Phenylethylamine, a possible link to the antidepressant effects of exercise?

Objectives-To determine in this pilot study whether aerobic exercise affects phenylacetic acid concentration in the urine. Methods-Twenty healthy men provided 24 hour urine samples on two consecutive days for the determination of phenylacetic acid levels. Before and during day 1, subjects refrained from physical activity; on day 2 subjects ran on a treadmill at 70% of their maximal heart rate reserve (MHRR) for 30 minutes. Results-The 24 hour mean urinary concentration of phenylacetic acid was increased by 77% after exercise. Conclusion-As phenylacetic acid concentration in urine reflects phenylethylamine level, which is known to have antidepressant effects, phenylethylamine may be linked to the therapeutic effects of physical exercise on depression.