Physiological and performance responses to nicotinic-acid ingestion during exercise

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Nutrition

Background:

• Plasma free fatty acids (FFA) normally increase during exercise, serving as a key energy substrate.
• Nicotinic acid is known to inhibit lipolysis, potentially blunting the exercise-induced rise in FFA.

Purpose of the Study:

• To investigate the physiological and performance effects of blunting the exercise-induced increase in plasma FFA using nicotinic acid.
• To examine the impact of altered FFA levels on hormonal responses and high-intensity exercise capacity.

Main Methods:

• Ten subjects performed a 120-minute cycling exercise at 68% VO2peak, followed by a 3.5-mile performance test.
• Four beverage conditions were administered: water placebo (WP), WP + nicotinic acid (NA), carbohydrate-electrolyte (CE), and CE + NA.
• Plasma FFA and human growth hormone concentrations were measured throughout exercise.

Main Results:

• Nicotinic acid ingestion (WP + NA, CE + NA) effectively blunted the rise in plasma FFA during exercise.
• FFA levels remained near rest values with NA administration.
• NA ingestion led to a 3- to 6-fold increase in human growth hormone concentrations during exercise.
• Performance time was significantly faster with CE compared to WP and WP + NA, but not significantly different from CE + NA.

Conclusions:

• Blunting the exercise-induced rise in plasma FFA alters the hormonal milieu during exercise, notably increasing human growth hormone.
• Reduced plasma FFA availability, despite carbohydrate availability, appears to impair the capacity for high-intensity exercise performance.