An alternate to accumulated oxygen deficit (AOD) for measuring anaerobic contribution: ‘AOD_alt’ is valid in normoxia and hypoxia

The gold standard measure of anaerobic contribution is accumulated oxygen deficit (AOD). The purpose of this study was to investigate the validity of an alternate measure, AOD_alt. AOD_alt is the sum of the phosphocreatine and glycolytic contributions, which are estimated from post-exercise oxygen uptake and blood lactate concentration, respectively.

In Study One, six women and three men performed 6-min bouts of heavy intensity cycle ergometer exercise, once in normoxia (F_IO₂ ~ 21%) and twice under hypoxic conditions (F_IO₂ ~ 15% and ~ 12%). In Study Two, four women and two men performed severe intensity tests to exhaustion, once in normoxia (~ 10 min) and twice in hypoxia (F_IO₂ ~ 15% and ~ 10%). Physiological responses were measured during exercise and 7 min of recovery.

In 6 min of heavy exercise, Study One, the alternate and criterion measures of anaerobic contribution (AOD_alt and AOD) were correlated, in normoxia and in hypoxia. In exhaustive severe exercise, Study Two, AOD_alt and AOD were correlated (r = 0.77) and similar, in normoxia and at F_IO₂ ~ 15%. However, AOD_alt and AOD values were neither correlated (r = 0.27) nor similar (57 ± 5 mL·kg^–1 vs 51 ± 7 mL·kg^–1) at F_IO₂ ~ 10%.

These results confirm the validity of AOD_alt as a measure of anaerobic capacity in severe intensity exercise, demonstrate its validity in heavy exercise, and assert its validity in conditions of hypoxia (F_IO₂ ~ 12%).