Body Weight Body weight was lower in females vs. males (P,0.0001) and in CR vs. AL mice (P,0.0001). CR reduced the weight of mice by 2361% for females and 2562% for males within 10 days, after which body weight remained stable until close to endpoint (Fig. 1). From age 50 d to 70 d, the CR mice weighed 28% less than the AL mice (1460 g vs. 2061 g, respectively; P,0.0001), similar to values previously reported for CR mice [9,17–20]. Body Condition Body condition was 35% lower in CR vs. AL mice (P,0.0001) and 15% lower in males vs. females (P,0.0001) (Fig. 1). For the AL mice, body condition was significantly lower after age 127 d as compared with baseline values (P#0.008). For the CR mice, body condition significantly decreased within the 10 days immediately following CR, after which values were similar until age 106 d. Body condition after age 120 d was significantly lower as compared with values at age 53–106 d (P#0.026). Ability to Move Ability to move was 14% lower in CR vs. AL mice (P,0.0001), with no sex differences (Fig. 2). For the AL mice, ability to move Caloric Restriction and ALS after age 130 d was significantly lower than baseline values (P#0.016). For the CR mice, ability to move after age 109 d was significantly lower than baseline values (P#0.004). Paw Grip Endurance There were no sex and diet differences in PaGE (Fig. 2). At age 120 d and 123 d, PaGE was significantly lower in the CR vs. AL mice (diet x time interaction; P,0.032). For the AL mice, PaGE after age 120 d was significantly lower than baseline values (P#0.031). For the CR mice, PaGE after age 113 d was significantly lower than baseline values (P,0.0001). Voluntary Activity When voluntary activity was recorded, the age of mice was 8261 d for AL females, 8161 d for AL males, 8161 d for CR females and 8161 d for CR males (not significant). Voluntary activity per 24 h was 18,52861850 revolutions (74116740 m) for AL females, 864261459 revolutions (34576584 m) for AL males, 25,29963121 revolutions (10,12061248 m) for CR females and 21,50462649 revolutions (860261060 m) for CR males. Females were 45% more active than males (P = 0.007), whereas CR mice were 72% more active than AL mice (P = 0.0002). Figure 2. Functional measures in CR vs. AL G93A mice. (A) Ability to move and (B) paw grip endurance (s) of 23 ad libitum (AL: N, 16 females; &, 7 males) and 31 calorie restricted (CR, 60% of ad libitum: #, 21 females; %, 10 males) G93A mice. Data are means 6 SEM. doi:10.1371/journal.pone.0009386.g002 PLoS ONE | www.plosone.org 5 February 2010 | Volume 5 | Issue 2 | e9386