Table 5.

Myofiber Profiles of EDL Muscles.

Cross-sectional area (µm2)	Young, Control	Young, Trained	Aged, Control	Aged, Trained
Types combined	1827 ± 171*	1505 ± 197	1459 ± 127	1169 ± 123
Type I	937 ± 101	924 ± 74	759 ± 54	933 ± 93
Type IIA	1155 ± 75	966 ± 85	936 ± 58	936 ± 91
Type IIX	1730 ± 151‡	1444 ± 138	1274 ± 124	1150 ± 96
Type IIB	2838 ± 289*	2260 ± 375	2452 ± 290	1712 ± 227
Fiber Type Composition (%)
Type I	9.8 ± 1.7	10.5 ± 2.6	9.6 ± 1.3	11.7 ± 1.8
Type IIA	33.3 ± 2.1	32.8 ± 2.9	26.9 ± 2.9	34.0 ± 3.3
Type IIX	26.3 ± 3.8	28.1 ± 3.2	35.0 ± 3.5	29.8 ± 2.7
Type IIB	30.4 ± 3.7	28.5 ± 4.1	28.2 ± 3.4	24.3 ± 4.6
% Area Occupied
Type I	5.7 ± 1.4	8.7 ± 3.1	5.1 ± 0.7	10.0 ± 2.1
Type IIA	21.5 ± 1.5	22.9 ± 2.9	18.6 ± 2.9*	27.7 ± 3.1
Type IIX	26.0 ± 4.5	27.8 ± 3.2	30.5 ± 3.6	29.8 ± 2.9
Type IIB	46.6 ± 5.7*	40.4 ± 5.6	45.5 ± 4.0	32.3 ± 4.7

Values are means ± SE, N=9/group.

^*indicates significant (P ≤ 0.05) difference from Aged, Trained.

^‡indicates significant (P ≤ 0.05) difference from Aged, Control and Aged, Trained.