Useful exercise protocol and method of evaluation for determining gas exchange threshold (V̇O2GET)

Abstract

The purpose of the present study was to investigate a useful exercise protocol and method of evaluation for determining the gas exchange threshold (V̇O2GET) and correlation coefficient between V̇O2GET and maximal oxygen uptake (V̇O2max), which is an index of aerobic capacity. Five healthy male volunteers (age : 25.6±2.0yrs ; height : 172.9±4.0cm ; weight : 69.5±6.6kg) performed exercise tests 82 times. Each volunteer randomly conducted a RAMP exercise ( 1 W · 3 sec-1), STEP-1 exercise (20W · min-1) and STEP-2 exercise (40W · 2min-1), respectively, at least 4 to 8 rotations. The gas exchange parameters (V̇E, V̇O2 and V̇CO2) for incremental exhaustive cycle ergometer exercise were measured using a "breath-by-breath" method. Three different methods of evaluation- (V̇E/V̇O2 and V̇E/V̇CO2) exchange (M-1), V-slope method (M-2), and M-1 & M-2 (M-S)-were attempted to determine V̇O2GET. The V̇O2GET values, determined by three different methods (M-1, -2 and -3) of evaluation, were classified as 'easy' (J-A) and 'difficult' (J-B) in all tests. Reproducibility of V̇O2max and V̇O2GET were assessed using the coefficient of variation (CV) and correlation coefficients (r) between V̇O2max and V̇O2GET. The results are summarized as follows : 1) The means of the reproducibility of V̇O2max were determined among the 5 subjects by using RAMP, 4.8% (n=25), STEP-1, 3.1% (n=28) and STEP-2, 2.9% (n = 29) exercise tests ; STEP-2 exercise test values (CV) were lower than the others. There was no significant difference in the means of V̇O2max among the 5 subjects according to the RAMP and two STEP exercise tests (Two-way ANOVA). 2) The best reproducibility value of V̇O2GET among the 5 subjects was determined using RAMP exercise tests with the V-slope method (M-2) and evaluations were classified as easy (J-A). The value (CV) was 2.8%. There was no significant difference in the VȮ2GET values (M-1 (J-A, -B), M-2 (J-A, -B) and M-3) (Two-way ANOVA) and their means among the 5 subjects concerning RAMP and two STEP exercise tests (Two-way ANOVA). 3) The best correlation coefficient (r) value between V̇O2max and V̇O2GET was obtained using RAMP exercise tests with M-2 (J-A) (r=0.976, n=20). The present results indicate that the most useful exercise protocol and method of evaluation for determining V̇O2GET is the RAMP exercise test with the V-slope method.