The protein tyrosine kinase-2 (PTK2) gene encodes focal adhesion kinase, a structural protein involved in lateral transmission of muscle fiber force. We investigated whether single nucleotide polymorphisms (SNPs) of the PTK2 gene were associated with various indices of human skeletal muscle strength and the inter-individual variability in the strength responses to resistance training. We determined unilateral knee extension single repetition maximum (1-RM), maximum isometric voluntary contraction (MVC) knee joint torque and quadriceps femoris muscle specific force (maximum force per muscle physiological cross-sectional area), before and after 9-wks knee extension resistance training in 51 untrained young men. All participants were genotyped for the PTK2 intronic rs7843014 A/C and 3' UTR rs7460 A/T SNPs. There were no genotype associations with baseline measures or post-training changes in 1-RM or MVC. Although the training-induced increase in specific force was similar for all PTK2 genotypes, baseline specific force was higher in PTK2 rs7843014 AA and rs7460 TT homozygotes than in their respective rs7843014 C- (P = 0.016) and rs7460 A-allele (P = 0.009) carriers. These associations between muscle specific force and PTK2 SNPs suggest that inter-individual differences exist in the way force is transmitted from the muscle fibers to the tendon. Therefore, our results demonstrate for the first time the impact of genetic variation on the intrinsic strength of human skeletal muscle.
- Protein tyrosine kinase-2 (PTK2)
- Focal adhesion kinase (FAK)
- Gene polymorphisms
- Lateral force transmission
- Copyright © 2012, Journal of Applied Physiology