Critical care
Preserved anabolic skeletal muscle capacity in response to exercise and protein intake after critical illness
By Fischer-Hammerschmied A, Tardif N, Mandić M and 8 others.
Abstract
Background
Low muscle mass and persistent weakness are common after critical illness, but the mechanisms behind impaired recovery are incompletely understood. The aim of this study was to investigate the skeletal muscle anabolic response to combined resistance exercise and protein intake in intensive care unit (ICU) survivors, compared to matched controls without a history of critical illness. We hypothesised that residual anabolic resistance limits muscle regeneration after ICU stay.
Methods
Former patients were enrolled within 3 to 6 months of intensive care unit discharge. Muscle biopsies were obtained before and after resistance exercise using a flywheel leg extension ergometer, combined with ingestion of 24 g hydrolysed protein. Muscle protein fractional synthetic rate was determined from the incorporation of [ring-²H₅]phenylalanine into mixed-muscle protein during a primed continuous intravenous infusion. Anabolic and proteolytic pathways were measured using standard assays. Group-by-time differences were analysed using linear mixed models. The primary comparison was the between-group difference in pre-to-post change in muscle protein synthesis.