Hypertension is associated with greater heat exchange during exercise recovery in a hot environment

Abstract

Individuals with systemic arterial hypertension have a higher risk of heat-related complications. Thus, the aim of this study was to examine the thermoregulatory responses of hypertensive subjects during recovery from moderate-intensity exercise performed in the heat. A total of eight essential hypertensive (H) and eight normotensive (N) male subjects (age=46.5±1.3 and 45.6±1.4 years, body mass index=25.8±0.8 and 25.6±0.6 kg/m2, mean arterial pressure=98.0±2.8 and 86.0±2.3 mmHg, respectively) rested for 30 min, performed 1 h of treadmill exercise at 50% of maximal oxygen consumption, and rested for 1 h after exercise in an environmental chamber at 38°C and 60% relative humidity. Skin and core temperatures were measured to calculate heat exchange parameters. Mean arterial pressure was higher in the hypertensive than in the normotensive subjects throughout the experiment (P<0.05, unpaired t-test). The hypertensive subjects stored less heat (H=–24.23±3.99 W m–2 vs N=–13.63±2.24 W m–2, P=0.03, unpaired t-test), experienced greater variations in body temperature (H=–0.62±0.05°C vs N=–0.35±0.12°C, P=0.03, unpaired t-test), and had more evaporated sweat (H=–106.1±4.59 W m–2 vs N=–91.15 ±3.24 W m–2, P=0.01, unpaired t-test) than the normotensive subjects during the period of recovery from exercise. In conclusion, essential hypertensive subjects showed greater sweat evaporation and increased heat dissipation and body cooling relative to normotensive subjects during recovery from moderate-intensity exercise performed in hot conditions. Key words: Hypertension; Hot Environment; Thermoregulation.