ACE I/D and ACTN3 R/X polymorphisms and muscle function and muscularity of older Caucasian men.

The progressive decline in strength and power with ageing leads to compromised mobility and an increased risk of falls. Angiotensin converting enzyme (ACE) I/D and alpha actinin 3 (ACTN3) R/X polymorphisms have been suggested to influence variations in skeletal muscle function and body composition. This study investigated the associations between these polymorphisms and knee extensor muscle function and muscularity in older Caucasian men. Strength was measured isometrically and isokinetically (at 30 and 240 degrees s(-1)), and the time course of the evoked twitch response recorded. A dual-energy X-ray absorptiometry scan measured thigh and whole body non-skeletal lean mass. ACE I/D and ACTN3 R/X polymorphisms were determined by polymerase chain reaction, and serum ACE activity using spectrophotometry. Whole body and thigh non-skeletal lean mass were independent of ACE and ACTN3 genotypes. Absolute and relative high velocity strength, and the time course of an evoked twitch were not associated with ACE or ACTN3 genotype. Serum ACE activity was negatively correlated with relative high velocity torque (R = -0.23, P = 0.03), and exhibited a positive trend with knee extensor isometric strength (R = 0.19, P = 0.07). ACE I/D and ACTN3 R/X polymorphisms were not associated with muscle function or muscularity phenotypes in older Caucasian men, although serum ACE activity appeared to have a small effect on muscle function.