Table 2– Exercise testing data

	Control group^#		COPD group^¶
	Baseline	p-value⁺	Baseline	Follow-up	p-value^§
Treadmill testing
V′_O₂,peak mL·kg⁻¹·min⁻¹	38.9±5.0	0.005	20.4±4.0	20.2±3.6**	0.68
WE mL·kg⁻¹·min⁻¹	ND		11.0±0.6	10.6±0.5	0.44
V′_E at peak work L·min⁻¹	87±8	0.001	49±9	49±11***	0.87
Knee-extensor testing
Peak work W	23.2±6.7	0.03	14.6±4.9	20.0±5.3	0.001
Quadriceps muscle mass kg	1.64±0.20	0.10	1.39±0.27	1.43±0.26	0.45
Femoral blood flow at 6 Watts L·min⁻¹	1185±236	0.85	1213±242	1195±250	0.87
Femoral blood flow at peak work L·min⁻¹	2854±168	0.03	2127±655	2631±348	0.03
Muscle V′_O₂ at 6 Watts mL·kg⁻¹·min⁻¹	ND		117±30	104±29	0.26
Muscle V′_O₂ at peak work mL·kg⁻¹·min⁻¹	ND		200±40	248±43	0.048
Pulmonary V′_O₂ at 6 Watts mL·kg⁻¹·min⁻¹	5.21±1.21	0.07	7.81±2.67	5.78±1.29	0.026
Pulmonary V′_O₂ at peak work mL·kg⁻¹·min⁻¹	14.6±4.9	0.036	10.9±1.8	11.7±1.2	0.30
Lactate at 6 Watts mmol·L⁻¹	ND		2.16±1.02	1.67±1.13	0.17
Lactate at peak work mmol·L⁻¹	ND		4.4±2.2	6.3±2.3	0.06
V′_E at 6 Watts L·min⁻¹	13.0±1.2	0.02	16.7±2.7	13.3±2.0	0.007
V′_E at peak work L·min⁻¹	33.9±9.9	0.16	27.4±4.3	29.3±2.8	0.18

Data are presented as mean±sd, unless otherwise stated. COPD: chronic obstructive pulmonary disease; V′_O₂,peak: peak oxygen consumption; WE: work economy; V′_E: minute ventilation; V′_O₂: oxygen uptake; ND: no data. ^#: n=5; ^¶: n=7; ⁺: significance levels between baseline control and baseline COPD; ^§: significance levels between baseline COPD and follow-up COPD. **: p<0.01; ***: p<0.001 between controls and COPD at follow-up.