Shoulder Kinematics Vary Over the Lifespan: A Study of Healthy Adults

Scapular kinematics are influenced by age, but the relationship in older populations and across functional tasks needs further investigation. The objective of this study was to examine scapular and humeral kinematics during the Work-Related Activities and Functional Task protocol across a broad age range. Eighty healthy adults (46 [20] y; 170 [11] cm; 78.8 [16.8] kg) completed the Work-Related Activities and Functional Task protocol and 2 planar elevations while shoulder motion was tracked with optical motion capture. Scapular and humeral angles were assessed in relation to age. Pearson correlation analyses showed that scapular tilt was significantly (P < .001) correlated with age at many humeral elevations during the comb hair (r = .443-.490), wash axilla (r = .478-.498), overhead reach (r = .256-.406), and sagittal flexion (r = .316-.426) movements. Two-way analyses of variance with sex and age group factors (older [>65] and younger [<35] only) revealed that the older group had significantly more scapular posterior tilt, and statistical parametric mapping independent t tests showed that older adults also used consistently more humeral elevation during several movements. These findings provide insight into the interacting influence of age and shoulder kinematics on shoulder musculoskeletal health.