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Table 3 Explained variance of VO2peak (Adjusted R2) of models with and without change points

From: Association between pulmonary function and peak oxygen uptake in elderly: the Generation 100 study

Added variable Hockey-stick model Linear model Curvilinear model
 FEV1 0.433* 0.423 0.429*
 DLCO 0.450* 0.440 0.451*
 DLCO/VA 0.440 0.441 0.441
 FEV1 0.460* 0.452 0.456*
 DLCO 0.470 0.469 0.470
 DLCO/VA 0.477 0.476 0.477
  1. Definition of abbreviations: VO2peak = peak oxygen uptake; FEV1 = forced expiratory volume in 1 s; DLCO – diffusing capacity of the lung for carbon monoxide; DLCO/VA – DLCO corrected for estimated alveolar volume. Resulting explained variance (Adjusted R2) of regression models with peak oxygen uptake as dependent variable with variable in first column added either as a variable with change point, as a linear variable or as a curvilinear variable (both variable and variable2). Age, self-reported physical activity, resting heart rate, body-fat percentage, self-reported history of heart disease and current smoking status are control variables in all models. *P-value < 0.05 for R2-change compared to linear model (f-test). Adjusted R2 for VO2peak in a multiple linear model without pulmonary function measurements, including only age, physical activity index, resting heart rate, body-fat percentage, smoking status and heart disease history were 0.393 for men and 0.448 for women