Who could deny that physical activity is a critical aspect of maintaining good health? A simple cost-benefit analysis paints a clear picture – exercise can be quite a bargain because it lowers blood glucose, cholesterol, and blood pressure; improves heart health and sleep quality; boosts your mood;helps to control weight; and more. All for a little time and effort, right? In this short article, we will discuss the different types of exercise, their benefits, and the unique challenges they present for people with diabetes.
Aerobic or Cardiovascular exercise:
What is it? The definition of aerobic is “requiring oxygen”. Think of aerobic exercise as activity that can be maintained with a steady but elevated breathing rate. Most moderate-intensity activities such as swimming, jogging, or even a brisk walk fall into this category. During aerobic exercise, the body uses glucose from the blood as fuel, meaning lower blood sugar readings once you’ve moved consistently for 30 minutes or more. However, keep in mind that very high-intensity aerobic activity like a 100-yard sprint can also release stress hormones that actually raise the blood sugar.
Who should participate? Everyone who is medically able. Regular exercise can potentially reduce the risk of cardiovascular disease, the number one cause of death for people with diabetes. If you aren’t sure whether it is safe for you to exercise, ask your doctor.
When to do it? The American Diabetes Association recommends at least 30 minutes of aerobic activity most days of the week. This does not have to happen all at once, so consider spreading your exercise throughout the day. Pick a time that works for you! This may mean getting 10 minutes in before work in the morning, 10 minutes on your lunch break, and another 10 after work, for example.
Where can I get my heart rate up? Aerobic exercise can be performed almost anywhere for free! You could go for a brisk walk in a park or swim at the local pool. If you have a dog, getting out with your furry friend will benefit you both! Some people prefer classes at local health clubs. Identifying the places and activities you enjoy are crucial to developing a sustainable plan.
Anaerobic exercise or Resistance training
What is it? Anaerobic exercise (or resistance training) is different from aerobic in the sense that oxygen is not required to generate energy. In general, anaerobic exercise is much more intense and usually falls into the ‘vigorous activity’ category if performed for long enough and with heavy weight or high resistance. Activities that you can only maintain for a very short period of time like sprinting or weight lifting would be considered anaerobic. The muscles use stored glycogen as fuel to perform these activities instead of utilizing glucose directly from the bloodstream.
Who should participate? Similar to aerobic activity, most people can perform some sort of resistance training. For some, this may be working with light resistance bands for 30 minutes per day, or this might mean 1 hour of weight lifting several times per week. Consider asking your doctor about starting a resistance-training program if you have not already. Additionally, consider working with a trainer – even just for a month. Being comfortable with proper technique is important to minimize risk of injury while ensuring you have a good workout!
When to do it? The American Diabetes Association recommends 2-3 resistance training sessions per week. Muscles need time to recover, so try to take at least one day off between intense resistance training workouts. You can combine your cardiovascular and resistance training on the same day for a full, efficient, workout. Consider 30 minutes of resistance training (such as weight lifting) and 30 minutes of cardiovascular training (like walking or biking) for a complete 60-minute session!
Where can I get started? If you’re pressed for time, you can always do a quick home workout, like a combination of body weight squats, lunges, push-ups and abdominal planks. Again, some people prefer the environment of a fitness club or gym. If you want to try a gym membership, it’s crucial that you choose a facility convenient for you.
Where diabetes fits in:
We can’t stress this enough: everyone’s diabetes is different. Goals of an exercise program may be to reduce or come off of medications, to lose weight, or just to increase physical fitness and decrease the risk of future disease. In general, exercise increases the body’s sensitivity to insulin, making it easier for the muscles to use the glucose in the blood. This has different implications for everyone, making it very important to understand how exercise and diabetes are connected in order to pursue your goals safely. Below are some things to consider for active type 1 and type 2 diabetics:
For people with type 1 diabetes, making adjustments to the amount of insulin you take or carbohydrates you eat may be needed before, during, and/or after exercise. Because every body reacts differently, individual people will have different strategies to maintain glycemic control while leading an active lifestyle.
Blood glucose (BG) targets and recommendations for safe exercise:
- <90 mg/dL: Have a 10-20 gram carbohydrate snack, delay exercise until BG > 90 mg/dL
- 90-125 mg/dL:
- For aerobic activity: Have a 10 gram carbohydrate snack and begin exercise
- Weight lifting/anaerobic activity: Begin exercise
- 126-180 mg/dL:
- Either form of exercise may be started
- 181-270 mg/dL:
- Either form of exercise may be started
- Be aware that weight lifting/anaerobic exercise may raise glucose
- >270 mg/dL:
- Check ketones
- If low, you may start aerobic exercise and continue to monitor blood glucose
- If moderate, keep exercise light and under 30 minutes
- If high, avoid exercise and begin hyperglycemia protocol
- Check ketones
- Either form of exercise may be started
General Tips for reducing risk of hypoglycemia during exercise:
If you use an insulin pump, setting a lower temporary basal rate 90 – 120 minutes before exercise can reduce your risk of hypoglycemia.
If you eat a meal within 2 hours of aerobic exercise, consider reducing your mealtime bolus by 25-50%, as you will burn carbohydrate during your activity.
Weight lifting generally requires minimal adjustments to insulin doses.
When exercising, have fast carbs like glucose tablets, SweetTarts, or Gatorade available for rapid glucose correction.
Continue to check your blood sugar after exercise, as you may be at risk of hypoglycemia up to 24-36 hours after activity. This is especially important if you have a particularly strenuous workout, or try a new form of exercise you are not accustomed to.
Keep records and look back at them before deciding how to manage a situation.
General Tips for reducing risk of hyperglycemia during exercise:
Having too little insulin in your system is the main cause of hyperglycemia during exercise. If you use a pump, try to avoid suspending it if you’re mostly performing anaerobic exercise (weight lifting). Eating a meal or snack that requires a bolus of insulin prior to anaerobic exercise is a good starting point to minimize your risk of hyperglycemia.
Remember to stay hydrated! Your urine should look like lemon juice, not apple juice.
Whether you have diabetes or not, exercise is hard. It requires ongoing effort and commitment and a fair amount of sweat. Fortunately, if you have type 2 diabetes, there’s far more benefit than risk. Figuring out what motivates each individual is key to developing a lasting, realistic exercise plan.
What exercise can do for you:
- Reduce your diabetes medications (insulin, oral medications)
- Allow you more flexibility with your diet
- Reduce or maintain weight
- Improve confidence
- Reduce blood glucose levels and A1C
If you are taking insulin or a sulfonylurea medication, you might consider some of the same suggestions listed in the Type 1 Diabetes section above. You may need to adjust your insulin dosage and/or carbohydrate intake before and after exercising.
Conclusion
The American Diabetes Association recommends a combination of at least 150 minutes per week of moderate-intensity aerobic exercise and 2-3 sessions of resistance exercise a week for individuals with diabetes. Many people find they’re most able to exercise consistently when they set aside a specific time in their schedule for exercise and make it a regular part of life.
Balancing exercise, carbohydrate intake, and insulin dosing will require some trial-and-error at first, as every body works differently. But don’t get discouraged- it will get easier the more you do it. Finding this balance and discovering what works for you will be much easier if you CHECK YOUR BLOOD SUGARS OFTEN.
Always consult with your healthcare team before making insulin adjustments.
by Eugene Arnold, MS LD RD CDE
