Samenvatting

Background: According to the CBS the number of elderly people in the Netherlands is growing rapidly. In people over 55 and older, the prevalence of people with type 2 diabetes is high. Not only old age, but also obesity increases the risk for type 2 diabetes. Losing weight is the first advice in the treatment of obesity and type 2 diabetes. However, weight loss is often accompanied by undesirable loss of muscle mass and loss of physical function. There are many studies that have investigated the relationship between protein, exercise and muscle mass in the elderly. But there are few studies that have examined the relationship between changes in body composition and changes physical fitness. Aim: The aim of this study is to examine the relationship between changes in body composition and changes in physical fitness in obese older adults with diabetes type 2. The outcome of this study together with the literature provides evidence for realizing new guidelines for the treatment of obese elderly with type 2 diabetes. Methods: In this analysis, overweight and obese participants aged 55 years or older with type 2 diabetes are included. All participants followed a weight loss program including a three-weekly strength training session and a hypo-caloric diet (with protein or control supplement). At baseline and after 13 weeks the body composition (fat mass and appendicular muscle mass, Dual-energy X- ray absorptiometry) and the physical fitness (leg press, steep ramp test, 400-meter walking test, gait speed test, chair stand test and knee extension power test) are measured. The relationship between body composition and physical fitness was assessed using a regression analysis, with the dependent variables being the change in physical fitness, and the independent variables being the change in appendicular lean mass and fat mass. The analysis were adjusted for potential confounders. The subjects were also split in 4 groups to compare differences between each physical test and the change in appendicular lean mass and fat mass. Results: The 13-week intervention program is completed by 101 subjects. Mean BMI at baseline is 33.2 ± 4.3 kg/m2. There are no significant differences between the 4 groups in fat mass loss (yes/no) and appendicular lean mass gain (yes/no) and the change in the physical fitness tests. Regression analysis showed a significant relation between the change in fat mass and leg press (P=0.008) and the 400-meter walking test (P=0.007). Losing 1 kg of fat mass led to an improved leg press and 400- meter walk. After adjusting for confounders there were no significant relations. The relation between change in appendicular lean mass and chair stand test had a negative significant effect (P=0.048), and it also lost its significance after adjusting for confounders. Conclusion: Results showed that there is not a strong relationship between changes in body composition and changes in physical fitness in obese older adults with type 2 diabetes. Fat mass change has a positive effect on the leg press and the 400-meter walk. On the other physical tests, no effect was seen. Change in appendicular lean mass showed to have a negative effect on the chair stand test. Our hypothesis that improvements in the body composition will lead to a significantly improved physical fitness, can only be partially confirmed