Proteins

During the process of digestion, the proteins in our food are broken down into their constituent amino acids that are in turn absorbed by the blood capillaries and transported to the liver. The amino acids are then synthesized into proteins or stored as fat or glycogen for energy. Each gram of protein produces approximately 4 Calories. Many proteins function as enzymes and others:

• Form the structural framework of various parts of the body - Keratin in skin and hair
• Function as hormones - Insulin
• Serve as antibodies
• Transport vital substances throughout the body - hemoglobin
• Serve as contractile elements in muscle tissues - actin & myosin

Amino Acids

Amino acids are the building blocks of protein. The formation of protein can result in dehydration because water molecules are lost as amino acids combine to form more complex molecules.

The body requires 20 different amino acids of which 8 are referred to as essential amino acids which cannot be synthesized by the human body. Animals and plants manufacture proteins that contain these essential amino acids. Non-essential amino acids can be synthesized by body but this does not mean they are unimportant, they are, it is just that the body is capable of producing sufficient to meet the demands for growth and tissue repair. It is therefore important that our diet contain appropriate levels of protein.

The essential Amino Acids are lsoleucine, Leucine, Lysine, Methionine, Phenylaianine, Threonine, Tryptophan and Valine.

The non-essential Amino Acids are: Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Clutamic acid, Clutamine, Glycine, Histidine*, Proline, Serine and Tyrosine.

* Histidine is essential for babies but not for adults.

Recommended Protein Intake

Despite the beliefs of many coaches and athletes, eating excessive protein provides little benefit. Muscle mass does not increase simply by eating high protein foods. Protein intake significantly above the recommended values can prove harmful because excessive protein breakdown strains the liver and kidney functions through the production and elimination of urea and other solutes.

The recommended daily allowance for men and women:

• Adolescent - 0.9 grm of protein per kg body weight
• Adult - 0.8 grm of protein per kg body weight

Training and Protein Needs

Research suggests that protein breakdown increases during and immediately after exercise, and that protein manufacture slows down at the same time. The more intense the exercise, the greater your protein breakdown will be, and the greater your needs will become. If you train to increase muscle mass, your protein needs will be greater still. Extra protein will be needed not only to compensate for protein breakdown but also for new protein to be made and for muscle growth. It is important to realise that a high-protein diet alone will not lead to any increase in strength or muscle size. It is only when it is combined with heavy resistance exercise that additional protein can cause this to happen.

Source of Protein

Proteins that contain all the essential amino acids in approximately the right proportions for your body's requirements are sometimes called 'high-biological-value' proteins. These are found in foods that are derived from animals: meat, fish, eggs, milk and dairy products

Associated Pages

The following Sports Coach pages should be read in conjunction with this page:

• Articles on Physiology
• Blood Pressure
• Body Fat
• Body Type
• Energy Pathways
• Ideal Weight
• Lactic Acid
• Maximum Heart Rate
• Movement Analysis
• Muscle Types
• Protein
• Range of Movement
• Vitamins
• VO2 max

• Training Books
• Training Products

Associated Books

The following books provide more information related to this topic:

• Principles of Anatomy and Physiology, G.J. Tortora et al., ISBN 0 06 046704 5
• Strength Training Anatomy, F. Delavier, ISBN 0 7360 4185 0
• Atlas of Skeletal Muscles, R.J. Stone et al., ISBN 0 697 13790 2
• The Muscle Book, P. Blakey, ISBN 1 873017 00 6
• Advanced Studies in Physical Education and Sport, P Beashel et al., ISBN 0 17 4482345
• Physical Education and the Study of Sport, B. Davis et al., ISBN 0 7234 31752
• Essentials of Exercise Physiology, W.D. McArdle et al., ISBN 0 683 30507 7
• Physical Education and Sport Studies, D. Roscoe et al., ISBN 1 901424 20 0
• The World of Sport Examined, P. Beashel et al., ISBN 0 17 438719 9
• Advanced PE for Edexcel, F. Galligan et al., ISBN 0 435 50643 9
• Examining Physical Education, K. Bizley, ISBN 0 435 50660 9
• Sport and PE, K Wesson et al., ISBN 0 340 683821
• PE for you, J. Honeybourne, ISBN 0 7487 3277 2