Sodium Nitrate Improves Oxidative Energy Contribution and Reduces Phosphocreatine Contribution During High-Intensity Intermittent Exercise.

The present study aimed to verify the effect of acute nitrate supplementation on oxidative, phosphocreatine, and glycolytic energy contribution (C OXI , C PCr , and C LAC , respectively) during a high-intensity intermittent exercise (HIIE). Fifteen physically active subjects were submitted to incremental running test on a treadmill and two random HIIE (10 × 1 min at maximal aerobic speed with 1 min of passive recovery) in the following conditions: sodium nitrate (SN) or Placebo (PL). Repeated measure ANOVA was used to compare C OXI , and C PCr within the 10 efforts. Student t test was used to compare total C OXI , C PCr , C LAC , as well oxidative and non-oxidative contribution. Considering the 10 efforts, C OXI presented the main effect for condition (F = 16.7; p  = .001; SN: 1.9 ± 0.1 L; PL: 1.6 ± 0.1 L), and no interaction effect (F = 0.9; p  = .415), while C PCr presented effect for condition (F = 13.4; p  = .003; SN: 1.2 ± 0.1; PL: 1.4 ± 0.8 L), and no interaction (F = 1.2; p  = .317). Total oxidative contribution were higher ( p  < .001) after SN (19.1 ± 3.4 L) than Placebo (16.7 ± 3.1 L), while total C PCr were lower ( p  = .002) after SN (12.4 ± 2.5 L) than PL (14.1 ± 2.6 L). Total energy contribution were not different between trials. Acute dose of SN supplementation improved oxidative contribution during HIIE, and reduced C PCr . Higher C OXI is likely related to increased oxygen kinetics, while the lower C PCr might be related to the improved energetic efficiency.