Effect of the o 2 time‐averaging interval on the reproducibility of o 2max in healthy athletic subjects

Summary Aims:  Limited research has investigated the most appropriate oxygen uptake ( o 2 ) data averaging method to obtain reliable and valid maximal oxygen uptake ( o 2max ) values. This study investigated the effect of the o 2 time‐averaging interval on the reproducibility of o 2max . 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 −1 , running speed was increased by 1 km h −1 per minute for five stages and 0·5 km h −1 thereafter. Breath‐by‐breath o 2 data collected during each incremental test were time‐averaged over 10‐, 15‐, 20‐, 30‐ and 60‐s and the highest averaged o 2 value was regarded as o 2max for each time‐averaging interval. The o 2max values derived from different o 2 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 o 2max to significantly increase as the time‐averaging interval became shorter. The reproducibility of o 2max was similar for all five o 2 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 o 2max is not affected by the length of the o 2 time‐average interval. However, o 2max was significantly altered by changing the o 2 time‐averaging interval between 10 and 60 s. Consistency in the o 2 time‐averaging interval is therefore an important methodological consideration for repeated determinations of o 2max .