Wednesday, August 19, 2009


What is protein?

Proteins consist of long chains of amino acids and are an essential building block for the effective structure and function of muscle and the rest of your body. They are digested in the gastrointestinal tract into their component amino acids and small peptide fractions. These are subsequently absorbed into your bloodstream and transported to your muscles. Peptides form by digestion of proteins into amino acids with shorter chain length.

There are 20 different amino acids which, when arranged in different orders, form different proteins. In some cases, not all of the amino acids will be present in a nutritionally significant concentration. Of the 20 amino acids, 9 are “essential amino acids” as they cannot be synthesized in your body and so must be consumed as part of your protein intake.

These are:

  • lysine
  • leucine
  • isoleucine
  • threonine
  • tryptophan
  • valine
  • methionine
  • phenylalanine
  • histidine

Some proteins contain only small quantities of these essential amino acids, quantities that are insufficient for maintaining your effective body function.

Bovine milk, and whey proteins in particular, are the richest source of the naturally occurring essential amino acids required for your body. But not all whey proteins are the same: their detailed composition and biological functionality is dependant on both the quality of the milk and the manufacturing, processing and storage conditions.

Why do athletes need protein?

  • Protein provides the building blocks for muscle growth.
    • Resistance training stimulates protein synthesis.
    • Type, amount and timing of protein intake is important.
    • Dietary protein surplus to that required for muscle function may become a source of energy.
  • Protein provides the amino acids to repair muscle damage caused by exercise.
    • Muscle damage involves micro tears and results in inflammation which is a normal part of your exercise regime.
    • Micro tears, if repaired properly, enhance muscle adaptation, growth/strength and reduce soreness/inflammation.
    • The appropriate protein/peptides need to be available to supply the amino acids that are critical for effective repair and recovery of your muscles.
  • Protein provides a source of energy.
    • With high intensity exercise, and/or prolonged endurance activity, once carbohydrate (glycogen) is depleted as a source of energy, protein use increases.
    • Protein makes a small contribution to total energy requirement of exercise.
    • Protein provides up to 5-10% of energy.

How much protein do you need?

The recommended protein intake for any individual varies depending on a number of factors, including the type of activity and the age and gender of the person in question.

Table of protein requirements for men and women depending on activity

Notes on the above table:

  • The amount and type of protein will vary according to the type of exercise and your individual goals.
  • Figures in the table should be used as a guide only. Current research has not yet defined absolute protein requirements.

When do you take protein?

The timing of protein consumption is critical to the rate of repair, which is highest in the first 1-2 hours post-exercise. Muscle repair generally continues for 24-36 hours, and after severe fatigue may continue for up to 5 days. Therefore, maintaining an appropriate protein source during these times is vital to effective repair and recovery.

Some research also indicates that consuming proteins and/or amino acids in combination with carbohydrates before and after exercise may minimise muscle damage and further enhance muscle repair.

(Baty et al, 2007; Tipton et al, 2001; Wolfe, 2001; Rasmussen et al, 2000)


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