Age-Related Changes in Morphology and Function of Scapular Muscles in Asymptomatic People

Shuhei Morise, Takayuki Muraki, Hiroaki Ishikawa, Shin Ichi Izumi

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Background Aging is a contributing factor to rotator cuff tears. Dysfunction of the scapular muscles can be a potential cause of rotator cuff tears. Although aging can contribute to dysfunction of the scapular muscles and subsequently result in rotator cuff tears, the effects of aging on scapular muscles are unclear. Objective To determine changes in sizes and electromyographic activities of the scapular muscles with age in asymptomatic subjects. Design Cross-sectional study. Patients Fifty-four asymptomatic subjects without shoulder pain and dysfunction (18 male and 36 female) were recruited for this study. Subjects consisted of 19 people aged 20-39 years (young adult group, 27.2 ± 5.2 years), 17 people aged 40-59 years (middle age group, 49.9 ± 6.6 years), and 18 people aged 60-79 years (elderly group, 68.0 ± 7.1 years). Methods Using ultrasonography, we measured the muscle thickness of the trapezius (upper and lower portions), serratus anterior, and middle deltoid muscles during rest with the subject in a sitting position. Activities of the same muscles were measured with surface electromyography during shoulder elevation in the scapular plane up to 120°. The electromyographic data were analyzed at ranges 0°-30°, 30°-60°, and 60°-90°. Analysis of variance and Bonferroni multiple comparisons were used for statistical analysis. Results Muscle thickness of the lower trapezius in the elderly group was decreased significantly compared with that in the young adult group (95% confidence interval −0.40, 2.24; P <.001) and middle age group (95% confidence interval −0.34, 1.89; P =.012). There were no significant differences in muscle activity and activity ratio between groups. Conclusion In scapular muscles, muscle thickness of the lower trapezius significantly decreased with aging, although there were no decreases in muscle thicknesses of the other muscles between different age groups. For the functional change, aging may not affect the scapular muscle activities and balance of the activities between the deltoid and scapular muscles. Level of Evidence IV

Original languageEnglish
Pages (from-to)892-900
Number of pages9
JournalPM and R
Volume9
Issue number9
DOIs
Publication statusPublished - 2017 Sep

ASJC Scopus subject areas

  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation
  • Neurology
  • Clinical Neurology

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