High- and Low-carb Diet and Fasting State Modify Alternative Maximal Accumulated Oxygen Deficit

This investigation aimed to assess whether the alternative method of estimating the maximal accumulated oxygen deficit (MAOD alt ) can detect changes in energy system contribution in different substrate availabilities. Following a graded exercise test to determine maximal oxygen uptake intensity (iVO(2max) ), 26 recreational runners performed a time to exhaustion effort (TTE) as baseline at 110% iVO(2max) . The same TTE was performed in fasting state, then, a muscle glycogen depletion protocol was executed. Subsequently, participants received a low-carbohydrate diet and beverages containing high (H-CHO, 10.8 +/- 2.1 g<middle dot>kg (- 1)), moderate (M-CHO, 5.6 +/- 1.1 g<middle dot>kg (- 1)), or zero (Z-CHO, 0.24 +/- 0.05 g<middle dot>kg (- 1)) carbohydrates. Another TTE was performed 24 h later. Each energy system contribution was assessed. Generalized linear mixed models were used for statistical analysis (p<0.05). H-CHO increased relative anaerobic capacity (slope effect [baseline -intervention]x[H-CHO - M-CHO]) due to the relative lactic contribution maintenance (slope effect [baseline - intervention]x[H-CHO - Z-CHO] or [H-CHO - M-CHO]) and increase in relative alactic contribution (6.3 +/- 3.5 kJ<middle dot>min(-1)). The aerobic contribution was lower (- 8.7 +/- 4.0 kJ<middle dot>min( - 1)), decreasing performance (- 34 +/- 16 s) for H-CHO. M-CHO and Z-CHO maintained anaerobic capacity due to increase in alactic contribution (slope effect [fasting - intervention]x[M-CHO - H-CHO]; and Z-CHO was 7.3 +/- 3.4 kJ<middle dot>min( - 1 )higher than baseline). Fasting increased relative alactic (2.9 +/- 1.7 kJ<middle dot>min (- 1)) but decreased aerobic contribution (-3.3 +/- 2.3 kJ<middle dot>min (- 1)), impairing performance (-17 +/- 12 s). In conclusion, MAOD alt can detect changes in energy system supply in different nutritional states. Therefore, participant's nutritional state must be considered prior to conducting the test.