Effect of a lifestyle intervention on change in cardiorespiratory fitness in adults with type 2 diabetes: results from the Look AHEAD Study

Objective: To examine the effect of an intensive lifestyle weight loss intervention (ILI) compared to diabetes support and education (DSE) on changes in fitness and physical activity in the Look AHEAD trial. Design: Randomized clinical trial to compare a lifestyle intervention for weight loss with a DSE condition in individuals with type 2 diabetes. Subjects: Data from 4376 overweight or obese adults with type 2 diabetes (age 58.7 +/- 6.8 years, body mass index (BMI) 35.8 +/- 5.8 kg/m(2)) who completed 1 year of the Look AHEAD trial and had available fitness data were analyzed. Intervention: Subjects were randomly assigned to DSE or ILI. DSE received standard care plus three education sessions over the 1-year period. ILI included individual and group contact throughout the year, restriction in energy intake and 175 min per week of prescribed physical activity. Measurements: Fitness was assessed using a submaximal graded exercise test. Physical activity was assessed by questionnaire in a subset of 2221 subjects. Results: Change in fitness was statistically greater in ILI vs DSE after adjustment for baseline fitness (20.9 vs 5.7%; P<0.0001). Multivariate analysis showed that change in fitness was greater in overweight vs obese Class II and III (P<0.05). Physical activity increased by 892 +/- 1694 kcal per week in ILI vs 108 +/- 1254 kcal per week in DSE (P<0.01). Changes in fitness (r-0.41) and physical activity (r = 0.42) were significantly correlated with weight loss (P<0.0001). Conclusions: The ILI was effective in increasing physical activity and improving cardiorespiratory fitness in overweight and obese individuals with type 2 diabetes. This effect may add to weight loss in improving metabolic control in patients in lifestyle intervention programs.