There were no apparent changes in mouse body weight (A), supraspinatus muscle maximum cross-sectional area (CSA; B), upper limb grip strength (C), total voluntary activities (D), respiratory exchange ratio (RER; E), and energy expenditure (F) in mice with Gja1 tendon and enthesis deficiency. ^, 2-way ANOVA, p < 0.05 for age. The sample size (N) in D applies to D–F.