Excercise has pain killing properties: and every1 thought this is due to opioids in our blood. However, new research points out that excercise induces diredtly increased levels of palmitoylethanolamide.
Doctors from the Department of Kinesiology and rehab, University of Wisconsin-Madison tested blood from 58 men, age around 21 year, who excersized quite a bit. PEA increased significantly (p < 0.05) following excersize compared to baseline measurements.
Koltyn KF, Brellenthin AG, Cook DB, Sehgal N, Hillard C. Mechanisms of Exercise-Induced Hypoalgesia. J Pain. 2014 Sep 23. pii: S1526-5900(14)00915-8. doi: 10.1016/j.jpain.2014.09.006.