PROTEINS PROTEIN

How Does the Body Use Protein? Found in 40% of skeletal muscle, 25% in organs and the remainder in the skin and blood

Structure of Protein

Structural Differences Between Carbohydrates, Lipids, and Proteins Figure 6.1

Best Sources of Protein Figure 6.14

Essential, Nonessential, and Conditional Conditionally essential – cannot be synthesized due to illness or lack of necessary precursors Premature infants lack sufficient enzymes needed to create arginine

Protein Quality Complete proteins Incomplete proteins Contain all nine essential amino acids Usually animal source are complete proteins Are considered higher quality Incomplete proteins Low in one or more essential amino acid Usually plant sources are incomplete

Protein Digestion Figure 6.6

Metabolic Fate of Amino Acids Figure 6.7

How Much Protein Do You Need? Healthy, nonpregnant adults Should consume enough to replace what is used every day The goal is nitrogen balance Pregnant woman, people recovering from surgery or injury, and growing children Should consume enough to build new tissue

Nitrogen Balance and Imbalance Figure 6.12

Eating Too Much Protein

Protein Deficiency http://www.bio.ilstu.edu/armstrong/syllabi/cassava/cassava8.htm

Dietary Recommendations healthy individuals: 0.8 g/kg/day Endurance athletes: 1.2 to1.4g/kg/day 9-10% daily energy Resistance athletes: 1.6 to 1.7g/kg/day 14-15% daily energy Extra protein is needed to repair damaged muscle fibers, decrease the rate of muscle protein breakdown, and synthesis of new protein molecules

Protein Bars Are marketed as convenient and portable Can be A peanut butter sandwich is portable and lower in saturated fat and sugar and higher in fiber than some protein bars

Whey is derived from cow’s milk. As the schematic on the right shows, whole milk is 13% “stuff”. That stuff is ~27% protein The protein is ~20% whey

What is whey anyway? contains little to no fat, lactose or cholesterol high proportion of branched chain amino acids (BCAA) BCAA – amino acids (leucine, isoleucine, valine) are not synthesized and therefore must come from the diet Leucine is an initiator of protein synthesis rapidly absorbed Whey protein is a dairy protein and recent research suggests that calcium and other minerals in dairy may aid in weight loss

Athletes have expensive urine... Food/Supplement Approx. $/kg G Protein/$1.00 Beef, ground 4.38 46 Chicken breasts 7.69 30 Nonfat milk 0.66 48 Eggs 1.58 76 High PRO Bars 20-25 13 (8-17) (10-34) Whey PRO-IEW 40-50 20 (14-24) (18-48) Soy Powders 27 31 (29-33) (38-62) Mean Repl. Powders 21-34 17 (10-24) (12-48)

Protein Needs in Athletes Endurance Athletes: Recommendations, agreed upon by most researchers: 1.2-1.8g/kgBW For 130lbs person (1.5g/kgBW)= 88g For 180lbs person (1.5g/kgBW)= 122g

Branched Chain Amino Acids BCAA levels can increase the availability of carbohydrates and help protect the muscles from exercise-induced protein breakdown. improve protein synthesis both mental and physical performance were improved by an intake of BCAAs during a marathon

Protein Needs in Resistance Training no clarity about how much “extra” protein a strength athlete needs. The goal of the resistance trained athlete is to be in positive protein balance after exercise and promote muscle synthesis The general consensus is that a general increase in dietary protein intake will promote muscle growth

What about those Carbohydrates? The effect of timing... If feeding is delayed by 24hours net protein balance is negative and no muscle hypertrophy occurs. CHO/PRO consumption during exercise...