Comparison of laboratory- and field-based exercise tests for COPD: a systematic review

Figures & data

Figure 1 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) diagram detailing the identification and inclusion process of the articles. Some studies are included in more than one analysis category; consequently, the aggregate number of studies in the repeatability, reproducibility, comparative, and protocol variation groups adds up to more than 71.

Table 1 Repeatability and reproducibility of the 6- and 12-minute walk tests

Study	Patients, n (males, n)	Disease severity (mean ± SD FEV1 [mean ± SD% predicted] or COPD grading, unless otherwise stated)	Comparison	Additional information
6-minute walk test
Repeatabilitya
Andersson et al^Citation16	47 (16)	1.20±0.49 (46.0±17.0)	First versus second test	Significant increase in distance from first to second test (Δ22 m [5.3%]) (ICC =0.94)
Bansal et al^Citation17	27 (15)	0.8±0.2 (38.1±14.3)	First versus second test	Significant increase in distance from first to second test, for linear (Δ14 m [3.5%]) and circuit (Δ12 m [3.0%]) track layouts
Eiser et al^Citation18	57 (30)	NR (35.0±12.0)	First versus second versus third test	Significant increase in distance from first to second test (Δ7 m [1.6%]); NSD from second to third test
Jenkins and Cecins^Citation19	245 (162)	1.06±0.5 (41.0±18.0)	First versus second test	Significant increase in distance from first to second test (Δ37 m [9.5%])
Stevens et al^Citation20	21 (9)	1.07±0.53 (NR)	First versus second versus third test	Hallway: significant increase in distance from first to second test (approximate Δ32.9 m [9.0%]); NSD in distance from second to third test Treadmill: significant increase in distance from first to second test (approximate Δ16.2 m [9.9%]); NSD in distance from second to third test
Vagaggini et al^Citation21	18 (15)	NR (48.0±14.0)	Familiarization then first versus second test	NSD in distance from first to second test after familiarization (Δ15 m [3.4%])
Reproducibilityb
Bansal et al^Citation17	27 (15)	0.8±0.2 (38.1±14.3)	First versus second test	NSD in distance from first to second day for straight (Δ12 m [2.9%]) and circular (25 m [6.0%]) track layouts
Behnke et al^Citation26	TG: 66 (51)	TG: 1.30±0.49 (41.9±13.9)	Familiarization then first versus mean of second and third tests	TG: significant increase in distance from first to mean of second and third test (Δ209.5 m [72.9%])
	CG: 22 (20)	CG: 1.45±0.51 (46.9±15.1)		CG: significant increase in distance from first to mean of second and third test (Δ57.5 m [18.9%])
Brooks et al^Citation27	18 (10)	1.0±0.3 (42.0±8.0)	First versus second test	NSD in distance from first to second test (NR)
Chatterjee et al^Citation28	88 (37)	Median ± IQR FEV1, L (mean ± SD%) 1.21±0.55 (52.0±19.4)	First versus second versus third test	NSD in distance from first to second test (Δ32 m [9.8%]); NSD in distance from second to third test (Δ4 m [1.1%])
Eiser et al^Citation18	57 (30)	NR (35.0±12.0)	First versus second versus third test	Significant decrease in mean distance from first to second day (Δ–9 m [–2.1%]); significant increase in mean distance from second to third day (Δ8 m [1.9%])
Kozu et al^Citation29	45 (38)	1.10±0.50 (45.0±12.0)	First versus second test	Significant increase in distance from first to second day (Δ13 m [4.3%])
Poulain et al^Citation30	10 (NR)	Moderate COPD	Familiarization then first versus second test	NSD in distance from first to second day after familiarization (Δ4.7 m [0.94%])
Rejeski et al^Citation31	209 (117)	1.57; 0.58 (57.1±17.0)	First versus second test	Significant increase in distance from first to second day (Δ22 m [4.6%]); significant correlation between tests (r=0.91)
Roomi et al^Citation32	15 (6)	NR (49.0±5.0)	First versus second test	NSD in distance from first to second day (Δ−1 m [0.0%])
Sciurba et al^Citation33	470 (287)	0.75±0.24 (26.3±7.4)	First versus second test	Significant increase in distance from first to second day (Δ20 m; baseline NR) (ICC =0.88)
Spencer et al^Citation34	44 (22)	NR (56.0±19.0)	First versus second test	Significant increase in distance from first to second day (Δ27 m [5.9%])
Troosters et al^Citation35	20 (NR)	1.36±0.46 (45.0±14.0)	First versus second test	NSD in distance from first to second day (Δ15 m [2.6%])
12-minute walk test
Repeatabilitya
O’Reilly et al^Citation22	10 (10)	Chronic bronchitis or radiological emphysema	Familiarization then first versus second test	NSD in distance from first to second test after familiarization (mean variation 3.1%; distance NR)
Reproducibilityb
Arnardóttir et al^Citation36	EIH group: 19 (8)	EIH group: 0.9±0.1 (34.6±2.4)	First versus second versus third test	EIH group: NSD in distance from first to second to third day
	Non-EIH group: 38 (19)	Non-EIH group: 1.0±0.1 (38.9±1.8)		Non-EIH group: significant increase in distance from first to second day (Δ92 m [12%]; baseline NR); significant increase in distance from second to third day (Δ28 m [4%]; baseline NR)
Beaumont et al^Citation37	12 (10)	1.03±0.27 (NR)	First versus second versus third test	Significant increase in distance from first to second day (Δ46 m [6.5%]); NSD in distance from second to third day (Δ37 m [4.9%])
Berger and Smith^Citation38	10 (10)	Moderate/severe COPD	Familiarization then first versus second test	NSD in distance from first to second test after familiarization (Δ13 m [2.2% using values from Beaumont et al^Citation37])
McGavin et al^Citation39	35 (35)	Chronic bronchitis	First versus second versus third test	Significant increase in distance from first to second day (Δ64 m [7.2%]); NSD in distance from second to third day (Δ41 m [4.3%])
Mungall and Hainsworth^Citation40	13 (13)	1.5±0.4 (NR); chronic bronchitis or radiological emphysema	First versus second versus third test (with three further tests NR in detail)	Significant increase in distance in third test compared with first and second; NSD distance on three subsequent tests (distances NR)
O’Reilly et al^Citation22	10 (10)	Chronic bronchitis or radiological emphysema	Familiarization then first versus second test	NSD in distance from first to second day after familiarization (Δ38 m [4.8%])
Swinburn et al^Citation41	17 (6)	0.77±0.30 (NR)	First versus second versus third versus fourth test	Progressive, significant increases in distance from first to fourth day (16%; baseline NR)

Notes:

a Repeatability = similarity of test results when performed on the same day;

b reproducibility = similarity of test results when performed on different days.

Abbreviations: CG, control group; CI, confidence interval; EIH, exercise-induced hypoxia; FEV₁, forced expiratory volume (L) in 1 second; ICC, intra-class correlation coefficient; IQR, interquartile range; NR, not reported; NSD, no significant difference; SD, standard deviation; TG, training group; m, meters; min, minutes.

Table 2 Repeatability and reproducibility of incremental shuttle walk test, endurance shuttle walk test, incremental treadmill test, and endurance treadmill test

Study	Patients, n (males, n)	Disease severity (mean ± SD FEV1 [mean ± SD% predicted] or COPD grading, unless otherwise stated)	Comparison	Additional information
Incremental shuttle walk test
Repeatabilitya
Eiser et al^Citation18	57 (30)	NR (35.00±12.00)	First versus second versus third test	Significant increase in distance from first to second test (Δ13 m; 4.7%]); NSD in distance from second to third test (Δ6 m [2.1%])
McKeough et al^Citation23	53 (34) 31 (NR)	NR (55.00±19.00) NR (51.00±16.00)	First versus second test Third versus fourth test	Significant increase in distance from first to second test (Δ20 m [6.3%])c Significant increase in distance from third to fourth test (Δ18 m [4.8%])d
Vagaggini et al^Citation21	18 (15)	NR (48.00±14.00)	Familiarization then first versus second test	Significant increase in distance from first to second test, after familiarization (Δ40 m [14.6%])e
Reproducibilityb
Arnardóttir et al^Citation44	93 (26)	Moderate/severe COPD	First versus second test	NSD in distance from first to second day (Δ9 m [2.9%])
Campo et al^Citation42	30 (18)	Mild/moderate/severe/very severe COPD	Familiarization then first versus second test	NSD in distance from first to second day (ICC =0.88) (distances NR)
Eiser et al^Citation18	57 (30)	NR (35.00±12.00)	First versus second versus third test	Significant increase in distance from first to second day (Δ13 m; 4.6%]); NSD in distance from second to third day (Δ−1 m [0.3%])
Perrault et al^Citation43	43 (36)	1.40±0.50 (49.00±16.00)	Familiarization then first versus second test	NSD in VO2, HR, VE, VT from first to second test at each of the four cadences (ICC >0.93); distance NR
Singh et al^Citation45	35 (25)	Group A: 0.50 (0.36–1.45) Group B: 1.10 (0.60–2.10)	First versus second versus third test	Downgraded protocol: NSD in distance on first, second, and third day Modified protocol: significant increase in distance from first to second day (Δ31 m [9.0%]); NSD in distance from second to third day
Endurance shuttle walk test
Repeatabilitya
Revill et al^Citation24	44 (33)	0.94±0.40 (37.00±13.00)	First versus second test	NSD in duration from first to second test (Δ12 s [6.2%])
McKeough et al^Citation23	53 (34) 31 (NR)	NR (55.00±19.00) NR (51.00±16.00)	First versus second test Third versus fourth test	NSD in duration from first to second test (Δ−2 s [5.8%]) NSD in duration from third to fourth test (Δ44 s [8.7%])
Reproducibilityb
Revill et al^Citation47	44 (22)	Group A: 1.01±0.36 (35.00±4.00) Group B: 0.79±0.21 (34.00±4.00) Group C: 0.80±0.18 (35.00±8.00)	First versus second versus third test	Significant increase in duration from first to second day (Δ59 s; 23.5%]); NSD in duration from second to third day (Δ15 s [4.8%])
Revill et al^Citation46	23 (13)	0.81±0.27 (33.00±12.00)	Familiarization then first versus second test	NSD in duration from first to second test after familiarization (tests performed with supplemental oxygen)
Endurance treadmill test
Reproducibilityb
Cooper et al^Citation52	470 (NR)	Moderate/severe/very severe COPD	First versus second test	NSD in duration from first to second test (Δ24 s [7.6%]) (ICC =0.85)
Incremental treadmill test
Reproducibility
Mathur et al^Citation50	8 (6)	0.69±0.16 (NR)	First versus second test	Numerical increase in peak VO2 from first to second test (Δ1.0 mL/min/kg [8.3%]; statistical test NR)

Notes:

a Repeatability = similarity of test results when performed on the same day

b reproducibility = similarity of test results when performed on different days

c P<0.001

d P≤0.05

e P≤0.01

Abbreviations: FEV₁, forced expiratory volume (L) in 1 second; HR, heart rate; ICC, intra-class correlation coefficient; NR, not reported; NSD, no significant difference; SD, standard deviation; V_E, expired volume; VO₂, oxygen consumption; V_T, tidal volume; m, meters; min, minutes; s, time in seconds.

Table 3 Repeatability and reproducibility of cycling tests

Study	Patients, n (males, n)	Disease severity (mean ± SD FEV1 [mean ± SD% predicted] or COPD grading, unless otherwise stated)	Comparison	Additional information
Incremental cycle ergometer test
Repeatabilitya
Brown et al^Citation25	11 (NR)	1.51±0.59 (NR)	First versus second test	NSD in peak VO2 from first to second test (Δ53 mL/min [4.0%]); NSD in Wmax from first to second test (Δ0 W [0%])
Reproducibilityb
Brown et al^Citation25	11 (NR)	1.51±0.59 (NR)	First versus third test	NSD in peak VO2 from first to third test (Δ93 mL/min [7.1%]); NSD in Wmax from first to third test (Δ0 W [0%])
Covey et al^Citation48	56 (40)	NR (49.00±16.00)	First versus second test	NSD in peak VO2 from first to second day (Δ0.011 L/min [0.9%]); NSD in Wmax from first to second day (Δ1 W [1.5%])
Cox et al^Citation49	11 (8)	Individually listed in paper	First versus second test	NSD in peak VO2 from first to second day (Δ0.04 L/min [2.0%]); NSD in Wmax from first to second day (Δ1 W [0.6%])
Mathur et al^Citation50	8 (6)	0.69±0.16 (NR)	First versus second test	Numerical increase in peak VO2 from first to second test (Δ0.8 mL/min/kg [6.8%]; statistical test NR)
Poulain et al^Citation30	10 (NR)	Moderate COPD	Familiarization then first versus second test	NSD in %-predicted peak VO2 from first to second day (Δ2.5%-predicted VO2 [3.9%]); NSD in Wmax from first to second day (Δ1 W [1.3%])
Swinburn et al^Citation41	17 (6)	0.77±0.30 (NR)	First versus second versus third versus fourth test	Progressive and significant increases in duration from first to fourth day (29%; baseline values NR) (VO2/Wmax NR)
Endurance cycle ergometer test
Reproducibilityb
van’t Hul et al^Citation51	60 (46)	Moderate/severe COPD	First versus second test	NSD in duration from first to second test (Δ−12 s [approximately −4.4%]) (ICC =0.85)

Notes:

a Repeatability = similarity of test results when performed on the same day;

b reproducibility = similarity of test results when performed on different days.

Abbreviations: FEV₁, forced expiratory volume (L) in 1 second; ICC, intra-class correlation coefficient; NR, not reported; NSD, no significant difference; SD, standard deviation; VO₂, oxygen consumption; W_max, maximum workload; W, watts; min, minutes; s, time in seconds.

Table 4 Between-test comparisons of sensitivity to interventions

Study	N	Result	Additional information
Pulmonary rehabilitation
6-minute walk test
Borghi-Silva et al^Citation54	8 (Car) 8 (Pla)	Significant increase in distance: Δ87 m (19.8%) (>MCID) Significant increase in distance: Δ34 m (7.3%) (>MCID)	Training with concomitant carnitine versus placebo; ITT conducted but peak VO2 and Wmax NR
Borghi-Silva et al^Citation53	20	Significant increase in distance: Δ105 m (27.8%) (>MCID)	Training significantly improved peak VO2 compared with control group
Carrieri-Kohlman et al^Citation57	51	Significant increase in distance: Δ52.1 m (11.7%) and Δ50.3 m (12.7%) (>MCID)	Improvements were similar in both tests whether patients were given a monitored or coached pulmonary rehabilitation program
Cooper^Citation55	7 (GPT) 9 (IMT)	Significant increase in distance: Δ32 m (6.9%) (>MCID) IMT, Δ23 m (4.8%)	Patients in IMT group showed significant improvement in pulmonary function test; increase in GPT group was not significant
Cortopassi et al^Citation58	71	NSD in distance	ITT and ETT both responded significantly to PR, but 6MWT did not
Eaton et al^Citation59	20	Significant increase in distance: Δ47 m (17%) (>MCID)	Standardized mean differences after PR: 6MWT, 0.32 versus ESWT, 0.54 The authors note: “The ESWT has potential advantages in that it may be more responsive than the 6MWT” Values taken from text (do not match Eaton et al)^Citation59
Ngaage et al^Citation61	14	Significant increase in distance: Δ68.3 m (36.3%) (>MCID)	ISWT values taken from Ngage et al;^Citation61 changes in both 6MWT and ISWT after PR were clinically significant
Ong et al^Citation63	37	Significant increase in distance: Δ36 m (9.0%) (>MCID)	6MWT did not correlate with ICET or ECET responses to PR; moderate correlation between ICET Wmax and ECET duration (r=0.406; P=0.013)
Ries et al^Citation64	1,218	Significant increase in distance: Δ23.0 m (6.6%) (non-MCID)	Patients who had never previously received PR responded more favorably than those who had (Δ6MW distance: 31.0 versus 18.5 m; ICET Wmax: 4.3 versus 2.4 W)
Van Helvoort et al^Citation65	18	Significant increase in distance: Δ63 m (14.8%) (>MCID)	6MWT, ICET, and ECET had greater validity in assessing responses to PR than cardiorespiratory measures
Van Ranst et al^Citation66	389	Significant increase in distance: Δ52 m (14.2%) (>MCID)	Clinically relevant response after PR for both tests; greater sensitivity in the ECET than in the 6MWT (not assessed statistically)
12-minute walk test
Arnardóttir et al^Citation56	28 (IT) 32 (CT)	Significant increase in distance: Δ75 m (9.0%) Significant increase in distance: Δ94 m (10.8%)	Similar improvements in 12MWT distance and Wmax whether training was IT or CT; peak VO2 was higher in CT, but VO2 values at isotime were lower in IT
Incremental shuttle walk test
Greening et al^Citation60	601	Significant increase in distance: Δ61 m (28.9%) (>MCID)	Clinically relevant response after PR for both tests; greater sensitivity in the ESWT than in the ISWT (not assessed statistically)
McKeough et al^Citation23	31	Significant increase in distance: Δ46 m (15%) (non-MCID)	Results are calculated from the better of two pre-PR test results versus the better of two post-PR test results Values taken from Table 2
Ngaage et al^Citation61	14	Significant increase in distance: Δ57.1 m (52.9%) (>MCID)	ISWT values taken from Ngage et al;^Citation61 changes in both 6MWT and ISWT after PR were clinically significant
O’Farrell et al^Citation62	85	Significant increase in distance: Δ52.9 m (33.3%) (>MCID)	ESWT more responsive than ISWT to determine improvements in exercise capacity following PR
Revill et al^Citation47	44	Significant increase in distance: Δ36 m (20.2%) (non-MCID)	Clinically relevant response after PR in ESWT but not ISWT; greater sensitivity in ESWT than in ISWT (effect size 2.90 versus 0.41)
Endurance shuttle walk test
Eaton et al^Citation59	20	Significant increase in distance: Δ302 m (92%) (>MCID); significant increase in duration: Δ270 s (88%) (>MCID)	Standardized mean differences after PR: 6MWT, 0.32 versus ESWT, 0.54 The authors note: “The ESWT has potential advantages in that it may be more responsive than the 6MWT” Values taken from text (do not match Eaton et al)^Citation59
Greening et al^Citation60	601	Significant increase in duration: Δ408 s (205.4%) (>MCID)	Clinically relevant response after PR for both tests; greater sensitivity in the ESWT than in the ISWT (not assessed statistically)
McKeough et al^Citation23	31	Significant increase in duration: Δ182 s (58%)	Results are calculated from the better of two pre-PR test results versus the better of two post-PR test results Values taken from McKeough et al^Citation23
O’Farrell et al^Citation62	85	Significant increase in distance: Δ271.0 m (106.7%) (>MCID); significant increase in duration: Δ293.1 s (no percentage change or baseline value provided) (>MCID)	ESWT more responsive than ISWT to determine improvements in exercise capacity following PR
Revill et al^Citation47	44	Significant increase in distance: Δ334 m (140%) (>MCID); significant increase in duration: Δ404 s (150%) (>MCID)	Clinically relevant response after PR in ESWT but not ISWT; greater sensitivity in ESWT than in ISWT (effect size 2.90 versus 0.41)
Incremental cycle ergometry test
Arnardóttir et al^Citation56	28 (IT) 32 (CT)	Significant increase in peak VO2: Δ53 mL/min (5.4%); significant increase in Wmax : Δ11 W (18.0%) (>MCID) Significant increase in peak VO2 : Δ146 mL/min (15.0%); significant increase in Wmax: Δ11 W (17.2%) (>MCID)	Similar improvements in 12MWT distance and Wmax whether training was IT or CT; peak VO2 was higher in CT, but VO2 values at isotime were lower in IT
Cooper^Citation55	7 (GPT) 9 (IMT)	NSD in peak VO2 or Wmax NSD in peak VO2 or Wmax	Patients in IMT group showed significant improvement in pulmonary function test, increase in GPT group was not significant
Ong et al^Citation63	37	Significant increase in peak VO2: Δ172 mL/min (20.0%); significant increase in Wmax: 6 W (12.0%) (>MCID)	6MWT did not correlate with ICET or ECET responses to PR; moderate correlation between ICET Wmax and ECET duration (r=0.406; P=0.013)
Ries et al^Citation64	1,218	Significant increase in Wmax : Δ3.1 W (8.6%) (non-MCID)	Patients who had never previously received PR responded more favorably than those who had (Δ6MWT distance: 31.0 versus 18.5 m; ICET Wmax: 4.3 versus 2.4 W)
Van Helvoort et al^Citation65	18	NSD in Wmax and peak VO2	6MWT, ICET, and ECET had greater validity in assessing responses to PR than cardiorespiratory measures
Endurance cycle ergometry test
Ong et al^Citation63	37	Significant increase in duration: Δ322 s (73.5%)	6MWT did not correlate with ICET or ECET responses to PR; moderate correlation between ICET Wmax and ECET duration (r=0.406; P=0.013)
Van Helvoort et al^Citation65	18	Significant increase in duration: Δ6.5 min (166%)	6MWT, ICET, and ECET had greater validity in assessing responses to PR than cardiorespiratory measures
Van Ranst et al^Citation66	389	Significant increase in duration: Δ241 s (84.6%)	Clinically relevant response after PR for both tests; greater sensitivity in the ECET than in the 6MWT (not assessed statistically)
Incremental treadmill test
Borghi-Silva et al^Citation54	8 (Car) 8 (Pla)	Peak VO2 and Wmax NR Peak VO2 and Wmax NR	Training with concomitant carnitine versus placebo; ITT conducted but peak VO2 and Wmax NR
Borghi-Silva et al^Citation53	20	Significant increase in peak VO2 : Δ2 mL/min/kg (14.3%)	Training significantly improved peak VO2 compared with control group
Carrieri-Kohlman et al^Citation57	51	NSD in peak VO2 in either group; significant increase in maximum work (exercise stage): Δ1.6 levels (34.0%) and Δ1.5 levels (34.1%)	Improvements were similar in both tests whether patients were given a monitored or coached pulmonary rehabilitation program
Cortopassi et al^Citation58	71	Significant increase in duration: Δ184 s (27.4%); significant increase in distance: Δ190 m (22.1%); VO2 and Wmax NR	ITT and ETT both responded significantly to PR, but 6MWT did not
Endurance treadmill test
Cortopassi et al^Citation58	71	Significant increase in duration: Δ534 s (106.0%); VO2 and Wmax NR	ITT and ETT both responded significantly to PR, but 6MWT did not
Bronchodilator therapy
6-minute walk test
Cazzola et al^Citation67	22	Significant increase in distance: Δ53.6 m (baseline values NR) (>MCID)	“6-MWT seems to be a more appropriate instrument than 12-MWT for assessing the exercise response to a bronchodilator”
Eiser et al^Citation18	54 (6MWT)	Significant increase in distance: Δ37 m (8.7%) (>MCID)	Sensitivity index: 6MWT, 0.84; ISWT, 0.76; distance calculated by number of shuttles performed (1 shuttle =10 m) “There is no important difference in either the reproducibility or sensitivity of self- paced or externally paced walking tests”
Oga et al^Citation68	38	Significant increase in distance: Δ6 m (1.2%) (non-MCID)	Percentage improvement: 6MWT, 1%; ICET, 3%; ECET, 19% “Among the frequently used post-PR exercise tests, the most responsive index, as measured by the percentage change from baseline, is the endurance time. The correlation between the post-PR changes in these exercise indices is poor”
Pepin et al^Citation14	14	NSD in distance	“The endurance shuttle walk is more responsive to the acute effects of bronchodilation than the 6MWT”
12-minute walk test
Cazzola et al^Citation67	22	Significant increase in distance: Δ59.9 m (baseline values NR) (>MCID)	“6-MWT seems to be a more appropriate instrument than 12-MWT for assessing the exercise response to a bronchodilator”
Incremental shuttle walk test
Eiser et al^Citation18	50 (ISWT)	Significant increase in distance: Δ30 m (11.1%) (non-MCID)	Sensitivity index: 6MWT, 0.84; ISWT, 0.76; distance calculated by number of shuttles performed (1 shuttle =10 m) “There is no important difference in either the reproducibility or sensitivity of self- paced or externally paced walking tests”
Endurance shuttle walk test
Pepin et al^Citation14	14	Significant increase in distance: Δ144 m (40.0%) (>MCID); duration NR	“The endurance shuttle walk is more responsive to the acute effects of bronchodilation than the 6MWT”
Pepin et al^Citation69	17	Significant increase in duration: 164 s (>MCID)	“Standardized response mean larger for walking than cycling (0.93 and 0.20, respectively)”; % change and baseline NR
Incremental cycle ergometry test
Oga et al^Citation68	38	NSD in peak VO2 ; significant increase in Wmax : 3 W (3.4%)	Percentage improvement: 6MWT, 1%; ICET, 3%; ECET, 19% “Among the frequently used post-PR exercise tests, the most responsive index, as measured by the percentage change from baseline, is the endurance time. The correlation between the post-PR changes in these exercise indices is poor”
Endurance cycle ergometry test
Oga et al^Citation68	38	Significant increase in duration: 34 s (18.0%)	Percentage improvement: 6MWT, 1%; ICET, 3%; ECET, 19% “Among the frequently used post-PR exercise tests, the most responsive index, as measured by the percentage change from baseline, is the endurance time. The correlation between the post-PR changes in these exercise indices is poor”
Pepin et al^Citation69	17	NSD in duration	“Standardized response mean larger for walking than cycling (0.93 and 0.20, respectively)”; % change and baseline NR
Zhang et al^Citation70	20	Significant increase in duration: Δ157 s (47.1%)	Values taken from Zhang et al^Citation70 (percentage estimates in text are different); greater percentage change in ECET than in TT
Endurance treadmill test
Zhang et al^Citation70	20	Significant increase in duration: Δ110 s (30.4%); Wmax NR	Values taken from Table 4 (percentage estimates in text are different); greater percentage change in ECET than in TT
Lung-volume reduction surgery
6-minute walk test
Lederer et al^Citation71	23	Significant increase in distance: Δ38 m (9.1%) (>MCID)	Measurements taken 1 year after surgery; clinically relevant change in 6MWT; greater percentage change in ICET than in 6MWT
Incremental cycle ergometry test
Lederer et al^Citation71	23	NSD in peak VO2; significant increase in Wmax: 6 W (15.4%)	Measurements taken 1 year after surgery; clinically relevant change in 6MWT; greater percentage change in ICET than in 6MWT

Abbreviations: 6MWT, 6-minute walk test; 12MWT, 12-minute walk test; Car, patients receiving carnitine supplements; CT, continuous training; ECET, endurance cycle ergometer test; ESWT, endurance shuttle walk test; ETT, endurance treadmill test; GPT, general physical training; ICET, incremental cycle ergometer test; IMT, inspiratory muscle training; ISWT, incremental shuttle walk test; IT, interval training; ITT, incremental treadmill test; MCID, minimal clinically important difference; NR, not reported; NSD, no significant difference; pla, patients receiving placebo; VO₂, oxygen consumption; PR, pulmonary rehabilitation; TT, treadmill test; VAS, visual analog scale; V_E, ventilation; W_max, maximum workload; W, watt.

Table 5 Protocol variations reported to affect performance of exercise capacity test

Test	Variation	Study
6MWT	Track layout	Sciurba et al^Citation33 Casas et al^Citation76 Bansal et al^Citation17
	Supplemental oxygen provided	Revill et al^Citation46 Borghi-Silva et al^Citation75 Davidson et al^Citation77 Ozalevli et al^Citation83
	Corridor versus treadmill	Stevens et al^Citation20
	Indoor versus outdoor environment	de Almeida et al^Citation78
	Wheeled walker support provided	Honeyman et al^Citation80
	Verbal encouragement provided	Crisafulli et al^Citation73
12MWT	Corridor versus treadmill	Swerts et al^Citation86
ISWT	Verbal encouragement	Rosa et al^Citation84
	Supplemental oxygen provided	Sandland et al^Citation85
ESWT	Supplemental oxygen provided	Sandland et al^Citation85
ICET	Incremental workload gradient used	Benzo et al^Citation74 Miyahara et al^Citation82
ECET	Supplemental oxygen provided	Dean et al^Citation79
ITT	Incremental workload gradient used	Hsia et al^Citation81

Abbreviations: 6MWT, 6-minute walk test; 12MWT, 12-minute walk test; ECET, endurance cycle ergometer test; ESWT, endurance shuttle walk test; ICET, incremental cycle ergometer test; ISWT, incremental shuttle walk test, ITT, incremental treadmill test.

Table S1 Embase™ search strings, search conducted January 22, 2013

Search	Search strings	Results
1	chronic obstructive pulmonary disease.mp. or exp chronic obstructive lung disease/	68,878
2	chronic obstructive lung disease.mp.	65,527
3	chronic obstructive respiratory disease.mp.	119
4	copd.mp.	33,438
5	chronic obstructive airway disease.mp.	378
6	chronic bronchitis.mp. or exp chronic bronchitis/	16,146
7	lung emphysema.mp. or exp lung emphysema/	19,606
8	chronic obstructive airway disease.mp.	378
9	chronic airflow obstruction.mp.	627
10	1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9	103,379
11	exp cardiopulmonary exercise test/or exp exercise tolerance/or exp aerobic exercise/or exp exercise/or exp exercise test/	228,181
12	(exercise or exercise capacity or exercise tolerance).mp.	302,038
13	(clinically important difference or mcid or clinically meaningful).mp.	6,903
14	11 or 12 or 13	311,378
15	(‘6 minute walk’ or ‘6m walk’ or ‘6 m walk’ or ‘six minute walk’ or ‘6MWD’).mp.	4,644
16	(‘12 minute walk’ or ‘12m walk’ or ‘12 m walk’ or ‘twelve minute walk’ or ‘12MWD’).mp.	90
17	(‘shuttle walk’ or ‘shuttle walking’ or ‘iswt’ or ‘10 metre walking’ or ‘10 meter walking’ or ‘ESWT’).mp.	1,010
18	cycle ergometer.mp. or exp bicycle ergometer/	5,540
19	bicycle ergometry.mp. or exp bicycle ergometry/	6,840
20	(cycle ergometry or cycle ergometric or bicycle ergometric).mp.	1,721
21	treadmill.mp. or exp treadmill/	29,379
22	(short physical performance battery or sppb).mp.	367
23	15 or 16 or 17 or 18 or 19 or 20 or 21 or 22	45,996
24	10 and 14 and 23	1,626
25	(test or assessment or capacity).mp.	3,225,394
24	10 and 14 and 23	1,408
25	(test or assessment or capacity).mp.	1,099

Table S2 Medline^® search strings, search conducted January 22, 2013

Search	Search string	Results
1	chronic obstructive pulmonary disease.mp. or exp pulmonary disease, chronic obstructive/	31,239
2	chronic obstructive lung disease.mp.	2,686
3	exp lung diseases, obstructive/or chronic obstructive respiratory disease.mp.	150,257
4	copd.mp.	21,567
5	chronic obstructive airway disease.mp.	239
6	chronic bronchitis.mp. or exp bronchitis, chronic/	8,867
7	lung emphysema.mp.	298
8	chronic obstructive airway disease.mp.	239
9	chronic airflow obstruction.mp.	502
10	1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9	161,227
11	exp exercise tolerance/or exp exercise test/or exercise.mp. or exp exercise/	239,508
12	(exercise capacity or exercise tolerance).mp.	16,495
13	(clinically important difference or mcid or clinically meaningful).mp.	4,675
14	11 or 12 or 13	243,911
15	(‘6 minute walk’ or ‘6m walk’ or ‘6 m walk’ or ‘six minute walk’ or ‘6mwd’).mp.	2,563
16	(‘12 minute walk’ or ‘12m walk’ or ‘12 m walk’ or ‘twelve minute walk’ or ‘12mwd’).mp.	62
17	(‘shuttle walk’ or ‘shuttle walking’ or ‘iswt’ or ‘10 metre walking’ or ‘10 meter walking’ or ‘eswt’).mp.	644
18	$cycle ergomet*.mp.	4,838
19	treadmill.mp.	20,912
20	(short physical performance battery or sppb).mp.	247
21	15 or 16 or 17 or 18 or 19 or 20	28,642
22	10 and 14 and 21	1,278
23	(test or assessment or capacity).mp.	1,939,771
24	10 and 14 and 21 and 23	1,065
25	limit 24 to (English language and humans)	928

Table S3 The Cochrane Library search strings, search conducted January 22, 2013

Search	Search string	Results
1	MeSH descriptor: [Pulmonary Disease, Chronic Obstructive] explode all trees	1,845
2	chronic obstructive pulmonary disease	4,929
3	MeSH descriptor: [Lung Diseases, Obstructive] explode all trees	12,759
4	chronic obstructive respiratory disease	3,340
5	copd	6,244
6	chronic obstructive airway disease	4,348
7	MeSH descriptor: [Bronchitis, Chronic] explode all trees	77
8	chronic bronchitis	1,969
9	lung emphysema	517
10	chronic obstructive airway disease	4,348
11	chronic airflow obstruction	416
12	#1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11	18,973
13	MeSH descriptor: [Exercise Tolerance] explode all trees	1,431
14	MeSH descriptor: [Exercise Test] explode all trees	5,816
15	MeSH descriptor: [Exercise] explode all trees	11,528
16	exercise or exercise capacity or exercise tolerance	38,220
17	clinically important difference or mcid or clinically meaningful	7,450
18	#13 or #14 or #15 or #16 or #17	45,480
19	‘6 minute walk’ or ‘6m walk’ or ‘6 m walk’ or ‘six minute walk’ or ‘6mwd’	3,377
20	‘12 minute walk’ or ‘12m walk’ or ‘12 m walk’ or ‘twelve minute walk’ or ‘12mwd’	2,233
21	‘shuttle walk’ or ‘shuttle walking’ or ‘iswt’ or ‘10 metre walking’ or ‘10 meter walking’ or ‘eswt’	716
22	*cycle ergomet*	2,392
23	treadmill	3,759
24	short physical performance batter or sppb	41
25	#19 or #20 or #21 or #22 or #23 or #24	9,217
26	test or assessment or capacity	211,756
27	#12 and #18 and #25 and #26	779

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