An alternative to oxygen deficit as a way to quantify anaerobic contributions in running

The purpose of this study was to determine if the sum of estimates of the phosphocreatine contribution and the glycolytic contribution (we refer to this sum as PCr+glycolysis) provides an alternative to oxygen deficit as a way to quantify the anaerobic contribution in running. Thirty university students performed three treadmill tests, each test at one speed individually selected for each participant; one test was terminated after 3 min, one after 7 min, and one at exhaustion (mean ± SD, 10.3 ± 0.4 min). Oxygen deficit was calculated by subtraction of the accumulated oxygen uptake from the total oxygen cost. Phosphocreatine and glycolysis contributions were determined from post-exercise VO2 responses and blood lactate concentrations, respectively. The mean values for PCr+glycolysis were ~3 mL·kg–1 lower (p < 0.05) than oxygen deficit across three exercise durations, but well correlated (r ≥ 0.80, p < 0.05) at each. These results confirm the validity of PCr+glycolysis as an alternative to oxygen deficit to quantify the anaerobic contribution in running exercise.