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.