Abstract
PURPOSE: To estimate the highest power output at which predominant energy contribution is derived from the aerobic system (aerobic limit power: ALP) and to compare ALP with the upper boundary of the severe intensity exercise domain. METHODS: Fifteen male individuals participated in this study. The upper boundary was estimated using i) linear relationship between time to achieve V˙ O(2max) and time to task failure (P(UPPERBOUND)), ii) hyperbolic relationships between time to achieve V˙ O(2max) vs. power output, and time to task failure vs. power output (P(UPPERBOUND)´), and iii) precalculated V˙ O(2max) demand (I(HIGH)). ALP was estimated by aerobic, lactic, and phospholytic energy contributions using V˙ O(2) response, blood [lactate] response, and fast component of recovery V˙ O(2) kinetics, respectively. RESULTS: ALP was determined as the highest power output providing predominant aerobic contribution; however, anaerobic pathways became the predominant energy source when ALP was exceeded by 5% (ALP + 5%) (from 46 to 52%; p = 0.003; ES:0.69). The V˙ O(2) during exercise at ALP was not statistically different from V˙ O(2max) (p > 0.05), but V˙ O(2max) could not be attained at ALP + 5% (p < 0.01; ES:0.63). ALP was similar to P(UPPERBOUND) and P(UPPERBOUND)´ (383 vs. 379 and 384 W; p > 0.05). There was a close agreement between ALP and P(UPPERBOUND) (r: 0.99; Bias: - 3 W; SEE: 6 W; TE: 8 W; LoA: - 17 to 10 W) and P(UPPERBOUND)´ (r: 0.98; Bias: 1 W; SEE: 8 W; TE: 8 W; LoA: - 15 to 17 W). ALP, P(UPPERBOUND), and P(UPPERBOUND)´ were greater than I(HIGH) (339 ± 53 W; p < 0.001). CONCLUSION: ALP may provide a new perspective to intensity domain framework.