PMC

(A) Grip strength, rotarod, dark activity and sleep fragmentation were not significantly associated with premature mortality in females, p > 0.99, p = 0.18, p > 0.99, p > 0.99, respectively. (B) Grip strength, rotarod, dark activity and sleep fragmentation were not significantly associated with premature mortality in males, p = 0.240, p > 0.99, p > 0.99, p > 0.99, respectively. All tests subjected to Bonferroni corrections for multiple comparisons. Animals suffering premature mortality shown in blue, survivors in black.

Visual representation of the relative performance on four healthspan measures by 28-month-old mice. Mice performing best (blue symbols) and worst (red symbols) on the grip strength test, did not perform similarly on other measures of healthspan in females (A) and males (B). Correlations and p-values are in Tables and .

Visual representation of the relative performance on four healthspan measures by 28-month-old mice. Mice performing best (blue symbols) and worst (red symbols) on the grip strength test, did not perform similarly on other measures of healthspan in females (A) and males (B). Correlations and p-values are in Tables and .

(A) Rotarod performance varied among female mice of all age groups. (B) 4-month -old males stayed on the rotarod longer than 28 and 32-month -old males (p = 0.042 and p = 0.006, respectively). Post-hoc tests subject to Bonferroni correction for multiple comparisons. Rotarod sample size: Females n = 20, 20, 26 and 27 for 4, 20, 28 and 32 months; Males n = 22, 20, 30 and 24 for 4, 20, 28 and 32 months.

Measures correlated among female mice include (A) grip strength and dark activity (p = 0.0003, R = 0.454); (B) grip strength and percent fat (p = 0.0037, R = 0.405); (C) percent fat and body mass, (D) rotarod performance (latency to fall) and body mass (p = 0.0006, R = −0.443); (E) dark and light phase metabolic rate (p < 0.0001, R = 0.880); (F) dark phase and resting metabolic rate (p < 0.0001, R = 0.823) and (G) light phase and resting metabolic rate (p < 0.0001, R = 0.860).
Measures correlated among male mice include (H) grip strength and dark activity (p = 0.0003, R = 0.454); (I) grip strength and percent fat (p = 0.0037, R = 0.405); J. percent fat and body mass; (K) dark phase activity and body mass; (L) rotarod performance (latency to fall) and body mass (p = 0.0006, R = −0.443); (M) rotarod performance and dark phase activity; (N) dark and light phase activity; (O) percent fat and light phase activity; (P) dark phase activity and metabolic rate; (Q). dark and light phase metabolic rate (p < 0.0001, R = 0.880); (R) dark phase and resting metabolic rate (p < 0.0001, R = 0.823) and (S) light phase and resting metabolic rate (p < 0.0001, R = 0.860).

(A, B) Gait width did not differ among the four age groups in female (p = 0.095) or male (p = 0.191) mice. (C) Mean rear-foot stride length among females in the four age groups was marginally different (p = 0.048). (D) Rear-foot stride length did not differ between males in the 4 age groups (p = 0.786). Post-hoc tests subject to Bonferroni correction for multiple comparisons. Sample size: Females n = 20, 20, 27 and 27 for 4, 20, 28 and 32 months; Males n = 22, 19, 26 and 22 for 4, 20, 28 and 32 months.

(A) Female mice of all ages had similar metabolic rates during the dark (=active) phase. (B) During the dark phase, 4-month -old male mice had higher metabolic rates on average than 20, 28 and 32-month-old males (p = 0.025, p < 0.0001, p < 0.0001 respectively). 20-month-old males also had higher mass-specific metabolic rates compared to 28 and 32-month-olds (p = 0.002 in both cases). 28 and 32- month-old males did not differ (p > 0.999). (C) Female mice of all ages had similar metabolic rates during the light (=inactive) phase (p = 0.943). (D) During the light phase, 4-month -old male mice had higher metabolic rates on average than 28 or 32-month-old males (p = 0.033, p = 0.012, respectively), as did 20-month-old males (p = 0.002, p = 0.010, respectively). 28 and 32- month-old males did not differ from one another (p > 0.999). Post-hoc tests subject to Bonferroni correction for multiple comparisons. Metabolism sample size: Females n = 20, 20, 26 and 26 for 4, 20, 28 and 32 months; Males n = 17, 21, 29 and 28 for 4, 20, 28 and 32 months.

(A) 4-month-old females were smaller than 20 and 28-month-old females (p < 0.0001 in both cases) but similar to 32-month-old females (p = 2.276). (B) 4-month -old males were smaller than 20, 28 and 32-month-old male mice (p <0.0001, p <0.0001and p = 0.018, respectively). (C) 20-month-old females had a greater percentage of body fat than 4, 28 and 32-month-old female mice (p < 0.0001 in all cases). 4-month -old females had a greater proportion of body fat than 32-month-old females (p = 0.014) but did not differ from 28-month-old females. (D) 4-old males had a greater proportion of fat than either 28 or 32-month-old males (p = 0.036, p < 0.0001, respectively), as did 20-month-old males (p = 0.0003 and p < 0.0001). But 4 and 20-month-old males and 28 and 32-month-old males did not differ (p > 0.999, p = 0.179, respectively). Post-hoc tests subject to Bonferroni correction for multiple comparisons. Body composition sample size: Females n = 20, 20, 30 and 27 for 4, 20, 28 and 32 months; Males n = 22, 22, 32 and 30 for 4, 20, 28 and 32 months.

(A) On average, older female mice (ages 28 and 32 months) slept less than 20-month-old females (p = 0.029, p = 0.0003, respectively) and 32-month-oldfemales slept less than 4-month -old females (p = 0.001). 4-month -old females did not differ from 20-month-old females or 28-month -old females (p >0.999, p = 0.068, respectively), and 28-month -old females did not differ from 32-month-olds (p = 0.796) in the amount of time spent sleeping. (B) Male mice did not show age differences in total amount of sleep measured over a 24-hour period (p = 0.40). (C) Sleep fragmentation was greater in older females (ages 28 and 32 months) than in 4-month -old females (p = 0.0006, p < 0.0001, respectively) and 20-month-old females (p = 0.036, p = 0.001, respectively). Sleep fragmentation did not differ between 28 and 32-month-old (p >0 0.999). (D) Sleep fragmentation was greater in older male mice (p = 0.028); however, in pair-wise comparisons only 4-month and 32-month-old males were significantly different (p = 0.030). Post-hoc tests subject to Bonferroni correction for multiple comparisons. Females n = 20, 20, 30 and 27 for 4, 20, 28 and 32 months. Males n = 18, 18, 26 and 23 for 4, 20, 28 and 32 months.

(A) Female grip strength was reduced in older females compared to younger ones (p < 0.0001). Grip strength was greater in 4-month -old females than 28 and 32-month -olds (p = 0.0002 and p< 0.0001, respectively) and did not differ from 20-month-olds (p =0.431). Grip strength measured in 20-month-old females was greater than that of 32-month -olds (p < 0.0001), but not 28-month -olds (p = 0.0942). (B) Grip strength was similar in 4 and 20-month old males (p > 0.999); both had greater grip strength than 28-month -old (p = 0.001 and p = 0.024, respectively) and 32-month -old males (p = 0.001 and p = 0.021, respectively). Grip strength was similar in 28 and 32-month old males (p > 0.999) (C, D) Performance on the tail flick test did not differ between age groups in female (p = 0.422) or male (p = 0.370) mice. Post-hoc tests subject to Bonferroni correction for multiple comparisons. Grip strength sample size: Females n = 20, 20, 31 and 27 for 4,20, 28 and 32 months; Males n = 14, 14, 18 and 14 for 4, 20, 28 and 32 months. Tail flick sample size: Females n = 20, 20, 26and 26 for 4, 20, 28 and 32 months; Males n = 22, 20, 31 and 27 for 4, 20, 28 and 32 months.

(A) 4-month -old female mice were more active during the dark (=active) phase than females in all other age groups (p < 0.0001 in all cases). 20-month-old females did not differ from 28 and 32-month-old females (p = 0.088, p = 0.066, respectively) and 28 and 32-month-old females did not differ from each other (p > 0.999) in dark phase activity. (B) 4-month -old males were more active than 20, 28 and 32-month-old males during the dark phase (p = 0.039, p < 0.0001 and p < 0.0001, respectively). 20-month-old males were more active than 28 and 32-month-old males (p = 0.002 in both cases). (C) Female activity levels during the light phase do not differ between the four age groups. (D) Male activity during light phase was highly variable in all age groups. 4-month -old males' activity levels did not differ from 20 and 32-month old males (p > 0.999 and p = 0.088, respectively). 4-month -olds were more active than 28-month -olds (p = 0.03) and 20-month-olds were more active than both 28 and 32-month-old males (p = 0.002 and p = 0.010, respectively). Post-hoc tests subject to Bonferroni correction for multiple comparisons. Females n = 20, 20, 30 and 27 for 4, 20, 28 and 32 months. Males n = 18, 18, 26 and 23 for 4, 20, 28 and 32 months.