摘要
We hypothesized that slowed oxygen uptake(VO_(2))kinetics for exercise transitions to higher power outputs(PO)within the steady state(SS)domain would increase the mean response time(MRT)with increasing exercise intensity during incremental exercise.Fourteen highly trained cyclists(mean±standard deviation[SD]);age(39±6)years[yr];and VO_(2) peak=(61±9)mL/kg/min performed a maximal,ramp incremental cycling test and on separate days,four 6-min bouts of cycling at 30%,45%,65%&75% of their incremental peak PO(Wpeak).SS trial data were used to calculate the MRT and verified by mono-exponential and linear curve fitting.When the ramp protocol attained the value from SS,the PO,in Watts(W),was converted to time(min)based on the ramp function W to quantify the incremental MRT(iMRT).Slope analyses for the VO_(2) responses of the SS versus incremental exercise data below the gas exchange threshold(GET)revealed a significant difference(p=0.003;[0.437±0.08]vs.[0.382±0.05]L·min^(-1)).There was a significant difference between the 45%Wpeak steady state VO_(2)(ss VO_(2))([3.08±0.30]L·min^(-1),respectively),and 30% Wpeak ss VO_(2)(2.26±0.24)(p<0.0001;[3.61±0.80]vs.[2.20±0.39]L·min^(-1))and between the iMRT for 45% and 30% Wpeak ss VO_(2) values([50.58±36.85]s vs.[32.20±43.28]s).These data indicate there is no single iMRT,which is consistent with slowed VO_(2) kinetics and an increasing VO_(2) deficit for higher exercise intensities within the SS domain.
