Table 3. Comparison between COPD patients who improved after pulmonary rehabilitation and those who did not, in terms of pre- and post-pulmonary rehabilitation exercise performance on an incremental exercise test and the six-minute walk test.^a .

Variable	Post- PR improvers	Post- PR non-improvers
	(n = 16)	(n = 6)
	Pre-PR	Post-PR	Pre-PR	Post-PR
Peak incremental exercise values
Workload
W	36 ± 22	46 ± 17*	27 ± 18	21 ± 13†
% of the predicted value	24.8 ± 14.3	34.2 ± 10.3*	19.1 ± 12	15.1 ± 9.6
VO2, L/min	0.76 ± 0.18	0.77 ± 0.21	0.70 ± 0.19	0.60 ± 0.15
VCO2, L/min	0.81 ± 0.23	0.80 ± 0.25	0.69 ± 0.20	0.53 ± 0.12†
VE, L/min	33.7 ± 8.1	33.7 ± 9.7	30.4 ± 3.6	24.3 ± 4.1*
VE/MVV ratio, %	87.9 ± 18.6	87.0 ± 21.2	89.1 ± 25.7	72.8 ± 28.3*
VT, L	1.08 ± 0.34	1.09 ± 0.37	0.92 ± 0.20	0.76 ± 0.14†
RR, breaths/min	32 ± 6	30 ± 6	30 ± 3	30 ± 4
TI, s	0.79 ± 0.19	0.81 ± 0.18	0.86 ± 0.18	0.83 ± 0.21
TE, s	1.24 ± 0.27	1.27 ± 0.31	1.25 ± 0.15	1.22 ± 0.19
TI/Ttot ratio	0.39 ± 0.04	0.39 ± 0.05	0.39 ± 0.05	0.39 ± 0.06
SpO2, %	93 ± 2	94 ± 2	92 ± 2	92 ± 1
Post-6MWT values
6MWD
m, median (range)	310 (170-425)	338 (230-490)*	285 (190-340)	290 (230-466)
% of the predicted value	29.8 ± 7.2	34.5 ± 7.7*	25.7 ± 5.0	30.2 ± 8.7
Borg dyspnea score, median (range)	3 (0-5)	3 (0.5-5)	3.5 (2-5)	3 (2-9)
Borg leg fatigue score, median (range)	2 (0-5)	1 (0-5)	1.75 (0-4)	1.5 (0-7)
SpO2, %	92 ± 3	90 ± 4*	92 ± 1	88 ± 2

PR: pulmonary rehabilitation; VO₂: oxygen consumption; VCO₂: carbon dioxide production; V_E: minute ventilation; MVV: maximal voluntary ventilation; V_T: tidal volume; RR: respiratory rate; T_I: inspiratory time, T_E: expiratory time; Ttot: total respiratory time; 6MWT: six-minute walk test; and 6MWD: six-minute walk distance. ^aValues expressed as mean ± SD, except where otherwise indicated. *p < 0.05 vs. pre-PR value. †p < 0.05 vs. post-PR improvers.