EFFECTS OF EXERCISE TRAINING ON PROTEIN KINETICS IN CHILDREN WITH CYSTIC FIBROSIS (CF). † 2293

In 12 CF patients (12-17 y; weight <P₁₀ and/or FEV₁ < 70%pred), we previously showed that 6 months (mo.) bicycle exercise training(20 min/day) had beneficial effects on maximal oxygen consumption and leg muscle force as compared with previous 6 mo. baseline measurements (P < 0.05). Exercise training could have detrimental effects on nutritional status however, and therefore we studied weight and lean body mass (LBM) at 0, 6, and 12 mo. and protein kinetics (¹³C-1-leucine continuous (6 μmol/kg/hr i.v.) infusion technique) at 3 and 9 mo. as well. In these patients, non-oxidative leucine disposal (calculated as leucine turnover (Q) minus leucine oxidation (OX)), was significantly increased (mean±SD: 102±28 vs. 87±11 μmol/kg/hr; P <0.05) and Q was also increased (118±28 vs. 105±13, P = 0.10) during training compared to pre-training. OX (17±5 vs. 17±5 μmol/kg/hr, NS), and increments of body weight and LBM were not different between both periods. We conclude that in clinically declined children with CF, exercise training does not affect LBM increment and is associated with an increased protein conversion rate (which maybe limited to the trained muscle compartment).