# Low‐dose ASA therapy does not alter core or skin temperature during hot‐dry or warm‐humid heat stress (PSU HEAT project)

## TL;DR

Low-dose aspirin reduces skin blood flow during heat stress in older adults but does not affect core or skin temperature.

## Contribution

The study is the first to examine low-dose ASA's effects on thermoregulation in older adults during heat stress.

## Key findings

- Low-dose ASA reduced forearm blood flow and vascular conductance during heat stress.
- ASA had no effect on core or skin temperature in either hot-dry or warm-humid conditions.
- Results suggest minimal impact of ASA on thermoregulation despite reduced blood flow.

## Abstract

Nearly 40% of US adults over the age of 50 use aspirin (ASA) therapy for the primary or secondary prevention of cardiovascular disease. Systemic platelet cyclooxygenase inhibition with low‐dose ASA attenuates reflex cutaneous vasodilation and accelerates the rate of rise of core temperature during passive heating in middle‐aged adults. The functional effect of low‐dose ASA therapy on thermoregulatory and cardiovascular responses to hot and humid environmental extremes in older (>65 years) adults has not been determined. Eleven older adults (5F; 66–80 years) were exposed to progressive heat stress in an environmental chamber at a metabolic rate comparable to activities of daily living (~80 W∙m−2) in a warm‐humid (WH; 36°C, 52% rh) and hot‐dry (HD; 40°C, 21% rh) environment following 7 days of low‐dose ASA (81 mg/day) or placebo. Core temperature (Tc), skin temperature (Tsk), heart rate (HR), mean arterial pressure (MAP) and forearm blood flow (FBF) were measured, and rate‐pressure product was subsequently calculated. Low‐dose ASA attenuated FBF and forearm vascular conductance (all p ≤ 0.04) but had no effect on Tc or Tsk in either environment. In conclusion, low‐dose ASA attenuates the skin blood flow response during minimal activity heat stress in both dry and humid environments but does not alter Tc.