NUTRITION AND SPORTS. OTHER SUBSTANCES
Creatinine
Creatinine is a compound synthesised in the liver, kidney and pancreas. It is mainly found in fish and diet in the diet.
It accumulates mainly in skeletal muscle as free creatinine or bound to a phosphate molecule, giving rise to creatinine phosphate. The creatinine phosphate molecule is an immediate source of energy for muscle contraction.
The level of creatinine phosphate is regulated by the body, in such a way a creatinine supplement does not change the levels of energy when the muscle is at rest; however, creatinine supplementation can increase the ability of the body to synthesise creatinine phosphate in high requirement situation and stress (at times of sporting practice).
Several studies have demonstrated that the intake of small amounts of creatinine can improve muscle capacity and muscle strength. It also accelerates the recovery when practicing high intensity sports. Nonetheless, other studies have not supported these findings and it appears that the benefit is dependant on the individual.
Creatinine has been employed in sports such as weight lifting, football, body building, disc throw, etc.) The recommended doses vary, but an initial loading dose of 20-30 g/day (divided into four times a day) is suggested for 5 to 7 days, followed by a maintenance dose of 2 g/day. Creatinine should be taken with drinks that are rich in carbohydrates to improve its absorption.
High doses of creatinine, or mid doses over a long period of time, have been associated with abdominal pain, diarrhoea, and increased levels of uric acid.
Antioxidant Vitamins
As a result of exercising, there is increased oxidation and therefore a higher amount of free radicals in the muscle.
Some studies that used vitamin A supplements (10 mg), vitamin E (800 IU) and vitamin C (1000 mg) daily have shown a decrease in oxidative levels and a faster recovery after exercise, maintaining the immune system in optimal condition. However, no improvement in the sporting performance has been demonstrated.