Effects of intense exercise training on endothelium-dependent exercise-induced vasodilatation.

To determine whether intense exercise training affects exercise-induced vasodilatation, six subjects underwent 4 weeks of handgrip training at 70% of maximal voluntary contraction. Exercise forearm vascular conductance (FVC) responses to an endothelium-dependent vasodilator (acetylcholine, ACH; 15, 30, 60 micrograms min-1) and an endothelium-independent vasodilator (sodium nitroprusside, SNP; 1.6, 3.2, 6.4 micrograms min-1) and FVC after 10 min of forearm ischaemia were determined before and after training. Training elicited significant (P < 0.001) increases in grip strength (43.4 +/- 2.3 vs. 64.1 +/- 3.5 kg, before vs. after, mean +/- SEM), forearm circumference (26.7 +/- 0.4 vs. 27.9 +/- 0.4 cm) and maximal FVC (0.4630 +/- 0.0387 vs. 0.6258 +/- 0.0389 units, P < 0.05). Resting FVC did not change significantly with training (0.0723 +/- 0.0162 vs. 0.0985 +/- 0.0171 units, P > 0.4), but exercise FVC increased (0.1330 +/- 0.0190 vs. 0.2534 +/- 0.0387 units, P < 0.05). Before and after the training, ACH increased exercise FVC above the control (no drug) exercise FVC, whereas SNP did not. Training increased (P < 0.05) the exercise FVC responses to ACH (0.3344 +/- 0.1208 vs. 0.4303 +/- 0.0858 units, before vs. after training, 60 micrograms min-1) and SNP (0.2066 +/- 0.0849 vs. 0.3172 +/- 0.0628 units, 6.4 micrograms min-1). However, these increases were due to the increase in control (no drug) exercise FVC, as the drug-associated increase in exercise FVC above control did not differ between trials (P > 0.6). These results suggest that exercise FVC is increased by both exercise training and stimulating the release of endothelium-dependent vasodilators. However, training does not affect the vascular response to these vasodilators.