Adenosine A2A receptor gene polymorphisms (ADORA2A) are associated with maximal concentric contraction pain

Abstract Objectives To test associations of adenosine A 2A receptor gene ( ADORA2A ) polymorphisms with maximal concentric contraction pain, caffeine-induced perceptual changes, and responses to mild eccentric injury. Design Targeted candidate gene association study. Methods ADORA2A (rs5751876) was genotyped in 26 adults. Pain of a maximal elbow flexor contraction was assessed. Participants performed 18 eccentric actions of the elbow flexors. Arm volume was measured before and 24- and 48-h post-injury. At 24- and 48-h post-injury, caffeine or placebo capsules were given using a randomized cross-over design and effort and pain were assessed. Results Maximal concentric contraction pain was higher for the CC compared to the CT/TT group (effect size d = 0.89) and lower for the TT compared to the CT/CC group (d = 0.62). There were moderate sized differences between CC and TT/CT groups for post-injury exertion and arm-volume 24-h post injury. Conclusions ADORA2A polymorphisms are moderately associated with muscle pain during maximal contractions in uninjured muscle.