Comparing peak and submaximal cardiorespiratory responses during field walking tests with incremental cycle ergometry in COPD.
OBJECTIVE
Field and laboratory-based tests are used to measure exercise capacity in people with COPD. A comparison of the cardiorespiratory responses to field tests, referenced to a laboratory test, is needed to appreciate the relative physiological demands. We sought to compare peak and submaximal cardiorespiratory responses to the 6-min walk test, incremental shuttle walk test and endurance shuttle walk test with a ramp cycle ergometer test (CET) in patients with COPD.


METHODS
Twenty-four participants (FEV(1) 50 ± 14%; 66.5 ± 7.7 years; 15 men) completed four sessions, separated by ≥24 h. During an individual session, participants completed either two 6-min walk tests, incremental shuttle walk tests, endurance shuttle walk tests using standardized protocols, or a single CET, wearing a portable gas analysis unit (Cosmed K4b(2)) which included measures of heart rate and arterial oxygen saturation (SpO(2)).


RESULTS
Between tests, no difference was observed in the peak rate of oxygen uptake (F(3,69) = 1.2; P = 0.31), end-test heart rate (F(2,50) = 0.6; P = 0.58) or tidal volume (F(3,69) = 1.5; P = 0.21). Compared with all walking tests, the CET elicited a higher peak rate of carbon dioxide output (1173 ± 350 mL/min; F(3,62) = 4.8; P = 0.006), minute ventilation (48 ± 17 L/min; F(3,69) = 10.2; P < 0.001) and a higher end-test SpO(2) (95 ± 4%; F(3,63) = 24.9; P < 0.001).


CONCLUSIONS
In patients with moderate COPD, field walking tests elicited a similar peak rate of oxygen uptake and heart rate as a CET, demonstrating that both self- and externally paced walking tests progress to high intensities.
Respiratory Medicine, West Park Healthcare Centre, University of Toronto, Toronto, Canada.
Kylie
K
Hill
Thomas E
TE
Dolmage
Lynda
L
Woon
Debbie
D
Coutts
Roger
R
Goldstein
Dina
D
Brooks
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D012720:Severity of Illness Index; D016138:Walking