The Effect of Caffeine and 1976T>C (ADORA2A) Genetic Variants on Anaerobic Performance during a 30‐Second Wingate Test
Authors: Beiler Joshua , Smith Caleb , Caldwell Rachel , Wright Madison , Mayo Anna , Beveridge Abigail , Kieffer H. Scott , Shin Michael 
Published: April 2020

INTRODUCTIONThe supplementation of caffeine is often used to elicit an enhancement of focus, arousal, or performance; however, intra‐individual response to caffeine has been shown to vary the effects of caffeine. Genetic variation of the adenosine receptor, 1976T>C (ADORA2A), has been linked to caffeine sensitivity and is a potential target for understanding individual differences. The TT genotype demonstrates an increased sensitivity to caffeine compared to the TC/CC genotype. The anxiogenic effects, genetic influences, and pharmacological interactions play a role in the ergogenic effects of caffeine.PURPOSETo examine the effects of caffeine and ADORA2A genetic variants on anaerobic performance during a 30s Wingate test.METHODSSixteen trained subjects (age=19.8±0.5 years, weight=70.5±10.3 kg, height=175.8±8.8 cm) volunteered for a randomized, counterbalanced, and double‐blind study. Sixty minutes prior to testing, the subjects ingested a gelatin capsule containing either caffeine (CAF), 5mg·kg−1 bodyweight (BW), or a proportional placebo (PLA) of maltodextrin. The 30‐second Wingate Test (WAnT30) trials were performed on a Velotron cycle ergometer at 0.075 kg·BW−1 resistance and were separated by a minimum of 48 hours. Anaerobic power (AP) (W·kg−1), anaerobic capacity (AC) (W·kg−1), and total power (TP) (W) were determined for each condition. Genotype was determined using a mouth rinse of 0.9% NaCl to obtain buccal epithelial cells, which were lysed using proteinase k. DNA was extracted using QiAmp Mini spin columns. The allelic determination of ADORA2A was identified using TaqMan® SNP Assay (rs5751876) and 40 thermocycles for amplification with a One‐Step qPCR (Life Technologies, Carlsbad, CA). The data was analyzed using a 2 (condition) × 2 (genotype) ANOVA with repeated measures, p < 0.05.RESULTSGenotypic distribution resulted in 6 TT and 10 TC/CC individuals. The main effect of condition, PLA vs CAF, produced no significant ergogenic effect for AP (P=0.52), AC (p=0.67), or TP (p=0.85). The main effect of ADORA2A, TT vs TC/CC, produced no significant difference for AP (p=0.95), AC (p=0.49), or TP (p=0.95). The interaction effect of condition x genotype showed no significant differences for AP (p=0.65), AC (p=0.94), or TP (p=0.95). Although follow up simple effect tests showed no significant differences for AP, individuals with the TT genotype showed a 4.5% (11.2±1.12 to 11.7±1.3), PLA to CAF, improvement compared to the 0.81% (11.4±1.4 to 11.5±1.3) improvement of the TC/CC individuals. Likewise, for TP (W), TT individuals improved by 1.8% (192975±25911 to 196525±21111) while TC/CC individuals increased only 0.94% (194787±48699 to 196635±44092).CONCLUSIONCaffeine did not elicit a significant anaerobic ergogenic effect for the WAnt30. However, the results indicate that individuals with the TT genotype did experience larger percent improvement than their TC/CC counterparts. As such, future research should continue to investigate these inter‐individual differences by increasing sample size and identifying other genes that interact with caffeine.Support or Funding InformationMessiah College