Human COL5A1 polymorphisms and quadriceps muscle-tendon mechanical stiffness in vivo

Purpose: Polymorphisms of the collagen type V alpha 1 chain (COL5A1) gene are purported to influence mechanical properties of collagenous tissues. Our purpose was to assess musculo-tendinous contractile properties of the quadriceps in relation to the genetic influence of mechanical stiffness.. Methods: Eighty, recreationally active males (ages 19–31 y) were assessed for the presence of three genetic polymorphisms associated with COL5A1 stability (rs4919510, rs1536482 and rs12722). Genotypes were determined using real-time polymerase chain reaction. Stiffness and contractile properties of the knee musculotendinous complex were assessed by maximal isometric voluntary contractions, ramp isometric voluntary contractions, electrically stimulated contractile events and ultrasonography. Results: All genotypes groups were able to fully activate their knee extensors (>97%) as assessed by the interpolated twitch technique and presented no differences in muscle-tendon contractile properties at low sub-maximal contraction intensities. For the quadriceps muscle-tendon at moderate ramp contractions of 50 and 60% MVC the rs12722 CT and TT genotypes had ∼30% greater mean stiffness. The rs1536482 AG and GG genotypes showed a similar trend, however, did not achieve statistical significance. Conclusion: Variants of the COL5A1 gene seem to influence quadriceps muscle-tendon stiffness, but do not affect low-level contractile properties.

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