Design and evaluation of sportswear integrated with electrical muscle stimulation

Abstract

Electrical muscle stimulation (EMS) technology integrated into sportswear offers promising potential for enhanced muscle building. However, there is limited understanding of strategic electrical parameters essential to maximize effectiveness. Therefore, this study aimed to design and develop an EMS-integrated sportswear capable of delivering targeted stimulation, and to evaluate its effectiveness through surface electromyography (sEMG) experiments. The root mean square (RMS) values of sEMG signals were analyzed, and a two-way repeated measure analysis of variance (ANOVA) with Tukey post hoc test was employed to examine the effects of varying electrical stimulation on muscle activation in the gastrocnemius, rectus femoris, and biceps femoris over nine time points (t₁ to t₉). The findings indicated that the activation patterns varied across different muscle groups in response to changes in frequency, voltage, and duration of stimulation. Notably, higher frequencies (70 and 100 Hz) significantly enhanced muscle activation in the rectus femoris and biceps femoris at earlier stages, while the gastrocnemius muscle demonstrated limited response. At higher voltages (10.8 and 13.5 V), the rectus femoris and biceps femoris exhibited strong activation across most time points, whereas the gastrocnemius remained unresponsive. Conversely, lower frequencies and voltages resulted in delayed activation responses. Perceived exertion increased over time across all conditions. In addition, tactile feedback was observed earlier at higher voltages (400 seconds at 13.5 V) and higher frequencies (200 seconds at 100 Hz), indicating faster neural responses at these levels. These findings provide critical insights for optimizing EMS-integrated sportswear designs, enhancing their practical application in sports performance enhancement and rehabilitative healthcare.