I’ve decided to do a series of blog posts highlighting some of the studies I’ve collected exploring the link between physical activity and metabolic health (specifically Insulin Resistance, as it’s central to many metabolic diseases including PCOS and Diabetes, and probably at least partially causative in more far ranging diseases such as cancer and Alzheimers, among others). You can view the entire series of posts here, keep in mind that I started this series on January 10, 2013. There will eventually be dozens of entries.
Today I’m looking at this study from the New England Journal of Medicine:
Increased Glucose Transport–Phosphorylation and Muscle Glycogen Synthesis after Exercise Training in Insulin-Resistant Subjects
The study drew from an initial pool of 55 subjects. All were between 19 and 45 years of age, and all were the children of people with Non-Insulin Dependent Diabetes Mellitis (NIDDM), meaning they all had a genetic risk factor for developing Diabetes. All were in good health and within 8% of an ideal body weight. Anyone who smoked, was on medication, was very sedentary or very active, or who had high blood pressure was excluded. From this pool, the study authors drew the 10 subjects with the highest degree of insulin resistance at study onset. A group of 8 subjects matched for age, weight and activity level, but who didn’t have a parent or parents with NIDDM, were selected for control. All subjects were placed on an isocaloric weight maintenance diet (which means they were put on a diet that provided the proper caloric intake to maintain the weight they were at when the study began).
The purpose of this study was to determine the effects of exercise training on the subjects’ insulin sensitivity. Several markers of insulin sensitivity were measured at study onset, after an initial exercise session, and again after 6 weeks of exercise training. The exercise protocol consisted of 3 15 minute intervals of stair climbing, four times a week.
The exercise-training program improved insulin sensitivity by 43%, and whole-body nonoxidative glucose metabolism by 60 to 70 percent in both groups. For perspective, Metformin, one of the most frequently prescribed medications for insulin resistance, generally improves insulin sensitivity by 16-25%.
The study goes into some detail regarding the mechanisms by which exercise improves insulin sensitivity, so if you’re interested in learning more, click on through.
Improving insulin sensitivity is the first line of defense against the development of Diabetes, and exercise improves insulin sensitivity better than the most effective medications. Insulin resistance has been linked to a whole host of diseases, so any protocol aimed at reducing metabolic risk that doesn’t include regular exercise is highly suspect in my eyes. Yes, there are fad diets out there that discourage exercise and/or claim that it’s unnecessary (as long as you eat the ‘right’ foods). In this series of blog posts I intend to shed some light on the fallacy, and ultimately the danger, of such philosophies. Keep watching the blog, I’ve got dozens and dozens of these studies to share and will be posting with some regularity.