Evaluation of protein requirements for trained strength athletes

Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.
Journal of Applied Physiology (Impact Factor: 3.06). 12/1992; 73(5):1986-95.
Source: PubMed


Leucine kinetic and nitrogen balance (NBAL) methods were used to determine the dietary protein requirements of strength athletes (SA) compared with sedentary subjects (S). Individual subjects were randomly assigned to one of three protein intakes: low protein (LP) = 0.86 g, moderate protein (MP) = 1.40 g, or high protein (HP) = 2.40 g for 13 days for each dietary treatment. NBAL was measured and whole body protein synthesis (WBPS) and leucine oxidation were determined from L-[1-13C]leucine turnover. NBAL data were used to determine that the protein intake for zero NBAL for S was 0.69 and for SA was 1.41 A suggested recommended intake for S was 0.89 and for SA was 1.76 For SA, the LP diet did not provide adequate protein and resulted in an accommodated state (decreased WBPS vs. MP and HP), and the MP diet resulted in a state of adaptation [increase in WBPS (vs. LP) and no change in leucine oxidation (vs. LP)]. The HP diet did not result in increased WBPS compared with the MP diet, but leucine oxidation did increase significantly, indicating a nutrient overload. For S the LP diet provided adequate protein, and increasing protein intake did not increase WBPS. On the HP diet leucine oxidation increased for S. These results indicated that the MP and HP diets were nutrient overloads for S. There were no effects of varying protein intake on indexes of lean body mass (creatinine excretion, body density) for either group. In summary, protein requirements for athletes performing strength training are greater than for sedentary individuals and are above current Canadian and US recommended daily protein intake requirements for young healthy males.

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    • "A study in which strength athletes were compared with sedentary individuals (3 randomly designed groups on a low (0.86 g/kg), moderate (1.40 g/kg) and high (2.40 g/kg) protein diet) found that varying protein intake had no effect on lean body mass indexes of when creatinine excretion and body density was measured for either group [26]. This however, gives a relative large window to inhibit protein absorption since an average protein consumption is around 150 grams/day taking into consideration that an average steak is 200 grams and that protein can be found also in eggs, cheese, milk etc. "
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    ABSTRACT: Obesity research focuses essentially on gene targets associated with the obese phenotype. None of these targets have yet provided a viable drug therapy. Focusing instead on genes that are involved in energy absorption and that are associated with a "human starvation phenotype", we have identified enteropeptidase (EP), a gene associated with congenital enteropeptidase deficiency, as a novel target for obesity treatment. The advantages of this target are that the gene is expressed exclusively in the brush border of the intestine; it is peripheral and not redundant. Potent and selective EP inhibitors were designed around a boroarginine or borolysine motif. Oral administration of these compounds to mice restricted the bioavailability of dietary energy, and in a long-term treatment it significantly diminished the rate of increase in body weight, despite ad libitum food intake. No adverse reactions of the type seen with lipase inhibitors, such as diarrhea or steatorrhea, were observed. This validates EP as a novel, druggable target for obesity treatment. In vivo testing of novel boroarginine or borolysine-based EP inhibitors validates a novel approach to the treatment of obesity.
    Full-text · Article · Nov 2012 · PLoS ONE
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    • "Urinary ammonia was isolated by cation exchange resin with the 15N]enrichment determined by isotope ratio mass spectrometry [14]. Whole-body protein turnover (Q) was calculated using the 15N]ammonia end-product method as described previously [15], which provides consistent rates over 12h [16]. Concentrations of urinary urea and creatinine, the major nitrogen containing metabolites in urine, were measured by automated analyser at the Laboratoire Central de Chimie Clinique (Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland). "
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    ABSTRACT: Background The pattern of protein intake following exercise may impact whole-body protein turnover and net protein retention. We determined the effects of different protein feeding strategies on protein metabolism in resistance-trained young men. Methods Participants were randomly assigned to ingest either 80g of whey protein as 8x10g every 1.5h (PULSE; n=8), 4x20g every 3h (intermediate, INT; n=7), or 2x40g every 6h (BOLUS; n=8) after an acute bout of bilateral knee extension exercise (4x10 repetitions at 80% maximal strength). Whole-body protein turnover (Q), synthesis (S), breakdown (B), and net balance (NB) were measured throughout 12h of recovery by a bolus ingestion of [15N]glycine with urinary [15N]ammonia enrichment as the collected end-product. Results PULSE Q rates were greater than BOLUS (~19%, P<0.05) with a trend towards being greater than INT (~9%, P=0.08). Rates of S were 32% and 19% greater and rates of B were 51% and 57% greater for PULSE as compared to INT and BOLUS, respectively (P<0.05), with no difference between INT and BOLUS. There were no statistical differences in NB between groups (P=0.23); however, magnitude-based inferential statistics revealed likely small (mean effect±90%CI; 0.59±0.87) and moderate (0.80±0.91) increases in NB for PULSE and INT compared to BOLUS and possible small increase (0.42±1.00) for INT vs. PULSE. Conclusion We conclude that the pattern of ingested protein, and not only the total daily amount, can impact whole-body protein metabolism. Individuals aiming to maximize NB would likely benefit from repeated ingestion of moderate amounts of protein (~20g) at regular intervals (~3h) throughout the day.
    Full-text · Article · Oct 2012 · Nutrition & Metabolism
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    • "However, the association between protein intake and muscle mass has not been yet scientifically proven [34, 35]. Even in athletes involved in intense training and with elevated dietary protein needs, a well-balanced diet that maintains energy balance can achieve these recommendations [36–38]. On the other hand, as observed in the current study, vitamin and mineral supplements were found to be frequently consumed in exercise [12–14]. "
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