The Effect of Environmental Temperature on Substrate Oxidation and Extracellular Heat Shock Proteins in Response to Heart Rate Matched Moderate-Intensity Cycling in Endurance Trained Males

aut.embargoNoen_NZ
aut.thirdpc.containsNoen_NZ
dc.contributor.advisorMaunder, Ed
dc.contributor.advisorKilding, Andrew
dc.contributor.authorCharoensap, Thanchanok
dc.date.accessioned2022-11-09T22:58:40Z
dc.date.available2022-11-09T22:58:40Z
dc.date.copyright2022
dc.date.issued2022
dc.date.updated2022-11-09T21:35:35Z
dc.description.abstractEndurance exercise combined with environmental heat stress alters substrate metabolism and upregulates extracellular heat shock protein 70 (HSP70) concentrations. Previous research has studied these stimulatory effects of heat stress at matched absolute, external work rates. In the real-world, however, a reduction in absolute work rate typically occurs when training and/or competing in hot environments compared to temperate conditions. The aim of the present investigation was to determine how heat stress impacts substrate oxidation rates and plasma HSP70 expression during endurance exercise regulated by relative physiological work rates, or heart rates (HR). Ten endurance-trained, male cyclists performed two experimental trials in an acute, randomised, counterbalanced cross-over design. Each trial involved a 90-minute bout of cycling exercise at a specified HR (95% of the HR associated with VT1) in either 18 (TEMP) or 33 ̊C (HEAT), with ~60% relative humidity. Mean power output (17 ± 11%, P = 0.0005) and whole-body energy expenditure (14 ± 8%, P = 0.0003) were significantly lower in HEAT. Sweat rate was significantly greater in HEAT (87 ± 63%, P = 0.0003). Whole-body carbohydrate oxidation rates were significantly lower in HEAT (19 ± 11%, P = 0.002), while fat oxidation rates were not different between-trials. Plasma HSP70 expression was not increased with exercise in either environment. The heat stress-induced reduction in carbohydrate oxidation was associated with the observed reduction in power output (r = 0.64, 95% CI, 0.01, 0.91, P = 0.05) and augmented sweat rates (r = 0.85, 95% CI, 0.49, 0.96, P = 0.002), while the lack of plasma HSP70 accumulation during endurance exercise may be explained by insufficient exercise duration, inadequate thermal stress, and/or the cycling-exercise modality employed in this present study. These data contribute to our understanding of how moderate environmental heat stress is likely to influence substrate oxidation and plasma HSP70 expression in an ecologically-valid model of endurance exercise.en_NZ
dc.identifier.urihttps://hdl.handle.net/10292/15605
dc.language.isoenen_NZ
dc.publisherAuckland University of Technology
dc.rights.accessrightsOpenAccess
dc.titleThe Effect of Environmental Temperature on Substrate Oxidation and Extracellular Heat Shock Proteins in Response to Heart Rate Matched Moderate-Intensity Cycling in Endurance Trained Malesen_NZ
dc.typeThesisen_NZ
thesis.degree.grantorAuckland University of Technology
thesis.degree.levelMasters Theses
thesis.degree.nameMaster of Sport and Exerciseen_NZ
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