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 has 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. This study was conducted in Urmia, northwest Iran (2015) and participants included ten young healthy male. During 2 h of continuous standing with two footwear conditions (stable and unstable shoes), surface electromyographic (EMG) data of bilateral tibialis anterior (TA) and medial gastrocnemius (MG) muscles were continuously recorded. 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. According to analysis of EMG recordings, standing with stable shoe yielded significantly higher rates of muscle fatigue for bilateral MG muscles (p < 0.05). 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, is more efficient to prevent the occurrence of muscle fatigue which seems to be advantageous for the musculoskeletal system. Therefore, unstable footwear can be recruited as an ergonomic intervention for individuals who stand for prolonged periods.