Oxidative stress does not influence local sweat rate during high‐intensity exercise

Abstract

What is the central question of this study? We evaluated whether oxidative stress attenuates the contribution of nitric oxide to sweating during high-intensity exercise. What is the main finding and its importance? In contrast to our previous report of an oxidative stress-mediated reduction in nitric oxide-dependent cutaneous vasodilatation in this cohort during intense exercise, we demonstrated no influence of local ascorbate administration on the sweating response during moderate- (∼51% peak oxygen uptake) or high-intensity exercise (∼72% peak oxygen uptake). These new findings provide important mechanistic insight into how exercise-induced oxidative stress impacts sudomotor activity. Nitric oxide (NO)-dependent sweating is diminished during high- but not moderate-intensity exercise. We evaluated whether this impairment stems from increased oxidative stress during high-intensity exercise. On two separate days, 11 young (24 ± 4 years) men cycled in the heat (35°C) at a moderate [500 W; 52 ± 6% peak oxygen uptake (V̇O2 peak )] or high (700 W; 71 ± 5% V̇O2 peak ) rate of metabolic heat production. Each session included two 30 min exercise bouts separated by a 20 min recovery period. Local sweat rate was monitored at four forearm skin sites continuously perfused via intradermal microdialysis with the following: (i) lactated Ringer solution (Control); (ii) 10 mm ascorbate (Ascorbate; non-selective antioxidant); (iii) 10 mm N -nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor); or (iv) 10 mm ascorbate plus 10 mm l-NAME (Ascorbate + l-NAME). During moderate exercise, sweat rate was attenuated at the l-NAME and Ascorbate + l-NAME sites (both ∼1.0 mg min cm ; all P < 0.05) but not at the Ascorbate site (∼1.1 mg min cm ; both P ≥ 0.28) in comparison to the Control site (∼1.1 mg min cm ). However, no differences were observed between treatment sites (∼1.4 mg min cm ; P = 0.75) during high-intensity exercise. We conclude that diminished NO-dependent sweating during intense exercise occurs independent of oxidative stress.

Local arginase inhibition does not modulate cutaneous vasodilation or sweating in young and older men during exercise

“…Differences in heat-loss responses between young and older adults can be influenced by the site of measurement (46), and a more pronounced separation between groups may have been seen if measurements were performed on the chest or back, skin sites that typically exhibit greater sudomotor activity than the forearm (27). The forearm was chosen to reduce movement artifacts during cycling and to facilitate comparison between previous studies, given that the majority of work aimed at evaluating the mechanisms underpinning heat loss previously employed forearm skin sites (9,12,13,19,20,22,23,38,39,41,47,48,52). That said, we observed greater elevations in esophageal temperature during exercise in the older versus younger men (Table 3), despite having both groups exercise at the same absolute heat load (400 W) to elicit similar drives for whole-body heat loss between age groups (27,40).…”

Assessment of Exhaustive Exercise under Internet of Things Exercise Monitoring System and Mechanism Analysis of Cardiovascular Endothelial Cell Apoptosis Induced by Oxidative Stress

“…The selection of threshold has a great influence on the effect of information denoising. The heuristic threshold method [24] was adopted to select the threshold. When the SNR is low, the fixed threshold is selected, and τ = δ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 log eK p .…”