Endorphins came first, those home-grown opioids or pain-killers called runners high. Then came the endocabbinoids, the pleasure-inducing molecules released during hard exercise that turn exercise nuts into gym rats. Now, decades after scientists first speculated on the effects of physical activity on the brain, Swedish researchers have discovered a new reason for lacing up those sneakers:
Exercise not only feels good, it protects the brain from depression.
In mouse studies at the Karolinska Institutet, neuroscientists showed that changes in skeletal muscles, incurred through exercise helped rid the body of a stress-induced amino acid called kynurenine that has been associated with mental illness.