Moderate Physical Activity Can Increase Dietary Protein Needs

Abstract

Six healthy men completed three 1-hr bouts of treadmill Walk-jogging at low (L; 42 ± 3.9% VO2max), moderate (M; 55 ± 5.6%), and high (H; 67 ± 4.5%) exercise intensity in order to determine whether moderate physical activity affects dietary protein needs. Both sweat rate and sweat urea N loss were greater (p < .10) with increasing exercise intensity. Seventy-two hour postexercise urine urea N excretion was elevated (p < .05) over nonexercise control (26.6 ± 2.96 g) with both M (31.0 ± 3.65) and H (33.6 ± 4.39), but not L (26.3 ± 1.86), intensities. Total 72-hr postexercise urea N excretion (urine + sweat) for the. M and H exercise was greater than control by 4.6 and 7.2 g, respectively. This suggest that 1 hr of moderate exercrise increases protein oxidation by about 29-45 g, representing ∼16-25% of the current North American recommendations for daily protein intake. These data indicate that the type of exercise typically recommended for health/wellness can increase daily protein needs relative either to sedentary individuals or to those who exercise at lower intensities. Key words: dietary protein/amino acid requirements, exercise intensity, aerobic exercise, moderate exercise, health/wellness, nitrogen excretion, sweat, urine