Reproducibility of time at or near V̇O2max during intermittent treadmill running

Abstract

The purpose of this study was to determine the reproducibility of time at or above 90% (t90% V̇O2max) and 95% (t95% V̇O2max) maximal oxygen uptake during an intermittent treadmill run to exhaustion. Twenty-two distance runners (age 38.0 ± 7.1 yrs) performed two identical incremental and two identical intermittent tests on four separate days. Respiratory exchange was measured continuously throughout each test by an automated open-circuit gas analysis system. The incremental test consisted of increases in treadmill speed every minute until volitional exhaustion. The highest averaged 30-s oxygen uptake (V̇O2) value was defined as V̇O2max and the minimum speed that elicited V̇O2max was defined as vV̇O2max. The intermittent test consisted of 30-s work intervals ran at 105% vV̇O2max interspersed by 30-s relief intervals ran at 60% vV̇O2max and was continued until volitional exhaustion. The time that V̇O2 was at or above 90% and 95% of the mean maximum values elicited during the two previous incremental tests was determined for the intermittent tests. The mean t95% V̇O2max was 232 (SD 174) s and 244 (SD 195) s and the mean t90%V̇O2max was 480 (SD 220) s and 488 (SD 252) s, for trial 1 and trial 2, respectively. Reproducibility statistics for t95%V̇O2max and t90%V̇O2max, respectively, were: 95 % limits of agreement 12 ± 227 s and 8 ± 328 s; coefficient of variation 34.5% and 24.5%; and intraclass correlation coefficient 0.80 and 0.75. Statistical power analysis indicated that this level of reproducibility would allow mean differences of 15 - 20% between intermittent training protocols to attain statistical significance in future experimental research, with sample sizes probably within the resources of most researchers. © Georg Thieme Verlag KG.