Beetroot juice and exercise: pharmacodynamic and dose-response relationships

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry
• Cardiovascular Health

Background:

• Dietary inorganic nitrate (NO3(-)) from beetroot juice (BR) increases plasma nitrite, potentially improving cardiovascular function and exercise performance.
• The dose-response relationship between BR intake and physiological effects remains unclear.

Purpose of the Study:

• To investigate the dose-response effects of beetroot juice supplementation on plasma nitrite concentration and physiological responses during exercise.
• To determine the optimal dose of BR for enhancing exercise performance and cardiovascular health.

Main Methods:

• Healthy men ingested varying volumes of concentrated BR (70, 140, 280 ml) or placebo in a crossover design.
• Plasma nitrate and nitrite concentrations were measured over 24 hours.
• Subjects completed moderate- and severe-intensity cycle exercise tests post-ingestion.

Main Results:

• Plasma nitrite concentration increased dose-dependently with BR ingestion, peaking at 2-3 hours.
• 140 ml and 280 ml BR reduced steady-state oxygen uptake during moderate exercise by 1.7% and 3.0% respectively.
• Time to task failure was extended by 14% and 12% with 140 ml and 280 ml BR, with no further benefit at the highest dose.

Conclusions:

• Beetroot juice supplementation alters plasma nitrite levels and reduces the oxygen cost of moderate-intensity exercise in a dose-dependent manner.
• Ingesting 8.4 mmol NO3(-) (140 ml BR) appears sufficient to improve exercise tolerance, with no additional benefits from higher doses.
• These findings support the use of specific doses of BR for enhancing cardiovascular health and exercise performance.