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Joslin’s Diabetes Deskbook, Updated 2nd Edition, Excerpt #25: Physical Activity: The Physical Fitness Program

Jan 20, 2013





There are three components of a physical fitness program: cardiopulmonary endurance, flexibility and strength training.

Cardiopulmonary endurance training is exercise carried out over an extended period of time and requiring sustained energy expenditure. It stimulates the heart and lungs and uses most of the body muscles for at least 30 or more minutes each session. Strength training is physical exertion such as weight lifting that applies heavy resistance to specific muscle groups. Flexibility involves stretching of specific muscle groups and increasing range of motion. It is important in the "warm up" and "cool down" phases of an exercise session.

Most physicians and exercise physiologists recommend endurance training or a combination of endurance and strength training as the most useful activity for adults because of the beneficial stress effect on the cardiovascular and metabolic systems. Although all types of exercise are recommended for most people with diabetes, more time should be spent on endurance exercises.
Evaluation before Starting 

Before starting a fitness program, your patients with diabetes should first be carefully evaluated. This evaluation is important at any age. It is assumed that older individuals have increased risk of heart, lung, or circulatory disease, particularly if they have multiple macrovascular risk factors.

Medical clearance prior to starting the fitness program is assumed to be most important in this age group. Yet younger people with long-term diabetes still have a potential for underlying circulatory or cardiac disease as well, and should also undergo evaluation prior to starting a physical exertion program.

People can still engage in a physically active lifestyle in spite of the presence of diabetes complications, but an evaluation of these complications is important before starting the physical fitness regimen. These findings will be useful to identify any necessary modifications to the fitness program.

A poorly designed program can exacerbate complications. Specific complications to focus on during an evaluation include:

  • Proliferative retinopathy
    • vitreous hemorrhage
    • retinal detachment
  • Nephropathy
    • increased proteinuria
  • Peripheral neuropathy
    • soft-tissue and joint injuries
    • falls
  • Autonomic neuropathy
    • decreased cardiovascular response to physical exertion
    • decreased maximum aerobic capacity
    • impaired response to dehydration
    • postural hypotension
As noted above, each evaluation must be individualized. However, for people with diabetes, the evaluation should focus on areas in which complications are likely to be present: 

1. Cardiovascular system — Take a detailed history, focusing on cardiovascular risk factors in addition to the diabetes, including:

  • dyslipidemia
  • hypertension
  • smoking history
  • gender
  • age
  • family history
  • weight
  • active vs. sedentary lifestyle
  • duration of diabetes
  • any history of cardiac or vascular disease
Look for symptoms suggestive of coronary artery disease. An exercise tolerance test, or perhaps a stress echo or stress thallium, should be considered, particularly if the patient is over 35 years of age or has had type 1 diabetes or type 2 diabetes for over 10 years or type 2 diabetes and at least one of the following:
  • microalbuminuria
  • overweight/obesity: BMI > 28km/m2
  • dyslipidemia: LDL-C > 100mg/dl, HDL- C < 40 mg.dl in men or <50 mg.dl in women, fasting TG > 150 mg/dl
  • known macrovascular disease (PVD)
  • family h/o CAD: under 55 y/o
  • hypertension: 130/85 mmHg on 3 occasions
  • smoker
  • start of a new physical activity program
  • autonomic neuropathy evidenced by
    • cardiac autonomic function abnormalities
    • orthostatic hypotension
    • erectile dysfunction
    • gastroparesis
Be aware that people with diabetes may have atypical symptoms of coronary disease. Significant occlusion of coronary arteries may be present with either no anginal symptoms at all ("silent ischemia") or with angina pain being manifest in an atypical manner such as jaw or shoulder pain ("anginal equivalents"). If there is any suggestion of cardiovascular disease, it is recommended that the patient participate in a supervised cardiovascular fitness program. 

Screening for autonomic neuropathy affecting cardiac function can consist of testing for decreased respiratory rhythm variation, as well as measurement of postural blood pressures, watching for an excessive (20mmHg. with standing) drop in systolic blood pressure. A resting tachycardia of 100 beats/minute is also a good screen. Certainly, a history of postural symptoms such as dizziness or lightheadedness should be a warning of possible problems. People with significant autonomic dysfunction, particularly postural hypotension, might consider armchair exercise routines rather than activities involving walking or standing. Patients with autonomic dysfunction affecting cardiac function may not be able to achieve increases in heart rate comparable to those with no dysfunction. Also, patients taking beta blockers cannot achieve their predicted maximum heart rate during exercise. Therefore, caution should be taken not to push these people to exert themselves to the usual predicted maximum heart-rate levels. They might not be able to increase their pumping frequency as much and could, with significant exertion, experience cardiac insufficiency.

2. Eyes — All patients starting a physical fitness program should have a thorough dilated (or equivalent) evaluation by an ophthalmologist. Patients with severe or progressive diabetic retinopathy should not perform certain physical activities, as changes in blood pressure induced by these activities can increase the risk of blood vessel leakage or hemorrhage. Low to moderate intensity options are usually better for these people. For people who do have active proliferative retinopathy, vigorous activity may precipitate a vitreous hemorrhage or retinal detachment. Such individuals should be advised not to participate in anaerobic activities or physical movements that include jarring, straining, or Valsalva-like maneuvers. The degree of retinopathy often dictates the risk associated with physical exertion.

3. Renal Function — Exercise will often result in increased microalbuminuria, which is usually transient and is not harmful. However, if a patient is found to have microalbuminuria on a routine screening examination, be sure to obtain an exercise history and, if the patient has participated in strenuous exercise within the previous 24-48 hours, repeat the test after at least 48 hours without strenuous exercise.

4. Lower Extremities — Patients should undergo a careful examination of their lower extremities, with particular attention to detection of:

  • neuropathies
  • peripheral vascular disease orthopedic or podiatric abnormalities and/or histories
Low-impact activities such as swimming that minimize trauma to the lower extremities should be considered. Any evidence of injury, particularly to the skin integrity, should be monitored closely. Proper footwear for different physical activities is also very important. 

In addition, for everyone with diabetes, the quality of diabetes control needs to be assessed prior to initiating a physical fitness program. If poor, control should be improved before the physical fitness program begins.In general, for people with type 1 diabetes, physical exertion should not be performed unless the blood glucose level is below 250-300 mg/dl, except in the immediate post-prandial state. There should also be no evidence of ketosis in such individuals (see Table 6-2).

Diabetes control should be maximized through careful attention to glucose patterns, insulin doses and adjustments, and dietary guidelines. The patient should be educated on the adjustments for his or her program to compensate for physical exertion in order to avoid hyper-or hypoglycemia. Frequently adjustments of medications are needed, both for insulin and oral treatments. Usually, if an oral medication needs adjustment, it is an insulin secretagogue. These medication doses may be reduced if the individual engages in intermittent, acute increases in daily physical activity.




Next excerpt: Prescribing the Fitness Program

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Professionals must use their own professional medical judgment, training and experience and should not rely solely on the information provided in this book to make recommendations to patients with regard to nutrition or exercise or to prescribe medications.

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