Research suggests that exercise is an effective antidepressant, but exactly how it works has not been clear. Now it appears that the antidepressant effects may be due to a chemical called phenylethylamine.This is reported in a pilot study in the British Journal of Sports Medicine.
The study focused on 20 healthy young men, average age 22. The men did around four hours of moderate to hard exercise of the aerobic and anaerobic variety every week.
The study required that they stop exercise completely for a day, during which their urine samples were measured for phenylacetic acid, a by-product of phenylethylamine turnover, and a more accurate measure of the chemical.
The following day, the men exercised on a treadmill at 70 per cent of their maximal heart rate capacity, a level thought to be capable of changing mood. They were also asked to rate how hard they felt the exercise had been, and once again a urine sample was taken.
The results showed that, overall, phenylacetic acid increased by 77 per cent after exercise. But the amount it rose varied considerably among the group. It was between 14 and 572 per cent higher than it had been the day before in 18 of the 20 men. Three men rated the exercise as hard, and the highest rises were seen in two of them.
There may be many factors involved in the phenylacetic acid response to exercise, say the authors, but considering that its chemical structure is very similar to that of amphetamines, it may be that this chemical is part of a “runner’s high,” a phenomenon linked to natural endorphin activity in the brain.
(Reference: Phenylethylamine, a possible link to the antidepressant effects of exercise? British Journal of Sports Medicine 2001; 35: 342-3)
28-Sep-2001
