ANAEROBIC METABOLISM IN HYPERTENSIVE PATIENTS DURING EXERCISE STRESS TEST

An impaired maximal vasodilating capacity has been reported in hyperte nsives. This study aimed to assess whether mild hypertensives depend o n anaerobic metabolism more than do normal subjects during the exercis e stress test. The oxygen uptake (VO2) and carbon dioxide output (VCO2 ) were measured at the anaerobic threshold (AT) and at peak exercise ( VO(2)p and VCO(2)p) during the cardiopulmonary exercise test by breath -by-breath expiratory gas analysis in 21 mild hypertensives and 19 age -matched normotensives. AT was reached earlier in hypertensives than i n normotensives, but with similar VO2 uptake, VCO2 output, and VCO2/ V O2 ratio. At peak exercise, however, hypertensives showed lower Vo(2)p than controls (29 +/- 5 v 33 +/- 5 mL VO2/kg/min, (P < .03) but simil ar VCO(2)p (36 +/- 6 v 39 +/- 6 mL VCO2/kg/min, P = .19). As a result, the slope of carbon dioxide output increase versus oxygen uptake afte r anaerobic threshold was steeper in hypertensives than in controls (P < .002). The higher CO2 production per unit of O-2 in hypertensives a s compared with controls seems to reflect a greater involvement of the anaerobic metabolism to supplement energy output.