A comparison of methods to estimate anaerobic capacity: Accumulated oxygen deficit and W’ during constant and all-out work-rate profiles

This study investigated (i) whether the accumulated oxygen deficit (AOD) and curvature constant of the power–duration relationship (W′) are different during constant work-rate to exhaustion (CWR) and 3-min all-out (3MT) tests and (ii) the relationship between AOD and W′ during CWR and 3MT. Twenty-one male cyclists (age: 40 ± 6 years; maximal oxygen uptake [V̇O2max]: 58 ± 7 ml · kg−1 · min−1) completed preliminary tests to determine the V̇O2–power output relationship and V̇O2max. Subsequently, AOD and W′ were determined as the difference between oxygen demand and oxygen uptake and work completed above critical power, respectively, in CWR and 3MT. There were no differences between tests for duration, work, or average power output (P ≥ 0.05). AOD was greater in the CWR test (4.18 ± 0.95 vs. 3.68 ± 0.98 L; P = 0.004), whereas W′ was greater in 3MT (9.55 ± 4.00 vs. 11.37 ± 3.84 kJ; P = 0.010). AOD and W′ were significantly correlated in both CWR (P < 0.001, r = 0.654) and 3MT (P < 0.001, r = 0.654). In conclusion, despite positive correlations between AOD and W′ in CWR and 3MT, between-test differences in the magnitude of AOD and W′, suggest that both measures have different underpinning mechanisms