[MUSIC] Many people start exercising in order to lose weight, and many people get disappointed and stop exercising because they do not lose as much weight as expected. It is important to propagate the message that physical exercise has other health beneficial effects than weight reduction, and that physical exercise, although without a loss of body weight, has valuable effects. Even if the body weight is not reduced by physical exercise, the body composition might change. Skeletal muscles contractions will stimulate growth and increase muscle mass, and some of the energy expended during exercise comes from adipose tissue, wherefore fat mass can be decreased. Also, distribution of body fat is often changed by exercise training. When exercising, the abdominal fat is mobilized to a greater degree than the femoral fat. Metabolic health is not firmly defined in the literature, and I will define it as the opposite of the metabolic syndrome. The metabolic syndrome is a cluster of risk factors, which when present in a given person, signifies an increased risk of development of Type II diabetes and cardiovascular disease. The metabolic syndrome has several definitions, but abdominal obesity and insulin resistance are common to all definitions. A much used definition of the metabolic syndrome is by the International Diabetes Federation. According to this definition, a person with three or more of the following five risk factors has the metabolic syndrome. High waist circumference, 95 centimeters or above in men. High blood pressure, 130 above 85 millimeter mercury or above. High plasma triacylglycerol, 1.7 millimolar or above. High blood glucose, 5.6 millimolar or above, which is a proxy for insulin resistance. And low HDL cholesterol, below 1.03 millimolar. Hence, I define metabolic health as the opposite, namely low waist circumference, blood pressure, and plasma triacylglycerol, and high insulin sensitivity and HDL cholesterol. In our recent study in which moderately overweight men were randomized to 12 weeks control, moderate a high dose endurance training, we also investigated how metabolic health was influenced by the interventions. We found that waist circumference was decreased similarly in the two training course. Peripheral incident sensitivity was measured by the hypoglycemic isoglycemic clamp and increased by 28% in the moderate dose training group, and by 36% in the high dose training group. Likewise, a measure of insulin resistance, homa IR, decreased by 70% in the moderate dose training group, and by about 18% in the high dose training group. Fasting plasma glucose, blood pressure, did not change in any of the groups, which is not surprising, as the men had to be normal glycemic and normotensive to be included in the study. High dose endurance training reduced plasma triglyceride and increased HDL cholesterol. When all the metabolic factors were combined to define the metabolic syndrome, the number of subjects fulfilling the criteria decreased by approximately 80% in both training groups. In summary, we found marked improvements in metabolic health in healthy, moderately overweight men after 12 weeks of daily endurance training, and only minor additional health benefits were found when exercising approximately 60 as opposed to 30 minutes per day. In another randomized control study, we evaluated metabolic health effects of 12 weeks of endurance training with or without weight loss in a group of sedentary, moderately overweight men with similar inclusion criteria as mentioned before. The effects of exercise training were compared to the effects of an equal caloric energy restricted diet. 12 out of 60 subjects dropped out of the study after randomization, and their training compliance was 96%. The design of the study can be seen in this slide. The training induced weight loss group expended 600 kilocalories per day by endurance training. They were to continue with their habitual diet and neither increase nor decrease their energy intake. The diet induced weight loss group decreased their energy intake by 600 kilocalories per day and continued their sedentary living. The training and increased diet group endurance trained as the first group, but had to increase their energy intake by 600 kilocalories per day, meaning that they exercised without changing their energy balance. The last group was a control group. We did very well with respect to the study this time. As the 2 weight loss groups reduced their body weight to a similar degree, 5 to 6 kilos, during the 12 week intervention, and body weight changed in neither the training increased diet nor the control group. Body composition was assessed by scanning, and reductions in fat mass was observed from predisposed interventions in all intervention groups, but not in the control group. Fat-free mass, most likely skeletal muscle, increased in the two training groups and decreased in the diet induced weight group. The peripheral insulin sensitivity increased in both training groups, but not in the triad or control groups. Also, skeletal muscle enzymes, of importance for insulin sensitivity, increased in the two training groups. Insulin resistance, as measured by HOMA-IR, decreased in all intervention groups, but not in the control group. Overall, the study demonstrated that endurance training per se increases various metabolic health parameters, and endurance training should preferably always be included in any intervention regimen for improving metabolic health in moderately overweight men. Overweight and a low physical fitness level both increase the incidence of Type-II diabetes. In a population-based prospective study, Wei and coworkers examined nearly 9,000 men who were non-diabetic at baseline. Tests included a maximum exercise test on a treadmill and measurement of weight, height, and fasting plasma glucose. Based on BMI, the men were divided into a group of normal weight men, here defined as BMI below 27, and a group of overweight men, here defined as BMI about 27. As expected, the overweight men had a 1.5-fold higher risk of developing Type-2 diabetes than the normal weight men. Further, based on the treadmill test, the men were divided in three groups. The 20% percent least fit were designated unfit, the 40% most fit were designated very fit, and the remaining 40% are designated fit. After correcting for a number of confounders, the unfit men were found to have a 1.9-fold higher risk of impaired fasting glucose than the very fit men, and a 3.7-fold higher risk for Type-2 diabetes. Men who were both overweight and unfit had an eightfold higher incidence of Type-2 diabetes compared to men who were normal weight and very fit. Randomized control trials rank higher than cohort studies in the research evidence hierarchy, and several randomized control trials have evaluated potential of lifestyle changes to prevent Type-2 diabetes in high risk individuals. In the Finnish Diabetes Prevention Study, 522 middle-aged, overweight subjects with impaired glucose tolerance were randomized to individualized counseling aimed at reducing physical activity, reducing weight, and eating healthier, or to control mean duration of follow-up was 3.2 years. And, in this time period, the risk of developing Type-2 diabetes was reduced by 58% in the lifestyle intervention group. Likewise, in the American diabetes prevention program, more than 3,000 non-diabetic, middle aged subjects with elevated fasting glucose or impaired fasting glucose were randomized to a lifestyle intervention program, treatment with the diabetes drug Metformin or placebo. Average followup was 2.8 years, and lifestyle intervention reduced the incidence of Type-2 diabetes by 58% percent, exactly as in the Finnish study. Treatment with metformin reduced the incidence of Type-2 diabetes by only 31% percent, indicating that a lifestyle intervention is more effective than a diabetes drug in prevention of Type-2 diabetes. Similar results as in the Finnish and American studies have been found in a study of Japanese men, and taken together, all these studies demonstrate that a lifestyle intervention aiming at increase physical activity, healthy diet, and reduced body weight can postpone the development of Type 2 diabetes in high-risk individuals. None of the mentioned studies examined the effect of physical exercise alone, but this was done in a Chinese study in which nearly 600 subjects with impaired glucose tolerance were randomized to diet plus exercise, diet only, exercise only, or control. After six-year follow-up period, the cumulative incidence of diabetes was 46% in the diet plus exercise group, 44% in the diet group, 41% in the exercise group, and 68% in the control group, meaning that the risk of developing Type 2 diabetes was reduced by 42%, 31%, and 46% respectively in the three intervention groups. Thus, the Chinese study shows that physical exercise alone is also effective in prevention of Type 2 diabetes in high-risk individuals. The American Diabetes Association states that regular physical activity is important for everyone, but it is especially important for people with diabetes and those at risk for diabetes. Important benefits of regular physical activity in Type 2 diabetic patients include lowering of blood glucose, hemoglobin A1C, cholesterol, and blood pressure. During physical exercise, glucose is removed from the blood by skeletal muscle. Glucose transporter proteins lie dormant inside resting skeletal muscle cells, but, during muscle contractions, glucose transporters are translocated to the plasma membrane, whereby glucose can be transported into the muscle cell and oxidized to provide energy for muscle contractions. This process does not depend on insulin and is also present in skeletal muscles of individuals with Type 2 diabetes. Accordingly, skeletal muscle contractions can lower blood glucose in both endurance type and resistant type. Exercise has been shown to lower the subsequent 24-hour mean glucose concentration as well as prevalence of hyperglycemia in Type 2 diabetic patients. Regular physical exercise increases peripheral insulin sensitivity in healthy subjects, but can insulin resistance be treated by endurance exercise training in subjects with Type 2 diabetes? This was investigated by Dala and co-workers in 8 healthy and 7 Type 2 diabetic men who endurance trained only one leg at 70% of maximum oxygen uptake for 30 minutes per day, 6 days per week in 10 weeks. After the intervention period, hyperinsulinemic, isoglycemic clamps were performed in combination with a leg intravenous balance technique. By this method, the insulin stimulated glucose clearance can be determined simultaneously in both legs of the subject. As expected, they found that insulin stimulated glucose clearance into untrained leg was slower in Type 2 diabetic compared with healthy subjects. Reassuringly, the insulin sensitivity was higher in the trained than any untrained leg of both Type 2 diabetic and healthy subjects. Moreover, insulin sensitivity in the trained leg of the Type 2 diabetic subjects was just as high in the insulin sensitivity in the untrained leg of the healthy subjects. Improvements in insulin sensitivity in the trained legs involved both enhancements of insulin stimulated muscle blood flow and the ability to extract glucose. Interestingly, a subsequent one-legged exercise training study revealed that the resistant strain had similar effects as one-legged endurance training in Type 2 diabetes subjects. Systematic reviews and meta analyses have the highest rank in the research-evidence hierarchy. A recent Cochrane meta analysis identified 14 randomized controlled trials comparing exercise training to no exercise training in Type 2 diabetic subjects. Types of exercise training included both endurance and resistance training and the training periods were varied between eight weeks and one year with an exercise frequency of approximately three sessions per week. According to the meta-analysis, the exercise intervention improved glycemic control, as indicated by a decrease in HbA1C of 0.6%, which is considered clinically relevant. Also, reductions of visceral and subcutaneous adipose tissue depots and blood lipids were detected. No study reported adverse effects or diabetic complications. Therefore, regular physical activity should be recommended also to Type 2 diabetic individuals. [MUSIC]
