β-Adrenergic receptor blockade does not modify non-thermal sweating during static exercise and following muscle ischemia in habitually trained individuals.

Abstract

This study investigated the influence of β-adrenergic receptor blockade on sweating during bilateral static knee extension (KE) and lateral isometric handgrip (IH) exercises followed by post-exercise muscle ischemia (PEMI) in habitually trained individuals. Ten habitually trained men (maximum oxygen uptake, 57.1 ± 3.4mlkg-1min-1) were mildly heated by increasing their skin temperature, and bilateral KE or lateral IH exercises at an intensity of 60% maximum voluntary contraction were subsequently performed for 1min, followed by PEMI to stimulate muscle metaboreceptors for 2min. Sweat rates were measured on the bilateral forearms (KE) or thighs (IH) transdermally administered with 1% propranolol (propranolol, a non-selective β-adrenergic receptor inhibitor) or saline (control) via iontophoresis. Relative to the pre-exercise baseline values, IH exercise (P = 0.038) followed by PEMI (P = 0.041) similarly increased sweat rates on the thighs at both control and propranolol sites (baseline, 0.05 ± 0.04 vs. 0.05 ± 0.04; IH, 0.14 ± 0.12 vs. 0.15 ± 0.14; PEMI, 0.14 ± 0.16 vs. 0.14 ± 0.16mgcm-2min-1). KE increased sweat rates on the forearms (P = 0.001) at both control and propranolol sites similarly (baseline, 0.02 ± 0.03 vs. 0.02 ± 0.03; KE, 0.21 ± 0.19 vs. 0.20 ± 0.18), whereas PEMI did not significantly induce sweating at these sites (P = 0.260) (0.09 ± 0.12 and 0.10 ± 0.12mgcm-2min-1, respectively). These results suggest that non-thermal drives induced by static exercise and PEMI do not elicit β-adrenergic sweating in habitually trained individuals even when the non-thermal drives are originated from leg(s) under the conditions in the present study.