Cardiovascular Responses to Sustained Isometric Work in a Hot Environment

Abstract The purpose of this study was to investigate the alterations in blood pressure, heart rate (HR), left ventricular ejection time (LVET), and myocardial oxygen consumption (as depicted by TRIP) during a maximal and submaximal isometric contraction of the forearm in a closed heated environment. Simultaneous recordings of the ECG, carotid pulse wave, blood pressure, and skin temperature were taken from a sitting position during rest and static exertion. Twelve male subjects 20 to 31 years old (mean age = 25.4) were tested in room temperature and in a closed sauna where skin temperature was maintained between 40°C and 41 °C. Analysis of variance demonstrated that although the oxygen consumption of the myocardium (TRIP index) increased (p < .001) during isometric handgrip contraction, there was no appreciable change when heat stress was introduced. Although systolic (BPs) and diastolic (BPd) arterial pressures rose (p < .001) during static exertion they were substantially lower (p < .001) when forearm ...