Introduction
muscle mass, sarcopenia, Sarcopenia, sarcopenic
SARCOPENIA, ATROPHIC, SARCOPENIA
The maintenance of a healthy muscle mass is important in giving individuals the strength to perform the tasks of daily living. Muscle protein is continually turned over such that muscle mass is maintained by balancing the rates of protein synthesis and degradation within relatively tight windows [Sarcopenia, is defined by the European Working Group on Sarcopenia in Older People (EWGSOP) as the loss of both muscle mass and strength, leading to low muscle mass together with a walking speed less than 0.8m/s or a reduced grip strength [Myostatin, perhaps the best-known atrophic signalling protein, signals through a complex of the activin type II B receptor (ACVR2B) and activin type I receptors to initiate a SMAD2/3-dependent signalling cascade. In muscle, this activation increases the expression of the muscle-specific ubiquitin ligases, MuRF and atrogin-1, to promote muscle protein catabolism [Consistent with a role in the development and maintenance of muscle, polymorphic variation in the activin receptors has been associated with muscle mass and strength. One polymorphism in the first intron of Myostatin is expressed in other tissues including adipose tissue where it has been suggested to contribute to the differentiation of adipocytes [The above studies suggest that variation in activin receptor function may contribute to body composition in individuals with sarcopenia but a search for studies exploring these polymorphisms in the sarcopenic population did not yield any results. We therefore determined the frequency of the activin type I receptor polymorphisms rs2854464 and rs10783486 in individuals with sarcopenia in the LACE trial and compared these with body mass determined by DXA scans and grip and quadriceps strength at enrolment to determine whether these polymorphisms associated with body composition or strength in individuals with sarcopenia.