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) can detect changes in energy system contribution in different substrate availabilities. Following a graded exercise test to determine maximal oxygen uptake intensity (iVO), 26 recreational runners performed a time to exhaustion effort (TTE) as baseline at 110% iVO. 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·kg), moderate (M-CHO, 5.6±1.1 g·kg), or zero (Z-CHO, 0.24±0.05 g·kg) 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·min). The aerobic contribution was lower (- 8.7±4.0 kJ·min), 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·min higher than baseline). Fasting increased relative alactic (2.9±1.7 kJ·min) but decreased aerobic contribution (- 3.3±2.3 kJ·min), impairing performance (- 17±12 s). In conclusion, MAOD can detect changes in energy system supply in different nutritional states. Therefore, participant's nutritional state must be considered prior to conducting the test.