Characteristics and determinants of endurance cycle ergometry and six-minute walk distance in patients with COPD
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BACKGROUND: Exercise tolerance can be assessed by the cycle endurance test (CET) and six-minute walk test (6MWT) in patients with Chronic Obstructive Pulmonary Disease (COPD). We sought to investigate the characteristics of functional exercise performance and determinants of the CET and 6MWT in a large clinical cohort of COPD patients. METHODS: A dataset of 2053 COPD patients (43% female, age: 66.9 +/- 9.5 years, FEV1% predicted: 48.2 +/- 23.2) was analyzed retrospectively. Patients underwent, amongst others, respiratory function evaluation; medical tests and questionnaires, one maximal incremental cycle test where peak work rate was determined and two functional exercise tests: a CET at 75% of peak work rate and 6MWT. A stepwise multiple linear regression was used to assess determinants. RESULTS: On average, patients had impaired exercise tolerance (peak work rate: 56 +/- 27% predicted, 6MWT: 69 +/- 17% predicted). A total of 2002 patients had CET time of duration (CET-Tend) less than 20 min while only 51 (2.5%) of the patients achieved 20 min of CET-Tend . In former patients, the percent of predicted peak work rate achieved differed significantly between men (48 +/- 21% predicted) and women (67 +/- 31% predicted). In contrast, CET-Tend was longer in men (286 +/- 174 s vs 250 +/- 153 s, p < 0.001). Also, six minute walking distance (6MWD) was higher in men compared to women, both in absolute terms as in percent of predicted (443 m, 67%predicted vs 431 m, 72%predicted, p < 0.05). Gender was associated with the CET-Tend but BMI, FEV1 and FRC were related to the 6MWD highlighting the different determinants of exercise performance between CET and 6MWT. CONCLUSIONS: CET-Tend is a valuable outcome of CET as it is related to multiple clinical aspects of disease severity in COPD. Gender difference should temper the interpretation of CET.
Andrianopoulos, V., Wagers, S. S., Groenen, M. T. J., Vanfleteren, L. E., Franssen, F. M. E., Smeenk, F. W. J. M., Vogiatzis, I., Wouters, E. F. M., CIRO+ Rehabilitation Network, T., & Spruit, M. A. (2014). Characteristics and determinants of endurance cycle ergometry and six-minute walk distance in patients with COPD. BMC Pulmonary Medicine, 14, . https://doi.org/10.1186/1471-2466-14-97