Table 1.

Blood and muscle intracellular phenylalanine and leucine concentration before and after resistance exercise in young and older subjects

	Basal	3 h Post	6 h Post	24 h Post
Blood phenylalanine, μmol/l
Young	65 ± 3	62 ± 2	60 ± 3	68 ± 4
Old	66 ± 4	60 ± 3	60 ± 3	66 ± 4
Blood leucine, μmol/l
Young	157 ± 6	136 ± 4*	147 ± 5	157 ± 9
Old	144 ± 9	126 ± 8*	144 ± 9	138 ± 5
Muscle intracellular phenylalanine, μmol/l
Young	65 ± 5	54 ± 3*	48 ± 2*	50 ± 4*
Old	70 ± 4	59 ± 3*	57 ± 5*	57 ± 4*
Muscle intracellular leucine, μmol/l
Young	170 ± 18	153 ± 15	150 ± 18	165 ± 18
Old	176 ± 12	168 ± 21	148 ± 15	144 ± 12

Values are means ± SE; n = 13 young and n = 13 older subjects, except for muscle intracellular leucine (young, n = 12; old, n = 12). Post, after resistance exercise.

^*Significantly different from basal (P < 0.05). Time main effect at 6 h for blood phenylalanine (P < 0.05).