Introduction
muscle mass, sarcopenia, muscle loss
SARCOPENIA
The normal human growth cycle includes periods of muscle growth, muscle maintenance and muscle loss [The renin-angiotensin system has gained significant attention as a potential target pathway to treat sarcopenia [These data suggest that reducing ACE activity and thereby AII could preserve muscle mass and strength in older individuals and one interventional study has supported this suggestion [Studies of genetic variation show that the relationship between ACE activity and strength is not as simple as lower ACE activity associating with increased strength. One well-studied ACE promoter polymorphism, the insertion (I)/deletion (D) polymorphism, affects ACE synthesis with the D allele associated with greater ACE synthesis and higher circulating ACE activity [These effects of the I/D polymorphism could be explained by variations in muscle fibre proportions. Skeletal muscle can be broadly categorised into two major fibre types (oxidative type I and more glycolytic type II). Type I fibres are used in endurance activities, whereas type II fibres are associated with power activities. In untrained volunteers, the D allele is associated with a greater proportion of type II fibres, with the I allele associated with a greater proportion of type I fibres [Type II fibres are more sensitive to both anabolic and catabolic stimuli than type I fibres [It is therefore difficult to predict the effect of ACE genotype on the likelihood of sarcopenia as DD individuals may have started with a larger muscle mass and greater strength with a higher type II fibre composition that is more susceptible to loss. The effects of these polymorphisms may have contributed to the findings of the LACE study by affecting the muscle mass of individuals before the study or by modifying the response to therapy. In this study therefore, we analysed the genotypes of individuals with sarcopenia, enrolled into the LACE study to determine any association of ACE genotype with strength or muscle mass. We also determined the effect of genotype on the change in muscle mass, strength and physical performance 1 year later in those who completed the trial.