Figure 1.

Changes in body composition, grip strength, and rotarod performance in mice across the life span. (A) Total body, (B) lean, and (C) fat mass, as well as (D) forelimb grip strength, (E) hindlimb grip strength, and (F) rotarod performance over time for males (solid black line), females (gray line), and combined male and female data (dotted black line). The importance of including intermediate time points for aging studies is demonstrated by showing that hindlimb grip strength (G) increases with aging if 4 months is considered maximal performance, but (H) decreases with aging when a time point with the true maximal force (ie, 15 months) is included. Repeated-measures analysis of variance was performed for G1 (4–7 months) and G2 (12–24 months) separately. Data are expressed as mean ± SEM. *Significant difference from maximal, p < .05 (ie, 18 months for all body composition measures, 15 months for hindlimb grip strength and rotarod, and 4 months for forelimb grip strength); §Significant difference between males and females at the specified time point, p < .05.