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Abstract
The product of walking distance and body weight (D·W) mimics the work of walking. We hypothesized the superiority of D·W to walking distance (D) alone in any correlation with lung function, anaerobic threshold (AT) and maximal oxygen uptake (V̇O2max). We further hypothesized that the D·W product for a 6-min walk test (6 MWT) would correlate with the AT andV̇O2maxbecause all three are markers of exercise ability.
Thirty-three male chronic obstructive pulmonary disease (COPD) patients with mean forced expiratory volume in 1 sec (FEV1) of 1·2±0·4 l (range 0·58–1·86 l) were enrolled. Six patients were excluded due to inability to achieve a maximal test. Lung function and self-assessed every-day activities using a oxygen–cost diagram were evaluated before entry of the study. A maximal effort ramp-pattern cardiopulmonary exercise test (CPET) and a 6 MWT were conducted in random order. Borg score, heart rate, and O2saturation with pulse oximetry (SPO2) were measured during both exercise tests.V̇O2AT and minute ventilation were also measured during the CPET. Correlations were sought between the distance covered in the 6 MWT, and the D·W product with AT,V̇O2maxand other variables.
The average D and D·W were 456 m and 27·5 kgkm−1, respectively. D·W was superior to D alone when correlated with theV̇O2maxand AT determined from the CPET, while modestly correlated with the change (Δ) in Borg score and ΔSpO2in the 6 MWT and self-assessed every-day activities. Distance×weight product was correlated with the AT andV̇O2max. In addition, D·W was better correlated with diffusing capacity for carbon monoxide and vital capacity than D alone.
We conclude that D·W mimics the work of walking better than D and is suggested as a parameter for evaluation of patients' fitness if gas exchange measurements are not available.
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References
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Publication history
Accepted:
April 16,
2001
Received:
June 27,
2000
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© 2001 Harcourt Publishers Ltd. Published by Elsevier Inc.
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