Field-based walking tests of exercise capacity elicit similar peak heart rate and oxygen uptake as incremental cycle ergometry tests in patients with COPD
K. Hill, L. Woon, T. Dolmage, R. Goldstein, D. Brooks (Toronto, ON, Canada)
Source: Annual Congress 2008 - Physiological response to exercise performance
Session: Physiological response to exercise performance
Session type: E-Communication Session
Number: 3290
Disease area: Airway diseases
Abstract Walking-based protocols, including the 6-minute walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) are used to assess exercise capacity in patients with COPD. It is unclear how the cardio-respiratory responses elicited during these tests relate to each other, and to those elicited during an incremental cycle ergometry test (ICET). This information is important in determining the relative physiological demands among exercise tests. Methods: 6 patients (FEV1 = 55 ± 20% pred; 4 males) completed two 6MWTs, two ISWTs, two ESWTs and one ICET on separate days, in random order. Using a portable gas analysis system, measurements of oxygen uptake (VO2 ), minute ventilation (VE ) and heart rate (HR) were averaged over the last 20 seconds of each test. Arterial oxygen saturation (SpO2 ) by pulse oximetry was measured on test completion. For each walking test, the mean was analysed.
Results 6MWT ISWT ESWT ICET VO2 (L/min) 1.46 ± 0.56 1.27 ± 0.47 1.40 ± 0.60 1.37 ± 0.66 VE /MVV (L/min) 108 ± 30* 101 ± 27* 108 ± 38* 123 ± 38 %HRmax 84 ± 8 84 ± 8 86 ± 10 84 ± 17 SpO2 (%) 82 ± 6* 82 ± 5* 82 ± 6* 93 ± 5
Mean ± SD; *: p<0.05 vs. ICET; MVV: maximum voluntary ventilation; %HRmax: percentage of estimated maximum HR Conclusions: Walking and cycle-based tests elicited similar HR and peak VO2 indicating that field-based walking tests elicit similar cardiac and oxidative demands in these patients. Despite greater hypoxemia, the difference in VE /MVV suggests that there is a ventilatory reserve at the end of walk tests. Financial support: Physicians‘ Services Incorporated Foundation.
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K. Hill, L. Woon, T. Dolmage, R. Goldstein, D. Brooks (Toronto, ON, Canada). Field-based walking tests of exercise capacity elicit similar peak heart rate and oxygen uptake as incremental cycle ergometry tests in patients with COPD. Eur Respir J 2008; 32: Suppl. 52, 3290
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