Sports and Protein Metabolism Dept. Exercise Health Science National Taiwan College Physical Education

Proteins Proteins are one of many types of natural polymers, and they are the most versatile Make up about 20% or 200g/kg of muscle tissue

Functions Functions As Enzymes As Carriers and Receptors As Regulators of Water Balance As Biological Buffers As Structural Elements and Structural Units As Lubricants In the Immune System As Signaling Molecules

Structures

Overview of protein metabolism

Protein Turnover whether the body is in a state of anabolism (building up) or catabolism (breaking down), also known as positive or negative Nitrogen Balance Is governed by hormonal factors, caloric intake and availability of amino acids, particularly of the nine ‘essential’ amino acids

Amino Acid Metabolism in Muscle During Exercise Amino acid can be broken down to produce energy follows a unique catabolic pathway Have to remove alpha-amino group (deamination) to form ammonia

Effect of Exercise on Protein Metabolism Exercise changes the rates of protein synthesis and the proteolysis in muscle During hard resistance exercise, the rat of protein synthesis will increase, provide a.a. in contracting muscle Moderate-intensity endurance exercise seem to increase the rate of proteolysis, and net decrease in muscle protein Can reversed some hours after exercise

Prolonged running decreased the rate of collagen synthesis and increase its rate of breakdown in the Achilles tendon but synthesis rate higher the baseline, makes connective more resistant to mechanical stress of exercise

Plasma Amino Acid, Ammonis and Urea Concentrations During Exercise Total a.a. concent. In plasma is 3 to 4 mmol/L Most abundant plasma a.a.; Glutamine and Alanine Not big affect the total a.a. exercise < 1 hr Exercise > 2 hrs, plasma a.a. drops 30%

Moderate-intensity or hard exercise rises plasma ammonia which relates to plasma lactate concentration. Plasma urea concentration. Increases by exercise at 60% of VO 2max Not change during hard exercise as blood flow to liver decrease; not enough blood to carry urea out of hepatocytes

Effects of Training on Protein Metabolism Muscle hypertrophy by Resistance training Cross-section area increase and maximal strength increase Can be measured few weeks after and proceeds at a rate of 1% to 3 % Muscle hypertrophy reach a plateau after 6 months of hard resistance training

Endurance training usually not accompanied by muscle hypertrophy unless it use high intensity Endurance training increases in mitochondrial proteins, leading to an increase in mitochondrial number and size.

Protein supplementation Improves exercise performance Maintains strength during workouts Increases muscle protein synthesis Develops and maintains bone strength Assists in muscle cell repair after exercise Reduces inflammation, soreness and fatigue Reduces length of recovery between training Provides immune support following exercise

The Recommended Dietary Allowance (RDA) for the average male and female adult is just 0.83 grams of protein per kilogram (2.2lbs) of bodyweight. In a 70kg (154lb) individual this equates to just 58 grams of protein per day or about two chicken breasts worth

Competitive athletes, particularly those involved in heavy weight training, may require more protein. The recommendation for strength and endurance athletes ranges from 1.2 to a maximum of 2.0 grams per kilogram (1kg = 2.2lbs). Research has shown that consuming more protein than this serves no benefit and may be harmful in the long term.

Protein should make up 10-15% of an athlete's diet derived from fish, poultry, low fat milk and lean red meat for example.

Discussion From your point of view, which one amino acid is of imperative important in young weight lifter. Can you plan a dietary project regarding protein requirement to a distance-runner. What is your protein consumption per day and why. (hint: RDA)