Protein in bodybuilding: Protein metabolism (II)

Proteins are important molecules comprised of amino acids — compounds containing an amino group (–NH 2), a carboxylic acid group (–COOH), and a radical group (different for each of the amino acids). Structural proteins include cytoskeletal proteins such as dystrophin, vimentin, and desmin, and connective tissue proteins such as collagen; regulatory proteins include enzymes such as lactate dehydrogenase, citrate synthase, or cytochrome c oxidase. There are 20 amino acids that are found as constituents of proteins or present as free amino acids.

Nine amino acids are onsidered essential or indispensable (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine), and arginine is sometimes considered to be conditionally essential. The essential amino acids must come from the diet or from endogenous protein breakdown. Since proteins serve such critical roles in the survival of the organism, it is not surprising that their metabolism is complex, tightly regulated, and in a constant state of flux with simultaneous synthesis and degradation.

Protein in bodybuilding: Quantity and Quality (1)

The quantity of protein intake for athletic populations has been a matter of controversy for several years. Interest in protein intake can even be traced to ancient Greece, where records from the Olympics indicated that athletes consumed huge amounts of meat to try to maximize strength performance. By the 18th century, muscle contraction was believed to be fueled by the oxidation of muscle protein.

As the importance of lipid and carbohydrate (CHO) oxidation in muscle metabolism became clear, a central role for protein oxidation in the supply of energy during muscle contraction waned. In contrast, the quality of protein intake for athletic populations has received much less scientific attention. Only recently have researchers attempted
to distinguish the potential benefits of varying compositions of amino acids and protein type (e.g., whey vs. casein). The question as to whether physical activity of any type alters the dietary requirement for protein remains open for debate.

The pathways of protein metabolism in skeletal muscle with emphasis on the effects of exercise on metabolic and anabolic regulation will be reviewed, including the factors that modify these responses. We will then reviewstudies that have attempted to determine whether athletes require dietary protein intakes higher than those for sedentary individuals and whether protein quality influences metabolic and anabolic regulation. Throughout the chapter, exercise will be broadly classified as either endurance or resistance to highlight the two major classifications of exercise at opposite ends of the metabolic demand spectrum.Endurance activities can be broadly defined as those that utilize predominantly
oxidative phosphorylation as the primary energy source; resistance activities lead to increases in strength, power, and muscle mass as outcomes.

Creatine usage

There are two effective and most popular ways to use creatine. The first - rendering. Rendering takes 4-5 days and used 20 to 30 grams per day. After rendering the transition phase to the maintenance phase, during which the dose of 5-15 grams per day in order to ensure a lean startup. Alternatively, a more progressive, spent the rendering phase and immediately used after 5 to 15 grams per day. Muscle creatine is achieved through the completion of 25 to 35 days of dosing and continued no use in the results, so it is recommended to take a break.

It was found that stimulation of insulin secretion with creatine use common carbohydrates (glucose, dextrose) enhances the absorption of creatine and related sports performance. It is therefore recommended to take creatine with high glycemic-index carbohydrates.
Among other things Steenge and colleagues (2000) found that creatine uptake was the same with him and with 50 g protein, 47 g carbohydrates, and only with 96 g of carbohydrates potreniruotiniu drink. So it is safe to use creatine, protein - carbohydrate cocktails.