Context: Electrical muscle stimulation (EMS) was designed for artificial muscle activation or superimposed training. Objectives: To compare the effects of 8 weeks of superimposed technique (ST; application of electrical stimulation during a voluntary muscle action) and EMS on the cross-sectional area of the rectus abdominis, lateral abdominal wall, and on lumbopelvic control. Setting: University research laboratory. Design: Randomized controlled trial. Participants: Fifty healthy subjects were recruited and randomly assigned to either the ST or EMS group. Intervention: The participants engaged with the electrical stimulation techniques (ST or EMS) for 8 weeks. Main Outcome Measures: In all participants, the cross-sectional area of the rectus abdominis and lateral abdominal wall was measured by magnetic resonance imaging and lumbopelvic control, quantified using the single-leg and double-leg lowering tests. Results: There were no significant differences in the cross-sectional area of the rectus abdominis (right: P = .70, left: P = .99) or lateral abdominal wall (right: P = .07, left: P = .69) between groups. There was a significant difference between groups in the double-leg lowering test (P = .03), but not in the single-leg lowering test (P = .88). There were significant differences between the preintervention and postintervention in the single-leg (P < .001) and double-leg lowering tests (P < .001). Conclusions: ST could improve lumbopelvic control in the context of athletic training and fitness.
Effect of Abdominal Electrical Muscle Stimulation Training With and Without Superimposed Voluntary Muscular Contraction on Lumbopelvic Control
Ui-Jae Hwang, Sung-Hoon Jung, Hyun-A Kim, Jun-Hee Kim, and Oh-Yun Kwon
Comparison of Shoulder Protraction Strength and Electromyography Activity of Serratus Anterior and Pectoralis Major in Subjects With or Without a Winged Scapula
Jun-Seok Kim, Moon-Hwan Kim, Duk-Hyun Ahn, and Jae-Seop Oh
Context: A winged scapula (WS) is associated with faulty posture caused by weakness of the serratus anterior (SA), which mainly acts as a scapular stabilizer muscle. It is important to accurately assess and train the SA muscle with a focus on scapula stabilizers during musculoskeletal rehabilitation of individuals with a WS. Objective: The authors examined muscle activity in the SA and pectoralis major (PM), upper trapezius (UT), and anterior deltoid (AD) as well as shoulder protraction strength during isometric shoulder protraction in individuals with and without a WS. Design: Cross-sectional study. Setting: A clinical biomechanics laboratory. Participants: In total, 27 males with no shoulder, neck, or upper-extremity pain participated. Main Outcome Measures: Isometric shoulder protraction strength was collected and surface electromyography used to measure the activity of the SA, PM, UT, and AD muscles and selective SA activity ratio to other shoulder muscles. Results: Electromyography activity of the SA muscle and shoulder protraction strength were significantly lower in individuals with a WS compared with the non-WS group (P < .05). In contrast, PM muscle activity and the PM-to-SA, UT-to-SA, and AD-to-SA ratios were significantly greater in individuals with a WS than in individuals without winging (P < .05). Conclusions: Isometric shoulder protraction for measuring SA strength in individuals with a WS should focus on isolated muscle activity of the SA, and SA strengthening exercises are important for individuals with a WS.