The effects of different V-sit positions on abdominal muscle activation

Objective: This study aimed to identify the effects of performing shoulder and hip abduction during the V-sit exercise on abdominal muscle activity. Design: Cross-sectional study. Methods: Thirty healthy adults volunteered for this experiment. The participants randomly performed 6 types of V-sit exercises, including V-sit alone (hip 0°, shoulder 0°), V-sit with hip abduction 0° and shoulder abduction 15°, V-sit with hip abduction 0° and shoulder abduction 30°, V-sit with hip abduction 15° and shoulder abduction 0°, V-sit with shoulder and hip abduction 15°, and V-sit with shoulder abduction 30° and hip abduction 15°. EMG data were recorded from the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles of both sides. All abdominal EMG data during the six types of V-sit exercises were measured for 5 seconds, three times, and recorded for the middle 3 seconds excluding the 1 second at the start and end. Results: V-sit with shoulder abduction 30° resulted in significantly greater muscle activity of both RA, EO compared to shoulder abduction 0°, shoulder abduction 15° (p<0.05) and V-sit with shoulder abduction 15° showed significantly greater muscle activation of the RA compared with shoulder abduction 0° (p<0.05). The muscle activity of both EO and IO in the V-sit with hip abduction 15° was significantly greater than hip abduction 0° in all shoulder conditions (p<0.05). Conclusions: Greater angles of shoulder and hip abduction produced more abdominal muscle activity increases during the V-sit exercises. Shoulder abduction affected the RA, EO muscle activation and hip abduction affected the EO, IO muscle activation. This study showed that shoulder and hip abduction during V-sit exercises enabled effective activation of the trunk muscles.