Training, endurance

Denis, C., Linossier, M.-T, Dormois, D., Cottier-Perrin, M., Geyssant, A., and Lacour, J,-R. (1989). Effects of endurance training on hyperammonaemia during a 45-min constant exercise intensity. Eur. J. Appi Physiol. 59, 268-272. 

Notes Assuming a moderately active 70 kg man with 40% of body weight as muscle (28 kg), a liver weight of 1.8 kg, a plasma volume of 3 L, and 9 kg of adipose tissue. Endurance trained individuals store -125-150 mmol/kg wet muscle of glycogen in muscle and 400-700 mmol/kg wet tissue of glycogen in liver,... 

Describe how cardiac output varies in a sedentary individual vs. an endurance-trained athlete... 

Ford GA, James OF. Effect of autonomic blockade on cardiac beta-adrenergic chronotropic responsiveness in healthy young, healthy elderly and endurance-trained elderly subjects. Clin Sci (Lond) 1994 87(3) 297-302. 

Fujii, H. Shimomura, Y. Murakami, T. Nakai, N. Sato, T. Suzuki, M. Harris, R.A. Branched-chain a-keto acid dehydrogenase kinase content in rat skeletal muscle is decreased by endurance training. Biochem. Mol. Biol. Int., 44, 1211-1216 (1998)... 

C28. Child, R. B., Wilkinson, D. M., and Fallowfield, J. L., Resting serum antioxidant status is positively correlated with peak oxygen uptake in endurance trained runners. J. Sports Med. Phys. Fitness 39, 282-284 (1999). 

Kihlstrom, M. 1990. Protection effect of endurance training against reoxygenation-induced injuries in rat heart. J. Appl. Physiol. 68 1672-1688. 

Exercise was found to cause a 50% increase in o-tyrosine, m-tyrosine, and dityrosine in mitochondrial proteins but not cytosolic proteins of rat heart muscle. This increase was transient, and levels returned to normal when exercised animals were allowed to rest. There was also a transient increase in the level of o,o -dityrosine in the urine of exercised rats (L8). A single bout of exhaustive running or endurance training for 12 weeks significantly increased the level of protein carbonyls in rat skeletal muscles (R8, W14). Extensive running of rats induces a 40% increase in protein carbonyls in the lung (Rl). 

Aerobic exercise inyolyes endurance training. As the body performs activities for extended periods, physiological and cellular adaptations occur (10-12). These adaptations focus on the ability of the body to supply oxygen to the muscle cells, the capacity of the cells to utilize oxygen, and a shift in the fuel source to greater use of fatty acids. The magnitude of these changes defines aerobic capacity and endurance. 

Costlll, D, L., Fink, W. J., Getchell, L. H., Ivy, J. L. and Wltzmann, F. A. (1979) Lipid metabolism In skeletal muscle of endurance trained males and females. J. Appl. Physiol. Resplrat, Environ. Exercise Physiol. 47 787-91. 

Gollnlck, P. D. and Saltln, B. (1982) Significance of skeletal muscle oxidative enzyme enhancement with endurance training. Clin. Physiol. 2 1-12. 

Recognition of a beneficial effect of exercise on the Incidence of CHD has led to numerous cross-sectional and longitudinal studies designed to examine the Influence of physical activity on major coronary risk factors, with particular emphasis on plasma lipids and lipoproteins. A number of comprehensive reviews have summarized these studies (14-18). In general. In cross-sectional studies, high density lipoprotein (HDL) cholesterol is elevated (14) and total plasma and very low density lipoprotein (VLDL) triglycerides are lower In endurance trained subjects than In sedentary control subjects (14). In a study of 23 top-level male athletes, Lehtonen and Vllkarl (19) found a statistically significant relationship between the number of kilometers that the athletes ran or skied weekly and their plasma HDL cholesterol concentration (P<0.05 r=0.554). Low density lipoprotein (LDL) cholesterol Is frequently lower, and plasma total cholesterol Is Inconsistently lower In trained subjects (19). 

Figure 4. Maximal run times and maximal treadmill speed of anemic trained (AT) and normal trained (NT) rats following six weeks of endurance training. Reproduced with permission from Ref. 30. Copyright 1984 Springer-Verlag New York, Inc.

Provided that the diet is adequate, there is no substantial evidence to suggest that loss of trace elements in sweat affects nutritional status or exercise performance adversely (28). A possible exception is iron the low level of bone marrow iron content observed in some endurance-trained athletes (33) may be due to excessive losses of as much as 40 micrograms of iron per 100 milliliters of sweat (34). Iron metabolism is discussed in more detail in the chapter by McDonald and Saltman. 

Heat Acclimatization and Endurance Training. Primary adaptive responses to repeated intermittent exposure to exercise in the heat are (1) chronic expansion of the plasma volume, (2) increased retention of body sodium, (3) Increased capacity for sweating and, hence. 

Pollock, M. L. (1973) The quantification of endurance training programs. In Exercise and Sport Sciences Reviews,... 

Soussi, B., Idstrom, J.P., Schersten, T., Bylund-Fellenius, A.C. (1989). Kinetic parameters of cytochrome c oxidase in rat skeletal muscle effect of endurance training. Acta Physiol. Scand. 135 373-9. 

Ijeeuwenbuigh,C., Hollander, j., Leichtweis, S., Griffiths, M., Gore, M., and Ji, L. L. (1997). Adaptations of glutathione antioxidant system to endurance training are tissue and muscle fiber specific. Am. J. Physio . 272, R363-R369. 

The proportions of fibers within a muscle are determined by a combination of genetic and developmental factors and by the pattern of recruitment of the muscle unit. Due to this latter influence, the twitch and enzyme characteristics of muscle fibers are somewhat malleable, being influenced by training (especially endurance training) or by detraining (as in bed rest). 

---