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Background: Caffeine is widely recognized as a potent ergogenic aid commonly used to enhance exercise performance and recovery. However, individual responses to caffeine can vary significantly, a variability that might be explained by genetic differences.Aim: This study aimed to investigate the influence of the CYP1A2 rs762551 SNP on the effects of caffeine (CAF) consumption on growth hormone (GH) and testosterone (TS) levels response to resistance exercise (RE) in male athletes.Materials and Methods: Thirty resistance-trained men (mean age 21.72±4.06 years, weight 77.31±14.07 kg, height 179.31±5.08 cm) participated in a randomized, double-blind, placebo-controlled, crossover study. They consumed either CAF (6 mg/kg) or placebo (PL; 6 mg/kg maltodextrin) one hour before performing a RE protocol including three sets with 85% of 1RM and two-minute rest. CYP1A2 genotyping categorized participants as AA homozygous ("fast" metabolizers) or AC heterozygous ("slow" metabolizers). GH and TS levels were measured by ELISA methods.Results: Repeated measures ANOVA showed significant differences in GH levels across time (F=10.94, P=0.000), with significant time-group (F=4.3, P=0.019) and time-genotype-group interactions (F=3.83, P=0.024). One-way ANOVA indicated significant differences in GH levels between CAF and PL conditions in AA individuals, but not in AC/CC genotypes. For testosterone, significant effects of time (F=14.88, P=0.000) and time-group interaction (F=3.197, P=0.045) were observed. Post-RE CAF supplementation significantly increased serum GH and TS levels in AA individuals compared to PL. Both CAF and PL groups showed increased serum hormone concentrations post-exercise.Conclusion: In conclusion, the study demonstrated that caffeine consumption significantly increased serum levels of growth hormone and testosterone in individuals with the AA genotype of the CYP1A2 rs762551 SNP. These findings suggest that genetic variations play a role in the hormonal response to caffeine, which may have implications for exercise performance and recovery strategies.

There is ample research evidence indicating that task implementation options and design features differentially affect the linguistic quality of second language (L2) oral output. The overarching aim of the current research was to add to the available body of research findings by investigating what effects the combination of two task implementation options, namely pre-task planning and post-task transcription, exerts on L2 learners’ focus on form. The study involved sixty Iranian L2 learners who were presented with a picture story to be narrated under one of the following four conditions: pre-task planning (PTP), post-task transcription (PTT), both pre-task planning and post-task transcription (PTP/PTT), and control. Findings showed that while pre-task planning increased fluency and complexity, the anticipation of post-task transcription enhanced focus on form as indicated by more accurate performance. More importantly, pre-task planning along with the foreknowledge of post-task transcription of performance made for an exponential increase in accuracy, a gain which was achieved to the detriment of complexity. The outcomes are of pedagogical significance in that they lend support to the efficacy of using pre-task planning opportunity along with the anticipation of post-task transcription to elicit the highest accuracy level while learners are primarily concerned with conveying meaning.