Cycle ergometer and inspiratory muscle training offer modest benefit compared with cycle ergometer alone: a comprehensive assessment in stable COPD patients

Figures & data

Table 1 Patient characteristics at baseline

Parameter	Control group (n=26)	CET group (n=27)	Combined training group (n=28)	F	P-value
Age (years)	69.8±6.4	70.0±6.3	70.8±4.5	0.237	0.790
PImax (cmH2O)	63.81±23.73	74.66±13.83	72.40±20.41	2.227	0.115
PEmax (cmH2O)	64.74±39.09	77.24±30.03	77.40±35.82	1.132	0.327
6MWD (m)	525±70	511±77	538±60	1.101	0.338
VO2max (mL/min)	1,011±390	1,154±297	994±272	2.015	0.140
VO2max %pred (%)	61.83±22.23	66.81±16.64	65.25±15.61	0.492	0.613
VO2max/kg (mL/min/kg)	17.01±6.24	18.13±4.82	17.18±3.94	0.374	0.689
AT (mL/min)	823±321	923±197	804±188	1.912	0.155
AT%pred (%)	50.75±19.67	53.59±11.62	52.93±11.26	0.266	0.767
FVC (L)	2.69±0.70	2.78±0.66	2.41±0.62	2.276	0.110
FVC%pred (%)	84.15±20.56	80.89±18.73	75.21±16.19	1.620	0.204
FEV1 (L)	1.42±0.46	1.33±0.47	1.19±0.40	1.959	0.148
FEV1 %pred (%)	57.54±18.98	51.26±18.00	49.82±16.14	1.429	0.246
FEV1/FVC	53.19±10.18	47.23±9.90	49.60±11.18	2.180	0.120
MVV (L)	51.33±17.92	52.65±18.21	46.54±18.75	0.850	0.431
IC (L)	1.77±0.52	1.90±0.46	1.71±0.53	0.994	0.375
mMRC	1.19±0.85	1.41±0.84	1.29±0.81	0.444	0.643
CAT	7.96±5.24	8.93±5.21	8.93±5.64	0.285	0.753
SGRQ	12.62±7.40	14.93±8.82	16.14±6.79	1.446	0.242
HADS	5.27±3.26	4.85±2.70	5.50±4.35	0.239	0.788
HADS depression	3.00±2.28	2.44±1.72	3.54±3.23	1.309	0.276
HADS anxiety	2.27±2.05	2.41±1.28	1.96±1.64	0.501	0.608
BMI (kg/m^2)	21.31±3.78	22.40±2.85	21.31±2.76	1.071	0.348
FFMI (kg/m^2)	16.65±1.92	16.86±1.54	16.24±1.36	1.075	0.346
BODE	1.81±1.36	2.33±1.90	2.46±1.58	1.211	0.303

Notes: Data are presented as mean ± SD unless otherwise stated; P-value results of analysis of variance (ANOVA) comparison between three groups at baseline.

Abbreviations: CET, cycle ergometer training; PI_max, maximal inspiratory pressure; PE_max, maximal expiratory pressure; 6MWD, 6-minute walking distance; VO_2max, maximal oxygen consumption; AT, anaerobic threshold; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; %pred, percent predicted; MVV, maximal voluntary ventilation; IC, inspiratory capacity; mMRC, modified Medical Research Council; CAT, COPD Assessment Test; SGRQ, St George’s Respiratory Questionnaire; HADS, Hospital Anxiety and Depression Scale; BMI, body mass index; FFMI, fat-free mass index; BODE, body mass index, airflow obstruction, dyspnea, and exercise capacity index.

Figure 1 Changes of ventilatory pattern, HR, SPO₂, and Borg scale during CPET.

Notes: Data are presented as mean ± SE unless otherwise stated; Δ, difference (after minus before intervention); P-value results of analysis of repeated measures analysis of variance (ANOVA) comparison of the differences between groups.
Abbreviations: CET, cycle ergometer training; IMT, inspiratory muscle training; AT, anaerobic threshold; VE, minute ventilation; Rf, respiratory frequency; VT, tidal volume; SPO₂, pulse oxygen saturation; HR, heart rate; RER, respiratory exchange ratio; CPET, cardiopulmonary exercise testing.

Figure 2 Flow diagram for studies included.

Abbreviation: CET, cycle ergometer training.

Table 2 Effects of pulmonary rehabilitation in the combined training, CET, and control groups

Parameter	Control group (n=26)	CET group (n=27)	Combined training group (n=28)	F	P-value
ΔPImax (cmH2O)	−2.38±0.94	1.32±0.91a	5.20±0.89a,b	17.151	<0.001
ΔPEmax (cmH2O)	−5.29±1.97	5.42±1.92a	2.37±1.88a	7.943	0.001
ΔFVC (L)	0.00±0.05	−0.02±0.05	0.11±0.05	2.211	0.117
ΔFVC%pred (%)	−2.10±2.20	−0.69±2.15	4.83±2.13	2.832	0.065
ΔFEV1 (L)	−0.02±0.03	0.01±0.03	0.06±0.03	0.593	0.555
ΔFEV1 %pred (%)	1.75±1.61	0.16±1.56	1.23±1.54	0.264	0.769
ΔFEV1/FVC	−3.23±2.00	0.55±1.96	−0.13±1.90	1.007	0.370
ΔMVV (L)	1.11±1.20	0.90±1.18	4.14±1.17	2.360	0.101
ΔIC (L)	−0.04±0.02	0.06±0.02a	0.10±0.02a	13.209	<0.001
ΔmMRC	0.11±0.13	−0.33±0.13a	−0.47±0.13a	5.534	0.006
ΔCAT	0.30±0.35	−3.00±0.34a	−2.39±0.34a	25.715	<0.001
ΔSGRQ	0.95±0.56	−3.51±0.54a	−3.32±0.54a	20.598	<0.001
ΔHADS	−0.12±0.39	−3.47±0.39a	−3.16±0.38a	22.410	<0.001
ΔHADS depression	−0.15±0.28	−2.20±0.27a	−2.10±0.27a	17.605	<0.001
ΔHADS anxiety	−0.10±0.20	−1.32±0.20a	−1.07±0.20a	14.470	<0.001
ΔBMI (kg/m^2)	−0.02±0.21	0.54±0.21	0.23±0.21	1.712	0.187
ΔFFMI (kg/m^2)	−0.11±0.24	0.68±0.24a	0.87±0.23a	4.825	0.011
ΔBODE	−0.07±0.13	−0.02±0.12	−0.24±0.12	1.194	0.309

Notes: Data are presented as mean ± SE unless otherwise stated; Δ, difference (after minus before intervention); P-value results of analysis of covariance comparison of the differences between groups;

a P<0.05 vs control group;

b P<0.05 vs CET group.

Abbreviations: CET, cycle ergometer training; PI_max, maximal inspiratory pressure; PE_max, maximal expiratory pressure; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; %pred, percent predicted; MVV, maximal voluntary ventilation; IC, inspiratory capacity; mMRC, modified Medical Research Council; CAT, COPD Assessment Test; SGRQ, St George’s Respiratory Questionnaire; HADS, Hospital Anxiety and Depression Scale; BMI, body mass index; FFMI, fat-free mass index; BODE, body mass index, airflow obstruction, dyspnea, and exercise capacity index.

Table 3 Change in exercise capacity and CPET paraments after pulmonary rehabilitation in the combined training, CET, and control groups

Parameter	Control group (n=26)	CET group (n=27)	Combined training group (n=28)	F	P-value
6MWD
ΔDistance (m)	−1.64±4.64	32.55±4.59a	21.68±4.51a	14.320	<0.001
ΔBorg	0.35±0.24	−0.10±0.24	−0.23±0.23	1.620	0.205
Rest CPET variables
ΔVE (L/min)	0.14±0.23	0.16±0.23	−0.43±0.22	2.301	0.107
ΔRf (b/min)	0.05±0.31	−0.21±0.30	−0.69±0.30	1.666	0.196
ΔVT (L)	−0.01±0.01	0.01±0.02	−0.01±0.02	0.630	0.535
ΔRER	0.01±0.01	0.03±0.01	0.02±0.01	0.746	0.478
ΔSPO2 (%)	0.12±0.13	0.30±0.12	0.31±0.12	0.714	0.493
ΔHR (b/min)	−1.37±1.56	−2.64±1.53	−4.22±1.49	0.878	0.420
Peak CPET variables
ΔVE (L/min)	0.91±0.92	1.96±0.90	0.20±0.89	0.989	0.377
ΔRf (b/min)	0.51±0.61	0.50±0.60	−0.60±0.59	1.140	0.325
ΔVT (L)	0.01±0.02	0.00±0.02	0.01±0.02	0.057	0.945
ΔRER	−0.01±0.01	0.00±0.01	−0.02±0.01	1.089	0.342
ΔSPO2 (%)	0.28±0.44	−0.39±0.43	0.22±0.42	0.743	0.479
ΔHR (b/min)	−1.96±1.83	0.81±1.79	−1.21±1.76	0.631	0.535
ΔVO2max (mL/min)	3.45±20.96	149.01±20.04a	122.96±19.47a	14.180	<0.001
ΔVO2max %pred (%)	0.34±1.43	9.56±1.35a	6.28±1.32a	11.143	<0.001
ΔVO2max/kg (mL/min/kg)	−0.58±0.39	2.56±0.36a	2.26±0.36a	21.037	<0.001
ΔAT (mL/min)	−0.29±34.72	157.53±33.19a	104.75±32.30a	5.482	0.006
ΔAT%pred (%)	−0.27±1.96	7.68±1.84a	4.90±1.81a	4.453	0.015
ΔPower (Watt)	−0.62±2.29	11.86±2.25a	6.10±2.21a	7.547	0.001
ΔBorg	0.08±0.20	−0.18±0.20	−0.36±0.20	1.258	0.290

Notes: Data are presented as mean ± SE unless otherwise stated; Δ, difference (after minus before intervention); P-value results of analysis of covariance comparison of the differences between groups;

a P<0.05 vs control group.

Abbreviations: CET, cycle ergometer training; CPET, cardiopulmonary exercise testing; 6MWD, 6-minute walking distance; VE, minute ventilation; Rf, respiratory frequency; VT, tidal volume; RER, respiratory exchange ratio; SPO₂, pulse oxygen saturation; HR, heart rate; VO_2max, maximal oxygen consumption; %pred, percent predicted; AT, anaerobic threshold.

Table 4 Effects of combined training in patients who had COPD with or without respiratory muscle weakness

Parameter	Normal respiratory muscle group (n=19)	Weakened respiratory muscle group (n=9)	F	P-value
ΔPImax (cmH2O)	6.89±1.45	1.22±2.44	2.980	0.097
ΔPEmax (cmH2O)	0.46±1.69	4.03±2.52	1.308	0.264
Δ6MWT (m)	16.67±6.70	28.14±10.70	0.673	0.420
ΔVO2max (mL/min)	137.93±24.76	78.60±37.13	1.642	0.212
ΔVO2max%pred (%)	6.65±1.95	5.63±2.97	0.073	0.790
ΔVO2max/kg (mL/min/kg)	2.32±0.34	2.08±0.50	0.154	0.698
ΔAT (mL/min)	102.50±38.09	96.72±57.39	0.006	0.937
ΔAT%pred (%)	5.38±2.58	3.87±3.95	0.091	0.766
ΔFVC (L)	0.12±0.08	0.10±0.12	0.018	0.985
ΔFVC%pred (%)	6.71±3.41	2.95±4.99	0.380	0.543
ΔFEV1 (L)	0.02±0.06	0.15±0.08	1.789	0.193
ΔFEV1 %pred (%)	0.01±2.64	4.66±3.87	0.966	0.335
ΔFEV1/FVC	0.51±1.23	0.90±1.81	0.403	0.531
ΔMVV (L)	2.55±1.94	7.72±2.83	2.244	0.147
ΔIC (L)	0.10±0.03	0.13±0.04	0.305	0.586
ΔmMRC	−0.53±0.17	−0.33±0.25	0.361	0.553
ΔCAT	−2.45±0.32	−2.38±0.48	0.016	0.899
ΔSGRQ	−3.19±0.74	−4.26±1.15	0.520	0.478
ΔHADS	−2.88±0.40	−4.25±0.60	3.320	0.080
ΔHADS depression	−2.07±0.35	−3.19±0.52	3.046	0.093
ΔHADS anxiety	−0.94±0.12	−1.01±0.18	0.093	0.762
ΔBMI (kg/m^2)	0.49±0.30	−0.25±0.43	1.980	0.172
ΔFFMI (kg/m^2)	1.28±0.37	0.27±0.55	2.240	0.147
ΔBODE	−0.20±0.22	−0.47±0.34	0.410	0.528

Notes: Data are presented as mean ± SE unless otherwise stated; Δ, difference (after minus before intervention); P-value results of analysis of covariance comparison of the differences between groups.

Abbreviations: PI_max, maximal inspiratory pressure; PE_max, maximal expiratory pressure; 6MWD, 6-minute walking distance; VO_2max, maximal oxygen consumption; AT, anaerobic threshold; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; %pred, percent predicted; MVV, maximal voluntary ventilation; IC, inspiratory capacity; mMRC, modified Medical Research Council; CAT, COPD Assessment Test; SGRQ, St George’s Respiratory Questionnaire; HADS, Hospital Anxiety and Depression Scale; BMI, body mass index; FFMI, fat-free mass index; BODE, body mass index, airflow obstruction, dyspnea, and exercise capacity index.

Table 5 Effects of pulmonary rehabilitation in COPD patients with malnutrition

Parameter	Normal nutrition group (n=43)	Malnutrition group (n=12)	F	P-value
ΔPImax (mmH2O)	3.17±0.90	1.78±1.73	0.039	0.844
ΔPEmax (mmH2O)	4.25±1.79	−0.95±3.39	1.847	0.180
Δ6MWT (m)	27.84±4.21	24.01±8.02	0.177	0.675
ΔVO2max (mL/min)	125.91±17.34	176.91±34.03	1.711	0.197
ΔVO2max %pred (%)	7.52±1.24	9.72±2.38	0.656	0.422
ΔVO2max/kg (mL/min/kg)	2.38±0.28	2.56±0.53	0.097	0.757
ΔAT (mL/min)	125.65±31.76	153.51±65.37	0.134	0.716
ΔAT%pred (%)	6.59±1.79	5.07±3.57	0.136	0.714
ΔFVC (L)	0.04±0.05	0.06±0.09	0.042	0.838
ΔFVC%pred (%)	2.73±1.78	1.21±3.4	0.156	0.694
ΔFEV1 (L)	0.03±0.03	0.07±0.06	0.306	0.582
ΔFEV1 %pred (%)	0.76±1.35	1.43±2.56	0.054	0.818
ΔFEV1/FVC	0.86±0.73	−0.75±1.39	1.054	0.309
ΔMVV (L)	2.51±1.13	2.76±2.16	0.01	0.919
ΔIC (L)	0.02±0.02	−0.03±0.03	1.844	0.180
ΔmMRC	−0.43±0.10	−0.38±0.19	0.046	0.832
ΔCAT	−2.87±0.25	−2.20±0.47	1.587	0.213
ΔSGRQ	−3.58±0.41	−3.43±0.78	0.026	0.872
ΔHADS	−3.18±0.27	−3.18±0.54	<0.001	0.989
ΔHADS depression	−2.03±0.23	−2.99±0.47	3.228	0.078
ΔHADS anxiety	−1.19±0.12	−0.92±0.23	1.015	0.318
ΔBMI (kg/m^2)	0.37±0.21	0.36±0.42	0.001	0.981
ΔFFMI (kg/m^2)	0.76±0.25	0.86±0.59	0.020	0.889
ΔBODE	−0.16±0.12	−0.10±0.23	0.049	0.825

Notes: Data are presented as mean ± SE unless otherwise stated; Δ, difference (after minus before intervention); P-value results of analysis of covariance comparison of the differences between groups.

Abbreviations: PI_max, maximal inspiratory pressure; PE_max, maximal expiratory pressure; 6MWD, 6-minute walking distance; VO_2max, maximal oxygen consumption; AT, anaerobic threshold; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; %pred, percent predicted; MVV, maximal voluntary ventilation; IC, inspiratory capacity; mMRC, modified Medical Research Council; CAT, COPD Assessment Test; SGRQ, St George’s Respiratory Questionnaire; HADS, Hospital Anxiety and Depression Scale; BMI, body mass index; FFMI, fat-free mass index; BODE, body mass index, airflow obstruction, dyspnea, and exercise capacity index.