Abstract
PURPOSE: We used a within-subject, cross-over study to determine the relationship between the intra-individual adaptations to four weeks' resistance (RT) versus four weeks' endurance (END) training, and we investigated whether three single nucleotide polymorphisms (SNPs) were associated with these adaptations. METHODS: Thirty untrained, healthy, young men completed a cycling test to exhaustion to determine peak oxygen uptake (V̇O(2peak)), and a knee extension (KE) maximum voluntary isometric contraction (MVIC) of the right leg before and after four weeks' supervised RT (four sets of 10 repetitions at 80% single repetition maximum unilateral KE exercise, three times weekly) and four weeks' supervised END (30 min combined continuous/interval cycling, three times weekly), separated by a three-week washout phase. Participants were genotyped for the ACTN3 rs1815739, NOS3 rs2070744 and VEGFA rs2010963 SNPs. RESULTS: The intra-individual adaptations regarding percentage changes in MVIC force and V̇O(2peak) following RT and END, respectively, were unrelated (r(2) = 0.003; P = 0.79). However, a VEGFA genotype × training modality interaction (P = 0.007) demonstrated that VEGFA GG homozygotes increased their MVIC force after RT (+ 20.9 ± 13.2%) more than they increased their V̇O(2peak) after END (+ 8.4 ± 9.1%, P = 0.005), and more than VEGFA C-allele carriers increased their MVIC force after RT (+ 12.2 ± 8.1%, P = 0.04). There were no genotype × training modality interactions for the ACTN3 or NOS3 SNPs. CONCLUSION: High/low responders to RT were not consequently high/low responders to END or vice versa. However, preferential adaptation of VEGFA rs2010963 GG homozygotes to RT over END, and their greater adaptation to RT compared to VEGFA C-allele carriers, indicate a novel genetic predisposition for superior RT adaptation.