Changes in Shoulder Girdle Muscle Activity and Ratio During Pilates-Based Exercises

Among the Pilates-based exercises, the modified side-arm (MSA) and modified high-five (MHF) are commonly used for shoulder strengthening and rehabilitation. This study examined shoulder girdle muscle activity and ratios across different spring intensities. Twenty-two healthy males performed the MSA and MHF using yellow (low), blue (medium), and red (high) springs. Surface electromyography (EMG) was used to measure serratus anterior (SA), lower trapezius (LT), levator scapulae (LS), upper trapezius (UT), and middle deltoid (MD) muscle activity, along with LS/SA, LS/LT, and UT/LT ratios during concentric, isometric, and eccentric phases. Muscle activities were generally higher in the MHF than in the MSA with the same spring. Both exercises demonstrated a proportional increase in activity with spring intensity, though the activity of the SA and LT in the MHF plateaued. MHF ratios were significantly higher with the red spring. These findings indicate that the MHF stimulates shoulder girdle muscles more than the MSA, and that the MSA can further stimulate shoulder girdle muscles by increasing spring intensity. Additionally, optimal spring intensity exists in the MHF for targeting shoulder stabilization muscles. However, excessive spring intensity during the MHF may lead to abnormal compensation, emphasizing the need for careful spring intensity progression.