Is an Individual Prediction of Maximal Work Rate by 6-Minute Walk Distance and Further Measurements Reliable in Male Patients with Different Lung Diseases?

Abstract

Background: In patients with chronic lung diseases, the work rate for endurance training is calculated by the maximal work rate (W_max). Because the assessment bears side effects, a prediction by easier accessible tests would be of practical use. Objective: We addressed the reliability of predicting W_max on the basis of the 6-min walk distance (6MWD) test and a set of further parameters in patients with different lung diseases. Methods: Baseline data of a longitudinal study including 6MWD, W_max, peripheral muscle force, lung function, fat-free mass and dyspnea (Modified Medical Research Council score) of 255 men with occupational lung diseases (104 asthma, 69 asbestosis, 42 silicosis, 40 chronic obstructive pulmonary disease) were evaluated. Results: 6MWD correlated with W_max (r = 0.51, p < 0.05). The product of 6MWD and body weight, in particular fat-free mass, led to an improvement in the correlation of W_max with 6MWD. Muscle force, lung function and Modified Medical Research Council score correlated moderately but significantly with W_max (p < 0.05 each). The maximum correlation gained by including 6MWD and further parameters in the prediction equations was r = 0.76 in patients with obstructive lung function impairment and r = 0.61 in asbestosis patients. The residual standard deviations of W_max predicted by the calculated equations ranged between 20 and 28 W, and the 95% prediction intervals of W_max ranged between ±47 and ±65 W. Conclusions: A reliable prediction of individual W_max by 6MWD or related measures and therefore a replacement by other tests is not possible. Nevertheless, it may be useful for the comparison of average values in epidemiological and clinical studies.

ERS statement on standardisation of cardiopulmonary exercise testing in chronic lung diseases

“…The selected work rate increment allows the duration of the incremental exercise phase to be approximately 10 min, typically ranging between 8 and 12 min [8]. Choice of the rate of increment depends on underlying disease, age, sex, body size, pulmonary function, physical activity, fitness and possible other factors such as genetics and medication [65][66][67]. The incremental phase is designed to last about 10 min, somewhat shorter or longer tests may also provide useful information.…”

“…Cycle ergometry protocols Some studies have provided work rate increment estimation for cycle ergometry based on different variables for patients with COPD [65], CF [66], asbestosis, silicosis and asthma [67]. Other, more general recommendations for the selection of work rate, increments are based on estimated V′ O 2peak and V′ O 2 during unloaded pedalling [8].…”

Winter Exercise Reduces Allergic Airway Inflammation: A Randomized Controlled Study

“…Although a significant effect was found for the peak respiratory frequency, the RTEs show a rather small treatment effect. The 6MWT distance is a simple surrogate parameter for cardio-respiratory fitness [54]. Both groups presented high 6MWT distances (exercise group 104.35 ± 8.17%; control group 103.36 ± 10.49%) at baseline.…”

Standardisation of cardiopulmonary exercise testing in chronic lung diseases: summary of key findings from the ERS task force

“…However, work rate increments have proved difficult to estimate due to the lack of reported patient datasets and heterogeneity of lung diseases that clearly limits the use of the work rate increment estimations for clinical practice. Previous studies have provided work rate increment estimation for cycle ergometry for people with COPD [14], cystic fibrosis [15], asbestosis, silicosis and asthma [16], and for treadmill testing for healthy adults [17,18] and COPD patients [19,20]. Other, more general recommendations for the selection of work rate increments are based on estimated peak oxygen uptake (V O 2 peak) and V O 2 during unloaded pedalling [8].…”