Exercise and Diabetes. Sheri R. Colberg

and progress slowly to prevent injuries, and use appropriate gear and sports equipment in safe environments.

      Although specific safety considerations required for exercise participation by individuals with diabetes will be addressed in many chapters that follow, it is important to mention a few of these guidelines here (also see Table 4.4):

      • Individuals should monitor their blood glucose both before and after activity to promote safety and understanding of its glycemic effects.

      • All individuals with diabetes who are treated with insulin, sulfonylureas, or meglitinides should carry rapidly absorbed carbohydrates (e.g., glucose tablets or gels) with them while performing physical activity to treat hypoglycemia rapidly.

      • They should be aware that certain medications can impair exercise tolerance; for example, β-adrenergic blockers lower the HR response to physical activity, as well as mask hypoglycemic symptoms and lessen the strength of counterregulatory (glucose-raising) hormonal responses.

      • All individuals should wear clothing and shoes appropriate for the activity to reduce chance of injury.

      • They should wear some form of diabetes and personal identification.

      • Individuals need to use caution when exercising—particularly vigorously—in extremely hot, humid, smoggy, or cold environments.

      • Because seasonal changes in blood glucose control have been related to environmental temperature, they should find safe and available places to be active indoors when the weather is colder.

      • An individual should stop any activity if he or she experiences any symptoms like pain, lightheadedness, or shortness of breath.

Table 4.4 General Guidelines for Safe Exercise Participation with Diabetes

Perform self-monitoring of blood glucose (SMBG)	Check SMBG levels before and after each exercise session to ensure adequate pre-exercise control and to better understand and predict future glycemic responses. If blood glucose is >250–300 mg/dl with moderate or higher levels of urinary or blood ketones, exercise should be postponed; >250–300 mg/dl without ketones, okay to exercise, but use caution; <100 mg/dl, consider eating a snack consisting of easily absorbed carbohydrates (~20–30 g), based on insulin regimen and circulating insulin levels expected during the activity; 100–240 mg/dl, exercise is recommended.
Keep a daily log	Record the time of day the SMBG values are obtained and the dose of any medications taken. Also, approximate the time (min), intensity (heart rate), and distance (miles or meters) of exercise session. Such details aid the individual in understanding the glucose response to an exercise bout.
Plan ahead for exercise sessions	The need for adjustments to medications or food intake can be anticipated based on anticipated exercise (duration and intensity). If needed, carry extra carbohydrate (~10–15 grams for every 30 min) to prevent or treat hypoglycemia.
Ensure hydration	Hydrate before and rehydrate after each exercise session to prevent dehydration.
Modify caloric intake accordingly	Through frequent SMBG, caloric intake can be regulated more carefully on days with and without exercise participation.
Adjust insulin accordingly	If using insulin, reduce rapid- or short-acting insulin dosage to limit hypoglycemic episodes.
Exercise with a partner	Diabetic individuals should exercise with a partner until their glucose response is known and to promote exercise adherence.
Wear a diabetes identification (ID) tag	Diabetes ID with relevant medical information should always be worn. Hypoglycemia and other problems can arise that require immediate attention.
Wear good shoes	Always wear proper-fitting and comfortable footwear with socks to minimize foot irritations and limit orthopedic injury to the feet and lower legs.
Practice good hygiene	Always take extra care to inspect feet for any irritation spots to prevent possible infection. Tend to all sores immediately, and limit any irritations.

      Case in Point: Wrap-Up

      Because KK has most recently led a sedentary lifestyle, she should start with an initial exercise prescription that allows her to progress slowly toward higher levels of cardiovascular fitness over a period of weeks to months.

      Exercise Program Goals

      Mode of Activity: KK has stated that she enjoys walking and has done that activity from time to time, so the recommended activity to start will be brisk walking.

      Intensity: Because KK already does quite a bit of lifestyle activity, she should be able to start with moderate (brisk) walking at a comfortable pace that feels “somewhat hard” to maintain. To improve her fitness levels faster, she should consider adding short intervals of faster walking interspersed into her normal walking pace. If she wants to monitor her intensity using a target HR, a minimal starting intensity of 40% HRR gives her a target of 117 bpm, or a moderate range (40–59%) of 117 to 135 bpm.

      Frequency: KK’s goal should be a minimum of 3 nonconsecutive days of walking per week, with a goal of progressing to 5 or more days over the next several months. She should be advised to not go more than 2 consecutive days without doing some aerobic activity (to keep insulin action higher).

      Duration: If KK initially cannot walk for 30 min continuously, she should be advised to aim to do 10–15 min at a time spread over the day. Her initial goal should be a minimum of 150 min spread throughout the week, or possibly a lesser total time if she walks more intensely.

      Progression: KK’s long-term exercise goals should focus on progressively increasing her activity to reach the minimum recommended levels of 150 min of moderate or vigorous exercise spread throughout the week. Her target HR can remain either in the improvement phase (minimum target HR of 117 bpm, equal to 40% HRR) or progress as she is able, as fitness gains will result more quickly with a higher-intensity workout. Once she has reached the maintenance phase, she can substitute some alternative aerobic activities for variety, and she should consider adding in resistance training at least 2 days a week.

      Daily Movement: To help with weight loss, KK should engage in as much daily movement as possible, including standing more and taking steps throughout the day. As a possible motivator, she should consider getting a pedometer and setting a daily step goal.

      Possible Precautions: KK has minimal risk factors for cardiovascular disease (mainly diabetes), so she should not be required to have an exercise stress test before starting her walking progress. She has had a recent checkup with her doctor with good results (other than the diagnosis of T2D). She should consider, however, investing in a good pair of walking shoes and athletic socks to avoid the development of any orthopedic limitations related to her exercise program.

      People with diabetes of any type will benefit from getting specific aerobic exercise prescriptions from their health-care or fitness professional. This prescription should include specifics about what types of activities they should be doing, how hard they should be working out, how often and how long, and when they need to progress and what to expect in terms of reasonable progression through the phases of a training program. Empowering individuals to set their own specific goals is the ultimate aim of such programming.

      Professional Practice Pearls

      • Aerobic (or cardiorespiratory) exercise is defined as continuous, dynamic exercise that uses large muscle groups and requires aerobic metabolic pathways to sustain the activity (such as brisk