Six-Minute Walk Test Before and After a Weight Reduction Program in Obese Subjects

Obejctive: Weight loss and physical activity have shown favorable effects on risks associated with obesity. It is therefore of interest to evaluate exercise capacity and related co-morbidities in obese patients. Design and Methods: We present data from obese subjects evaluated by the 6-minute walk test (6MWT) before and after a 7.3 (6.1-8.2) month weight reduction program. Results: 251 subjects completed the test at baseline (BMI 40.6 [36.9-44.6] kg/m(2)) and 129 (51.4%) repeated the test after intervention (BMI 35.6 [31.2-38.5] kg/m(2)). The six minute walking distance (6MWD) at baseline (535 [480-580] m) and at follow up (599 [522-640] m) correlated to several cardiovascular risk markers. Age, weight, height, resting heart rate, smoking status, fP-glucose and use of beta-blockers explained 43 % of the variance in predicted 6MWD at baseline. The effect of smoking status, fP-glucose, beta-blockers, and resting heart rate lost significance at follow up. Presence of diabetes and the metabolic syndrome had a negative influence on 6MWD but did not affect the impact of intervention based on percentage increase in walking distance. Gender had no impact on 6MWD. Reported pain during the test was common but decreased after intervention (57.0% vs. 28.7%, P < 0.001). Conclusions: The 6MWT may be used to evaluate intervention success beyond kilogram weight loss in obese subjects. We present formulas to predict 6MWD and the effect of weight loss on walking distance in clinical practice. Pain is a common problem which has to be considered when giving advice on exercise as a part of weight loss intervention.