Regular physical activity or exercise has been found to provide physiological and psychological benefits that can improve blood glucose control, overall health and quality of health. For people with diabetes, exercise is one of the three cornerstones of diabetes management, in addition to meal planning and insulin/medication. Physical activity appears to help muscle cells take up and use glucose, even when there are lower levels of insulin in the blood.
Although exercise has positive health benefits for people with diabetes, it also carries some potential risks. Hyperglycemia, hypoglycemia, severe micro vascular and macro vascular complications can be exacerbated when the exercise plan is not individualized for the person with diabetes or preventative precautions are not followed.
- MECHANISM OF ACTION
A key feature of type 2 diabetes is insulin resistance. This resistance to insulin occurs in the tissues of body where glucose is taken up from the blood. Exercise acts to decrease insulin resistance making cells more sensitive to circulating insulin and causing lower blood glucose.
During exercise, the following physiological changes occur:
After 5-10 minutes of activity:
Muscle glycogen breakdown decreases. Glucose broken down in the liver is released into the blood stream and is taken up by the muscles as fuel. This glucose becomes the major source of fuel (hepatic glycogenolysis).
At 20 minutes or more:
The muscles’ glycogen stores are now depleted. Blood glucose is now maintained by hepatic glycogenolysis and triglycerides that are broken down from adipose tissue. As exercise continues fat breaks down to free fatty acids (FFA) and is used as a source of fuel for the muscles, through the process of hepatic gluconeogenesis rather than hepatic glycogenolysis.
Longer duration of exercise:
- Should low-to-moderately intensive exercise continue for a long period of time, the muscles will continue to use the glucose derived from hepatic gluconeogenesis.
- FFA cannot completely replace the use of glucose and if carbohydrates are limited, then ketones bodies may form.
- Increase the risk of DKA in a person who is insulin deficient; such as Type I with elevated blood glucose.
- If carbohydrate is consumed during exercise, the decrease in blood glucose can be delayed and the exercise can be sustained for a longer period. This is often done by people with diabetes who are marathon runners or engage in moderate to intensive exercise for long periods of time.
- CLINICAL IMPLICATIONS OF THE EFFECTS OF EXERCISE IN DIABETES
- Even short-term (2-week), regular aerobic exercise in type 2 diabetic patients results in significant improvement in both aerobic capacity and whole-body insulin sensitivity.
- Long-term endurance training in diabetic patients markedly improves whole-body insulin sensitivity and the expression of key muscle enzymes regulated by insulin. However, the maintenance of this effect seems to require dedication to a regular and uninterrupted exercise regimen.
- Intramyocellular lipid accumulation, which is associated with insulin resistance in muscle, can be acutely decreased by even a single bout of sustained endurance exercise.
- Exercise is beneficial for both glucose uptake mechanisms and the anti-lipolytic effects of insulin.
- BENEFITS OF EXERCISE IN PEOPLE WITH DIABETES.
- Improves overall blood glucose control and HBA1c levels in type 2 diabetes.
- Improves insulin sensitivity and lowered insulin requirements often leading to a reduced dosage of insulin and or oral hypoglycemic agents especially in people with Type 2 diabetes.
- Attainment and maintenance of ideal body weight.
- Reduction of coronary risk factors
- Favorable changes in body composition (decreased body fat and weight, increase in muscle mass).
- Lowers cardiovascular and overall mortality
- EVALUATION OF EXERCISES
Before beginning an exercise programme more strenuous than the current pattern of exercise, the person with diabetes should undergo a medical assessment that will screen for the presence of microvascular or macrovascular complications. By identifying the presence of these complications, an exercise prescription can be developed that will minimize the risk to the person of worsening their identified conditions.
The following are the evaluation before prescribing exercise;
- ECG stress test
- Borg’s Rate of Perceived Exertion
- Karvonyn’s Formula
- Graded exercise test
- EXERCISE PRESCRIPTION
Exercise prescription should always include:
- a) the mode of exercise
b) the intensity of exercise
c) the duration of exercise
d) the frequency of exercise
e) the rate of progression of the patient’s physical activity
These parameters should be taken into account whether prescribing exercise for the healthy individual or the patient with disease. In all cases, the exercise prescription should be developed with careful consideration for the individual’s health history, risk factor profile, the patient’s strength and flexibility, any orthopedic conditions that may exist, behavioral characteristics, personal goals and availability of exercise facilities.
The exercise prescription for these two types of diabetic populations is somewhat different. In the case of Type I diabetics, the emphasis is on glucose regulation. Hence, these patients are encouraged to exercise 7 days a week. On the other hand, in the case of Type II diabetics, the emphasis is on weight reduction and increased physical activity. For these reasons they are encouraged to exercise 3-5 times a week since they do produce insulin and absolute glucose regulation is not the primal reason for the exercise prescription.
Below is a suggested initial exercise prescription for both Type I and Type II diabetic patients.
|Parameters||Type I Diabetics||Type II diabetics|
|Frequency||7 days/week||5 days/week|
|Duration||20-30 minutes||30-60 minutes|
|Intensity||45% – 85% MHR||45% – 70% MHR|
|Borg Scale||10-14 RPE||10-14 RPE|
The exercise prescription should also include:
- Warm-up period: 5-10 minutes of aerobic activity such as walking or bicycling at a low intensity. The warm-up is to prepare the muscles, heart and lungs for the more intensive activity that will follow. A stretching of the muscles to be used during the activity should also occur.
- Period of intense exercise
- Cool down period: occurs following the period of intense exercise. It should last for 5-10 minutes and consist of the same activities as the warm-up. The purpose is to gradually bring the heart rate down to pre-exercise level.
The following walking programme is an example prescribed who is interested in walking but has not been active
|A SAMPLE WALKING PROGRAM|
|Warm Up||Target Zone Exercising||Cool Down Time||Total|
|Session A||Walk normally 5 min.||Then walk briskly 5 min.||Then walk normally 5 min.||15 min.|
|Session B||–Repeat above pattern–|
|Session C||–Repeat above pattern–|
|Continue with at least three exercise sessions during each week of the program. If you find a particular week’s pattern tiring, repeat it before going on to the next pattern. You do not have to complete the walking program in 12 weeks.|
|Week 2||Walk 5 min.||Walk briskly 7 min.||Walk 5 min.||17 min.|
|Week 3||Walk 5 min.||Walk briskly 9 min.||Walk 5 min.||19 min.|
|Week 4||Walk 5 min.||Walk briskly 11 min.||Walk 5 min.||21 min.|
|Week 5||Walk 5 min.||Walk briskly 13 min.||Walk 5 min.||23 min.|
|Week 6||Walk 5 min.||Walk briskly 15 min.||Walk 5 min.||25 min.|
|Week 7||Walk 5 min.||Walk briskly 18 min.||Walk 5 min.||28 min.|
|Week 8||Walk 5 min.||Walk briskly 20 min.||Walk 5 min.||30 min.|
|Week 9||Walk 5 min.||Walk briskly 23 min.||Walk 5 min.||33 min.|
|Week 10||Walk 5 min.||Walk briskly 26 min.||Walk 5 min.||36 min.|
|Week 11||Walk 5 min.||Walk briskly 28 min.||Walk 5 min.||38 min.|
|Week 12||Walk 5 min.||Walk briskly 30 min.||Walk 5 min.||40 min.|
Whenever you work with patients with diabetes, the following considerations should be mentioned along with the exercise prescription:
- Avoid exercising during periods of peak insulin activity
- Always exercise with a partner in case the patient needs help
- Know the signs of hypoglycemia – lightheadedness, diaphoresis, palpitations, loss of motor control, changes in mood, etc.
- Wear good foot wear
- Practice scrupulous foot inspections for fissures, blisters or reddened areas
- Inject the insulin into a muscle mass that does not directly participate in the physical work
- Learn to drop insulin requirement once understand how exercise effects your insulin needs
- Do not take beta-blockers because they mask the symptoms of hypoglycemia
- Never exercise if blood glucose is over 300 mg/dl
- If glucose is between 110 – 280 mg/dl, it is okay to start exercise
- Learn to monitor blood glucose every thirty minutes of continued exercise
- TYPES OF PHYSICAL ACTIVITY
The Mnemonic: “SAFE” exercises are recommended:
- Strengthening exercises
- Aerobic exercises
- Flexibility exercises
- Endurance exercises
Aerobic exercise is the type that moves large muscle groups and causes you to breathe more deeply and your heart to work harder to pump blood. It’s also called cardiovascular exercise. It improves the health of your heart and lungs. It requires oxygen.
ANAEROBIC (STRENGTHENING) EXERCISE
Anaerobic exercise uses large muscles that do not require oxygen for short periods of exercise. It helps build strong muscles; lowers blood glucose makes the action of insulin more effective.
FLEXIBILITY (STRETCHING) EXERCISE
Flexibility exercises are aimed at increasing or maintaining range of motion at joints, also improve tone in muscles and keep it supple. They develop better muscular and body control.
Low Resistance, High Repetition Exercises
- Examples: Walking, cycling, swimming, or upper extremity ergometry that involve the use of the large muscle of the body.
- YOGA AND BENEFITS IN PEOPLE WITH DIABETES
Yoga is a group of ancient techniques originating in India. It is based on a harmonising system of development for the body, mind and spirit. The yoga practice (asana) includes yoga poses, breathing exercises, cleansing techniques, medication and lots of relaxation practices. Yoga complements the lifestyle changes that are necessary to control diabetes. The asnas can be done every day for 30-40 minutes.
Benefits of practicing yoga are as follows:
- Improvement in the insulin sensitivity
- Reduction in fasting, blood glucose and HbA1c levels
- Improvement in day-day performance
- Reduction of stress and feeling of wee-being
- Improvement in nerve functions in type 2 diabetes with subclinical neuropathy
RECOMMENDATIONS FOR PEOPLE WITH DIABETIC COMPLICATIONS
Peripheral and autonomic neuropathy
- Non-weight-bearing activities
- Chair and arm exercises
- Prolonged walking
- Step exercises
Low to moderate intensity forms of exercise
High intensity forms of exercise
Low-impact cardiovascular conditioning, such as swimming, walking, low-impact aerobics, stationary cycling, endurance exercises
Strenuous activities, pounding or jarring, such as weight lifting, jogging, high-impact aerobics, racquet sports.
The person should be instructed to stop exercising. People at risk for hypoglycaemia should always carry a source of glucose with them such as glucose tablets, candy or juice in order to treat hypoglycaemia
Snacking to prevent hypoglycemia
Snack prior to activity to prevent hypoglycemia
Adjust quantity based on pre-activity BG or direction of BG
BG low or dropping: ñ usual carbs
BG OK or stable: usual carbs
BG High or rising: ò usual carbs
Snack at least once per hour during prolonged activity
Choose high-glycemic forms of carbohydrate
Useful Tips for Exercise
- Always carry an identification card with you
- Check your feet before you walk
- Choose good footwear, light clothing
- Drink lots of water
- Don’t exercise during hot seasons, and when not feeling well
- Physical activity should be encouraged in all people with diabetes
- People need to be educated about prevention and treatment of hypoglycaemia
- People should be taught to plan for periods of physical activity