Deficits in muscle strength and physical performance in sarcopenic children after liver transplantation influences physical activity.

Sarcopenia is a muscle disease characterized by reduced skeletal muscle mass (SMM), muscle strength, and physical performance. Reduced SMM has been identified in children after liver transplantation (LT), but no information related to muscle strength/physical performance or lifestyle factors contributing to sarcopenia is available. We hypothesized that sarcopenia, as determined by measures of SMM, muscle strength, and physical performance, is highly prevalent in children after LT and is related to poor diet quality (DQ) and physical inactivity. A cross-sectional study in post-LT children (n = 22) and age-matched healthy controls (n = 47) between the ages of 6 and 18 years examining body composition (dual energy X-ray absorptiometry and multiple skinfold), measures of muscle strength (handgrip, sit-to-stand, and push-ups), physical performance (6-minute walk test and stair climb test), diet (3-day food intake), and physical activity (accelerometer) was conducted. Low muscle strength/physical performance and SMM (SMM z scores <=-1.5) were defined by values 2 standard deviations below the mean values for age- and sex-matched controls. Sarcopenia occurred in 36% of children who underwent LT, and they had significantly lower scores for muscle strength (sit-to-stand and push-up tests) and physical performance (stair climb test) than controls (P < 0.05). Deficits in physical performance in children with sarcopenia were predominantly revealed by longer stair climbing times (P = 0.03), with no differences in other muscle tests. Low SMM, muscle strength, and physical performance were associated with a lower amount of time spent in fairly and very active physical activity, but no associations with DQ were found. Sarcopenia is highly prevalent in children after LT and is related to lower moderate-to-vigorous physical activity. Development of effective rehabilitation strategies to treat sarcopenia are needed in post-LT children.