Does α₁-adrenergic receptor blockade modulate sweating during incremental exercise in young endurance-trained men?

Area of Science:

• Exercise Physiology
• Adrenergic Receptor Signaling
• Thermoregulation

Background:

• Human eccrine sweat glands are known to respond to alpha-1 adrenergic receptor agonists.
• Previous research indicated adrenergic mechanisms contribute to sweating in endurance-trained men during exercise.
• The specific role of alpha-1 adrenergic receptor activation in this sweating response remained unclear.

Purpose of the Study:

• To investigate whether alpha-1 adrenergic receptor activation mediates eccrine sweating during incremental exercise in endurance-trained men.
• To determine the contribution of alpha-1 adrenergic receptors to sweat production under exercise conditions.

Main Methods:

• Twelve endurance-trained men underwent incremental cycling to exhaustion while skin temperature was controlled.
• Bilateral forearm sweat rates were measured, with one limb treated with terazosin (alpha-1 antagonist) and the other with saline (control).
• Phenylephrine (alpha-1 agonist) was administered post-exercise to confirm alpha-1 adrenergic receptor blockade efficacy.

Main Results:

• No significant difference in sweat rates was observed between the proximal untreated forearm sites.
• Terazosin treatment did not affect sweat rates compared to the control limb during exercise.
• Post-exercise phenylephrine administration confirmed successful alpha-1 adrenergic receptor blockade, as sweat response was significantly suppressed at the treated site.

Conclusions:

• Alpha-1 adrenergic receptors on eccrine sweat glands do not play a significant role in eccrine sweating during incremental exercise in young endurance-trained men.
• The findings clarify the specific adrenergic pathways involved in exercise-induced sweating.