The effects of methyldopa and propranolol on the response to dynamic and static exercise during treatment of mild hypertension in men

This study was designed to examine the effects of two commonly prescribed antihypertensive medications, methyldopa and propranolol, on the capacity to perform dynamic exercise and on the pressor response to both dynamic (treadmill) and static (isometric handgrip) exercise. Both drugs reduced the mean resting blood pressure comparably and significantly (P < .01). Methyldopa had no significant effect upon treadmill exercise capacity as determined by mean V̇O₂max, although the mean exercise duration was reduced by 3.9% (P < .05). Propranolol significantly reduced treadmill exercise capacity, as determined by a 13.2% reduction in mean V̇O₂max (P < .001) and by a 10.5% reduction in mean exercise duration (P < .001). These differences between the two drugs in effect on exercise capacity and V̇O₂max were significant (P < .001). Both drugs reduced the systolic blood pressure response to maximal treadmill exertion comparably, by approximately 9.0% (P < .001). The systolic pressor response to isometric handgrip exercise was also reduced significantly by both drugs (P < .05); however, the magnitude of this response was significantly different, comparing the two drugs (P < .05). The maximal reduction in the systolic blood pressure response to isometric exercise was 19.0% (P < .001) with methyldopa, whereas the maximal reduction in the systolic pressor response with propranolol was 9.0% (P < .01). Neither drug significantly reduced the diastolic pressor response to isometric handgrip exercise. In conclusion, both drugs comparably reduced resting blood pressure and the pressor response to treadmill exercise; however, propranolol significantly impaired treadmill exercise capacity while methyldopa did not. Methyldopa was also slightly more effective than propranolol in preventing the rise in systolic blood pressure during isometric handgrip exercise.