Comparison of continuous and intermittent multistage maximal exercise testing during beta-adrenoceptor blockade in physically active men.

Abstract

Cardiorespiratory responses of 11 healthy males were studied, with placebo and propranolol, during a continuous and an intermittent multistage maximal treadmill test. With placebo, equivalent maximal heart rates were attained for the disparate test modes, and the intermittent protocol yielded a slightly higher (2%, P less than 0.01) maximal O2 consumption. In contrast, during beta-adrenoceptor blockade, higher maximal heart rates (5.1%, P less than 0.01) and O2 consumptions (4.4%, P less than 0.02) were reached with intermittent compared with continuous testing. Values were, however, markedly lower (P less than 0.001) for both protocols than with placebo. These results demonstrate that the precise degree of attenuation of maximal heart rate and O2 consumption observed in physically active persons receiving propranolol is partly dependent upon the actual test protocol utilized. Furthermore, the present data suggest an advantage for intermittent testing when accurate evaluation of the maximal cardiorespiratory capacity is desired in such individuals.