Aims: Limited research has investigated the most appropriate oxygen uptake (VO2) data averaging method to obtain reliable and valid maximal oxygen uptake (V2max) values. This study investigated the effect of the VO2 time-averaging interval on the reproducibility of VO2max. Methods and results: Twenty-two competitive distance runners (six female) performed two identical incremental treadmill tests to their limit of exercise tolerance separated by at least 48 h. Commencing at 7 km/h, running speed was increased by 1 km/h per minute for five stages and 0·5 km/h thereafter. Breath-by-breath inline imageo2 data collected during each incremental test were time-averaged over 10-, 15-, 20-, 30- and 60-s and the highest averaged VO2 value was regarded as VO2max for each time-averaging interval. The VO2max values derived from different VO2 time-averaging intervals were significantly different for the first (F = 39·6; P<0·001) and second (F = 68·9; P<0·001) incremental test. There was a tendency for VO2max to significantly increase as the time-averaging interval became shorter. The reproducibility of VO2max was similar for all five VO2 time-averages, with no significant differences between the within-subject variance (F = 0·4; P = 0·6). Conclusion: The results of this study suggests that the reproducibility of VO2max is not affected by the length of the VO2 time-average interval. However, VO2max was significantly altered by changing the VO2 time-averaging interval between 10 and 60 s. Consistency in the VO2 time-averaging interval is therefore an important methodological consideration for repeated determinations of VO2max.
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