Determinants of physical activity in daily life in candidates for lung transplantation

Participation in daily physical activity (PA) has never been objectively assessed in candidates for lung transplantation (LTx). The main research questions were: 1) How active are LTx-candidates in daily life? 2) What are determinants of activity behavior before LTX?

Ninety-six candidates for LTx (diagnosis of COPD or interstitial lung disease; mean age 55 ± 7 years) underwent measurements of PA, pulmonary function, 6-min walking distance (6MWD), muscle force and health-status (SF-36 scale).

Patients were markedly inactive (5% of waking hours walking, 26% standing and 69% sedentary). Backward multiple regression identified 6MWD (expressed as % of predicted value; β = 73.0 steps, partial r(2) = 0.36, p = 0.00), a higher score on the energy/fatigue scale of the SF-36 (β = 28.6 steps, partial r(2) = 0.09, p = 0.00) and a higher expiratory muscle force (expressed as % of predicted value; β = 11.8 steps, partial r(2) = 0.05, p = 0.02) as determinants of daily steps. Minutes of mild to moderate (≥2 METs) activity were determined by 6MWD (expressed as % of predicted value; β = 2.14 min, partial r(2) = 0.30, p = 0.00), inspiratory muscle force (expressed as % of predicted value; β = 0.33 min, partial r(2) = 0.04, p = 0.05) and seasonal influences (spring/summer vs. autumn/winter: β = 18.95 min, partial r(2) = 0.04, p = 0.05). The overall fit of the models was r(2) = 0.50 and r(2) = 0.38, respectively.

The 6MWD was the main determinant of an inactive lifestyle in these patients. Respiratory muscle force, energy and fatigue and seasonal variations explained some additional variability in activity behavior. Patients should be encouraged to participate in interventions aimed at improving physical fitness and participation in daily physical activity before LTx.