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

Abstract

BACKGROUND: Backward extrapolation technique (BE) was used to estimate V. O2 from postexercise measuring, eliminating oronasal mask (OM) during the efforts. Despite its advantage, literature presents discrepancy in applied methods. Thus, the first aim of this study was to compare different mathematical criteria to estimate values of V. O2 during a supramaximal effort (V.O2PEAK), while the second aim was to verify the effects of OM on cycling performance. METHODS: Twenty-four male cyclists (35}6 years, 81.3}8.9 kg, 180}6 cm) 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 (MAP). The second and the third day were destined to supramaximal efforts at 120% of MAP, 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: V.O2peak can be estimated using different curve lengths. However, only curves between 20 and 60 s with extrapolation to 3 s or lesser shows at least one consistent criterion. The 60 s curve extrapoled to -3 s was the most accurate criteria (P=0.723; ES=-0.055; r=0.824; Bias=-0.36 and LoA=7.72 mL.kg.min-1). Performance was not impaired with OM 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.