Table 1.

Descriptive characteristics of each age group

	AGE40	AGE61	AGE76
n	38	27	22
Age, yr	40.4 ± 1.1	61.1 ± 0.6	75.5 ± 0.7
Body composition and muscle mass
BMI, kg/m2	25.1 ± 0.4	24.7 ± 0.5	25.6 ± 0.6
Body fat*, %	32.4 ± 1.1	34.2 ± 1.2†	36.5 ± 1.4†
SMI*, kg/m2	7.55 ± 0.11	6.87 ± 0.13†	6.73 ± 0.14†
TMM*, kg/m2	3.86 ± 0.06	3.51 ± 0.70†	3.35 ± 0.8†
Knee extensor strength and power
Strength (UMVC)*, kg	55.1 ± 1.6	42.8 ± 1.8†	36.2 ± 2.0†‡
Relative strength (UMVC/UTMM)*	9.34 ± 0.34	8.44 ± 0.40	7.37 ± 0.45†
Power*, W	349 ± 14	257 ± 17†	204 ± 19†‡
Relative power*, W/kg TMM	29.7 ± 1.2	24.6 ± 1.4†	20.8 ± 1.5†‡

Values are least squares (adjusted) means ± SE; n, no. of subjects. AGE40, AGE61, AGE76: 40, 61, and 76 yr of age, respectively. BMI, body mass index = weight (kg)/height (m)²; SMI, skeletal muscle index = (bilateral arm + leg lean mass)/height (m)²; TMM, bilateral thigh muscle mass (kg) adjusted by height (m)²; power, maximum bilateral, concentric knee extension power (W); UMVC, unilateral (right) knee extension maximum voluntary contraction strength (kg); UTMM, unilateral thigh muscle mass (kg); TMM, thigh muscle mass.

^*Main age effect,

^†different from AGE40, and

^‡different from AGE61: P < 0.05.