Metabolic responses to exercise

Spriet, L.L., Gledhill, N., Froese, A.B., Meyers, E.C. (1986). Effect of graded erythrocythemia on cardiovascular and metabolic responses to exercise. J. Appl. Physiol. 61, 1942-1948. 

What is the likely metabolic response to exercise in skeletal muscle by an unfit individual SOLUTION... 

Graham, T. E. and Spriet, L. L., Performance and metabolic responses to a high caffeine dose during prolonged exercise, Journal of Applied Physiology, 71, 2292, 1991. 

Smith, C. M., Narrow, C. M., Kendrick, Z. V, and Steffan, C. (1987). The effect of pantothenate deficiency in mice on their metabolic response to fast and exercise. Alc/fflwfKrn 36, 115-121. 

C14. Costill, D. L., Cahill, P. J., and Eddy, D., Metabolic response to submaximal exercise in three water temperatures. J. Appl. Physiol. 22, 628-632 (1967). 

Ahlborg, G., Weitzberg, E., Sollevi, A. Lundberg, J.M. (1992) Splanchnic and renal vasoconstrictor and metabolic responses to neuropeptide Y in resting and exercising man. Acta... 

Thompson, Ri., Hayward, J.S., 1996. Wet-cold exposure and hypothermia thermal and metabolic responses to prolonged exercise in rain. J. Appl. Physiol. 81 (3), 1128-1137. 

Vanhatalo et investigated the influence of dietary nitrate supplementation on muscle metabolism and oxidative function. P MRS showed muscle PCr, P and pH changed at a faster rate in hypoxic conditions with no dietary nitrate compared to hypoxia with nitrate or normoxia conditions. The limit of tolerance to exercise was similarly affected and there was also a longer recovery of PCr under hypoxic conditions with no nitrate supplementation. Davies et assessed the impact of exercise-induced muscle damage on muscle metabolic response to dynamic exercise. Incremental knee extensor exercise was performed inside the bore of a 1.5 T magnet before, and 48 h after, executing 100 squats with a load corresponding to 70% of body mass. 

Maughan RJ, Sadler DJ. The effects of oral administration of salts of aspartic acid on the metabolic response to prolonged exhausting exercise in man. Int J Sports Med 1983 4 119-123. 

Phinney, S.D., Bistrian, B.R., Evans, W.J., Gervino, E., and Blackburn, G.L., The human metabolic response to chronic ketosis without caloric restriction preservation of submaximal exercise capability with reduced carbohydrate oxidation. Metabolism, 32, 769-776, 1983. 

Beyond this point, during more severe exercise associated with anaerobic metabolism, minute ventilation increases faster than the rate of oxygen consumption, but proportionally to the increase in carbon dioxide production. The mechanism of the ventilatory response to severe exercise involves metabolic acidosis caused by anaerobic metabolism. The lactic acid produced under these conditions liberates an H+ ion that effectively stimulates the peripheral chemoreceptors to increase ventilation. 

Proprioceptors originating in muscles and joints of the exercising limbs provide substantial input to the medullary respiratory center. In fact, even passive movement of the limbs causes an increase in ventilation. Therefore, the mechanical aspects of exercise also contribute to the ventilatory response. The increased metabolism associated with exercise increases body temperature, which further contributes to the increase in ventilation during exercise. (Not surprisingly, ventilation is also enhanced in response to a fever.) Exercise is associated with a mass sympathetic discharge. As a result, epinephrine release from the adrenal medulla is markedly increased. Epinephrine is believed to stimulate ventilation. 

Adrenal medulla. On the one hand, release of epinephrine elicits cardiovascular effects, such as increases in heart rate und peripheral vascular resistance. On the other, it evokes metabolic responses, such as glycogenolysis and li-polysis, that generate energy-rich substrates. The sensation of hunger is suppressed. The metabolic state corresponds to that associated with physical exercise - silent stress . 

Other factors. A number of additional factors may alter the predicted response of the patient to a drug. As discussed earlier, environmental and occupational hazards may produce certain toxins that alter drug absorption and metabolism. 9 62 Factors such as cigarette smoking and alcohol consumption have been shown to influence the metabolism of specific compounds.39,49 Drug distribution and metabolism may be altered in the obese patient,6 or in response to chronic and acute exercise.7,43 Individuals with spinal cord injuries have a decreased ability to absorb cer-... 

Increase in TAC is not always a good prognostic it may simply indicate an initial response to oxidative stress, as with concentrations of individual antioxidants and activities of antioxidant enzymes, or when it is due to disturbances in uric acid metabolism. Because uric acid is the main determinant of TAC of blood plasma, TAC increases in situations when the concentration of urate is increased, for example, in metabolic disorders and kidney failure. TAC is increased in urine from renal transplant recipients with delayed graft function (SI6). Ischemia of small intestine leads to an increase in TAC of rat blood serum, which is maximal (almost twofold) immediately after termination of 45-min ischemia (S22). TAC of blood plasma of rats poisoned with a high dose of carbon tetrachloride (1200 mg/kg, intraperitoneal injection, measurement 16 hr after injection) was significantly (over twofold) increased (Kl). These apparently paradoxical effects can be explained, however, by release of antioxidants from cells undergoing necrosis. Increase in TAC after intensive physical exercise also may be a marker of tissue... 

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