Hypervolemia and blood alkalinity: effect on physiological strain in a warm environment

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Thermoregulation

Background:

• Athletes often seek strategies to enhance performance and reduce physiological strain during exercise in warm environments.
• Sodium citrate is known for its buffering capacity, potentially influencing hydration status and exercise responses.

Purpose of the Study:

• To investigate the effects of acute hypervolemia induced by sodium citrate-rich beverages on cardiovascular strain and thermoregulation during moderate aerobic exercise in heat.
• To assess the impact of sodium citrate on blood buffering capacity.

Main Methods:

• Twelve endurance-trained athletes participated in two randomized, double-blind trials, consuming either a control beverage or a sodium citrate-enhanced beverage before cycling.
• Physiological parameters including core and skin temperature, heart rate, and blood markers were monitored during exercise under controlled heat stress conditions.

Main Results:

• Sodium citrate ingestion significantly expanded plasma volume, maintaining higher levels throughout exercise compared to the control.
• While blood buffering capacity (increased [HCO3-], base excess, and pH) was enhanced, no significant differences were observed in heart rate, core/skin temperature, or metabolic data between groups.

Conclusions:

• Acute oral sodium citrate intake effectively induces mild hypervolemia and improves blood buffering capacity in athletes.
• Mild hypervolemia achieved through sodium citrate supplementation does not appear to reduce physiological strain or improve thermoregulation during prolonged moderate-intensity exercise in the heat.