Fractional Utilization of V˙O2max-A Key Performance Determinant in Endurance Sports?

PURPOSE: Identifying physiological factors that underly elite performance in endurance sports drives the work of many practitioners and researchers. Current models outline the maximal oxygen uptake (V˙O2max), fractional utilization of V˙O2max (%V˙O2max) at lactate threshold (LT) or competition intensity, and gross mechanical efficiency or economy as key determinants of endurance performance. While the importance of V˙O2max and efficiency/economy has been confirmed repeatedly, less conclusive evidence has been presented on %V˙O2max. In this review, we provide a narrative overview of the current literature on %V˙O2max as one of the performance-determining variables in endurance sports, and whether it can be improved through training. RESULTS: Out of the 35 studies assessing the relationship between %V˙O2max and performance, only a few studies confirm a substantial relationship between %V˙O2max and performance. This holds for %V˙O2max at a specific physiological "landmark," such as LT and %V˙O2max at a competition-specific intensity. Additionally, there is limited evidence suggesting that %V˙O2max can be systematically altered through training in trained athletes. Methodological differences in the assessment of V˙O2max, LT, and endurance performance across the included studies, as well as variation in the training interventions, confound the interpretation of the findings. CONCLUSION: According to the current literature, %V˙O2max at LT or competition intensity does not seem to be a strong predictor of endurance performance. Practical recommendations on how to improve %V˙O2max via training can currently not be given. We encourage researchers to collect and publish data on %V˙O2max for a more comprehensive conclusion about its role for endurance performance.