Responses to specific needs
Recovery
After exercise all aerobic sports (those that use oxygen) necessitate food intake to compensate for losses and to replace the body's glycogen reserves.
The replacement of glycogen reserves is most effective immediately after the end of exercise; resynthesis of glycogen is closely dependent on the types of drinks and foods consumed.
Poor recovery can be the cause of chronic fatigue and muscular damage or lesions. So the recovery phase is vital !
Key points for a good recovery :
- glucose and high GI carbohydrates, combined with proteins if possible, to resynthesise muscle and liver glycogen reserves,
- proteins to ensure repair of muscular micro-lesions arising during exercise,
- electrolytes to compensate for losses through perspiration and to avoid cramps,
- vitamins to restore losses caused through exercise
In practice a carbohydrate-peptide drink is very beneficial after finishing exercise (150 to 300 ml every 15 minutes). You should always drink pure water as required after carbohydrate drinks.
Note :
certain constituents of proteins, the branched amino acids (leucine, isoleucine and valine) are appropriate to use in recovery.
certain constituents of proteins, the branched amino acids (leucine, isoleucine and valine) are appropriate to use in recovery.
Long lasting exercise
As stated previously (cf. p 11), long lasting exercise requires good hydration and specific intake of carbohydrates (high GI carbohydrates + low GI carbohydrates) and sodium.Vitamins and minerals
Minerals such as iron, zinc and chromium are associated with energy production mechanisms. Iron, for example, plays an important role in transporting oxygen from the lungs to the tissues. The first symptom of anaemia (iron deficiency) is general tiredness, with a drop or plateau in performance.Intense training of a sport can result in sportsmen and women having an unbalanced diet (by favouring certain food groups more than others) and thus having a mineral deficiency.
It is also important to meet requirements for the vitamins thiamin (B1), riboflavin (B2), B6 and niacin adequately, as these are needed to enable the cells to use carbohydrates properly.
The sportsmen and women most at risk of vitamin and/or mineral deficiencies are :
- those bound by restricted diets (< 1500 kcal/day) associated with intense training: dancers, gymnasts, stable boys/jockeys,
- those worried about staying thin,
- those subject to weight categories: combat sports (boxing, Graeco-Roman wrestling, judo), etc
Production of free radicals
Physical exercise in the presence of oxygen leads to the production of free radicals, which can then lead to muscular lesions and the development of sources of inflammation; intake of anti-oxidants enables these free radicals to be trapped. The main anti-oxidants are vitamins C and E, zinc and selenium.Cramps
An excess of hydrogen ions is observed during exercise (they reduce the pH of muscle fibres, in other words they become "acid") along with significant changes in the balance between sodium and potassium (which is generally the cause of cramps). These changes must be prevented so that the right balance of cellular and extracellular ions is maintained.This ionic balance depends on :
- the diet,
- the level of activity: anaerobic exercise (without oxygen) produces lactic acid and therefore hydrogen ions
Cramps can also be caused for different reasons. They can arise separately from exercise, in the hours or days following training, because they can be due to poor warming up and/or insufficient active recovery (stretches), and poor hydration.
Note : cramps at night can be linked to a magnesium or potassium deficiency.