (with the eyes open and with the eyes closed for 30 seconds). Muscle fatigue was then induced in the calf muscle of the dominant leg, and both muscle fatigue and postural sway were measured using an EMG. To compare the degree of postural sway between the three groups after muscle fatigue was induced, the change values were calculated. The results were analyzed using a Kruskal–Wallis test, and a post-hoc test was conducted using the Bonferroni correction.
Results: Significant inter-group differences were detected for postural sway during two-leg standing with the eyes closed and during one-leg standing with the eyes open and with the eyes closed (p<0.05). The post-hoc test showed significant differences between the pes cavus and normal foot groups and between the pes planus and normal foot groups for all three variables (p<0.05). However, no significant difference was detected between the pes cavus and pes planus groups (p>0.05).
Conclusion: The results of this study show that the pes cavus and pes planus cause more fatigue and postural sway than a normal foot. Therefore, attention should be paid to changes in balance caused by muscle fatigue.
Keywords: Muscle fatigue, Foot posture, Postural sway

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