_9-11Protein 2010

_9-11Protein 2010 - PROTEIN AND ATHLETES Not a major energy...

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Unformatted text preview: PROTEIN AND ATHLETES Not a major energy source but other important roles Bruce is a bodybuilder and makes a big effort to eat lots of protein as other guys in the gym say this is critical to gain muscle His diet record says he eats ~2 g/kg via food and an additional 1 g/kg as supplement so total of 3 g/kg/d. What do we tell him about this? My son a few years ago…wants to “get big” Mom- can I get steroids? Can I use creatine? Can I use creatine? Alan is an endurance cyclist and is interested in whether he is on target on protein in his diet (at 1.5 g/kg) Does he need to eat more each day? Should he consume one of the protein- containing sports drinks during cycling? Should he consume protein after a workout or event? In order to answer his questions, we need to understand basics of protein metabolism and requirements Is there evidence that protein needs are different in athletes compared to sedentary? Proteins are made up of linked amino acids Absorb as individual to three amino acids in length but cannot digest full proteins Basic Structure of an Amino Acid No, I’m not going to ask you to draw any amino acid on test… Amino acids ¡ Each type (e.g. neutral, basic, anionic) has different transporter; can move against concentration gradient ¡ Some are essential (~9) and others can be synthesized from other compounds synthesized from other compounds ¡ Required, obviously, for synthesis of enzymes and structural proteins but also: – TCA cycle intermediates – Synthesis of neurotransmitters (e.g. serotonin) or hormones (insulin, epinephrine) – Antioxidants (glutathione from cysteine) – Creatine from arginine, glycine METABOLISM Proteins/other a.a. ¡ Can be converted to Energy Carbohydrate/fat Nitrogen Intake, Turnover, and Excretion Deamination of an Amino Acid When proteins broken down we must get rid of nitrogen Nitrogen is converted to urea in liver for excretion in urine Protein turnover ¡ Proteins all turnover but differ in rate – Enzymes & hormones rapid – Structural slower ¡ This translates to rapid or slower adaptation response – Tells us how quickly you’d get synthesis and gain but also how fast you’d lose it if stopped training Each day ~1-2% of total body protein is broken down and must be resynthesized ~80% of the amino acids from protein breakdown are recycled to synthesize proteins but rest need to come from diet Skeletal Muscle Protein Turnover Figure 5.4 Amino Acid Metabolism Unique depending on amino acid Amino Acid Catabolism ¡ Most are catabolized in liver; exception BCAA (leucine, isoleucine, valine) in muscle – This is of importance to later discussion of exercise Protein Quality ¡ Proper amounts and types of amino acids ¡ Animal and plant proteins differ – Animal proteins are termed complete – Animal proteins are termed complete » Proper amounts and types of all the indispensable amino acids – Plant proteins are termed incomplete » Missing one or more of the indispensable amino acids » Complementary proteins...
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This note was uploaded on 03/23/2010 for the course HNFE 4174 taught by Professor Rankin during the Spring '10 term at Virginia Tech.

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_9-11Protein 2010 - PROTEIN AND ATHLETES Not a major energy...

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