ABSTRACT
The effect of electromyographic (EMG) activity on agonist muscles during exercises performed on stable and unstable surfaces remains uncertain. We aimed to review the literature regarding the comparison of the EMG activity of the agonist muscles of exercises performed on stable and unstable surfaces. Eighty-six studies that evaluated the EMG activity of 1783 individuals during exercises for the lower limbs, upper limbs, and core were included. The EMG activities of the pectoralis major (SMD = 0.28 [95% CI 0.09, 0.47]) and triceps brachii muscles (SMD = 0.45 [95% CI 0.25, 0.66]) were significantly increased when the unstable device was added to the exercise. Likewise, the EMG activity of all core muscles showed a significant increase with the unstable surface during the exercises, such as the rectus abdominis (SMD = 0.51 [95% CI 0.37, 0.66]), external oblique (SMD = 0.44 [95% CI 0.28, 0.61]), internal oblique (SMD = 1.04 [95% CI 0.02, 2.07]), erector spinae (SMD = 0.37 [95% CI 0.04, 0.71]), and lumbar multifidus (SMD = 0.35 [95% CI 0.08, 0.61]). However, the lower limb muscles did not show greater EMG activity during the exercise with unstable surfaces compared to the stable surface. In conclusion, unstable conditions increase the EMG activity of some upper limb and core muscles compared to a stable surface.
ABSTRACT
BACKGROUND: Shoulder pain affects millions of workers worldwide and is considered one of the leading causes of absenteeism and presenteeism. Therefore, using exercises in the work environment emerges as a strategy to prevent or reduce shoulder pain. OBJECTIVE: The objective of this study was to evaluate the effects of a workplace-based exercise program on shoulder pain and function in fruit workers. METHODS: This was an 8-week parallel two-arm randomized controlled trial. Forty-four fruit workers who reported chronic shoulder pain were randomized to an Experimental Group (EG) or Control Group (CG). The EG was submitted to a program of resistance and stretching exercises for eight weeks, twice a week. The CG received a booklet with muscle stretching and mobility exercises. The primary outcome was shoulder pain intensity; the secondary outcomes were Shoulder Pain and Disability Index (SPADI) and perceived global effect. RESULTS: Both groups showed reductions in pain intensity EG: 4.26 (95% CI 2.78-5.74) and CG: 3.74 (95% CI 1.98-5.50) points. The SPADI results showed an average reduction of 17.76 (CI 95% 3.10-32.43) for the EG and 18.39 (CI 95% 3.66-33.13) for the CG. The mean value of the perceived global effect for the CG was 3.45±2.01, and for the EG, the mean was 4.13±1.24. No differences were observed between groups in any outcome analyzed. CONCLUSION: Both groups showed significant changes in the analyzed outcomes. However, the workplace-based exercise program was not superior to the exercise booklet.
