The effect of CYP1A2 genotype on the ergogenic properties of caffeine during resistance exercise: a randomized, double-blind, placebo-controlled, crossover study.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
caffeine supplementation | increase | resistance exercise performance | resistance-trained men who were homozygous for the A allele | - | significantly enhanced | #1 |
caffeine supplementation | no change | resistance exercise performance | resistance-trained men who were C allele carriers | - | no effect | #2 |
caffeine supplementation | neutral | repetitions performed in sets 1, 2, and 3 of bench press | resistance-trained men | - | differences between AAs and AC/CCs | #3 |
caffeine supplementation | neutral | repetitions performed in sets 1, 2, and 3 of leg press | resistance-trained men | - | differences between AAs and AC/CCs | #4 |
caffeine supplementation | neutral | repetitions performed in sets 1, 2, and 3 of shoulder press | resistance-trained men | - | differences between AAs and AC/CCs | #5 |
caffeine supplementation | neutral | total repetitions performed in bench press | resistance-trained men | - | differences between AAs and AC/CCs | #6 |
caffeine supplementation | neutral | total repetitions performed in leg press | resistance-trained men | - | differences between AAs and AC/CCs | #7 |
caffeine supplementation | neutral | total repetitions performed in shoulder press | resistance-trained men | - | differences between AAs and AC/CCs | #8 |
caffeine supplementation | neutral | total volume load in bench press | resistance-trained men | - | differences between AAs and AC/CCs | #9 |
caffeine supplementation | neutral | total volume load in leg press | resistance-trained men | - | differences between AAs and AC/CCs | #10 |
caffeine supplementation | neutral | total volume load in shoulder press | resistance-trained men | - | differences between AAs and AC/CCs | #11 |
AIM: The purpose of this study was to examine the effect of CYP1A2 -163C>A polymorphism on the ergogenic effects of caffeine supplementation during a resistance exercise (RE) session. METHODS: In a randomized, double-blind, placebo (PL)-controlled, crossover study, 30 resistance-trained men took part in two RE sessions (three sets to failure at 85% of one repetition maximum, 2-min rest between sets), including bench press (BP), leg press (LP), seated cable row, and shoulder press (SP) following caffeine (CAF) (6 mg kg RESULTS: The two-way ANOVA with repeated measures revealed differences between AAs and AC/CCs under CAF conditions for repetitions performed in sets 1, 2, and 3 of BP (F CONCLUSION: In conclusion, acute ingestion of CAF significantly enhanced RE performance in resistance-trained men who were homozygous for the A allele, but not for C allele carriers. Further studies are needed to replicate the potential role of the CYP1A2 -163C>A polymorphism on the ergogenic effects of CAF in other modes of exercise and in other populations.