Food Components to Enhance Performance An Evaluation of Potential Performance-Enhancing Food Components for Operational Rations (1994) / Chapter Skim
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14. Performance-Enhancing Effects of Protein and Amino
14. Performance-Enhancing Effects of Protein and Amino
Pages 263-276
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From page 263... ...
by provision of specialized meals or AAs? Second, since military personnel may find themselves in combat situations for prolonged periods of time, can the overall diet be modified to help individuals overcome the continuing stress associated with combat situations?
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From page 264... ...
The relevant issue here is whether the chronic high levels of stress under combat situations influence the protein requirements of the individual. Unfortunately, direct experimental evidence is not available; however, there is evidence that the chronic physiologic stress associated with endurance training in athletes may raise protein requirements.
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From page 265... ...
Thus, it would appear that, at least over the short term, food shortages or energy deficits do not impair an individual's ability to perform physically demanding tasks. What was not addressed in that study, however, was whether higher forms of performance, such as cognitive performance including decision making, were influenced by the energy deficit.
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From page 266... ...
ROLE OF INDIVIDUAL AAs OR MIXTURES OF AAs Space limitations preclude an extensive examination of all AAs with regard to their potential performance-enhancing effects, and detailed reports on the impact of single-AA supplementation can be found elsewhere (Health and Welfare Canada, l990b; (Federation of the American Societies for Experimental Biology, Life Sciences Research Office, 1992~. At present, the most promising effect of AA supplementation appears to be with tyrosine (TYR)
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From page 267... ...
; however, this effect of TRP is unlikely to have application in combat situations. Consideration should be given, however, to the provision of the branchedchain amino acids (BCAAs)
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From page 268... ...
Indeed, brain TRP levels were significantly lower in animals fed a 40 percent protein diet in comparison with those consuming a 12 percent protein diet (Table 14-2~. Thus, it would appear that the lower the protein concentration of the chronic diet, the greater the likelihood that individual LNAAs will enter the CNS, even when they are administered in the fasting state.
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From page 269... ...
However, if energy needs are met in the individual, the increase in protein consumption associated with increased food intake will more than meet the protein requirements of the individual. More realistic, however, is a situation in which food intake is decreased under combat situations because of a number of adverse physical and psychologic conditions.
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From page 270... ...
and a high-carbohydrate meal (vegetarian) on satiety measured by automated computerized monitoring of subsequent food intake, motivation to eat and food preferences.
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From page 271... ...
Peters J.C., and A.E. Harper 1985 Adaptation of rats to diets containing different levels of protein: Effects on food intake, plasma and brain amino acid concentrations and brain neurotransmitter metabolism.
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From page 272... ...
On first observation, it may suggest that with the lower protein diet, the brain uptake carrier was saturated with 75 mg/kg TRP and hence higher TRP doses would not be effective in further increasing brain TRP levels. This could be consistent with any carrier-mediated process.
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From page 273... ...
Neverthless, you must remember that in these clinical tests, arginine is given on an acute basis. It would not be surprising that with chronic exposure to arginine that its catabolism would be increased so that in the long term, circulating arginine levels would be within a normal range and that chronic arginine feeding or administration would not result in chronic elevations in plasma hormone levels.
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From page 274... ...
Just to add to what John is saying, I did not mention it in terms of the changes that are going on during postexercise recovery. John Devlin in our group has really looked at glucose and amino acid metabolism during the first 14 hours of postexercise recovery, and John mentioned that you continue to get lactate output from nonexercising muscles if you do cycle exercise and forearm balance
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From page 275... ...
In addition to that, you also get continued alanine output, and so there is amino acid oxidation going on during the postexercise recovery period with continued alanine. So I think your point is very well taken, that we should be providing the substrates for gluconeogenesis and rebuilding glycogen stores after exercise to both carbohydrate and amino acid.
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