Cutaneous adrenergic nerve blockade attenuates sweating during incremental exercise in habitually trained men

Area of Science:

• Exercise Physiology
• Neuroendocrinology
• Human Thermoregulation

Background:

• The role of cutaneous adrenergic nerves in sweat production during exercise is not fully understood.
• Investigating this pathway is crucial for understanding human thermoregulation during physical exertion.

Purpose of the Study:

• To determine if blocking cutaneous adrenergic nerves affects sweating during incremental exercise.
• To compare this effect between habitually trained and untrained individuals.

Main Methods:

• 10 trained and 10 untrained males underwent incremental cycling exercise.
• Sweat rates were measured using ventilated capsules on forearms treated with bretylium tosylate (BT) or saline.
• BT inhibits neurotransmitter release from sympathetic adrenergic nerve terminals.

Main Results:

• Bretylium tosylate delayed sweating onset in both groups.
• Sweat suppression was observed at high exercise intensities (≥70% max) in trained individuals but not untrained.
• Trained individuals showed a greater reduction in sweat production with BT treatment compared to untrained individuals.

Conclusions:

• Cutaneous adrenergic nerves modulate sweating during incremental exercise, especially at high workloads.
• Habitual exercise training may enhance neural adrenergic sweat production, though further research is needed.
• This study provides new insights into the neural mediation of adrenergic sweating during exercise.