Influence of protein intake and training status on nitrogen balance and lean body mass.

  title={Influence of protein intake and training status on nitrogen balance and lean body mass.},
  author={Mark Andrew Tarnopolsky and J. Duncan Macdougall and Stephanie A. Atkinson},
  journal={Journal of applied physiology},
  volume={64 1},
The present study examined the effects of training status (endurance exercise or body building) on nitrogen balance, body composition, and urea excretion during periods of habitual and altered protein intakes. Experiments were performed on six elite bodybuilders, six elite endurance athletes, and six sedentary controls during a 10-day period of normal protein intake followed by a 10-day period of altered protein intake. The nitrogen balance data revealed that bodybuilders required 1.12 times… 

Figures and Tables from this paper

Impact of Protein Intake on Protein Metabolism and Exercise Performance in Endurance-Trained Males

Background: Current recommendations for athletes consider dietary protein requirements that maintain nitrogen (i.e. protein) balance rather than an optimal dosage to enhance metabolism and exercise

Dietary protein requirements and body protein metabolism in endurance-trained men.

It is shown that habitual endurance exercise was associated with dietary protein needs greater than the current Recommended Dietary Allowance of, and whole body protein turnover and 3-methylhistidine excretion were not different from values reported for sedentary men.

Nutritional Practice and Nitrogen Balance in Elite Japanese Swimmers during a Training Camp

A protein intake of 2.96 g/kg/day with a well-designated pattern of protein and amino acid intake may satisfy the increased need for protein in an elite swimmer.

Gender differences in leucine kinetics and nitrogen balance in endurance athletes.

The current Canadian RNI for protein is inadequate for those who chronically engage in endurance exercise and leucine kinetics during exercise is concluded.

Within-Day Amino Acid Intakes and Nitrogen Balance in Male Collegiate Swimmers during the General Preparation Phase

The population-safe protein intake level in competitive swimmers was in the upper range of the current recommendations for athletes, but the protein intake distribution and quality throughout the day may be suboptimal for the maximization of the skeletal muscle adaptive response to training.

What are the dietary protein requirements of physically active individuals? New evidence on the effects of exercise on protein utilization during post-exercise recovery.

New evidence suggests that individuals engaging in strenuous activity consume a meal rich in amino acids and carbohydrate soon after the exercise bout or training session, as well as the timing and nutritional content of the post-exercise meal, which are known to have synergistic effects on protein accretion after exercise.

The Effect of Dietary Protein on Protein Metabolism and Performance in Endurance-trained Males

The data suggest that athletes who consume dietary protein toward the upper end of the current recommendations by the American College of Sports Medicine would better maintain protein metabolism and potentially exercise performance during training.

Protein intake for skeletal muscle hypertrophy with resistance training in seniors.

It is suggested that variability in total daily protein intake does not affect variability in lean mass gains with RET in the context of post-exercise protein supplementation.

Increased protein maintains nitrogen balance during exercise-induced energy deficit.

Increased dietary protein maintained NB during exercise-induced energy deficit, but this did not impact resting whole-body protein turnover.



Nitrogen balance in men with adequate and deficient energy intake at three levels of work.

Investigation of the effects of mild exercise on nitrogen balance in men given diets supplying adequate or slightly limiting energy found circumstances of negative energy balance with adequate protein intake are better tolerated when the energy deficit is generated by physical activity than when it derives from reduced intake.

Protein metabolism during intensive physical training in the young adult.

Although the men did increase body protein stores and muscle mass with high-protein diets, the additional body protein did not enhance physiological work performance and it is suggested that in this sutdy 100 g of protein/day was adequate for men performing fairly heavy work.

Failure of weight training to affect urinary indices of protein metabolism in men.

It is commonly believed by some athletes that strength building exercise "tears down" skeletal muscle tissue, thereby enhancing the dietary need for protein, but this has not been demonstrated. Ten

Quantitative effect of an isoenergetic exchange of fat for carbohydrate on dietary protein utilization in healthy young men.

The protein-sparing effect was greatest in those subjects who were on marginal energy and protein intakes and who were losing weight, and whether or not the longer-term effects of the change in dietary carbohydrate:fat ratio on N metabolism are mediated solely by the action of insulin remains to be determined.

Effect of exercise on protein turnover in man.

Studies of free 3-methylhistidine in muscle, plasma and urine samples suggest that exercise decreases the fractional rate of myofibrillar protein breakdown, in contrast with the apparent rise in whole-body breakdown.

Effect of reduced energy intake versus increased physical activity on the outcome of nitrogen balance experiments in man.

No significant differences between the two kinds of energy deficiency were found but the effect on the parameters studied tended to be less pronounced the longer the subjects had been on the experimental diets.

The Importance of Protein for Athletes

The observations suggest that the protein requirements of active individuals are greater than those of inactive individuals, and this statement applies to both endurance and strength/power athletes.

Effect of initial muscle glycogen levels on protein catabolism during exercise.

  • P. LemonJ. Mullin
  • Medicine, Biology
    Journal of applied physiology: respiratory, environmental and exercise physiology
  • 1980
It was concluded that protein is utilized during exercise to a greater extent than is generally assumed and that under certain conditions protein carbon may contribute significantly to exercise caloric cost.

Influence of exercise on urea, creatinine, and 3-methylhistidine excretion in normal human subjects.

Light to moderate exercise results in an increase in net protein catabolism and a increase in creatinine excretion and there is no evidence of a disproportionate increase in breakdown of myofibrillar contractile proteins.

Isotopic determination of amino acid-urea interactions in exercise in humans.

The data confirm the original findings that leucine decarboxylation is enhanced in light exercise but urea production is unchanged, and test the previous assumption that [1-13C]leucine metabolism in exercise was representative of the metabolism of other essential amino acids by infusing [alpha-15N]lysine throughout rest and exercise.