Effects of endurance exercise on serum concentration of calcitonin gene-related peptide (CGRP): a potential link between exercise intensity and headache.

Background Calcitonin gene-related peptide (CGRP) is a powerful neuropeptide that is strongly involved in headache pain pathogenesis by triggering vasodilation, mast cell degranulation and neurogenic inflammation. This evidence has prompted us to investigate the acute influence of endurance exercise on CGRP concentration in blood. Methods The study population consisted of 48 male amateur runners, who ran a half-marathon distance at 75%-85% of maximal oxygen uptake. Blood was drawn before the run (pre-run) and immediately after each runner ended his trial (post-run). The serum concentration of CGRP was measured with a commercial enzyme-linked immunosorbent assay (ELISA) technique. Results Overall, 22/48 subjects (45.8%) reported suffering from headache, three of whom (6.2%) had an exertional headache, whilst 26/48 (54.2%) subjects did not report at least one headache episode during the previous 6 months (i.e. headache-free). All 48 athletes successfully covered the 21.1 km distance. Serum concentration of CGRP significantly increased by 1.5-fold in the entire group, as well as in the headache-positive and headache-free cohorts. Univariate Spearman's correlation revealed that post-run variation of serum CGRP was significantly and inversely associated with running time (r = -0.30; p = 0.036). Conclusions The serum concentration of CGRP is significantly enhanced by medium-distance endurance exercise and the post-exercise increase is dependent on running intensity. Accordingly, high-exercise intensity might be directly related to triggering both exertional headache and/or migraine episodes.