Author(s): HOSSEINI, E., CABUK, R., TESO, M., DE POLI, R., MURIAS, JM., Institution: HAMAD BIN KHALIFA UNIVERSITY, Country: QATAR, Abstract-ID: 1105

INTRODUCTION:
It has been suggested that achieving maximal oxygen uptake (V̇O2max) and task failure during incremental exercise is linked to depletion of anaerobic work capacity (W′) (1–3). However, this remains controversial, as recent data indicated that what determines task failure within the severe intensity domain is the inability to sustain a given mechanical power with the available W′, rather than W′ depletion per se (4). The aim of this study is to clarify whether W′ depletion is responsible for task failure and V̇O2max attainment at the end of a ramp-incremental test (RI).
METHODS:
Fourteen recreationally trained females (n = 5) and males (n = 9) completed two RI tests to task failure on separate days. During the first test, V̇O2max and peak power output (PPO) were determined. At the end of the second RI test, when participants reached task failure, the workload was immediately reduced to a constant-load (CL) power output 20% above the estimated maximal metabolic steady state (MMSS) until task failure. The highest 20-s rolling average V̇O2 was calculated for each RI test and for the CL exercise. W′ was calculated as the work performed between the power output at MMSS and PPO during the first (RI1) and second (RI2) RI tests as W′RI1 and W′RI2, respectively. In RI2, W′ during the CL phase (W′CL) was additionally computed, and total W′ was calculated: W′TOT = W′RI2 + W′CL. A repeated-measures ANOVA was used to assess statistical differences. A post hoc Bonferroni correction was applied when a significant main effect was detected. Effect sizes were reported as partial eta squared (pη2) Systematic bias and agreement between measurements were evaluated using Bland-Altman analysis and Lin’s concordance correlation coefficient (CCC), respectively.
RESULTS:
There was no significant main effect of condition on V̇O2max: RI1: 43.9 ± 7.2 mL·kg-1·min-1, RI2: 43.9 ± 6.2 mL·kg-1·min-1, and CL: 44.3 ± 6.4 mL·kg-1·min-1 (F(2, 26) = 0.24, p = 0.79, ηp2 = 0.02). These measurements demonstrated good-to-excellent agreement (CCC = 0.88–0.97) with low bias (0.10–0.44 mL·kg-1·min-1; p = 0.43–0.88). There was a significant main effect of condition on W′ (F(2, 26) = 20.7, p < 0.001, ηp2 = 0.61). Post hoc comparisons indicated no significant difference between W′RI1 (17.0 ± 5.3 kJ) and W′RI2 (16.5 ± 5.4 kJ) (p = 0.80). In contrast, W′TOT (20.1 ± 6.7 kJ) was significantly greater than both W′RI1 and W′RI2 (p < 0.005 for both comparisons), with fair-to-moderate agreement (CCC = 0.70–0.78) and high bias (3.13–3.62 kJ; p < 0.001) observed for W′TOT compared to W′RI1 and W′RI2.
CONCLUSION:
These results indicate that task failure and attainment of V̇O2max during ramp-incremental exercise do not require complete depletion of W′. [1] Azevedo 2023/ [2] Chidnok 2013/ [3] Morton 1997/ [4] Marinari 2025