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Exercise Prescription for Diabetes

May 4, 2002

Despite all the information that has been discussed time and time again regarding the benefits of regular exercise and it’s role in blood glucose management, there are millions of people with diabetes who don’t exercise. Their excuses include having no time, no energy, lack of motivation, and on and on. In a past article I discussed the decisional balance, which is when a patient makes a decision based on the evaluation of his/her current behavior patterns. Specific to exercise, the patient may recognize that current exercise behaviors are not helping him/her to avoid certain medical/health consequences. Perhaps the following information will help weigh a client’s decisional balance in favor of participation in regular exercise.

The March 14, 2002 edition of the New England Journal of Medicine reported on a study of 6,213 men referred for exercise testing for clinical reasons. The study began in 1987 and of the 6,213 male subjects, 3,679 were found through health history questionnaires to have some indication of cardiovascular disease. The other 2,534 had no evidence of cardiovascular disease. Medications and risk factor profiles were collected for all subjects. Each subject was tested to determine exercise capacity and results were expressed in METs (metabolic equivalents). One MET is the energy it takes to sit quietly, or in other words a resting state. Those subjects with an exercise capacity of less then 5 METs were considered to have a high risk of death. To help clarify METs, if we looked at a selected list of activities and the corresponding MET value, 5 METs would correspond to walking down a series of stairs. The subjects with an exercise capacity of more than 8 METs were considered low risk of death. Again, looking at the activity list, 8 METs would correspond to jogging one mile in 11.5 minutes. In July 2000, the researchers followed up to find out which of the subjects in the test were still alive and which were deceased. What they found, quite simply is that those who were most fit were about four times as likely to still be alive compared to those who were least fit. This finding held true for both those with and without cardiovascular disease. In addition, fitness had a greater influence than classic risk factors like high blood pressure, smoking or body weight.


The study concluded that for every one MET improvement in treadmill performance, there was a 12 percent improvement in survival. This information parallels with the National Exercise and Heart Disease Project, which showed that every one MET increase in exercise capacity reduces mortality by 8 to 14 percent. It also supports the finding of another major study showing a 7.9 percent reduction in the risk of death for every one-minute increase in treadmill time, which is roughly the same as one MET.

Why is this information important for people with diabetes? As many of us are aware, people with diabetes are 4-6 times more likely to have a heart attack. Other researchers have stated that a diabetes patients risk for a heart attack is similar to a non-diabetic who has already had a heart attack. There has also been discussion that individuals who have been recently diagnosed with diabetes probably had the disease for as long as 5-7 years before being officially diagnosed. In addition, the latest numbers report that 80% of diabetes patients’ die of cardiovascular related complications. More studies show that no matter what type of diabetes patients have, exercising regularly is one of the most beneficial things they can do for themselves.

Patients might want to think of exercise as a form of diabetes medication. When they exercise, just like when they take a drug, they must strike a fine balance between two goals: safety and effectiveness. Determining an appropriate starting point is essential when promoting a safe and positive experience. Most patients have a history of sedentary living, therefore it is unrealistic to think that these individuals will automatically be exercising at a high level of intensity. Keep in mind that a high level doesn’t necessarily have to correlate with running a mile in 11.5 minutes. It could be walking up a hill at a brisk pace. These activities are obviously what the patients are working towards. As I discussed in my previous article, many patients have arthritis and other co-morbidities, which limits the amount and intensity of their exercise. However, one of the easiest forms of activity to promote to all populations is walking. Walking doesn’t require a gym membership or expensive equipment other than a good pair of supportive and comfortable shoes. Patients can start by walking around the block and progress by walking longer distances. When the walking is no longer challenging, patients can look at other options like swimming and bicycling. The study that I discussed at the opening of this article found that the least fit individuals had the most to gain from even modest increases in fitness. When the activity is no longer challenging patients minimize the effectiveness of the activity. Specifically, the amount of calories burned per session, heart rate responses, glucose uptake by muscle and improved conditioning level.

If we look at the F.I.T.T. principal and its application to those with diabetes, it may help guide our patients to achieve maximum benefits of their chosen activity with the least amount of risk:

Frequency: 4-7 days per week (The Goal)

Intensity: 70-75% age predicted heart rate response using the Karvonen Formula *

12-13 reported effort using the Borg Scale **

“Walk Talk” test ***

Time: 180-240 minutes (3-4hours) per week (The Goal) ****

Type: Walking, Swimming, Bicycling, Hiking, Dancing, Stair Climbing, or light jogging

Intensity is an important concept. When a patient is just introducing exercise into their lives any movement is beneficial. In order to continue to “reap the benefits” we need to continue to challenge our bodies so that we are gaining the most during the time that we are setting aside to engage in regular exercise

Below are the equations and Borg scale, which were referred to earlier. They can serve as a guide for your patients.

*Karvonen Formula Calculation:

1. 220-age=maximum heart rate

2. maximum heart rate – resting heart rate = heart rate reserve (HRR)

3. HRR x .70 = __________ + Resting Heart Rate = 70% intensity

4. HRR x .75 = __________ + Resting Heart Rate = 75% intensity

To find resting heart rate count pulse for 10 seconds and multiply by 6.

** Borg Scale

Rating of Perceived Exertion Verbal Description


7 Very, very light


9 Very light


11 Light


13 Somewhat heavy


15 Heavy


17 Very Heavy


19 Very, very Heavy



When explaining the Borg scale to a patient use these pointers:

1. “6” is a resting state, like sitting or lying in bed. Notice how you are breathing through your nose during a resting state.

2. “9/10” would be slowing walking across the room as if you were headed to another room and you were in no particular hurry.

3. “11” would be a walking at a “strolling” pace, not brisk.

4. “12/13” this is the intensity that you are shooting for. You are walking briskly, you are breathing through your mouth because you need more oxygenated flow, you are beginning to feel warm, perhaps starting to perspire, BUT you are able to continue doing the activity for a while (e.g. 15-20 minutes).

5. “15 and beyond” there is absolutely nothing to be gained by exercising at this high of an intensity. As a matter of fact, you are increasing your risk as you work beyond the “14.”

6. Keep the exercise in the green. You will be achieving the most benefit with the least amount of risk.

The beauty of the RPE scale is the fact that the patient can take this scale and use it no matter where they are. If they have trouble taking their pulse because the tips of their fingers have lost feeling, then the RPE scale is a wonderful substitute. Once they work with the scale and experience what a “12/13” on effort feels like for them, then it’s a tool they can use forever. If the client prefers numbers and w a specific heart rate range to exercise in, then calculate the Karvonen formula and encourage them to purchase a heart rate monitor that they can wear throughout their exercise session. Many patients have heard of the “walk talk” test. If they can converse with their exercise partner, probably taking breaths in between words but still completing the sentence, then they are exercising at the appropriate intensity. If the patient cannot talk to their partner without becoming severely short of breath, then the patient needs to recognize that the intensity is too great, therefore slowing their pace down.

***The time stated in the F.I.T.T. principle was formulated based on the findings from two research studies, specifically the Lifestyle Heart Trial and the Heidelberg German study of secondary prevention.