Key result
Exercise-induced heat stress significantly increased systolic pressure time-integral and decreased diastolic pressure time-integral and reflected wave pressure compared to no heat stress (p<0.05).
Why the study?
Does moderate exercise-induced heat stress alter vascular function, central hemodynamic load, and indices of coronary perfusion in healthy men?
RCT (n=12)
randomized
Does moderate exercise-induced heat stress alter vascular function, central hemodynamic load, and indices of coronary perfusion in healthy men?
Exercise-induced heat stress increases indices of myocardial work and reduces indices of coronary perfusion, potentially increasing cardiac vulnerability to ischemia during strenuous work.
Exercise-induced heat stress may raise ischemic risk during strenuous work; extends central hemodynamic and coronary perfusion data from RCT in healthy men.
This study examined the effects of moderate exercise-induced heat stress (EIHS) on vascular function, central hemodynamic load and indices of coronary perfusion. Vascular-hemodynamic measures were collected in 12 healthy men (aged 22±3 years) pre and post 100 minutes of moderate, intermittent exercise in two randomized conditions: heat stress (HS; wearing firefighter personal protective equipment (PPE)), and no heat stress (NHS; wearing a cooling shirt and equivalent PPE weight). Aortic blood pressure, reflected wave pressure (Pb), systolic (SPTI) and diastolic pressure time-integral (DPTI), and aortic stiffness were assessed before and after each condition. SPTI was significantly greater, and DPTI and Pb were significantly lower for HS-post compared to NHS-post (p<0.05). Pulse wave velocity was not different between conditions. In conclusion, EIHS does not affect aortic stiffness, but increases indices of myocardial work and reduces indices of coronary perfusion which may be related to chronotropic responses to EIHS. The mismatch between oxygen demand and oxygen supply may increase cardiac vulnerability to ischemia during strenuous work in the heat.
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Lefferts et al. (2015) conducted an RCT in Healthy (n=12). Exercise-induced heat stress (wearing firefighter PPE) vs. No heat stress (wearing a cooling shirt and equivalent PPE weight) was evaluated on Aortic blood pressure, reflected wave pressure (Pb), systolic (SPTI) and diastolic pressure time-integral (DPTI), and aortic stiffness (p=<0.05). Exercise-induced heat stress significantly increased systolic pressure time-integral and decreased diastolic pressure time-integral and reflected wave pressure compared to no heat stress (p<0.05).
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