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.


METHODS
Cross-sectional observational study.


METHODS
Outpatient physiotherapy and pulmonary physiology clinics in a tertiary hospital.


METHODS
Patients (N=50; 36 men) with chronic obstructive pulmonary disease (forced expiratory volume in 1 second [FEV(1)]=37%+/-11% of predicted).


METHODS
Not applicable.


METHODS
Measurements were obtained of 6MWD and Wmax achieved during a laboratory-based, symptom-limited incremental cycle ergometry test. Linear regression analyses were performed using 6MWD, height, weight, and FEV(1) and using 6-minute walk work, height, and FEV(1) to determine their contribution to Wmax and to develop predictive equations for estimating Wmax.


RESULTS
The equations derived to estimate Wmax using 6MWD and 6-minute walk work, respectively, were as follows: Wmax (W)=(0.122 x 6MWD)+(72.683 x height [m])-117.109 (r(2)=.67, standard error of the estimate [SEE]=10.8W) and Wmax (W)=17.393+(1.442 x 6-minute walk work) (r(2)=.60, SEE=11.8W).


CONCLUSIONS
Wmax can be estimated from equations based on 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.
Hill
Kylie
K
Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia. Kylie.Hill@westpark.org
Jenkins
Sue C
SC
Cecins
Nola
N
Philippe
Danielle L
DL
Hillman
David R
DR
Eastwood
Peter R
PR