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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #232338
Title: Increased Protein Maintains Nitrogen Balance during Exercise-Induced Energy Deficit

Author
item PIKOSKY, MATTHEW - US ARMY RSCH INST ENV MED
item SMITH, TRACEY - US ARMY RSCH INST ENV MED
item GREDIAGIN, ANN - US ARMY RSCH INST ENV MED
item Castaneda-Sceppa, Carmen
item BYERLEY, LAURI - UNIV OF NORTH CAROLINA
item GLICKMAN, ELLEN - US ARMY RSCH INST ENV MED
item YOUNG, ANDREW - US ARMY RSCH INST ENV MED

Submitted to: Medicine and Science in Sports and Exercise
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2007
Publication Date: 3/1/2008
Citation: Pikosky, M.A., Smith, T.J., Grediagin, A., Castaneda-Sceppa, C., Byerley, L., Glickman, E.L., Young, A.J. 2008. Increased Protein Maintains Nitrogen Balance during Exercise-Induced Energy Deficit. Medicine and Science in Sports and Exercise. 40(3):505-512.

Interpretive Summary: Because exercise and physical activity can alter dietary protein requirements, it is important to understand the role of dietary energy balance on whole body protein utilization. This study examined how a diet high in protein can influence nitrogen balance and protein metabolism during a caloric deficit induced by exercise. Young male volunteers consumed either their baseline dietary intake and usual physical activity (BL) for 11 days, their baseline energy intake with 09 g/kg/day of protein plus a 1000 kcal per day of exercise (DEF), or their baseline energy intake with 1.8 g/kg/day of protein plus a 1000 kcal per day of exercise (DEF-HP). In the DEF subject nitrogen balance was negative, whereas in the BL and DEF-HP subjects nitrogen balance was unchanged. There were no differences between the three conditions in measures of whole body protein turnover. These results suggest that high protein diets maintain nitrogen balance during an exercise-induced energy deficit in young men.

Technical Abstract: PURPOSE: This study examined how a high-protein diet affected nitrogen balance and protein turnover during an exercise-induced energy deficit. METHODS: Twenty-two men completed a 4-d (D1-4) baseline period (BL) of an energy balance diet while maintaining usual physical activity level, followed by 7 d (D5-11) of 1000 kcal/d increased energy expenditure via exercise (50-65% V O2peak). One group consumed 0.9 g of protein per kilogram per day and maintained energy balance throughout the 11-d intervention (BAL, N = 8). The other two groups consumed their BL energy intake throughout the 11 days, resulting in a 7-d, 1000-kcal/d energy deficit. These groups consumed either 0.9 g of protein per kilogram per day (DEF, N = 7) or 1.8 g of protein per kilogram per day (DEF-HP, N = 7). Mean nitrogen balance (NB), calculated per kilogram of fat-free mass (FFM), was determined for BL, days 5-8 (EX1), and days 9-11 (EX2). Whole-body protein turnover was derived from phenylalanine and tyrosine kinetics assessed while fasting at rest on days 4, 7, and 12, using a priming dose of L-[ring-N]tyrosine and a 4-h, primed, continuous infusion of L-[N]phenylalanine and L-[ring-H4]tyrosine. RESULTS: DEF experienced a decrease in NB from BL to EX 1 that was maintained in EX 2. No changes in NB occurred for BAL or DEF-HP over time. No within- or between-group differences were found over time for Phe flux (Qp), conversion rate of Phe to Tyr (Qpt), or the derived protein synthesis value (Sp). CONCLUSION: Increased dietary protein maintained NB during exercise-induced energy deficit, but this did not impact resting whole-body protein turnover.