According to the World Health Organization, obesity is the fifth most important risk factor responsible for cardiovascular mortality. The Six- Minute Walk Test (6MWT) is a very useful assessment of patients' exercise tolerance in clinical circumstances. Owing to submaximal exercise during the test, its results reflect patients' ability to perform daily activities.
Aim: Assessment of cardiorespiratory functions in obese patients using the 6MWT.
Materials and methods: The study group included 234 patients, divided into 3 groups depending on their BMI: Group 1 - BMI<30kg/m2, Group 2 - BMI≥30<40kg/m2, Group 3 - BMI≥40kg/m2. Laboratory tests were performed for all patients. Cardiorespiratory fitness was assessed with the 6MWT. Pulse rate, blood pressure (BP) and oxygen saturation, the degree of dyspnea and perceived exertion, the total distance walked, and the percent of the predicted mean value for the walked distance were recorded and analyzed.
Results: Pre and post the 6MWT test BP and pulse rate increased significantly with the higher BMI and were highest in Group 3. Patients with the highest BMI felt more fatigue after the test than those with the lowest BMI. Patients in Group 1 walked a significantly longer total distance compared to Group 3, However, a significantly higher pulse rate and degree of dyspnea and exertion were observed in more obese patients.
Conclusions: Morbidly obese patients covered the same walking distance as adjusted according to Enright's reference equations in the 6MWT as patients with a lower BMI. They required more effort as evidenced by the increased pulse rate and BP, and they complained of a higher degree of dyspnea and perceived exertion. Resting higher heart rates in this patient group may be an issue of concern in the context of subsequent morbidity and all-cause mortality.
Keywords: 6-minute walk test; Enright; cardiorespiratory fitness; exercise tolerance; obesity.
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