Supplements that boost the brain's dopamine concentration are of interest to endurance athletes. At least, they are if the athletes have to perform in warm weather, sports scientists at Aberystwyth University in Wales discovered.
The Brits published the results of an experiment they did with eight athletic males, in the European Journal of Applied Physiology. The subjects had to cycle to the point of exhaustion on two occasions. On one occasion the men were given a placebo, on the other tyrosine.
Previous studies had shown tyrosine supplementation to have no effect on endurance performance. [J Appl Physiol. 2002 Nov; 93(5): 1590-7.] But it may be that tyrosine does work. The amino acid first converts into L-Dopa in the body, and this is then converted into the pep-hormones adrenalin and noradrenalin.
These researchers approached the matter from a different angle, though. They suggested that tyrosine might have an effect at a high temperature. At high temperatures athletes tire more quickly. In the brain tyrosine is converted – also via L-Dopa – into dopamine. Dopamine is a neurotransmitter that motivates people to continue and suppresses feelings of fatigue.
The researchers gave their test subjects water containing no active ingredients, or water containing 150 mg tyrosine per kg bodyweight from myprotein.com/uk. [myprotein.com/uk] So if you weigh 80 kg you'd need 12 g. An hour later the subjects had to cycle for as long as they could at a temperature of 30 degrees.
After taking tyrosine the men cycled for 16 percent longer: 80 min instead of 69 min.
During the exertion tests the men felt less tired and were less troubled by the heat. The researchers found no effects of the supplementation on heart rate or body temperature.
Not everyone reacts well to tyrosine supplementation. If you are thinking of experimenting with tyrosine it's a good idea to try out lower doses of 1-2 g first. Also, supplements containing L-Dopa, such as Maca or Mucuna pruriens may be more effective.
Eur J Appl Physiol. 2011 Dec;111(12):2941-50.