Effects of Supine Scapular Punch Exercise Combined with the Maximum Abdominal Contraction Maneuver on Abdominal and Shoulder Stabilizer Muscle Activities and Upper Trapezius Muscle Tone

PURPOSE This study investigated the effects of combining the maximum abdominal contraction maneuver (MACM) with supine scapular punching (SSP) on abdominal and shoulder stabilizer muscle activity and upper trapezius (UT) muscle tone in healthy adult men. METHODS Twenty-one healthy men (aged 20-40 years) without shoulder dysfunction participated in a randomized crossover trial. The participants performed both SSP and SSP+MACM exercises in a randomized order. Surface electromyography was used to assess the muscle activity of the rectus abdominis (RA), external oblique (EO), internal oblique (IO), serratus anterior (SA), and UT. UT muscle tone was measured using MyotonPRO. Data were analyzed using paired t-tests or Wilcoxon signed-rank tests, and one-way repeatedmeasures ANOVA or Friedman tests based on data normality (α = 0.05). RESULTS Compared with SSP alone, the SSP+MACM condition significantly increased the RA, EO, IO, and SA muscle activity (p < 0.05) and significantly reduced the UT activity (p < 0.05). Additionally, UT muscle tone was significantly decreased after SSP+MACM compared to both baseline and SSP (p < 0.001). CONCLUSIONS The combination of MACM and SSP effectively enhances abdominal and scapular stabilizer activation while reducing compensatory upper trapezius tension. This integrated approach may be a practical and efficient strategy for trunk and shoulder stabilization in rehabilitation and athletic training.