Evaluating the fatigue rate of lower leg muscles during prolonged standing: a comparison between stable and unstable footwear

It is well established that unstable footwear with a rounded sole design have the potential to alter lower limb muscle activity during standing and walking activities. Thus, the main objective of this study was to compare lower leg muscles fatigue rates between stable and also unstable footwear during prolonged standing. Ten young healthy man were participated in this study. During 2 h of continuous standing with two footwear conditions (stable and unstable shoes), surface electromyography (EMG) data of bilateral tibialis anterior (TA) and medial gastrocnemius (MG) muscles were continuously collected. The probability of muscle fatigue was identified through recording simultaneous increase in the EMG amplitude and shift in the EMG frequency spectrum towards lower frequencies. Analysis of EMG recordings revealed that standing with stable shoe significantly yielded higher rates of muscle fatigue for bilateral MG muscles. Furthermore, no significant differences were observed for the fatigue rates of TA muscles between two footwear conditions. However, none of monitored muscles were indicated fatigue during standing with unstable shoe. The results suggested that unstable footwear, compared to stable one, more efficient to prevent the occurrence of muscle fatigue which seemed to be advantageous for the musculoskeletal system. Therefore, unstable footwear can be recruited as ergonomic intervention for individuals whose stand for prolonged periods.