PHYSIOLOGICAL-RESPONSES TO SHOVELING AND THERMAL-STRESS IN MEN WITH CARDIAC DISEASE

To investigate the effect of temperature stress on responses to static dynamic work in patients with ischemic heart disease (IHD). 10 men wit h IHD shoveled gravel tor 30 min in a warm (29-degrees-C). neutral (24 -degrees-C), and cold (-8-degrees-C) environment (on separate days). A pace of 15 lifts.min-1 was set, and the load per lift approximated 5. 5 kg. Heart rate (HR). oxygen consumption (VO2). and systolic (SBP) an d diastolic blood pressures (DBP) were evaluated at 5-min intervals. A rrhythmias and ST-segment depression were evaluated by ambulatory elec trocardiographic monitoring. At 30 min. VO2, SBP, and DBP were higher (P < 0.05) in the cold environment. and HR was higher (P < 0.05) in th e warm environment compared with the neutral environment. HR increased (P < 0.05) from 5 to 30 min in all three conditions. The increase in HR was greater (P < 0.05) in the warm environment. None of the subject s reported angina or demonstrated electrocardiographic ST-segment chan ges during shoveling in any environment. The results indicate that low -risk patients with stable IHD show modest temperature-induced alterat ions in hemodynamic and VO2 responses during 30 min of moderate intens ity (50-60% of peak VO2) static-dynamic work without adverse electroca rdiographic responses or symptomatology.