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EFFECTS OF NORMOXIC NITROUS OXIDE AND HYPERTHERMIA ON PERFORMANCE DURING A WINGATE TEST

Abstract

EFFECTS OF NORMOXIC NITROUS OXIDE AND HYPERTHERMIA ON PERFORMANCE DURING A WINGATE TEST

A.Yogev, A. Hall, O. Jay and M.D. White.

Simon Fraser University, Burnaby, BC, Canada

It was hypothesized that normoxic 30% nitrous oxide gas and passively-induced hyperthermia would increase performance during short duration, high intensity exercise. Ten college age males (24.0 ± 1.9 y; mean ± SE), of normal physique (BMI, 23.7 ± 2.2 kg • m-2), performed 4 separate 30 s Wingate tests on an electrically braked, seated, cycle ergometer. Mean power, peak power, time to peak power and rate of fatigue were assessed in 2 way experimental design with factors of Thermal State (normothermia or hyperthermia) and Gas Type (Air or 30% normoxic nitrous oxide (N2O)). Prior to the 2 hyperthermic Wingate tests the TES was elevated to ~38.5ºC in a 40ºC bath and without prewarming TES remained at ~37.1ºC for the 2 normothermic Wingate tests. The main results indicated a significant interaction between Gas Type and Thermal State for mean power(F=10.9, P = 0.01). The mean powerduring the normothermic AIR and hyperthermic AIR condition exercise was similar at ~560 watts (W) and it was decreased to 522 ± 145 W in the normothermic N2O condition relative to that of 624 ± 129 W in hyperthermic N2O condition. After accounting for hyperthermia-induced changes, the changes in mean powerin this interaction was explained by a ~18% increase in mean power between the normothermic N2O to the hyperthermic N2O exercise condition. In conclusion, for normoxic nitrous oxide breathing, mean power output during hyperthermia is significantly increased relative to that during normothermia.

Supported by NSERC and CFIF

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