Athletes endurance

The total number of calories a person needs each day is the sum of the basal requirement plus the energy used for physical activities, as shown in Table 29.1. A relatively inactive person needs about 30% above basal requirements per day, a lightly active person needs about 50% above basal, and a very active person such as an athlete or construction worker may need 100% above basal requirements. Some endurance athletes in ultradistance events can use as many as 10,000 keal/day above the basal level. Each day that your caloric intake is above what you use, fat is stored in your body and your weight rises. Each day that your caloric intake is below whatyou use, fat in your body is metabolized and your weight drops. 

Similar results were obtained by Graham and Spriet75 using eight well trained, male endurance athletes who received either 0, 3, 6, or 9 mg/kg caffeine 1 h before testing. Subjects ran to exhaustion and showed signifi-... 

EPO is used in blood doping to generate more red blood cells for carrying oxygen. It is particularly favored by endurance athletes to enhance their performance. Human growth hormone (hGH, see description in Section 4.5.2) is used to build up muscle and bone strength. Both EPO and hGH are banned in sports. 

Fast-twitch muscle fibers have a high capacity for anaerobic glycolysis but are quick to fatigue. They are involved primarily in short-term, high-intensity exercise. Slow-twitch muscle fibers in arm and leg muscles are well vascularized and primarily oxidative. They are used during prolonged, low-to-moderate intensity exercise and resist fatigue. Slow-twitch fibers and the number of their mitochondria increase dramatically in trained endurance athletes. 

Those athletes who are genetically adapted to become very muscular -weightlifter types and body builders - are likely to have 40% Type I and 60% Type II whereas those destined to become great endurance athletes probably have 60 80% Type I and 20 0% Type II muscle fibres. 

There are several reports on reduced IMCL levels during exercise (e.g., Refs. 19, 79, 99-103) and some of these studies additionally concentrate on the determination of replenishment of IMCL after exercise. It was reported that most IMCL are replenished after endurance running within approximately 3-5 days. Based on the results it was suggested that diets containing moderate amounts of fat should be consumed and, consequently, that diets too low in fat are probably not ideal for endurance athletes. 

Figure 9.20 The creatine/phosphocreatine shuttle between subsarcolemmal mitochondria and myosin ATPase in muscle. The distance between the mitochondria that reside just below the plasma membrane (sarcolemma) and the myofibrils in which the myosin ATPase results in contraction, is long in such muscles. The advantage of the position of these mitochondria is ready access to oxygen and fuel from blood. Such mitochondria are common in endurance athletes.

The different fibres have different properties, and different proportions are present in different individuals. The biochemical and physiological characteristics of the different fibres explain why some individuals are good sprinters whereas others are good endurance athletes. These differences are most marked in... 

The triad is the combination of disordered eating, amenor-rhoea and osteoporosis that occurs in female endurance athletes, ballet dancers, gymnasts and lightweight rowers. 

Lehmann M, Foster C, Keul J. Overtraining in endurance athletes a brief review. Med Sci Sports Exerc 1993 25 854-862. 

Carnitine is used as a dietary supplement by endurance athletes and in the treatment of certain metabolic diseases. Apparently the extra carnitine allows more rapid transport of fatty acids and a more efficient energy metabolism. 

METABOLIC REGULATION IN ELITE ENDURANCE ATHLETES AND IN HIGH-ALTITUDE NATIVES... 

Gayagay, G., B.Yu, B.Hambly, T. Boston, A. Hahn, D.S. Celermajor, and R.J. Trent (1998). Elite endurance athletes and the ACE I allele—the role of genes in athletic performance. Human Genet. 103 48-50. 

In a well-controlled study designed to assess the influence of the type and amount of dietary lipid on plasma lipid concentrations in endurance athletes, Lukaskl et al. (46) reported that the plasma response to dietary lipid was not attenuated in men who were physically very active. In contrast, Qulg and associates (47) reported that plasma total cholesterol concentration was lower in subjects who exercised and who ate a diet containing 0.4 or 1.4 gm of cholesterol dally. Thus, the influence of diet on the relationship between exercise and plasma lipids remains equivocal. 

If decreased hemoglobin concentration results in impaired work performance, what effect would an increase in hemoglobin have on exercise This question has been answered by reinfusing packed erythrocytes into endurance athletes, a procedure known as blood doping. 

Glycerol is a three-carbon metabolic intermediate. In the 1990s, human endurance athletes used it to expand their circulating volumes prior to exercise in an attempt to enhance performance. Glycerol typically ingested in water or saline Ih or so prior to exercise at a dose rate of 0.5-1. Og/kg. 

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