Joslin’s Diabetes Deskbook, Updated 2nd Ed., Excerpt #27: Physical Activity for Fitness, Part 4

Richard S. Beaser, MD,
Edward S. Horton, MD and
Catherine A. Mullooly, MS, RCEP, CDE

 The week’s excerpt answers the following questions: 

• How much resistance training is needed to improve insulin sensitivity
• Frequency, duration and intensity levels required
• Self-care skills applied to physical exertion
• Individualized physical activity for type 2 diabetes….

Aerobic or endurance exercise training programs traditionally have been recommended for individuals with diabetes and have been associated with weight loss, improved glucose control, improved cardiovascular fitness and improved cardiovascular risk profile. For individuals with morbid obesity, musculoskeletal limitations (e.g., arthritis), physical disabilities, and/or diabetes complications, sustained weight bearing activities (e.g., walking) may be challenging or uncomfortable to perform. Progressive resistance training has emerged as a therapeutic intervention to enhance insulin sensitivity, muscle strength, lean muscle mass and bone mineral density, favorably impacting functional status and quality of life. The addition of resistance training to an aerobic exercise program has been shown to provide additional benefit with regard to insulin sensitivity and glycemic control over aerobic training alone. Specifically, resistance training should be undertaken at least 2-3 days per week, with a minimum of 8-10 exercises involving the major muscle groups (e.g. chest, shoulder, back, abdominal, biceps, triceps, anterior and posterior thigh), progressing to 2-3 sets of 8-10 repetitions at a weight that can’t be lifted  more than 8-10 times. Traditionally, free weights (e.g. dumbbells, barbells) and resistance training machines (e.g. Nautilus, Cybex) are utilized.

The Physical Fitness Routine

The physical activity session consists of 1) the warm-up phase, 2) the workout or exercise phase, and 3) the "cool-down" phase.

The warm-up should include a period of 5 to 10 minutes of light activity preceding the workout or exercise session. For example, begin with a leisurely walking pace before increasing to a power walk or jogging tempo. Or use a stationary cycle for 5-10 minutes before performing a more strenuous lifting routine. This approach will gradually increase blood flow to the working muscles to prepare them for the more vigorous workout phase and possibly reduce the chance of injury. The workout phase, consisting of aerobic and resistance exercise should be followed by a gradual cool-down over the remaining 5 to 10 minutes of the activity session. The final phase may include light aerobic activity and stretching movements. This helps restore the energy expenditures and the blood flow to the resting state.

Once patients decide to start a fitness program, it takes motivation to continue after the first enthusiasm wanes. The program works better if it is designed specifically for the individual, with his or her input. It should be written down. Goals should be short-term, focusing on an interval such as two weeks. They should also be realistic. Patients should let family or friends know of their fitness plans, so they can encourage the patient to stick with the workout program, perhaps joining them to provide the added motivation of knowing that "someone is watching!" Activities should be selected that the patient enjoys. Alternate activities should also be included in the plan so that bad weather, equipment failure, etc., will not provide an excuse to skip a workout session. The intensity and duration of the activity must be realistic so that the patient does not overexert herself. A bad experience can turn someone off to the fitness program altogether. Written schedules also help, especially in integrating physical exertion with eating and insulin. Small rewards for reaching goals are helpful too, but often the best reward is the feeling of accomplishment, or merely just feeling good!

Physical Activity for People with Disabilities

When disabilities affect a person’s ability to be independent, or when medical conditions limit an individual’s ability to get out and move, some form of activity may still be possible, and, in fact, often quite valuable. Such physical fitness programs must be individualized to the person’s particular abilities and disabilities, and consultation with an exercise physiologist may be recommended. There are also videos that are available that are geared for people with disabilities or lesser levels of fitness, showing armchair exercises, or even bed exercises that can help maintain muscle strength and cardiovascular health. Similarly, television broadcasts of fitness programs for those with some limitations might be available. So-called senior fitness programs often include activities such as Tai Chi, stretching, aerobic dance, or weight lifting. Home exercise equipment such as stationary bicycles or treadmills might also be considered.

Adjusting Diabetes Treatment to Meet the Demands of Physical Exertion

While the glucose lowering effect of physical activity may be beneficial, it is also important that it be balanced with the two other major components of glucose control — food and insulin. Successfully achieving this balance requires many of the skills that are basic to diabetes self-care, though the application of these skills does differ somewhat between the two major types of diabetes.

Self-monitoring of blood glucose (SMBG) is central to developing a selfcare routine that maintains metabolic balance. Monitoring before and after — even during — physical exertion allows the patient to observe the impact of physical activity on blood glucose levels and to chart the course of glucose variations as affected by the activity performed. In addition, monitoring helps document the presence of hypoglycemia, even if symptoms are not obvious, and also helps guide the development of hypoglycemic avoidance strategies. Continuous glucose monitoring (CGM) may be useful to determine the responses to various types, intensities and durations of exercise and may detect nocturnal hypoglycemia following exercise that would otherwise go unrecognized. Real time CGM combined with insulin pump therapy may also be useful for managing exercise in patients with type 1 diabetes.

No matter how much care is taken, hypoglycemia is still a possibility during and after physical exertion. Patients should always have hypoglycemia treatment items readily available during physical activity. As hypoglycemic symptoms may not always be present or obvious during physical exertion, blood glucose values, rather than symptoms, should be the determinant of a hypoglycemic event.

Physical Activity and Type 2 Diabetes

As noted previously, endurance training for people with type 2 diabetes can be quite beneficial, as it lowers insulin resistance and improves glucose tolerance. Over time, the right endurance program may allow the dose of insulin or oral antidiabetic medication to be reduced. However, as physical exertion can be detrimental in the presence of an absolute deficiency, it is important to identify those people with type 2 diabetes who have progressed to this point of severe β-cell dysfunction. It is a good rule that those with type 2 diabetes who do not use insulin should not begin physical exertion if the blood glucose level is above, or close to, 400 mg/dl.

For those patients who have type 2 diabetes adequately controlled using oral antidiabetic medications, and who are engaged in a physical fitness program, monitoring blood glucose levels can help determine appropriate medication adjustments. The goal for these people may include weight loss and/or reduced medication dose. As some antidiabetes medications can cause hypoglycemia, particularly those medications that increase insulin secretory capacity, careful self-monitoring is important. If hypoglycemia is detected either through glucose checking or by recognition of symptoms during or after physical exertion and it is confirmed by performing a glucose check, the medication dosage may be reduced. Medication dose reduction is certainly preferable to extra snacking if weight loss is a goal. Improvements in physical fitness can also increase insulin sensitivity, so dose reduction for all days, not just the physically active days, can often be achieved.

When occasional physical exertion results in hypoglycemia, however, it is often ineffective to reduce the oral agent dose, particularly if the increased activity is not predictable. Instead, small snacks before or after physical exertion on those occasional active days may be needed to prevent hypoglycemia despite any efforts at weight reduction.

For people with type 2 diabetes who use insulin, the approach is similar to that taken by people with type 1 diabetes using insulin, and the guidelines listed in the sections below apply.

Next Joslin Text Excerpt: Physical Activity and Type 1 Diabetes

 

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