Aims] This study examined whether cutaneous adrenergic nerve blockade attenuates sweating during incremental exercise specifically in habitually trained individuals. [Methods] 10 habitually trained and 10 untrained males (V ・ O 2 max: 56.7 ± 5.4 and 38.9 ± 6.7 ml/kg/min, respectively; P < 0.001) performed incremental semirecumbent cycling (20 W/min) until exhaustion. Sweat rates were measured at two bilateral forearm skin sites on which either 10 mM bretylium tosylate (BT) (an inhibitor of

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... transmitter release from sympathetic adrenergic nerve terminals) or saline (Control) was transdermally administered via iontophoresis. [Results] BT treatment suppressed the sweat rate relative to the Control treatment at higher than 70% relative total exercise time in trained individuals (all P < 0.01) but not in untrained counterparts (P = 0.122). Changes in total sweat production at the BT site relative to the Control site were greater in trained individuals than in untrained counterparts (area under the curve, -0.86 ± 0.67 and -0.22 ± 0.39 mg/cm2, respectively; P = 0.023). [Conclusions] We demonstrated that cutaneous adrenergic nerves do modulate sweating during incremental exercise, which appeared to be more apparent in habitually trained men.