Table 4.

Effects of training in the fasted state vs. training in the carbohydrate-fed state on muscle GLUT4 content, maximal mitochondrial enzyme activities, and capillary density

	F	CHO
GLUT4, AU
Pretest	0.79 ± 0.10	0.86 ± 0.07
Posttest	1.20 ± 0.16*	1.28 ± 0.11*
Citrate synthase, μmol · min−1 · g−1§
Pretest	245 ± 27	285 ± 33
Posttest	361 ± 35*	301 ± 45
β-HAD, μmol · min−1 · g−1
Pretest	133 ± 12	126 ± 20
Posttest	179 ± 27*	141 ± 12
Capillary density, number per fiber
Type I fibers
Pretest	4.9 ± 0.2	4.9 ± 0.2
Posttest	5.4 ± 0.1*	5.6 ± 0.2*
Type IIa fibers
Pretest	4.9 ± 0.2	4.8 ± 0.2
Posttest	5.3 ± 0.2*	5.5 ± 0.1*

Data provided are means ± SE (F: n = 6–10; CHO: n = 6–10) and represent values before (pretest) and after (posttest) a 6-wk training period in either the fasted state (F) or with ample carbohydrate intake before and during the training sessions (CHO). Total GLUT4 protein content was measured by Western blotting (expressed relative to GAPDH; AU, arbitrary units), maximal mitochondrial activities of citrate synthase and β-hydroxyacyl coenzyme A dehydrogenase (β-HAD) were measured using enzymatic spectrophotometric assays, and the number of capillaries per fiber was determined by immunohistochemistry.

^*P < 0.05 vs. pretest.

^§P < 0.05, time × group effect.