Table 2—

Subject characteristics

ControlCOPD
Subjects n825
Age yrs69±666±5
BMI kg·m−226.0±2.527.6±3.9
Lung function
 FEV1 % pred100±1334±12***
 FEV1/FVC %72±346±11***
 RV % pred108±13176±39***
 TLC % pred103±5105±17
 RV/TLC %40±363±8***
Pa,O2 mmHg97±365±3***
Respiratory muscle function
 MIP % pred85±2065±22*
Pth,max cmH2O-66±22-40±19*
tth80 min15.8±5.610.7±5.8
 MEP % pred93±2370±19**
  • Data are presented as mean±sd, unless otherwise stated. COPD: chronic obstructive pulmonary disease; BMI: body mass index; FEV1: forced expiratory volume in one second; % pred: % predicted; FVC: forced vital capacity; RV: residual volume; TLC: total lung capacity; Pa,O2: arterial oxygen tension; MIP: maximal inspiratory mouth pressure; Pth,max: maximum inspiratory sustainable pressure (obtained during progressive inspiratory threshold loading); tth80: endurance time under constant submaximal inspiratory loads (80% of Pth,max); MEP: maximal expiratory mouth pressure. *: p<0.05; **: p<0.01; ***: p<0.001; all between control subjects and COPD patients. 1 mmHg = 0.133 kPa; 1 cmH2O = 0.098 kPa.