Exercise your brain

Abstract

New light has been shed on the well-known antidepressant effect of exercise by a pilot study reported in the British Journal of Sports Medicine. It was suspected that an endorphin-like substance, phenylethylamine, might be responsible for the well-being associated with as little as four hours of exercise weekly. On non-exercising days, urine samples were tested for phenylacetic acid, a by-product of phenylethylamine turnover. Urine samples were again collected after treadmill exercise in which heart rate had climbed to at least 70% of maximal heart rate capacity, a level thought to be capable of changing mood. Phenylacetic acid levels increased by ∼77% after exercise. However, the rise in levels varied widely across the group tested, with maximal increases seen in those subjects who rated the exercise as difficult. The authors believe that many factors might be involved in the phenylacetic acid response to exercise but, considering that the chemical structure of phenylethylamine is very similar to that of amphetamines, this chemical might be part of a ‘runner's high,’ a phenomenon linked to natural endorphin activity in the brain. S de B