Purpose: 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.
Method: Ten habitually trained men (maximum oxygen uptake, 57.1 ± 3.4 ml kg-1 min-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 1 min, followed by PEMI to stimulate muscle metaboreceptors for 2 min. 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.
Results: 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 ± 0.16 mg cm-2 min-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 ± 0.12 mg cm-2 min-1, respectively).
Conclusion: 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.
Keywords: Handgrip exercise; Knee extension exercise; Sweat rate; Thermoregulation; β-Adrenergic receptor.