Histamine-receptor blockade does not influence the heavy-severe domain boundary and time to task failure in the
Kieran S S Abbotts1, Jake H Hudgins1, Isabella S Viveros1
1Department of Human Physiology, University of Oregon, Eugene, Oregon, USA.
Abstract:
The influence of histamine in skeletal muscle during exercise is poorly characterized. This investigation tested the hypothesis that histamine-receptor blockade lowers the power associated with the heavy-severe domain boundary and reduces time to task failure in the severe domain. Following a graded exercise test and a familiarization trial, 17 participants (8 M/9 F, 29 ± 8 years, VO2peak 60.0 ± 7.5 mL/kg/min, mean ± SD) completed cycle ergometer exercise on two separate occasions, after either histamine-receptor blockade or placebo, in a double-blind randomized crossover protocol. Exercise intensities were designed to span the moderate, heavy, and severe domains. Skeletal muscle tissue oxygen saturation (%SmO2, via near-infrared spectroscopy) and expired gases were measured continuously throughout exercise. There were no differences between blockade and placebo in power associated with the heavy-severe domain boundary (216 [195, 236] vs. 213 [191, 234] W, mean [95% CI]; p = 0.41) or time to task failure (474 [377, 572] vs. 473 [380, 566] s; p = 0.95). %SmO2 slope decreased, and oxygen uptake increased with intensity (p < 0.01), but were not affected by blockade (all p > 0.05). These findings suggest that histamine is not crucial to supporting power at the heavy-severe domain boundary or short-duration exercise in the severe domain.
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