Affiliations: [a] Department of Health Science, Korea University Graduate School, Seoul, Korea | [b] College of Medicine, Korea University, Seoul, Korea | [c] Korea National Rehabilitation Research Institute, Seoul, Korea | [d] Department of Physical Therapy, College of Health Sciences, Korea University, Seoul, Korea
Abstract: BACKGROUND: The prevalence of degenerative shoulder disease is increasing, and most shoulder diseases are accompanied by changed activation of the scapular muscles. However, the characteristics of scapular muscle activation in older adults have not yet been reported. OBJECTIVE: The aim of this study was to investigate the effect of age and load on scapular muscle activation during shoulder abduction and flexion. METHODS: Eleven older adults (5 men, 6 women; 71.1 ± 5.3 years) and ten young adults (5 men, 5 women; 25.0 ± 2.7 years) performed shoulder elevation (abduction and flexion) with and without a dumbbell. Electromyography were recorded from the upper, middle and lower trapezius, and serratus anterior muscles in the dominant side. Muscle activation was normalized by reference voluntary contractions. RESULTS: During shoulder elevation with a dumbbell load, the activation of the middle trapezius (p= 0.036) in older adults was significantly higher than that in young adults during abduction. The activation of the upper trapezius (p= 0.001) in older adults was significantly higher than that in young adults during flexion. CONCLUSION: The older adults have a higher activation of the upper and middle trapezius during shoulder elevation with a weighted load.
