Accumulated oxygen deficit (AOD) is the gold standard measure of anaerobic contribution; however, its calculation requires several contentious assumptions and it is time-consuming, requiring participants to perform a number of submaximal exercise bouts to establish exercise efficiency. A new method, AODalt, requires performance of only a single bout of exercise, and is based on the presumption that the fast phase of the post-exercise oxygen uptake (VO2) profile reflects the alactic or phosphocreatine (PCr) contribution and that the exercise-induced increase in blood lactate concentration is quantitatively related to the lactic or glycolytic contribution representing a measure of total anaerobic contribution. PURPOSE: The purpose of this study was to investigate the validity of an alternate measure, AODalt. METHODS: In Study One, six women (mean ± SD age, 23 ± 1 y) and three men (23 ± 0 y) performed three 6-min bouts of heavy intensity cycle ergometer exercise, one in normoxia (FIO2 ~21 %) and two under hypoxic conditions (FIO2 ~15 % and ~12 %). In Study Two, four women (23 ± 1 y) and two men (23 ± 0 y) performed severe intensity tests to exhaustion, one in normoxia (time to exhaustion ~10 min) and two in hypoxia (FIO2 ~15 % and ~10 %; time to exhaustion ~7½ min and ~4 min). Physiological responses were measured during exercise and during 7 min of recovery. RESULTS: In 6 min of heavy exercise, Study One, the alternate and criterion measures of anaerobic contribution (AODalt and AOD, respectively) were correlated both in normoxia and in hypoxia (r ³ 0.82, p < 0.01) although AODalt values were slightly lower (p < 0.01) in normoxia (25 ± 3 mL·kg–1 vs 28 ± 4 mL·kg–1). In exhaustive severe intensity exercise, Study Two, the two measures of anaerobic capacity were correlated (r ³ 0.77, p £ 0.02) and not different (p ³ 0.43) in normoxia and at FIO2 ~15 % (e.g., 51 ± 9 mL·kg–1 vs 49 ± 8 mL·kg–1 in normoxia). However, the AODalt and AOD values were neither correlated (r = 0.27, p = 0.44) nor similar (p < 0.01; 57 ± 8 mL·kg–1 vs 51 ± 7 mL·kg–1) at FIO2 ~10 %. CONCLUSION: These results confirm the validity of AODalt as a measure of anaerobic contribution / anaerobic capacity in severe intensity exercise, demonstrate its validity in heavy intensity exercise, and assert its validity in conditions of hypoxia (FIO2 ³ 12%).



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