Table 1.
Characteristics of included studies
| Study | Publication year | Sample size (N) | Severity of COPD | Type of breathing exercise | Duration | Comparison | Outcome measures |
|---|---|---|---|---|---|---|---|
| Ambrosino et al. [16] | 1981 | 51 | Mild COPD | Combined BEs (PLB, DBE, relaxation and slow breathing) | Twice daily (4 weeks) | Rehabilitative and medical therapy vs Medical therapy | RR, VT, VO2, SpO2 |
| Tiep et al. [17]a | 1986 | 12 | Moderate COPD | PLB | 15 minutes (1 day) | PLB vs Relaxation | RR, VT, SpO2 |
| Collins et al. [18] | 2003 | 39 | Moderate to severe COPD | VF training | 30–50 minutes, three times/week (6 weeks) | VF plus exerciseb vs. VF vs Exerciseb | RR, Ve, Ti, Te, Ti/Ttot, IC, dyspnea score, SpO2, VO2 |
| Jones et al. [19]a | 2003 | 30 | Severe COPD | PLB, DBE, CB | 10 minutes for each breathing (1 day) | DBE, PLB, or CB vs Spontaneous | VO2, RR |
| Garrod et al. [20]a | 2005 | 48 | Severe COPD | PLB | Breathing with and without PLB during walking test (1 day) | PLB vs. non-PLB | RR, ISWT (m), SpO2, dyspnea score |
| Spahija et al. [21]a | 2005 | 8 | Mild to severe | PLB | Breathing with and without PLB during resting and exercise test (1 day) | PLB vs. non-PLB | VT, RR, Ve, Ti, Ttot, VT/Ti, EELV, dyspnea score, respiratory muscle capacity |
| Nield et al. [22] | 2007 | 40 | Severe COPD | PLB | Daily practice (12 weeks) | PLB vs. health education | Dyspnea score, human activity profile, SF-36 |
| Collins et al. [23] | 2008 | 64 | Moderate to severe COPD | VF training | 30–50 minutes, three times/week (36 sessions) | VF plus exerciseb vs. VF vs. exerciseb | RR, Ve, Ti, Te, IC, dyspnea score, VO2, QoL |
| Faager et al. [24]a | 2008 | 32 | Moderate to severe COPD | PLB | Breathing with and without PLB during walking test (1 day) | PLB vs. non-PLB | SpO2, dyspnea score, leg fatigue, PEF, lung function |
| Bonilha et al. [25] | 2009 | 30 | Moderate to severe COPD | Singing | 1 hour, once a week (24 weeks) | Singing vs. handcraft artwork | Lung function, IC, ERV, MIP, MEP, ABG, dyspnea score, QoL |
| Lord et al. [26] | 2010 | 28 | Severe COPD | Singing | Twice a week (6 weeks) | Singing vs. usual care | Control of breathing, QoL, HAD |
| Lin et al. [27] | 2012 | 40 | Moderate to very severe COPD | Respiratory training (PLB, DBE) | 20 minutes, twice daily (12 weeks) | Respiratory training vs. health education | Lung function, SpO2, 6MWD, QoL |
| Lord et al. [28] | 2012 | 24 | Moderate to severe COPD | Singing | 1 hour, twice a week (8 weeks) | Singing vs. film workshop | SpO2, HR, control of breathing, functional exercise capacity, daily physical activity, QoL |
| van Gestel et al. [29] | 2012 | 40 | Severe COPD | Control breathing training (by respiratory biofeedback training) | 1.5 hours, three times/week (4 weeks) | RBF plus exercise vs. exercise group | Lung function, FRC, RV/TLC, DLCO, IC, TLC, 6MWD, SpO2, dyspnea score, fatigue score, QoL |
| Yamaguti et al. [30] | 2012 | 30 | Moderate to very severe COPD | DBE | 45 minutes, three times/week (4 weeks) | DBE vs. medical treatment | Thoracoabdominal motion, diaphragm mobility, %predicted 6MWD, QoL, BODE index |
| Bhatt et al. [31]a | 2013 | 14 | Moderate to very severe COPD | PLB | Breathing with and without PLB during walking test (1 day) | PLB vs. non-PLB | RR, dyspnea score, 6MWD, QoL, MIP, MEP, diaphragmatic excursion |
| Araujo et al. [32]a | 2015 | 25 | Moderate to very severe COPD | PLB | Breathing with and without PLB during walking test (2 days) | PLB vs. non-PLB | Lung function, IC, 6MWD, %predicted 6MWD, TGlittre, dyspnea score |
| Borge et al. [34] | 2015 | 150 | Moderate to severe COPD | DBE | 15 minutes, twice daily (4 weeks) | DBE vs. sitting still | QoL, dyspnea score, Ti, Te, RR |
| Cabral et al. [33]a | 2015 | 40 | Moderate to severe COPD | PLB | Breathing with and without PLB during exercise endurance test (2 days) | PLB vs. control breathing | IC, VT, RR, Ve, Ti, Te, Ttot, Ti/Ttot, VT/Ti, SpO2, dyspnea score, deg discomfort score |
BEs, breathing exercises; PLB, pursed-lip breathing; DBE, diaphragmatic breathing; RR, respiratory rate; VT, tidal volume; VO2, oxygen consumption; SpO2, oxygen saturation; VF, ventilatory feedback; Ve, minute ventilation; Ti, inspiratory time; Te, expiratory time; Ti/Ttot, duty cycle; IC, inspiratory capacity; SF-36, short-form 36 questionnaires; PEF, peak expiratory flow; QoL, quality of life; ERV, expiratory reserve volume; MIP, maximal inspiratory pressure; MEP, maximal expiratory pressure; ABG, arterial blood gas; HAD, hospital anxiety and depression scale; 6MWD, six-minute walk distance; HR, heart rate; RBF, respiratory biofeedback training; FRC, functional residual capacity; RV/TLC, ratio of residual volume and total lung capacity; DLCO, diffusing capacity of the lungs for carbon monoxide; TLC, total lung capacity; TGlittre, the Glittre-ADL test; Ttot, total respiratory time; VT/Ti, mean inspiratory flow; CB, combined PLB and DBE; EELV, end expiratory lung volume; ISWT, incremental shuttle walking test; CRQ, Chronic Respiratory Disease Questionnaire; TCQ, Tai Chi Qigong; HQG, health qigong; QYJJ, Qigong Yi Jinjing; CAT, the COPD assessment test; RESE, the regulatory emotion self-efficacy questionnaire.
Randomized cross-over study.
Endurance and light upper body strengthening exercises (exercise intensity started at 60% VO2peak and progressively increased to 85% VO2peak).