Increased consumption and vasodilatory effect of nitrite during exercise

Area of Science:

• Exercise Physiology
• Cardiovascular Physiology
• Biochemistry

Background:

• Nitrite is a precursor to nitric oxide (NO), a vasodilator.
• The role of nitrite in human circulation during exercise is not fully understood.
• Previous studies suggest potential benefits of nitrite for exercise performance.

Purpose of the Study:

• To investigate the impact of aerobic-to-anaerobic exercise on circulating nitrite levels.
• To evaluate the effects of systemic sodium nitrite infusion on exercise capacity and hemodynamics.
• To explore the relationship between nitrite metabolism and nitric oxide production during exercise.

Main Methods:

• Six healthy volunteers participated in a randomized, placebo-controlled crossover study.
• Subjects received intravenous sodium nitrite or saline infusion for 70 minutes.
• Exercise involved cycling to exhaustion using a ramp protocol, with hemodynamic and blood measurements taken.

Main Results:

• Exercise significantly increased nitrite consumption/elimination rate by approximately 137%.
• Nitrite infusion led to increased cardiac output and pulmonary artery pressure, with a smaller increase in mean arterial pressure, suggesting vasodilation.
• Despite vasodilation, exercise capacity was not enhanced at the tested plasma nitrite concentrations.

Conclusions:

• Exercise promotes nitrite conversion, likely releasing nitric oxide and causing systemic vasodilation.
• The tested dose of sodium nitrite did not improve exercise performance, contrary to findings with lower doses.
• Further research is needed to optimize nitrite dosing for potential ergogenic effects.