Exercise: How much is enough? A discussion with Dr. Bryan Bergman concluded

July 8, 12:25 PMDiabetes ExaminerRobert Scheinman

Previous Next

1 comment Print Email RSS Subscribe

Subscribe

Get alerts when there is a new article from the Diabetes Examiner. Read Examiner.com's terms of use.

Email Address   Include other special offers from Examiner.com Terms of Use

Circuit Training (24 hour boot camp) at 24 Hour Fitness

This article finishes up an interview with Dr. Bryan Bergman, an exercise physiologist who does research on insulin signaling, diabetes, and exercise. To read the first part of this interview click here.

RS: “How does exercise fit in with diabetes prevention?”

BB: “Let’s start with insulin resistance. Exercising every other day appears to be the minimum necessary to maintain sensitivity. For example, when we look at people exercising, we find that if someone exercises on Monday, afterwards, their insulin sensitivity (the opposite of insulin resistance) is better. On Tuesday, assuming no exercise that day, their insulin sensitivity is still better than it was Monday before they exercised. By Wednesday they are back to where they were before they exercised.”

RS: “What do you think is going on?”

BB: “It probably has something to do with glycogen replenishment. Glycogen is made up of long chains of glucose and so this is where glucose is stored. When you exercise you deplete these glycogen stores and this provides empty space which can then be taken up by glucose entering the cells. Once it fills back up, insulin sensitivity is gone.”

RS: "Now I know you have an idea about old fat versus new fat" (to read about this in more detail click here).

BB: "That's true, I do think it contributes but we don't have a lot of data on it yet. it's more of a work in progress."

RS: “So how intense does this workout need to be?”

BB: “This will not surprise you. The more intense the workout, the greater the gain will be in insulin sensitivity. Harder and longer is better. In terms of a minimal dose, at least that I have data to support; it seems that 15 minutes is the minimal time necessary to get a measureable increase in insulin sensitivity. Now there is a caveat to the intensity issue. There was this great study done in South Carolina by a fellow named Joe Houmard and I quote his dataset a lot. The wild thing about his data set was that in his study exercise intensity turned out not to be so important. What was important was the duration of the exercise. He had 3 groups: high intensity short duration, moderate intensity moderate duration, and low intensity long duration. Things were set up so that each group did the same amount of work. What they were expecting to see was that the high intensity group would reap the greatest benefits but this is not what they saw at all. That group did not do as well as the long duration group. So it was the time people were moving in that study group that seemed to be the most important factor.”

RS: “So this is really interesting. What you are saying is that if someone is walking vigorously around the mall window shopping over their lunch break that could work?”

BB: “Yes, that could be effective. Now that could be effective for helping to maintain or facilitate weight loss. It will be effective for increasing insulin sensitivity. It will not be effective for improving cardiovascular disease prevention. The data says that for cardiovascular disease prevention you need a sustained bout of exercise.”

RS: “So to sum up: 20 – 30 min a day 2 – 3 times per week will improve cardiovascular health and will contribute to helping keep insulin sensitivity up but will not do much for either weight loss or maintaining weight loss. To really focus on weight loss, you need both diet and exercise with diet being the main component for losing the weight and about 45 min to an hour EVERY DAY to maintain the weight loss. For combating insulin resistance: the more the better. Increased intensity is good but long duration at even modest intensity is good.”

BB: “That’s the schema.”

Our bodies were made to move. In subsequent articles we will consult with experts as to how to transition from a sedentary lifestyle to one of movement while keeping pain, but most importantly, injury to a minimum.

Dr. Bryan Bergman is an Assistant Professor in the Division of Endocrinology at the University of Colorado Denver School of Medicine.