Table 2

 Exercise data from incremental and constant load cycle tests

COPD patientsHealthy controls
Except where stated, figures are mean (SD) values and between groups compared using unpaired Student’s t test.
Gas exchange and ventilation data on three patients are missing due to equipment failure.
o2peak, peak oxygen uptake; V˙e, ventilation; MVV, maximum voluntary ventilation; RQ, respiratory quotient; HR, heart rate; BS, Borg score; PE, perceived exertion.
*p<0.01, †p<0.05 compared with COPD patients
‡Median (interquartile range); comparison made using Mann-Whitney U test.
Incremental cycle test
    Peak work rate (W)72 (18.3)181 (30.4)*
    V̇o2peak (ml/kg/min)15.6 (3.7)34.7 (8.1)*
    V˙co2peak (ml/kg/min)15.8 (4.1)41.2 (10.1)*
    Peak V˙e (l)42.4 (11.0)77.3 (16.9)*
    Peak V˙e (% MVV)106 (33)67 (15)*
    Peak RQ1.00 (0.07)1.19 (0.09)*
    Peak Sao2 (%)94.7 (2.3)96.6 (1.3)†
    Peak HR (beats/min)123 (18)130 (22)
Constant load test
    Work rate (W)56.7 (15.9)143.2 (26.3)*
    End exercise HR (beats/min)125 (18)135 (15)
    End exercise Sao2 (%)91.8 (5.0)94.8 (2.0)
    End exercise BS‡5 (2.5)3 (3)†
    End exercise PE‡13 (4)15 (4.25)