Backward extrapolation technique: analysis of different criteria after supramaximal exercise in cycling.

BACKGROUND Backward extrapolation technique (BE) is used to estimate V O2 from post-exercise measuring, eliminating oronasal mask (OM) during the efforts. Despite its advantage, literature presents discrepancy in applied methods. Thus, the aim of this study is to compare different mathematical criteria to estimate values of V O2 during a supramaximal effort (V O2PEAK). Secondly, we aim to verify the effects of OM on cycling performance. METHODS Twenty-four cyclists performed three days of tests, with at least 24 h of interval between each test. Firstly, a graded exercise test was applied to determine V O2MAX and your correspondent intensity (iV O2MAX). The second and the third day were destined to supramaximal efforts at 120% of iV O2MAX, performed with (SupraMASK) and without (SupraBE) oronasal mask (OM) in a randomized order. After SupraBE, OM was coupled and BE was applied. Sixty-six values of V O2 were obtained based on a linear regression fitting. RESULTS We found that V O2PEAK can be estimated using different curve lengths. No significant differences, trivial effects sizes, high positive correlations and low systematic errors with consistent concordance were found in the selected criteria. Despite the inconvenient use of OM, the performance was not impaired and was similar in both condition (p = 0.84, ES = 0.04). CONCLUSIONS We conclude that it was possible to accurately estimate V O2 values of a supramaximal effort without any respiratory apparatus with a time-efficient analysis. Therefore, we recommended the use of a 60 seconds V O2 curve analysis with a negative extrapolation for 3 seconds.