Objective: The effects of fluid intake during prolonged exercise have been extensively studied but at present there exists little information on the effects of milk-based drinks on the response to prolonged exercise. Thus, the purpose of this study was to investigate the effects of milk-based drinks on exercise capacity.
Methods: Eight healthy males (age 24 +/- 4 y, height 1.76 +/- 0.04 m, mass 68.9 +/- 9.5 kg, body fat 12.5 +/- 2.4%, peak oxygen consumption 4.3 +/- 0.6 L/min) exercised to volitional exhaustion at 70% peak oxygen consumption on four occasions. Subjects ingested 1.5 mL/kg body mass of plain water, a carbohydrate-electrolyte solution, low-fat (0.1%) milk, or low-fat (0.1%) milk with added glucose before and every 10 min during exercise. The effect of the drink on exercise capacity and the cardiovascular, metabolic, and thermoregulatory responses to prolonged exercise were examined.
Results: Exercise time to exhaustion was not significantly influenced by the drink ingested (P = 0.19), but there was a tendency for subjects to exercise longer when the carbohydrate-electrolyte (110.6, range 82.0-222.7 min), milk (103.3, range 85.7-228.5 min), or milk plus glucose (102.8, range 74.3-167.1 min) was ingested compared with water (93.3, range 82.4-192.3 min). The solution ingested did not influence the cardiovascular, metabolic, or thermoregulatory response to exercise.
Conclusion: The results of this study suggest that although the low-fat milk-based fluids did not enhance exercise capacity over that seen with the ingestion of plain water, the effect was comparable to that observed with a carbohydrate-electrolyte beverage.