Food Components to Enhance Performance An Evaluation of Potential Performance-Enhancing Food Components for Operational Rations (1994) / Chapter Skim
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12. Food Components That May Optimize Physical Preformance: An Overview
12. Food Components That May Optimize Physical Preformance: An Overview
Pages 223-238
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From page 223... ...
A psychological ergogenic aid might be hypnosis or mental rehearsal. Blood doping or erythropoietin injections are considered powerful physiological ergogenic aids by virtue of their ability to increase red blood cell mass and increase maximum aerobic capacity.
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This chapter identifies some of the more effective food components that have been found to enhance physical performance and describes their methods of action. Some potential yet unproved ergogenic aids are also discussed.
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From page 225... ...
An Increase In plasma free fatty acid levels generally occurs with prolonged aerobic exercise. Whatever the circumstances, it has been suggested that BCAA supplementation may be beneficial in that it may prevent a rise in the tryptophan/BCAA ratio, thereby reducing the uptake of tryptophan by the brain and blunting or preventing a rise in brain serotonin levels.
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From page 226... ...
The increase in aerobic endurance is thought to be due to a reduced reliance on carbohydrate stores and/or reduced lactate production during submaximal exercise. Blood doping and erythropoietin injections have been used to increase the oxygen-carrying capacity of the blood and to increase VO2 maX by increasing the red blood cell mass (Spriet, 1991~.
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From page 227... ...
The difference in the muscle glycogen response elicited by a carbohydrate supplement during moderate- and low-intensity steady-state exercise is likely due to the differences in the plasma glucose and insulin responses. Ingestion of carbohydrate supplements during low-intensity exercise increases insulin and plasma glucose concentrations and maintains these variables at elevated levels throughout the exercise bout (Ivy et al., 1983; Yaspelkis and Ivy, 1991~.
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From page 228... ...
Several studies have found that ingestion of caffeine approximately 1 h prior to exercise increased the plasma free fatty acid concentration (Costill et al., 1978; Essig et al., 1980~. This was accompanied by a decrease in the exercising respiratory exchange ratio and an increase in aerobic endurance.
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From page 229... ...
Both arteriovenous glucose difference and blood fractional glucose extraction were higher after dietary consumption of the PD than after consumption of the control diet, suggesting an enhanced muscle glucose uptake. In addition, the muscle glycogen concentration was higher for the PD treatment compared with that for the control treatment before exercise but did not differ between the two groups at exhaustion.
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From page 230... ...
Therefore, even if they appeared to enhance aerobic endurance, their use is questionable. Ergogenic Aids That Reduce or Neutralize Metabolic By-Products During intense exercise, in which glycolysis is primarily responsible for resynthesis of ATP, lactic acid is formed and accumulates in the muscle and blood.
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From page 231... ...
That is, NH4C1 impaired muscle lactate efflux and increased the rate of muscle lactate accumulation, and NaHCO3 facilitated muscle lactate efflux and decreased the rate of muscle lactate accumulation. It has been demonstrated in various animal models that a low blood pH impairs and that a high blood pH facilitates lactate efflux from muscle to blood (Hirche et al., 1975~.
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From page 232... ...
Ergogenic Aids That Enhance Recovery Because of the importance of muscle glycogen for prolonged moderateintensity exercise, replenishment of the muscle glycogen stores is essential for high levels of daily physical activity and training. Following the depletion of muscle glycogen levels by a prolonged exercise bout, normal glycogen stores can be replenished within a 24-h period if sufficient carbohydrate is ingested.
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From page 233... ...
· Caffeine appears to be a strong enhancer of aerobic endurance. This may be due to its ability to spare muscle glycogen and facilitate neural processes.
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From page 234... ...
· Although it has been suggested that medium-chain triglycerides may enhance aerobic endurance, this has not been substantiated, nor have there been any definitive results demonstrating a positive effect of choline supplementation on physical performance. · Branched-chain amino acids may enhance aerobic endurance by reducing the rate of brain serotonin accumulation during prolonged exercise.
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From page 235... ...
Sparks 1971 Muscle glycogen utilization during prolonged exercise on successive days.
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From page 236... ...
Holloszy 1977 Effects of increased plasma fatty acids on glycogen utilization and endurance.
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Nasser 1990 Effects of phosphate loading on oxygen uptake, ventilatory anaerobic threshold, and run performance.
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From page 238... ...
Ding, and J.L. Ivy 1993 Carbohydrate supplementation spares muscle glycogen press during variable intensity exercise.
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