The Independent Influence of Aerobic Fitness and Running Economy on Thermoregulatory Responses During Treadmill Running

Title: The Independent Influence of Aerobic Fitness and Running Economy on Thermoregulatory Responses During Treadmill Running
Authors: Smoljanic, Jovana
Date: 2014
Abstract: The independent influence of maximum oxygen consumption (VO2max) and running economy (RE) on thermoregulatory responses during treadmill exercise have not been isolated due to the complex interactions between VO2max, RE, body mass, body surface area (BSA), and metabolic heat production (Hprod). The purpose of the thesis is to determine whether large differences in VO2max and/or running economy independently alter thermoregulatory responses during running in a neutral environment. Seven aerobically unfit (LO-FIT: ~ 40 mlO2·kg-1·min-1) and sevn aerobically fit (HI-FIT: ~ 60 mlO2·kg-1·min-1) males, matched for body mass and BSA ran at 1) a fixed metabolic heat production of 640 W (FHP trial) and 2) 60%VO2max (REL trial). Also, seven high RE (HI-ECO: ~ 185 mlO2·kg-1·km-1) and seven low RE (LO-ECO: ~ 220 mlO2·kg-1·km-1) males, matched for body mass, BSA and VO2max (~ 60 mlO2·kg-1·min-1) ran at a 1) fixed Hprod of 640 W (FHP trial) and 2) fixed running speed of 10.5 km·h-1 (FRS trial). All trials were performed in a thermoneutral environment. The data was analyzed using a two-way mixed ANOVA, with the significance level set at an alpha of 0.05 for all comparisons. It was hypothesized that thermoregulatory responses (i.e., core temperature and sweating), during exercise will not be independently altered by VO2max, but will be altered by any differences in heat production and running economy. The FHP trial resulted in similar changes in esophageal temperature (∆Tes), changes in rectal temperature (∆Tre), and WBSL between the HI-FIT and LO-FIT groups, despite vastly different %VO2max. Whereas the REL trial resulted in greater ΔTeso, ΔTre, and WBSL in the HI-FIT group, in parallel with their greater Hprod. In groups greatly differing in RE, the FHP trial elicited similar ∆Tes, ∆Tre, and WBSL; however the HI-ECO group had to run faster to achieve the same heat production as their LO-ECO counterparts. Moreover, a FRS of 10.5 kmh-1 produced a greater Hprod, ∆Tes, ∆Tre, and WBSL in the LO-ECO group. In conclusion, thermoregulatory responses are determined by Hprod and RE, not VO2max, when differences in mass and BSA are eliminated between groups. Thus, these findings support the initially stated hypotheses.
CollectionThèses, 2011 - // Theses, 2011 -