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Background: Improvements in motor control of the scapular muscles are important for the prevention and rehabilitation of shoulder and elbow injuries in overhead athletes. Purpose: To clarify scapular muscle activity during multijoint compound movement exercises using fine-wire and surface electrodes. Study Design: Descriptive laboratory study. Methods: Sixteen healthy men performed 5 types of exercises (cat and dog, trunk rotation, A-exercise, T-exercise, and Y-exercise). Muscle activity was measured as percentage of maximum voluntary isometric contraction (%MVIC) by using fine-wire electrodes in the rhomboid major (Rhom) and using surface electrodes in the upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior (SA) muscles. The Rhom/UT, MT/UT, LT/UT, and SA/UT muscle activity ratios were calculated. One-way analysis of variance was used to compare the %MVIC and muscle activity ratios between exercises. Results: There was no significant difference in Rhom activity between the exercises (34.6-54.2%MVIC; P =.25). LT activity was significantly greater in the trunk rotation (58.0 ± 24.6%MVIC) and Y-exercise (63.2 ± 40.1%MVIC) than in the cat and dog scapular retraction (19.6 ± 9.3%MVIC) and A-exercise (28.2 ± 14.2%MVIC) (P <.05). SA activity was significantly greater in the cat and dog scapular protraction (26.7 ± 11.0%MVIC) and Y-exercise (25.6 ± 19.3%MVIC) than in the other exercises (P <.05). The SA/UT activity ratio in the cat and dog scapular protraction exercise (9.64 ± 8.48) was significantly higher than in the other exercises (P <.05). Conclusion: All the exercises were effective for activating the Rhom. The trunk rotation and Y-exercise were effective for activating the LT, and the cat and dog scapular protraction exercise was effective for activating the SA while suppressing the UT. Clinical Relevance: These results enable exercise selection based on muscle activity characteristics (moderate [20%-50%MVIC] and high [>50%MVIC] levels contribute to muscle activation) to prevent and rehabilitate shoulder and elbow injuries. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Objective: Pelvic tilt exercises are used clinically to correct lumbopelvic alignment. The anterior and posterior layers of the quadratus lumborum are important for pelvic motor control in the coronal plane. This study aimed to evaluate whether the anterior and posterior activity is related to the pelvic tilt angle during pelvic tilt exercises. Design: The study design was single-occasion repeated measures in a randomized manner. Twelve healthy men performed the four directions of the pelvic tilt exercises (anterior or posterior pelvic tilt and lateral pelvic elevation on the ipsilateral or contralateral measurement side). The electromyographies of the anterior and posterior were recorded using intramuscular fine-wire electrodes and normalized to isometric peak electromyography. Results: The activity of the anterior and posterior during lateral pelvic elevation on the ipsilateral measurement side (19.0 ± 16.0 percent of maximal voluntary isometric contraction) was significantly higher than that during other directions of the pelvic tilt exercises (P < 0.01). There was a significant positive correlation between the anterior activity and the maximum change angles of pelvic tilt during lateral pelvic elevation on the ipsilateral measurement side (r = 0.674, P = 0.016). Conclusions: The anterior activity was related to a large lateral pelvic elevation angle on the ipsilateral side during pelvic tilt exercises. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the influence of a history of low back pain (LBP) on pelvic and lumbar kinematics during baseball hitting. Twenty collegiate male baseball players (age, 21±1 years; height, 172.8±4.7 cm; weight, 72.7±6.2 kg; baseball experience, 13±1 years) performed 5 bat swings. Participants were categorized into the LBP group (n=10) or control group (n=10) based on having experienced lumbar spine pain due to bat swing that lasted more than 24 h within the last 12 months. Three-dimensional kinematic data of the pelvis and lumbar spine during bat swing were measured. Two-way ANOVAs were used to compare pelvic and lumbar kinematics throughout the bat swing between groups, and independent t-tests were used to compare the other outcomes between groups. There was a significant main effect between groups in lumbar flexion angle throughout the bat swing (p=0.047). The mean lumbar flexion angle of the LBP group throughout the bat swing was less than that of the control group. Additionally, the peak angular velocity of lumbar flexion of the LBP group was significantly faster than that of control group (p=0.047). These results can be helpful for longitudinal studies that identify the risk factors of LBP due to bat swing. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the difference in the onset of EMG activity between eight trunk muscles, including the anterior (QL-a) and posterior (QL-p) layers of the quadratus lumborum during rapid shoulder joint abduction. Thirteen healthy men participated in this study. Electromyography of the QL-a, QL-p, transversus abdominis (TrA), internal oblique (IO), external oblique (EO), rectus abdominis (RA), lumbar multifidus (LMF), lumbar erector spinae (LES) on non-movement side, and middle deltoid (MD) on the movement side were measured. Subjects who were standing in a relaxed position performed rapid shoulder abduction with the dominant hand after light stimulus with or without a 3 kg wrist weight. Two-way ANOVA (muscles × weight conditions) was used to compare the onset of trunk muscles relative to that of MD. There was a significant main effect of the muscles. The onset of the QL-a, QL-p, and TrA was significantly earlier than that of the IO, EO, LMF, and LES (P < 0.01). This result suggests that the activities of the QL-a, QL-p, and TrA have a crucial role in controlling the center of mass within the base of support and stabilizing the lumbar spine in the coronal plane during shoulder abduction. [ABSTRACT FROM AUTHOR]