Nitrate-Containing Beetroot Juice Reduces Oxygen Consumption During Submaximal Exercise in Low but Not High...

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry

Background:

• Dietary nitrate (NO3-) is a precursor to nitric oxide, influencing vasodilation and mitochondrial efficiency.
• Understanding nitrate's impact on exercise oxygen cost across different fitness levels is crucial for optimizing performance and training.

Purpose of the Study:

• To investigate the effect of a 4-day inorganic nitrate (NO3-) loading protocol on submaximal exercise oxygen consumption.
• To compare these effects between low-fit and high-fit male participants at various exercise intensities.

Main Methods:

• A double-blind, placebo-controlled, crossover study design was employed.
• Participants (low-fit and high-fit males) underwent a 4-day supplementation period with either nitrate-rich (NR) or placebo (PL) capsules.
• Submaximal treadmill exercise tests at 45%, 60%, 70%, 80%, and 85% of maximal oxygen uptake (VO2max) were conducted.

Main Results:

• Low-fit participants showed significantly reduced oxygen consumption at 45% and 60% VO2max following nitrate supplementation compared to placebo.
• No significant differences in oxygen cost were observed in high-fit participants across any intensity.
• Heart rate, respiratory exchange ratio, and rating of perceived exertion remained unaffected by nitrate supplementation in either group.

Conclusions:

• Inorganic nitrate supplementation can enhance exercise economy by reducing oxygen cost at lower exercise intensities in less physically fit individuals.
• Higher fit individuals do not appear to benefit from nitrate supplementation regarding submaximal exercise oxygen cost.
• The findings suggest that nitrate's ergogenic potential may be intensity- and fitness-dependent, particularly below 60% VO2max.