Lung Transplantation Minimally Impacts Daily Physical Activity Post-Transplantation

Purpose While physical activity level (PAL) is an important functional measure in people with chronic respiratory disease, little is known about PAL post lung transplantation (LTx). Aim: To compare PAL pre- and post-LTx and determine the relationship between changes in PAL and demographic (age), lung function (FEV1%) and exercise capacity measures. Methods Using a prospective observational design, participants were assessed pre- and 12 months post-LTx. PAL was defined as total energy expenditure in twenty-four hours/basal metabolic rate. PAL, mean minutes/day being physically active (1.69 metabolic equivalents (METs) or greater), and mean minutes/day performing moderate activity (3.0 METs or greater) were measured using the SenseWear multi-sensor device. Age, FEV1%, six-minute walk distance (6MWD), and quadriceps strength corrected for body weight (QS%) were assessed. Results 67 participants (40 males; 29 COPD, 15 idiopathic pulmonary fibrosis, 12 cystic fibrosis, 11 other), mean (SD) age 50.7 ± 12.4 years were included. Mean FEV1% increased by 52.6 ± 32.1% (p=0.001) and 6MWD increased by 174 ± 128m (p=0.001) 12 months after transplant, but QS% did not improve (-2.0 ± 21.0%, p=0.437). Mean PAL at 12 months (1.49 ± 0.23) had significantly improved compared to pre-LTx (1.40 ± 0.29, p=0.028). However, 17 (25.4%) participants remained extremely inactive (PAL below 1.4) and 37 (55.2%) participants were sedentary (PAL 1.4 to 1.69). Mean time physically active increased by 32 ± 130 minutes/day (p=0.045) but time performing moderate activity remained unchanged (p=0.062). Post-LTx, PAL was correlated with 6MWD (r=0.58, p=0.001), QS% (r=0.47, p=0.001) and age (r=-0.24, p=0.050) but not FEV1% (p=0.575). ∆PAL was correlated with ∆6MWD (r=0.37, p=0.002) but not with ∆QS% (p=0.090), age (p=0.716), or ∆FEV1% (p=0.875). Conclusion Most recipients remain physically inactive 12 months after lung transplantation despite significant improvements in lung function and exercise capacity. Age, exercise capacity and quadriceps strength appear important determinants of post-transplant PAL. However, there were only modest increases in physical activity post-transplantation.