Muscle performance, carbohydrate

This requirement, however, conflicted with that of achieving a maximum exercise performance, fortoperform many hours of work each day, the diet should have been high in carbohydrate. This is because manhauling, despite being of fairly low intensity in exercise physiological terms, would still lead to marked muscle glycogen depletion in 10 to 12 hours of exertion daily. 

Thus, it is evident that the mobilization and provision of lipid to muscle during exercise, like during starvation, restricts the usage of carbohydrate. If this did not occur during exercise, glycogen stores within muscle (as well as in the liver) would be depleted more rapidly than normal and may significantly limit the duration of exercise. Hypoglycemia could also result and limit performance. 

One can usually predict from these various characteristics whether or not a particular muscle would be more involved in endurance versus sprint activity as well as the fuel or fuel mixture used. For example, as discussed in the preceding chapter by Terjung type I and IIA fibers are more involved with endurance performance relying on a fuel mixture of both lipids and carbohydrate. On the other nand, type IIB fibers are more involved with short sprint-type of activity with a fuel dependence almost exclusively on carbohydrate. The fiber composition of muscle from a few animals and man is shown in Table 111. Animals raised for quick "stop and go" activity... 

The ability to perform even the simplest of muscle movement requires complex coordination of the physical and chemical activities of the tissue. In recent years, nutritionists and exercise physiologists have described how the primary energy sources in food carbohydrates, fats, and proteins are transformed into the universal "currency" of biological energy, ATP. Oxidative metabolism processes the substrates through a cascade of enzymatic events to Insure maximal efficiency in energy conversion. At every level of this conversion, one or more metal ions serve as a cofactor to facilitate these biochemical reactions. The requirement of metals in the production of... 

According to the reaction scheme given in Fig. 26, the anaerobic oxidation of l-glycerol 3-phosphate was performed under the conditions of an indirect electrochemical process using a water-soluble ferrocene derivative as mediator in the presence of o-fruc-tose-1,6-diphosphate aldolase from rabbit muscle for the in situ generation of the carbohydrate product. With a mediator concentration fo 1.5 mM using about 80 U of immobilized enzyme, after 25 h a 75% turnover of the substrate L-glycerol phosphate... 

Concentrated feed is formulated ivith the specific needs of each animal group and the requirements of the particular industry in mind, whereby growth (fat and/or muscle development), endurance, subsistence, and special performances (e.g., high rate of egg production) are encouraged and supported. Since, in comparison to the basic nutritional feed components carbohydrates, proteins, fats, amides, fibers, and water, the relative gravimetric and volumetric amounts of additives, such as minerals and vitamins, are very small, uniform distribution in the bulk feed became a challenge (Section 6.2.1) and segregation a problem. It was also found that certain animals did... 

Potassium appears to perform many of the same functions inside the cell that sodium performs in the plasma and interstitial fluid. Potassium, in various ways 1) regulates the maintenance of the osmotic equilibrium of body fluids 2) acts as an available base to neutralize acids 3) maintains an ionic balance between potassium, sodium, calcium, and magnesium, which in turn affects capillary and cell functions and the excitability of nerves and muscles 4) maintains correct water balance in the body and 5) acts as a cofactor in several enzyme systems, including those used for energy transfer and utilization, protein synthesis, and carbohydrate metabolism (Oberleas et al. 

In the case of athletes, however, little evidence suggests that a low-carbohydrate diet is effective for athletic performance, because of the extended time needed to replenish muscle and liver glycogen when the athlete is not on a high-carbohydrate diet. 

EXAMPLE 13.28 To prevent muscles from wastefully using carbohydrate during the first few minutes of exercise, it may be beneficial to raise plasma fatty acid levels even before the race begins. Fatty acid release from adipose tissue can be stimulated by caffeine although competitively one would have to be wary of this strategy because, above certain levels, caffeine is considered to be an illegal performance enhancer. Caffeine may also have undesirable diuretic effects. 

Even during longer sprint events, such as 400 m, the race is completed before muscle glycogen stores have become depleted by -50%. If multiple races are to be run, adequate glycogen resynthesis between each event is important, so the consumption of rapidly digested carbohydrate has been shown to be useful for the best performances. 

He worked on the sources of energy for muscular contraction, a continuation of his first interest in muscle creatine. Phosphagen had been recently discovered. Einar Lundsgaard had just shown that muscle poisoned with iodoacetic acid was able to perform a certain amount of work without liberation of lactic acid. Using muscles with low carbohydrate content, Ochoa was able to demonstrate the muscle s ability to perform work using sources of energy different from those then known. It was an important piece of work on a topic of great interest at the time. 

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