Exercise and Endothelial Function

To the Editor: We read with interest the recent article by Higashi et al,1 which found that in both normotensive and hypertensive subjects, 12 weeks of walking increased forearm vasodilator responses to acetylcholine but that responses to NG-monomethyl-l-arginine were unchanged. These data concur with cross-sectional data from our group comparing elite athletes and sedentary controls, and in both studies, the increase in responsiveness to acetylcholine after training correlated with lipid differences.2 The extent to which dietary variation may have contributed is not clear in either study. In particular, the study by Higashi et al1 provides no objective evidence that a training response was achieved, and the reduction in LDL is more consistent with a dietary modification than a brisk walking program. Despite this limitation, both studies and previous animal studies suggest that training for periods of ≥12 weeks increases endothelium-dependent vasodilator reserve. With …