We investigated the association of multiple single nucleotide polymorphisms (SNPs) with athlete status and power/speed performance in elite male youth soccer players (ESP) and control participants (CON) at different stages of maturity. ESP (n = 535; aged 8-23 years) and CON (n = 151; aged 9-26 years) were genotyped for 10 SNPs and grouped according to years from predicted peak-height-velocity (PHV), i.e. pre-or post-PHV, to determine maturity status. Participants performed bilateral vertical countermovement jumps, bilateral horizontal-forward countermovement jumps, 20m sprints and modified 505-agility tests. Compared to CON, pre-PHV ESP demonstrated a higher ACTN3 (rs1815739) XX ('endurance') genotype frequency distribution, while post-PHV ESP revealed a higher frequency distribution of the PPARA (rs4253778) C-allele, AGT (rs699) GG genotype and NOS3 (rs2070744) T-allele ('power' genotypes/alleles). BDNF (rs6265) CC, COL5A1 (rs12722) CC and NOS3 TT homozygotes sprinted quicker than A-allele carriers, CT heterozygotes and CC homozygotes, respectively. COL2A1 (rs2070739) CC and AMPD1 (rs17602729) GG homozygotes sprinted faster than their respective minor allele carrier counterparts in CON and pre-PHV ESP, respectively. BDNF CC homozygotes jumped further than T-allele carriers, while ESP COL5A1 CC homozygotes jumped higher than TT homozygotes. To conclude, we have shown for the first time that pre-and post-PHV ESP have distinct genetic profiles, with pre-PHV ESP more suited for endurance, and post-PHV ESP for power and speed (the latter phenotypes being crucial attributes for post-PHV ESP). We have also demonstrated that power, acceleration and sprint performance were associated with five SNPs, both individually and in combination, possibly by influencing muscle size and neuromuscular activation.

We used a within‐subject, cross‐over design study to compare the impact of 4‐weeks' resistance (RT) versus endurance (END) training on vascular function. We subsequently explored the association of intra‐individual effects of RT versus END on vascular function with a single nucleotide polymorphism (SNP) of the NOS3 gene. Thirty‐five healthy males (21 ± 2 years old) were genotyped for the NOS3 rs2070744 SNP and completed both training modalities. Participants completed 12 sessions over a 4‐week period, either RT (leg‐extension) or END (cycling) training in a randomized, balanced cross‐over design with a 3‐week washout period. Participants performed peak oxygen uptake (peak VO2) and leg‐extension single‐repetition maximum (1‐RM) testing, and vascular function assessment using flow‐mediated dilation (FMD) on 3 separated days pre/post‐training. Peak VO2 increased after END (p < 0.001), while 1‐RM increased after RT (p < 0.001). FMD improved after 4‐weeks’ training (time effect: p = 0.006), with no difference between exercise modalities (interaction effect: p = 0.92). No relation was found between individual changes (delta, pre‐post) in FMD to both types of training (R2 = 0.06, p = 0.14). Intra‐individual changes in FMD following END and RT were associated with the NOS3 SNP, with TT homozygotes significantly favoring only END (p = 0.016) and TC/CC tending to favor RT only (p = 0.056). Although both training modes improved vascular function, significant intra‐individual variation in the adaptation of FMD was found. The association with NOS3 genotype suggests a genetic predisposition to FMD adapting to a specific mode of chronic exercise. This study therefore provides novel evidence for personalized exercise training to optimize vascular health.