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24. 3. 2012.

Protein supplementation

There are different thoughts about protein supplementation at athletes, about how much proteins should be intaked to keep positive nitrogen balance and to maintain high training volume, which means adequate muscle building at athletes.
Some energy balance researches generally point that for the initiation and keep moderate to high power training or  training in endurance disciplines needs relative protein intake above normal(0,8 g/kg TM) and it should approximately be around 1,0-1,6 g/kg per day, depending on intensity and training volume.
It is previously said that athletes which have bigger energy expenditure, enter bigger amount of proteins, so by respecting the principles of balanced nutrition, just as the intake of non-fat meat, fish, dairy products, eggs and plant products needs would be satisfied, and nitrogen balance should be maintained.
Hypotesis that amino-acids supplementation will work anabolically is set long-time ago. It is specially important for power trainings. It is based on clinical studies where intravenous infusion of some amino-acids(arginine, ornitine) stimulates growth hormone releasing(somatotropic-STH), which influences to muscle mass increasing. However, this was related to deficits of this hormone.
Oral intake cannot cause same effects like intravenous administration, cause it has to pass through gastrointestinal tract.
Relative protein needs can be bigger during resistance training beginning stadiums. During initial periods of these trainings, erythrocytes and plasma proteins can be exposed to increased degradation to help anabolism in skeletal muscles, which can lead to anemia. So theoretically in first phase of these trainings bigger way of amino-acids would be needed to renew mioglobins, new erythrocytes synthesis and growth in enzyme quality.
Protein supplementation is very often in sports where there is classification according to body mass, or combination of intensive training and program of body mass reduction(martial arts, wrestiling, body building…).
Results of researches about protein supplementation shown counterindications, so there is no 100% answer about physical performances, metabolic changes and body composition.
It cannot be absolutely said that supplementation of some amino-acids have positive effect to physical and mental performances at the athletes. Theoretic thoughts of metabolism and amino-acids role with branched chain are the base to this supplementation, but experimental data and results of numerous studies still can’t show valid data that can be used. Some experts think that glutamine supplementation is good.
Increased needs can exist at the athletes which are vegetarians or at athletes which cannot from any reason enter sufficient amount of proteins by normal nutrition. Same is related to athletes that use low energy diet in their nutrition. When energy intake is lower than 1500 kcal, protein deficit can be created.
Special situations are in sports where endurance dominates. If trainings or competitions last for more days, many problems can occur. So athlete should use easy digestive proteins, with CHO and fat. These are hydrolizats of milk proteins, whey proteins or kazeins for this purpose.
According to the literature and our personal opinion, it is thought that optimal protein amount is 1,3-1,9g/kg body mass(2g/kg top limit) in sports where power is dominant feature, if athlete wishes to keep nitrogen balance.

“Athletes’ nutrition”, Marina Djordjevic Nikic

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