TABLE 2.

Minimum feret diameter (A.U.) of gluteus medius (GM) and triceps brachii (TB) myosin heavy chain (MyHC) type I, type IIa, type IIx, and hybrid type IIa/x before (wk 0) and after 8 (wk 8) and 12 (wk 12) weeks of submaximal exercise training in aged (22 ± 5 yr; n = 10) and young (9.7 ± 0.7 mo; n = 8) horses.

						p-values
		wk 0	wk 8	wk 14	SEM	Age	Training	Muscle Group	Age $\times$ Training $\times$ Muscle Group
MyHC type I
Young	GM	103	115	103	8	0.144	0.905	0.094	0.501
	TB	115	113	114
Aged	GM	120	114	117
	TB	118	123	128
MyHC type IIa
Young	GM	108	124	109	8	0.002	0.689	0.0001	0.395
	TB	135 a	123 a	132 a
Aged	GM	138 b	128 b	124 b
	TB	155 a , b	158 a , b	156 a , b
MyHC type IIx
Young	GM	162	181	154	11	0.068	0.093	0.651	0.824
	TB	166	159	156
Aged	GM	173	194	173
	TB	183	187	176
MyHC type IIa/x
Young	GM	143	155	143	10	0.013	0.117	0.219	0.268
	TB	145	140	159
Aged	GM	192 a , c	162 a , c	134d
	TB	177 a , c	178 a , c	165d

^aWithin a muscle group and time point, aged differs from young (p < 0.05).

^bWithin a week and age group, GM differs from TB (p < 0.05).

^cWithin an age and muscle group, time points with different letters differ (p < 0.05).