[Adam F]

I thought that was a great read. Nice information on Protein, Weight Loss And Bulking, Amino Acids, Nitrogen balance, Calorie intake, protein and it’s effect on kidney function

The Practical Scientist
by Jamie Hale




Key Points from Protein Requirements and Recommendations for Athletes: Relevance of Ivory Tower Arguments for Practical Recommendations, Kevin D. Tipton, PhD, Oliver C. Witard, Msc

In general, scientific opinion on the protein controversy divides itself in two distinct camps- those who believe that exercise and sport increase the bodies demand for protein and those who believe protein requirements for exercising individuals and athletes are no different than the general population.

The demands of training vary within a particular sport or in individuals. Scientific studies often cited in the literature may be irrelevant for athletes, coaches, and nutrition practitioners. My comment: athletes are ultimately concerned with physique and performance not a bunch of scientific jargon.

The camp supporting the need for higher protein for athletes often cites nitrogen balance as an indicator. Numerous well-controlled studies have shown that nitrogen balance in athletes is greater the sedentary control groups. Increased protein needs may come from increased amino acid oxidation during exercise or growth and repair of muscle tissue.

There is no reason to recommend protein supplements per se because there is no evidence that supplements work better than foods

Increased MPS (muscle protein synthesis) is induced after resistance and endurance training (My comment: many endurance athletes do not consider the need for increased mitochondria and mitochondria enzymes which could lead to increased protein needs), suggesting additional protein would be necessary to provide needed amino acids.

The opposing camp argues that exercise, even when of long duration and intensive does not increase the dietary requirement for protein. Their argument is based on the fact that exercise has been shown to increase the efficiency of use of amino acids from ingested protein. Butterfield and others demonstrated this as they showed even at calorie deficits and low protein intakes nitrogen balance was improved with exercise.

A common criticism of studies that show increased use of amino acids with exercise (better utilization with exercise suggesting no need for higher intakes, more efficient shuttling to skeletal muscle) is that intensity or duration of exercise is not as great as that practiced by top athletes.

It has also been reported that low intensity endurance and resistance exercise does not stimulate protein synthesis. My comment: I guess it depends on what the definition of low intensity means. Studies indicate 40% (occlusion)- 130% of 1rm stimulates MPS relatively the same when total work is equal.

Arguments against higher protein requirements are based on difficulties showing increased muscle mass at higher levels of protein intake. When the increases in nitrogen balance are extrapolated to gains in lean body mass, the numbers don’t match. Gains of 200-500grams per day of lean body mass are physiologically impossible. Results suggest that nitrogen balance methods tend to overestimate nitrogen balance (My comment: among other problems with nitrogen balance studies) at high intakes. There are definitely studies providing evidence for higher protein needs for athletes as well as studying supporting the opposite.

Testing fallacies remain partly responsible for difficulties in determining protein requirements for athletes. In terms of design most studies use measurements of nitrogen losses or tracer-labeled amino acid oxidation rates.

In general, Nitrogen balance techniques are most commonly used to estimate protein requirements. A positive nitrogen balance indicates an anabolic situation while a negative nitrogen balance indicates protein catabolism. My comment: this procedure does not necessarily indicate where protein is going to and coming from, implications for MPS or breakdown limited. Healthy adults who are not growing are generally in nitrogen balance.

Nitrogen balance data is subject to numerous problems. Limitations have been well covered in previous papers and studies. One of the key criticisms of nitrogen balance studies is a lack of sensitivity because it involves only gross measures of nitrogen intake and excretion. My comment: was never intended to determine needs of bodybuilders or other athletes.

Nitrogen balance studies for strength athletes may be particularly inappropriate. The goal for a strength athlete is to increase lean body mass, strength and size. Nitrogen balance is not enough, as the goal would be inducing a positive nitrogen balance.

Establishing nitrogen balance for endurance athletes may not be appropriate either; as this could lead to a compromise in the up-regulation of enzyme activity, capillarization, or mitochondrial biogenesis after endurance training (positive nitrogen balance would be necessary to compensate for these needs).

As mentioned earlier nitrogen balance and stable isotope studies are of great interest to scientists, but from a practical standpoint coaches and athletes are generally not concerned with scientific debate. Performance is the ultimate outcome that interest athletes. Numerous authors have made this point. Millward stated, “Thus, the key test of adequacy of either protein or amino acid intake must be the long-term response in terms of the specific function of interest”.

It doesn’t seem optimal to suggest a given protein intake to broad category of athletes (strength or endurance athletes). Many sports require both strength and endurance. Consider a decathlete that participates in varied training and requires a multitude of motor qualities. Gender should also be considered. Protein recommendations should be based on individual circumstances. My comment: this would include different intakes for athletes participating in the same sport as their needs still vary.

Even if higher protein requirements for athletes are correct as some scientists indicate the argument is irrelevant because most athletes take in more protein than even the highest suggestions. My comment: the range given is generally 1.2-2gms/ kg/- bodyweight, I know many athletes who double or in some cases go even higher than double this amount. These athletes are at minimal risk for protein deficiency assuming that a maintenance level of calories are consumed an adequate nutritional practices are followed.

Tarnopolsky has suggested about 20% of athletes may consume levels of protein below recommended requirement for sedentary individuals. These individuals may be at risk for protein deficiencies. These athletes include vegetarians, weight class athletes, athletes suddenly increasing activity levels, and individuals under going weight loss programs. My comment: particularly people following rapid weight loss programs may be at risk for protein deficiencies as well as other problems. Rapid weight loss is not uncommon for athletes. I have seen numerous combat athletes drop over 20lbs in three days.