Research Paper Volume 10, Issue 11 pp 3327—3352

Figure 2. Skeletal muscle strength and endurance, as well as overall exercise performance, decline as early as 24 months of age. Exercise performance and skeletal muscle strength were evaluated in young (3 mo, open circles) and old (24-25 mo, grey circles; 29-30 mo, black circles) mice. (A-B) Exercise performance on a treadmill is presented as the percentage of mice still running (A) and the distance run and running time (B; means and standard deviations are shown); 3 mo (n=20), 24-25 mo (n=24). (C-D) Exercise performance on a rotarod is presented as the percentage of mice still running (C), and latency (D; mean time before falling and standard deviations are shown); 3 mo (n=9), 24 mo (n=9). (E) Muscle endurance assessed using a hang wire test is presented as time spent hanging on the wire before falling (means and standard deviations are shown); 3 mo (n=11), 24 mo (n=18), 29 mo (n=11). (F) Muscle strength was assessed using a four-limb grip strength test (means and standard deviations are shown); 3 mo (n=20), 24 mo (n=26), 25 mo (n=24), 29 mo (n=11). *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001.