The results showed that after exercise, cannabinoid receptors were activated on immune cells in the spinal cord, which had a numbing effect on exercise-related pain. It also increased the concentration of anandamide in the spine as well as caused immune cells to produce more CB2 receptors. Although previous research had already suggested anandamide’s role in runner’s high, this was the first study to implicate the immunoregulatory effect of CB2 receptors. In addition, researchers also found that anandamide’s lack of CB2 binding affinity suggested that exercise induced endocannabinoid activity at several levels.