IN THIS CHAPTER
Exercising good judgment about exercise safety
Planning a fitness routine and identifying the many benefits
Finding out what happens to fuel use when you exercise
Delving into fitness details pertinent to type 1 and type 2 diabetes
Physical activity offers health benefits for everyone on the planet. That pretty much sums it up. We all stand to benefit by being more active. Most of us know that, yet statistics from the Centers for Disease Control show that only 49 percent of American adults meet the physical activity guidelines for aerobic activity. When it comes to meeting the guidelines for both aerobic activity and strength training, the number drops to a mere 20.9 percent of adults.
If you aren’t currently engaging in physical activity, take the first step and start modestly. It’s never too late to begin healthy habits. Exercise is a critical component of overall well-being, weight control, cardiovascular fitness, and the management of insulin resistance. That’s not all: Exercise is good for mental health, and exercisers tend to live longer. If you don’t exercise, you miss out on the potential health benefits, but even more concerning is that the lack of exercise increases your risk of developing chronic diseases.
Most people can readily come up with a list of reasons why they don’t exercise. If pressed, those same people may be able to find solutions for each of their excuses. Prioritize exercise to the status it deserves. Find activities that interest you. Figure out what time of day works best for you. Strategize ways to fit fitness into your daily routine. Find activities that your family can enjoy together. Figure out what you can do indoors when weather prohibits outdoor activities. Enlist the support of family and friends. This chapter highlights the benefits of exercise, especially for people with diabetes, and how to do it safely.
Exercising Safely
If you’re a new recruit to exercise, start with something manageable. Your current level of fitness will determine what you can comfortably do. Someone who has been sedentary for years should start with a modest exercise goal. That may mean five minutes of physical activity, or it can be a walk around the block. People who have prior exercise experience but have been on an exercise hiatus may be able to jump back into their previous routines. The main thing is to get started. From there you can incrementally add more activity. The following sections explain how to proceed safely with an exercise program by checking in with your healthcare provider first and keeping essentials at your side.
If you aren’t sure about where to start or if you have limitations due to health issues, ask your healthcare team for guidance.
Getting the green light from your doctor
Your healthcare provider knows your medical history and thus is the most qualified person to guide you on exercise. If you use insulin, ask your doctor whether you should adjust your insulin dose when exercising to reduce the risk of hypoglycemia (which I discuss later in this chapter). If you are not at risk for lows and are generally healthy, there may not be any restrictions on increasing your level of activity.
The following sections describe the medical tests you should have before you start an exercise routine and the medical alert ID you should wear.
Undergoing medical exams
Everyone needs a complete physical examination annually. Whether you need to schedule additional follow-up visits depends on your medical history. For uncomplicated diabetes, follow-ups are generally recommended at least two to four times per year. Your provider may suggest more frequent visits if your blood glucose isn’t adequately controlled, if you start a new medication, or if you have diabetes complications or other significant medical issues.
Weight and blood-pressure checks should be routine at every medical visit. Your doctor should assess the health of your nerves and feet. Bring your meter and blood-glucose records to all visits and have your A1C checked every three months. Blood-glucose data drives management decisions (see Chapter 15 for more information).
Stay up to date with your diabetes checkup checklist. Take care of the following:
· The health of your kidneys and eyes should be assessed annually, and your feet at least annually. Screening for complications to your eyes requires a dilated exam. Kidney health is monitored with a blood test and a urine screening test that looks for a protein called albumin.
· Lipid levels should be monitored at a frequency determined by your provider and based on your medical history.
· Dental checkups are also important and recommended at least every six months.
Discuss exercise with your healthcare provider. Find out whether you have any exercise restrictions due to medical conditions.
An exercise stress test, sometimes called a treadmill test, is used to evaluate your heart’s response to exercise. An alternate method is available, which uses a medication rather than exercise to increase the heart rate. Stress tests are not done routinely for everyone with diabetes, but rather as deemed necessary by your healthcare provider based on your personal risk factors.
Wearing a medical alert ID
If you are injured during exercise (or any other time) and unable to communicate for any reason, or if you are incapacitated by hypoglycemia or a diabetic coma, the paramedics assisting you will need to know what to do. First responders look for medical alert identification. In extreme situations every minute counts. If you have insulin-dependent diabetes, it’s important for paramedics to assess your blood-glucose levels. Severe hypoglycemia requires glucagon or intravenous glucose to raise blood-glucose levels quickly. Diabetic ketoacidosis requires insulin and IV fluids (see Chapter 4 for details on ketones).
At the minimum, your medical alert ID should list that you have diabetes. If you use insulin, specify that. Provide your full name and the name and phone number of an emergency contact person. Some IDs allow you to create an online health profile to house all of your key information; the ID provides the access code. Some alert tags come with a USB drive that houses your personal medical history and key contact numbers.
Medical ID bracelets, necklaces, or watchband clips offer a wide range of options. From basic to bold, there are options for the sports-minded, outdoorsy types, polished executives, and the young or young at heart. Available styles include retro, western, classy, beaded, and jeweled. Search for medical alert identification on any web browser.
THE IMPORTANCE OF WEARING MEDICAL ALERT IDENTIFICATION
This is a true story. When I was a student at UC Berkeley, I was at the transit station waiting for my commuter train. Near me was a woman in a business suit who suddenly slumped to her knees. I rushed to her side and asked whether she was okay. She couldn’t manage to tell me what was wrong. I noticed her medical alert necklace, which said she had type 1 diabetes. It was apparent to me that she was having a low-blood-glucose reaction. I grabbed a juice from a nearby kiosk, which she was able to drink. After about ten minutes, she had recovered and thanked me. That was more than 25 years ago.
Occurrences such as these are less frequent these days because of technological advances, improved insulin options, and education. Nevertheless, they underscore the importance of wearing medical alert identification.
Being prepared: What to keep handy
With a little planning, you can engage in physical activity safely. If you take insulin or any pills that put you at risk for hypoglycemia, planning ahead and being prepared are especially important. Check out the following list of what to keep with you as you exercise:
· Planning for your particular activity: Dress appropriately for your activity. For example, if you’re stepping out for a walk, wear walking shoes that are comfortable and protect your feet. Use a helmet for bike riding. Apply sunscreen for outdoor activities and avoid exercising in temperature extremes.
· Bringing your glucose monitor with you: Glucose monitors are compact and lightweight. Keep yours with you when exercising. It can be left poolside while you swim, or in a backpack, fanny pack, or bike pack for walking, jogging, and biking.
· Toting insulin: Insulin users need access to insulin at all times; don’t leave home without it. It’s important to protect insulin from the elements. Keep insulin out of direct sunlight and don’t leave it in a hot car. When insulin gets too hot, it doesn’t work properly and must be discarded. It can be kept cool but must not freeze. Tote bags designed for insulin storage have compartments to hold refreezable ice packs.
· Carrying low supplies: If you use insulin or any of the oral medications that have the potential to cause hypoglycemia, be sure to carry glucose tablets, juice, or any other quick-digesting carb choice. Exercise can lower blood-glucose levels rapidly. For more information on the prevention, detection, and treatment of hypoglycemia, see Chapter 15 .
· Packing snacks: When exercise is strenuous or prolonged, you may need a snack, juice, or a diluted electrolyte drink to sustain your glucose levels.
· Staying hydrated: Drink plenty of water. Exercise increases fluid requirements, especially in hot climates. Drink additional water or carbohydrate-free beverages when blood-glucose levels run above target ranges. Elevated glucose levels can lead to increased urination, and if fluid losses are not replenished, you can become dehydrated. Reserve the carb-containing beverages for treating and preventing lows. See Chapter 11 for more advice on beverage choices.
Encouraging Exercise for Everyone
I often hear people say that they would like to exercise more but they just don’t have the time. Sometimes best intentions are thwarted because exercise gets bumped lower and lower on the list of things to do. Exercise needs to be higher on the priority list. As you read through this chapter, take note of the many health benefits exercise offers. Tell yourself that exercise is a “prescription,” and it’s as important as medicine or any other aspect of your healthcare. Continue reading for ideas on how to get started.
Developing an exercise plan
There’s something for everyone when it comes to exercise options. Discuss your circumstances with your healthcare team. It’s important to exercise within your capabilities. Start modestly and work your way up as you build stamina and strength. Keep safety in mind at all times.
The following sections describe different types of exercise as well as frequency, intensity, and duration.
Choosing exercises that you like and can safely do
To successfully incorporate exercise into your routine, it’s important to pick activities that you enjoy. Keep things interesting by including a variety of activities. For example, you may sign up for an exercise class that meets once or twice a week. On the off days, you can go for a walk (see the next section) or use an aerobics DVD or online exercise video that gets you moving in your own living room.
Look into what’s available in your community. Find out when local swimming pools are open for adult lap swimming. Consider health clubs, gyms, basketball or tennis courts, golf, walking trails, bike paths, or a local YMCA. Some communities put together walking groups, tai chi gatherings, bird-watching clubs, recreational sports teams, and exercise sessions at senior centers. Consider line dancing, ballroom dancing, a spin class, or investing in exercise equipment for your home. Save on costs and buy used equipment such as a stationary bike or treadmill. Even simple hand weights can be used while watching television.
Getting off on the right foot: The wonders of walking
Walking counts as exercise. It’s free, and the timing is flexible. Go for a walk whenever you can fit it in. Just be sure to take care of your feet by wearing shoes designed for walking and comfortable, moisture-wicking socks.
Add extra steps to your current daily routine. When you’re shopping, simply park farther from the entrance. When you’re inside a shopping mall, take a walk through it. Reserve part of your lunch break to walk around the building or the block. Take the stairs. Get off the bus one stop earlier and walk the rest of the way.
As you become more conditioned, push yourself to walk faster and farther. Consider a step counter, pedometer, or fitness tracker. Apps on smartphones track steps. Wear a fitness tracker on your wrist or on your belt. Many trackers sync with apps on your smartphone to track your progress over time. Increase your target incrementally until you’re walking 10,000 steps per day.
Adding aerobic activities and resistance training
Aerobic exercise, or cardio, involves using the major muscle groups in a repetitive fashion. Aerobic activities include walking (see the preceding section), jogging, stair climbing, cycling, rowing, dancing, swimming, elliptical machines, and aerobics classes. Cardio strengthens your heart and lungs.
Resistance training is also called strength training. The goal is to strengthen the major muscle groups in the legs, hips, back, abdomen, chest, shoulders, and arms. Studies have shown that resistance training improves A1C in adults with type 2 diabetes.
Lifting weights is an example of resistance exercise. Invest in hand weights to use at home. They come in a wide variety of weights, starting as low as one pound. Keep them handy and use them at least twice a week. If you enjoy watching TV, you can do your weight-lifting exercises while viewing. Elastic stretch bands are another alternative. If you belong to a gym, reduce the risk of injury by asking a trainer to show you how to use the exercise equipment properly.
Warming up, cooling down, and stretching
Prepare your muscles for the workout. Warming up simply means engaging in activity for three to five minutes at a relaxed pace to get your blood flowing and your muscles ready for action. As you end your workout, cool down by doing your activity at a relaxed pace for a few minutes.
You can incorporate gentle stretching before or after exercise. Whether you choose to bend and stretch at home or join a yoga class is up to you. It pays to stay limber and flexible. Stretching reduces the risk of injury.
Considering frequency, intensity, and duration targets
It isn’t necessary to take your pulse to rate your workout. Perceived exertion takes into account your level of fitness. If you feel like you can push yourself a little harder or go for a little longer, then do so. Do what is right and safe for you.
Consider the talk-sing test. You should be able to talk while working out, but if you can sing, you probably aren’t pushing yourself hard enough. You shouldn’t be breathless or gasping for air. Find the sweet spot where you feel challenged but comfortable.
You don’t have to sweat to call it exercise. Exercise means moving and using your body. Consider these three aspects of a workout:
· Frequency: The goal is to exercise at least five days per week. The eventual goal for aerobic activity is 30 minutes per day. Exercise can be completed in one session, or it can be split into two sessions of 15 minutes or three sessions of 10 minutes. Try not to go more than two consecutive days without exercise. Resistance exercise, also known as strength training, should be done at least twice per week.
· Intensity: You aren’t trying to break any records here. You are the best judge of how hard to push yourself. Start with what you are able to do and work your way up gradually. The eventual goal is to work out at a moderate intensity at least 150 minutes per week. Examples of moderate-intensity exercise include brisk walking, water aerobics, leisurely bicycling, and gardening.
An alternate option is to exercise at a vigorous level of intensity for at least 75 minutes per week. Vigorous activities include jogging, running, swimming laps, playing racket ball, riding a bicycle uphill or at higher speeds, and playing singles tennis.
The bulk of your workout can be somewhat challenging but shouldn’t lead to pain or discomfort. Interval training inserts short bursts of intense activity into your usual workout. For example, when walking, you can speed up and walk more briskly for one to two minutes every five minutes. The concept can be modified to fit your activity and your level of fitness.
If you have medical issues, have complications, or are older, ask your doctor for advice on how much to push yourself during your exercise sessions.
Exercise should not hurt or cause injury. Stop exercising if at any time you feel pain, discomfort, dizziness, or shortness of breath. Discuss symptoms with your doctor.
· Duration: The goal is for all adults to accumulate at least 150 minutes of moderate activity per week. If weight loss is your goal or you are trying to keep off the pounds you’ve already lost, 60 minutes of daily exercise has been shown to be more effective. The duration of individual exercise sessions is up to you. You can break exercise up into 10- or 15-minute mini sessions dispersed throughout the day. However, longer durations of moderate-intensity exercise burn more body fat. A moderately paced walk for 45–60 minutes burns glucose and fat. A quick dash or a couple of flights of steps burns primarily glucose.
It’s all good. You can make the argument that any exercise is beneficial. Don’t be discouraged if you can do only five minutes on the stationary bike or treadmill. Stick with it. Your stamina will improve and you will be able to tack on some extra time as you become more conditioned.
Enjoying the benefits
Exercise benefits the entire body: muscles, bones, joints, heart, lungs, and circulation. Good health is sometimes taken for granted — only when a problem develops do we realize how much we depend on our bodies! Exercise is an important part of keeping your bodily systems in top running condition. The list ahead highlights some of the benefits of being fit. There isn’t a single “medicine” that can do all of the following things:
· Maintaining strength, balance, and flexibility: Bones and muscles are strengthened through use. Walking or any weight-bearing activity reduces the risk of osteoporosis. Exercise helps to tone and build muscle. Preservation of muscle strength is important for everyone, but it’s essential as we age because it helps assure safety and independence in performing daily activities.
· Relieving stress and sleeping better: Who wouldn’t want to feel less stressed and sleep better? Sign me up right now. Exercise helps clear the head and releases tension.
If you use insulin or medications that stimulate insulin production, use caution if you’re exercising in the evening due to the risk of post-exercise hypoglycemia. Check your blood-glucose levels before bed. If you’re unusually active, you can set an alarm to check blood-glucose levels in the middle of the night. Delayed hypoglycemia is addressed in more detail later in this chapter.
· Reducing your risk of chronic disease: Heart disease and stroke are two of the leading causes of death. Exercising regularly lowers your risks. Research also shows that exercise reduces the risk of developing certain forms of cancer, including breast and colon cancers. Regular physical activity helps with arthritis and other joint conditions.
· Improving mental health: Exercise is good for your physical and mental health. Being active is associated with improved mood and decreased symptoms of depression. Exercising increases endorphins, the chemicals in the brain that improve mood and a sense of well-being.
· Having fun and socializing: Exercising with family and friends builds relationships. Spending quality time together builds memories too. Don’t sit back and wait for someone to ask you to be active. Take the initiative and invite someone to go for a walk or take an exercise class with you. Group fitness classes are also a great way to meet people and forge new friendships.
Exercise is a foundation treatment strategy for managing type 2 diabetes because exercise helps insulin work more effectively. Exercise is also good for heart health, weight control, blood pressure, and more. Exercise adds another variable to the complex management of type 1 diabetes, but with insight and planning, everyone with diabetes can enjoy exercise safely. Specifics are covered in more detail later in this chapter.
Being mindful of medical limitations
If you have medical issues and physical limitations as I describe in the following sections, you may need modifications to your exercise plan. Certain medical conditions, or having diabetes-related complications, may dictate what exercises are safe to do. If you have heart disease, retinopathy (damage to your eyes), or neuropathy (damage to your nerves), ask your provider to help you develop an appropriate exercise plan. Discuss reasonable targets for frequency, intensity, and duration of activity.
Find out whether your community has a swimming pool that accommodates people with handicaps. Some utilize lifts to safely lower you into the water. Temperatures are often kept warmer in these pools. The bottom of the pool may be rough, so wear appropriate water shoes.
Finding activities that are friendly for your feet
If you have peripheral neuropathy, you’ll need to be especially careful to protect your feet. Neuropathy is a complication that affects nerves and can lead to burning and tingling in the feet. It can also lead to decreased sensation and numbness. People with this complication are at risk for foot injury.
Avoid exercises that pound the feet. Walk, don’t run. Avoid the stair-climber and don’t jump rope. Safe exercises include stationary biking, swimming, walking, resistance exercises, chair exercises, and other non-weight-bearing activities.
Exercising while safely seated
If you are confined to a wheelchair or unsteady on your feet, it’s possible to get a good workout while seated. Moving muscles systematically improves fitness. Buy an exercise DVD or tune in to an online exercise video to learn appropriate armchair exercises. You can also follow along with a televised exercise program. Public television hosts a show called Sit and Be Fit that teaches armchair aerobics.
Using caution with specific complications
Having diabetic complications imposes certain restrictions on exercise, but there’s usually some form of activity that’s safe to do. Several specific medical conditions are addressed here:
· Autonomic neuropathy: Autonomic nerves direct many bodily functions including the heart and regulation of body temperature. Avoid exercising in the heat. You may need an exercise stress test, as described in the earlier section “Undergoing medical exams ”; discuss this with your doctor.
· High blood pressure: Avoid heavy lifting and straining. Use caution with strenuous activity. Your best options include walking and other moderate-intensity workouts. For weight lifting, use lighter weights and more repetitions.
· Nephropathy: Kidney health is affected by blood pressure, so it’s prudent to follow the same advice as listed for high blood pressure. Otherwise, there are no restrictions.
· Peripheral vascular disease: Fatty deposits in the arteries of the legs can reduce blood flow to the muscles and lead to pain and cramping. Avoid high-impact aerobics. Better alternatives include walking, swimming, and chair exercises.
· Retinopathy: Avoid heavy weight lifting and straining. Minimize jarring activities or those that position the head lower than the torso. Choose low-impact activities such as walking, cycling, swimming, or water aerobics.
Clarifying What’s Going On Behind the Scenes When You Exercise
This section explains how exercise taps into glucose, glycogen, and fat to fuel activity. In the absence of diabetes, hormones automatically regulate fuel use and control blood-glucose levels. Having diabetes alters that delicate balance. Here you also find out how to reduce the risk of exercise-induced hypoglycemia for those at risk.
Controlling blood glucose: How hormones are supposed to do it automatically
The glucose that is stored in the muscles and liver is called glycogen. Glycogen in the liver can be broken back down into individual glucose molecules and released into the bloodstream, where it can be transported to the muscles and tissues in need of fuel. The liver can synthesize new glucose as needed. (Chapter 4 provides details on the process.)
Hormones regulate blood-glucose levels. Several different hormones can raise blood glucose. Glucagon, epinephrine, growth hormone, and cortisol are the counter-regulatory hormones. They are responsible for mobilizing the fuels used by muscles: glucose and fat.
· The pancreas produces glucagon. You may be familiar with glucagon because it’s also available in prescription form. People with type 1 diabetes should have glucagon kits available for treating severe hypoglycemia. Glucagon is administered by injection if a person with diabetes loses consciousness due to hypoglycemia. Glucagon drives the liver to release glucose from glycogen stores and to make glucose from scratch in a process called gluconeogenesis.
· Epinephrine, which is adrenaline, is the “fight-or-flight” hormone. Adrenaline surges when you are in danger (or during competitive sports). It, too, mobilizes glucose.
· Growth hormone, which is released from the pituitary gland, drives the growth of bone, muscle, and tissue. It can also stimulate the liver to release glucose.
· Cortisol is made by the adrenal glands and helps the body modulate glucose levels.
Insulin is the only hormone that lowers blood glucose. Counter-regulatory hormones assure that there is enough fuel to burn during exercise, but insulin is needed to transport glucose into the muscles where it is burned for energy. In the absence of diabetes, insulin production increases and decreases automatically in relation to rising and falling blood-glucose levels. The working pancreas is adept at giving just the right amount of insulin for the situation. Type 1 diabetes means the pancreas can’t make insulin, and in type 2 diabetes, the insulin doesn’t work as well as it should. Details on both types of diabetes are addressed in the next section.
Identifying how diabetes alters fuel use
The absence of insulin in type 1 diabetes leads to metabolic mayhem. Insufficient insulin leads to elevated blood-glucose levels even during exercise. Recall that counter-regulatory hormones mobilize fatty acids from body stores and stimulate the liver to release glucose. Insulin is needed in appropriate amounts to move that fuel into the muscles. Without insulin, the glucose and fatty acids keep pouring into the bloodstream and levels rise higher and higher. Exercise doesn’t fix this problem. Only insulin can open the cell doors and let the glucose in. Insulin deficiency results in fatty acids that are metabolized by the liver into byproducts known as ketones (see Chapter 4 ). Kidneys try to reduce glucose and ketone levels through urination, which can lead to dehydration.
Type 2 diabetes causes insulin resistance. People with type 2 make insulin, but it doesn’t work very well. Early in the disease process, the pancreas works harder to make extra insulin. Prediabetes is the period of time when blood-glucose levels are above normal but not yet diagnostic of type 2 diabetes. You can be sure the pancreas is working overtime trying to prevent blood-glucose levels from rising further. Years into the process, the pancreas simply can’t keep up the pace, and insulin production drops. Sedentary lifestyles and obesity worsen insulin resistance. Exercise is beneficial because it improves insulin sensitivity. Losing weight, even modest amounts, also improves insulin action. That’s why diet and exercise are foundational treatment strategies when it comes to managing type 2 diabetes.
Sustaining exercise by tapping into fuels
Muscles burn both glucose and fat. We don’t get to pick the order in which they get used. It would be nice if we could choose to burn fat first, but it doesn’t work that way. If you walk across the room, you burn a small amount of glucose. If you walk out the door, you burn more glucose. If you keep walking, eventually you’ll burn fat too:
· Glucose is the muscles’ preferred fuel source. Glucose travels through the bloodstream and is delivered throughout the body to the working muscles.
· Muscles store glucose as glycogen. About 80 percent of the body’s reserved glucose is housed in the muscles. That convenient location means the glucose is readily available to burn when the muscles start moving. Sustained exercise relies on glycogen storage to fuel the muscles. The glycogen stored in the liver is released as needed to provide additional glucose to the muscles.
· Muscles burn a fuel mixture consisting of glucose and fat in appropriate proportions. As exercise duration increases, the amount of fat burned increases. You don’t have to be a marathon runner; just sustain your exercise sessions for longer periods of time to tap deeper into fat reserves.
Understanding hypoglycemia
Exercise increases the risk of hypoglycemia for people with diabetes who use insulin or any medication that stimulates the pancreas to produce insulin. Hypoglycemia is usually defined as blood glucose below 70 milligrams per deciliter (mg/dl). If your glucose levels are dropping, have a snack to prevent hypoglycemia.
Knowledge, experience, and proper planning can reduce the risk of hypoglycemia so that exercise can be enjoyed safely. Hypoglycemia is discussed briefly here; Chapter 15 is devoted to the topic.
Preventing lows
The proper balance between insulin and carbohydrates can mitigate the risk of hypoglycemia. You may need to snack on carbs before, during, or after exercise to sustain blood-glucose levels if you use insulin or medications that stimulate the pancreas to produce insulin. Adjusting insulin for planned activity is another strategy well worth discussing with your healthcare team. Fine-tuning carbs and insulin is discussed later in this chapter. If you don’t use medications that put you at risk for hypoglycemia, exercise won’t cause your blood-glucose levels to drop too low.
Treating lows
When blood-glucose levels fall too low, bringing them back up swiftly is important. Treat hypoglycemia by consuming carbohydrates that digest quickly. Glucose tablets are the gold standard. Carb-containing foods that are readily absorbed include fruit juice and sugar-sweetened beverages. Sugary candies can be used provided they do not contain fat. Fat delays digestion, which means no chocolate for treating lows.
The general rule of thumb is to take 15–20 grams of quick-acting carbs and recheck your blood-glucose levels in 15 minutes. If your levels have not adequately risen, take an additional 15 grams of carb. Repeat until your blood-glucose levels are within safe targets.
The next step is to consider the need for a snack to prevent recurrent hypoglycemia. A snack containing carbs, protein, and fat will digest over a sustained period of time and reduce the chance of subsequent hypoglycemia.
Looking out for delayed hypoglycemia
Hypoglycemia can occur up to 24 hours after exercise has ended. When muscle glycogen reserves are depleted during activity, storage sites refill in the hours post-exercise. Glucose is drawn out of the bloodstream and into the muscles until glycogen storage sites are filled to capacity.
After vigorous or long-duration exercise, consider checking blood-glucose levels in the middle of the night. Learn how to prevent episodes of delayed hypoglycemia by making adjustments to insulin and snacks. Details appear later in this chapter.
Exercising with Type 1: Staying Safe While Having Fun
Managing blood glucose during exercise can be a challenge for a person with type 1 diabetes, but learning to do so is well worth the effort. The following sections provide exercise pointers specifically for people with type 1 diabetes.
Monitoring matters
A car idling in the driveway doesn’t burn much fuel, and neither does sitting on the couch. Light activity burns more; moderate or intense activity burns even more. The fuels used by the human body are glucose and fat. Chapter 4discusses how muscles and the liver store glucose as glycogen. Glycogen provides glucose when food isn’t available. Exercise readily uses the glycogen that is stored in the muscles. Insulin is more effective when exercising. Contracting muscles suck up the glucose that is traveling through the bloodstream. Hypoglycemia can occur if medication is too strong or your carb intake is too low for the workout.
Glucose levels may rise during activity due to the mobilization of fuels, which is driven by counter-regulatory hormones. Hormones are the messengers telling the liver to make and release glucose. Competitive sports can cause an adrenaline rush that bumps up the glucose released from the liver. Intense exercise and heavy weight lifting can also result in temporary elevations in glucose if the liver lets out glucose faster than the muscles are able to use it. (See the earlier section “Clarifying What’s Going On Behind the Scenes When You Exercise ” for more information.)
Blood-glucose monitoring provides real-time data that is crucial for exercising safely. Check your glucose levels as frequently as needed to obtain the data you need to make diabetes self-management decisions. Blood-glucose monitoring provides valuable information about how you respond to exercise. Monitor your blood-glucose levels before, during, and after exercise and use that information to learn to balance insulin, carbs, and activity. Share your glucose records with your diabetes team for their input (as I explain in Chapter 15 ).
Knowing how to interpret blood-glucose data is an essential skill. Don’t judge your numbers. It’s easy to be hard on yourself when results aren’t where you wish they were. Don’t use that as a reason not to check. Share your glucose data with your diabetes team. Ask your doctor or a certified diabetes educator to teach you how to make sense of the numbers. After all, you are the one managing your diabetes on a day-to-day basis.
Fueling up or dialing down: Fine-tuning carbs and insulin
Through glucose monitoring, you can gather the information needed to balance insulin, diet, and exercise. Ask your diabetes care team about altering insulin doses on active days. Be sure to read Chapter 6 to review insulin action times. When heading out to exercise, reflect on which insulins will be active in your system. Consider the timing and carb content of your last meal to determine whether any of the carbs will be digesting and available during exercise.
Consuming carbs to fuel your fitness
Eat carbs as needed to fuel your activity. You may need to “carb up” before or during prolonged workouts. Playing team sports may require carb snacks between races or at halftime. Nonathletic weekend warriors may need to nibble on snacks. The only ways to ascertain whether you need a snack are to check your blood-glucose levels and consider your past experience.
Considering insulin adjustments
Insulin users may need to learn to make minor adjustments to insulin dosing to reduce the risk of hypoglycemia during planned activity.
If you plan to exercise within the first hour after eating, you may be able to take slightly less insulin for that meal. Consider someone who is skiing. He takes a lunch break but then hits the slopes again. Exercise facilitates insulin action, meaning the dose works better due to muscle activity. The muscles also burn more glucose to support the exercise. The net effect is that glucose will be used up faster. Knowing this, the skier may decide to reduce his dose of insulin at lunch.
Insulin requirements depend on the activity and the individual. Discuss insulin dosing with your doctor.
If you think you may have depleted your glycogen stores during afternoon activity, you may be able to cut back slightly on the dose of insulin you take at dinnertime. An alternate way to think about it is to take insulin for 45 grams of carb but eat 60 grams of carb. The extra 15 grams of carb are a gift to the muscles to replenish glycogen reserves.
Individual insulin needs and fuel usage depend on many variables. There’s no one-size-fits-all insulin recipe. The concept is that you may need different insulin-to-carb ratios and correction ratios on active versus sedentary days. Or you may need some extra carbs during exercise to support your activity.
The concepts in this section and this chapter are not a substitute for professional medical advice. Do not make any adjustments to medications without speaking to your medical providers. The information regarding adjustments to carbs and insulin during exercise is theoretical and meant only to clarify concepts.
Knowing when to postpone activity: Too high or too low, don’t go
Determining ideal blood-glucose targets can be tricky. If your blood-glucose levels are too low or too high, it may be a good idea to put exercise on hold and make adjustments to either carbs or insulin. Consider the following scenarios:
· The risk of driving on empty: Insulin users should check blood-glucose levels prior to exercising. The risk of hypoglycemia increases if pre-exercise glucose levels are below 100–120 mg/dl. Consider the need for a snack. Your doctor can help you determine the ideal blood-glucose range for exercise.
· Postponing when glucose levels hit the limits: If pre-exercise blood-glucose levels are elevated, the amount of insulin is insufficient in relation to available glucose. Well-meaning counter-regulatory hormones will drive the liver to release more glucose during exercise, even if blood-glucose levels are high to begin with. Insulin doesn’t work as well when glucose levels are very elevated. A glucose level above 250 mg/dl is cause for pause when you have type 1 diabetes. Consider the need for additional insulin, but dose conservatively due to the pending activity. This is a situation that should be discussed in advance with your diabetes specialist.
· Avoiding exercise if you have ketones: Ketones indicate a significant insulin deficiency. Do not exercise if you have ketones. Glucose can’t enter the muscles without the help of insulin. Counter-regulatory hormones always mobilize glucose and fatty acids to fuel exercise. The lack of insulin means those fuels can’t be used properly. Blood-glucose levels will continue to rise, and fats will be converted to ketone. Forcing muscles to exercise will accelerate the process and could lead to diabetic ketoacidosis.
Exercising with Type 2: Why It’s Right for You
Exercise is a treatment for type 2 diabetes. Studies show that exercise along with modest weight loss is one of the most effective ways to prevent prediabetes from progressing to type 2 diabetes. If you already have type 2 diabetes, exercise is one of the best ways to improve insulin sensitivity. The following sections describe the benefits of exercise specifically for people with type 2 diabetes.
Improving glycemic control
When it comes to type 2 diabetes, exercise is part of the treatment. People with type 2 diabetes have insulin resistance, and exercise increases insulin sensitivity. Insulin is more effective when muscles are moving. The glucose-lowering effect can persist beyond the actual exercise session.
During exercise, insulin is able to transport glucose into the muscle cells more readily. Imagine that insulin is the doorman assigned the task of opening cell doors to allow the glucose passage into the cell. Envision an exercising muscle cell eager to eat glucose. It pulls at the glucose. When the insulin doorman opens the cell door, a stream of glucose molecules is drawn into the contracting muscle.
Exercise can improve blood-glucose levels for hours after the exercise has ended. It has to do with burning glycogen from within the muscles’ reserves. Muscles replenish glycogen stores, so glucose from the bloodstream continues to move into the muscles until the glycogen levels are restored. The longer the duration of the exercise and the more strenuous it is, the longer the post-exercise glucose-lowering effect will last.
Keep in mind that if you eat a snack before exercising, you are more likely to burn the snack and not tap into glycogen or fat stores nearly as much. You should have a snack if you are at risk for hypoglycemia or if your pre-exercise blood-glucose levels indicate the need. But if your blood-glucose levels are fine, skip the additional carbs. When glucose levels are up but you are hungry, curb your appetite with a low-carb snack. See Chapter 22 for snack ideas.
Reducing cardiovascular risks
Exercise reduces the risk of heart disease and stroke. To cash in on the benefits, strive to meet the guidelines on physical activity: Accumulate at least 150 minutes of moderate-intensity activity each week and incorporate resistance exercises with mild to moderate weights twice weekly. Exercise improves heart health in the following ways:
· Lowering blood pressure: Walking, swimming, leisurely cycling, and water aerobics help lower blood pressure when done on a regular basis.
· Improving lipid levels: Staying physically fit and incorporating exercise helps to improve lipid levels in three ways:
o Exercise lowers LDL cholesterol (the artery-clogging type of cholesterol).
o Exercise raises HDL cholesterol (the kind that cleans out arteries).
o Exercise lowers triglycerides (the oily fats in the bloodstream).
· Promoting cardiovascular fitness: Physical activity strengthens your heart and improves circulation. Aerobic activity gets the heart pumping, which is a positive workout for the heart. The heart is a muscle; exercising helps keep it fit. Being overweight adds to the workload of the heart. Weight loss is good for your heart and good for your diabetes.
Supporting weight-control efforts
Modest weight loss has been shown to improve blood-glucose control in people with type 2 diabetes who are overweight to begin with. Losing 5–10 percent of starting weight is often enough to reap the rewards. Numerous variables affect body weight. One major influence on weight status is the balancing of calories consumed with calories burned. Individual caloric needs are determined by age, gender, genetics, body composition, and physical activity.
Staying at a steady weight indicates that calories consumed are balancing with calories burned. If more calories are consumed than actually needed, the body will convert the excess into fat. For perspective, one pound of body fat stores 3,500 calories. Your personal caloric requirements are the sum of the calories you need to sustain bodily functions along with the number of calories you need to move. Movement refers to your daily activities and exercise. You may be able to influence how many calories you burn, as discussed ahead.
Increasing your metabolic rate
Every organ uses fuel, including the brain, liver, lungs, and kidneys. Calories are used to regulate body temperature and to make new cells, tissues, and hormones. A flurry of activity happens behind the scenes even when you’re at rest. The sum of these physical and chemical processes is known as metabolism. About 70 percent of your daily caloric requirements go to metabolism. Activity level and exercise account for the remainder of the calories needed.
You can dispose of more calories by increasing your exercise, which is addressed next. However, you may also be able to increase your metabolic rate so that you burn more calories even at rest. It boils down to how much muscle you have. Muscles use up more fuel than body fat. Body fat doesn’t require many calories for upkeep. Muscles store energy in the form of glycogen (the storage form of glucose). When you exercise, the glycogen within the muscles is used. Muscles want their glycogen stores to be kept filled. It takes energy (calories) for the muscles to refill glucose stores. People who build and strengthen their muscles and who exercise regularly have a higher metabolic rate, especially those who work out at higher intensities. If you increase your metabolism, you will burn more calories even when relaxing, and that makes weight control easier.
Burning rather than storing calories
The sum of the calories consumed in a day is divvied up to feed all the body’s metabolic necessities. What happens next depends on how many calories are consumed and the level of activity and exercise on any given day. After distributing the calories needed to support metabolism and activity, any surplus calories are converted to fat. It’s simple math: If you eat more than you burn, you will gain weight. Any discussion about weight management should address the importance of physical activity. The more you exercise, the more calories you burn.
Keeping off the weight that’s lost
Successful weight loss means being able to keep the weight off. The National Weight Control Registry ( http://nwcr.ws ) says that a key factor to success is to engage in at least an hour of exercise per day. The data also suggests that the other components of long-term successful weight management include controlling dietary calories and fats, eating breakfast, weighing yourself regularly, and getting back on the wagon if you slip up. I second that motion! Temporary diets and crash dieting don’t work for the long haul. Skipping meals backfires too. Going long periods of time without food can slow down your metabolism and make it harder to lose weight. That’s why breakfast is a critical meal.
What works best for successful weight management is to eat a healthy, balanced diet, with appropriate portions, and to do so lifelong. Record-keeping can be useful. Track your weight with a home scale. Keep food logs periodically and take a good look at what you are actually eating.