Estimating maximum work rate during incremental cycle ergometry testing from six-minute walk distance in patients with chronic obstructive pulmonary disease

Objective: To develop a predictive equation to permit estimation Of the maximum work rate (Wmax) achieved during. an incremental cycle ergometry test from the measurement of 6-minute walk distance (6MWD) and its derivative, 6-minute walk work, which is the product of 6MWD and body Weight.Design: Cross-sectional observational Study.Setting: Outpatient physiotherapy and pulmonary physiology clinics in a tertiary hospital.Participants: Patients (N=50, 36 men) with chronic obstructive pulmonary disease (forced expiratory volume in I second [FEV1]=37% +/- 11 % of predicted).Interventions: Not applicable.Main Outcome Measures: Measurements were obtained of 6MWD and Wmax achieved during I laboratory-based, symptom-limited incremental cycle ergometry test. Linear regression analyses were performed using, 6MWD. height, weight and FEV1 and using 6-minute walk work. height, and FEV1 to determine their contribution to Wmax and to develop preditive equations for estimating Wmax.Results: The equations derived to estimate Wmax using 6MWD and 6-minute walk work, respectively, were as follows: Wmax (W)=(0.122X6MWD)+(72.683Xheight [m])-117.109 (r(2)=.67, standard error of the estimate [SEE]= 10.8W) and Wmax (W)=17.393+(1.442X6-minute walk work) (r(2)=.60,, SEE = 11.8W).Conclusions: Wmax can be estimated from equations based oil measurements of 6MWD or 6-minute walk work. The estimate of Wmax derived from either equation may provide a basis on which to prescribe cycle ergometry training work rates that comply with the current guidelines for pulmonary rehabilitation.