Apudumalike Mieryazi

Background/Objectives: Whether caffeine provides additional benefit when superimposed on individualized plyometric conditioning remains unclear. We examined whether 3 mg·kg⁻¹ caffeine altered the temporal countermovement jump (CMJ) response following reactive strength index (RSI)-derived individualized drop-jump (DJ) conditioning and explored moderation by habitual caffeine exposure. Methods: Thirty Chinese Han male basketball players (median age, 22.0 years [IQR, 21.0–27.75]) entered a randomized, double-blind, placebo-controlled crossover trial; 17 reported no caffeine exposure and 13 reported exposure during the preceding 4 weeks. After caffeine (CAF; 3 mg·kg⁻¹) or placebo (PLA), a 60-min absorption period, and warm-up, participants performed a post-supplement, pre-conditioning CMJ followed by 3 × 5 DJs. CMJ was assessed at 15 s, 3, 6, 9, and 12 min. The primary outcome was the Condition × Time effect on CMJ. All 30 randomized participants contributed data; three did not complete Period 2 because readiness criteria were not met, but Period 1 data were retained (57 participant-period observations). Results: CMJ varied across time (p < 0.001), but Condition × Time was not significant (p = 0.305). CAF–PLA differences at 15 s, 3, 6, 9, and 12 min were 0.89 cm (95% CI, −0.11 to 1.88), 0.39 (−0.61 to 1.38), 0.21 (−0.79 to 1.21), 0.84 (−0.15 to 1.84), and 0.71 (−0.29 to 1.71), respectively (all Holm-adjusted p ≥ 0.399). Habitual caffeine exposure showed no global moderation continuously (p = 0.158) or categorically (p = 0.116). An isolated 9-min contrast at zero reported exposure favored CAF by 1.83 cm (95% CI, 0.74–2.92; Holm-adjusted p = 0.031) but was exploratory. RPE showed no Condition × Time interaction (p = 0.253); at 15 s, CAF–PLA was −0.60 points (95% CI, −1.09 to −0.12; Holm-adjusted p = 0.088). Conclusions: This study did not obtain clear evidence that 3 mg·kg⁻¹ caffeine provided additional CMJ improvement following this specific RSI-derived individualized DJ protocol. Habitual caffeine exposure did not systematically moderate the temporal response; the isolated signal was exploratory.

Background/Objectives: Previous multi-ethnic genome-wide association studies (GWAS) have identified the GALNT13 rs10196189 polymorphism as a potential genetic marker linked to sprint–power performance. However, its relevance in East Asian populations, particularly the Han Chinese, remains untested. This study aimed to replicate the association of rs10196189 with elite sprint–power athlete status in Han Chinese males and examine its potential influence on physical performance traits and tissue-specific gene regulation. Methods: A total of 188 healthy Han Chinese males (49 elite sprint–power athletes and 139 non-athletic controls) were genotyped using the TaqMan assay. Assessments included strength, sprint, jump, anaerobic power, DXA-derived body composition, and muscle ultrasound. Logistic regression and ROC analyses evaluated the predictive value of rs10196189. Linear regression models adjusted for age and BMI tested genotype–phenotype associations. Tissue expression and functional networks were analyzed using GTEx and HumanBase databases. Results: The G allele frequency was significantly higher in athletes (12.2%) than in controls (5.4%, p = 0.042). Dominant and additive models effectively predicted athlete status (OR = 2.53–2.58, p < 0.05). Although most traits showed no significant associations post-correction, medial gastrocnemius thickness showed a nominal association (β = 0.371, p = 0.011). Functional analyses revealed high GALNT13 expression in brain tissue and co-expression networks enriched in synaptic signaling and glycosylation pathways. Conclusions: This is the first study to validate the association of GALNT13 rs10196189 with elite athletic status in Han Chinese males. Findings provide novel population-specific evidence and propose tissue-specific glycosylation and neural mechanisms as pathways linking this variant to sprint–power phenotypes.