Question

, Chapter 14, Special Considerations for Type 1 and Type 2 Diabetes Mellitus

Case Study

This patient is a 48-year-old male who has always participated in exercise throughout his life. The patient often included sports or outdoor pursuits as part of his leisure time activity. He was surprised based on his lifelong level of physical activity to learn that he had abnormally elevated blood glucose levels and was initially treated for Type 2 diabetes. After a couple of months when his blood glucose levels did not improve on oral agents, he was finally correctly diagnosed with Type 1 diabetes and started on basal-bolus insulin therapy (basal: Lantus [insulin glargine] twice daily; bolus: Apidra [insulin glulisine] prior to meals and snacks or for blood glucose correction).

He has a BMI of 22.5 and has tried to remain active despite his diabetes. His blood lipid levels have returned to a normal range since he started on insulin; his resting blood pressure is 115/80 mm Hg; his resting heart rate is 62 bpm; his last HbA1C level was 6.3% (indicating an average blood glucose level of 134 mg · dL⁻¹ over the prior 2–3 months); and he sees his endocrinologist regularly (twice a year). Having trouble exercising at the level that he once was able to before his diabetes was diagnosed, he now presents to your facility for a supervised exercise program, which he hopes will help him get his workouts back on track.

Case Study Questions

1.   Determine risk factors and the patient’s guidelines for preparticipation screening.

2.   Determine exercise prescription guidelines for aerobic and resistance training according to FITT; prescribe intensity by HRR, %HR_max, and RPE.

3.   Determine classification, mechanism of action, and adverse effects on exercise testing and training for all medications prescribed.

Answer 1

1.   Determine risk factors and the patient’s guidelines for preparticipation screening.

Ans:-

When screening for genetic or congenital cardiovascular abnormalities, physicians should use the AHA's 14-point screening guidelines, as well as those from other societies (e.g., preparticipation physical evaluation from the American Academy of Pediatrics), combined with a history and physical examination.

The risk factors and the patient’s guidelines for pre-participation screening includes the following assessment:

· Chest pain or pressure related to exertion.

· Unexplained syncope or presyncope.

· Dyspnea, fatigue, or palpitations related to exercise.

· History of a heart murmur.

· Elevated blood pressure.

· Previous restrictions from the sport.

· Previous cardiac testing.

· Family history of premature death.

· Family history of disability from heart disease.

· Family history of hypertrophic.

· Family history of Dilated.

· Family history of Cardiomyopathy.

· Family history of Long-QT syndrome.

· Family history of other ion channelopathies.

· Marfa syndrome.

· Significant arrhythmias.

· Specific genetic cardiac conditions.

· Heart murmur on examination.

· Femoral pulses for aortic coarctation.

· Physical examination findings consistent with Marfan syndrome.

· Brachial artery blood pressure.

2.   Determine exercise prescription guidelines for aerobic and resistance training according to FITT; prescribe intensity by HRR, %HRmax, and RPE.

Ans:-

A variety of physical activities to improve the components of physical fitness is recommended for all.   Different types of physical activities work on different health-related components of physical fitness.

Aerobic Activity:

• Improves body composition and cardiorespiratory fitness

Muscle-strengthening Activity:

• Improves muscular fitness such as muscular strength and endurance

Stretching Activity:

• Improves flexibility such as range of motion

Neuromuscular Activity:

• Improves neuromuscular fitness such as balance, agility and proprioception

The F.I.T.T. Principle

Frequency

The first thing to set up with your workout plan is frequency—how often you exercise. Your frequency often depends on a variety of factors including the type of workout you're doing, how hard you're working, your fitness level, and your exercise goals.

In general, the exercise guidelines set out by the American College of Sports Medicine give you a place to start when figuring out how often to work.

• For cardio: Depending on your goal, guidelines recommend moderate exercise five or more days a week or intense cardio three days a week to improve your health. If you want to lose weight, you'll want to work up to more frequent workouts, often up to six or more days a week.
• For strength training: The recommended frequency is two to three non-consecutive days a week (at least one to two days between sessions). Your frequency, however, will often depend on the workouts you're doing, because you want to work your muscles at least two times a week. If you do a split routine, like upper body one day and lower body the next, your workouts will be more frequent than total body workouts.

Intensity

Intensity has to do with how hard you work during exercise. How you can change the intensity depends on the type of workout you're doing.1

• For cardio: For cardio, you will usually monitor intensity by heart rate, perceived exertion, the talk test, a heart rate monitor, or a combination of those measures. The general recommendation is to work at a moderate intensity for steady-state workouts. Interval training is done at a high intensity for a shorter period of time. It's a good idea to have a mixture of low, medium, and high-intensity cardio exercises so you stimulate different energy systems and avoid overtraining.
• For strength training: Monitoring the intensity of strength training involves a different set of parameters. Your intensity is made up of the exercises you do, the amount of weight you lift, and the number of reps and sets you do. The intensity can change based on your goals. If you are a beginner looking to build muscle stability and endurance, use a lighter weight and do fewer sets with high repetitions: two or three sets of 12 to 20 reps. If your goal is to grow muscle, do a higher number of sets with a moderate amount of repetitions (for instance, four sets of 10 to 12 reps each). If you want to build strength, use heavy weights to do a more sets with fewer reps (five sets of three reps each, for example).

Time

The next element of your workout plan is how long you exercise during each session. There isn't one set rule for how long you should exercise and it will typically depend on your fitness level and the type of workout you're doing.

• For cardio: The exercise guidelines suggest 30 to 60 minutes of cardio but the duration of your workout depends on what you're doing.1 If you're a beginner, you might start with a workout of 15 to 20 minutes. If you're doing steady-state cardio, such as going for a run or getting on a cardio machine, you might exercise for 30 to 60 minutes. If you're doing interval training and working at a very high intensity, your workout will be shorter, around 20 to 30 minutes. Having a variety of workouts of different intensities and durations will give you a solid, balanced cardio program.
• For strength training: How long you lift weights depends on the type of workout you're doing and your schedule. For example, a total body workout could take up to an hour, whereas a split routine could take less time because you're working fewer muscle groups.

Type

The type of exercise you do is the last part of the F.I.T.T. principle and an easy one to manipulate to avoid overuse injuries or weight loss plateaus.

• For cardio exercise: Cardio is easy to change, since any activity that gets your heart rate up counts. Running, walking, cycling, dancing, and the elliptical trainer are some of the wide variety of activities you can choose. Having more than one go-to cardio activity is the best way to reduce boredom, and your body needs variability along with progressive overload.
• For strength training: Strength training workouts can also offer variety. They include any exercise where you're using some type of resistance (bands, dumbbells, machines, etc.) to work your muscles. Bodyweight exercises can also be considered a form of strength training. You can easily change the type of strength workouts you do, from total body training to adding things like supersets or pyramid training to liven things up.

How to Use the F.I.T.T Principle in Your Workouts

The F.I.T.T. principle outlines how to manipulate your program to get in shape and get better results. It also helps you figure out how to change your workouts to avoid boredom, overuse injuries, and weight loss plateaus.

For example, walking three times a week for 30 minutes at a moderate pace might be a great place for a beginner to start. After a few weeks, however, your body adapts to these workouts and several things may happen:

• Your body becomes more efficient at exercise: The more you workout, the easier it is to do the exercises, causing you to burn fewer calories than you did when you started.
• Weight loss: Your new workouts may lead to weight loss. When you weigh less, you expend fewer calories moving your now-smaller body around.
• Boredom: Doing the same workout for weeks or months on end can get old, eating into your motivation to exercise.

It's at this point you want to manipulate one or more of the F.I.T.T. principles, such as:

• Changing the frequency by adding another day of walking
• Changing the intensity by walking faster or adding some running intervals
• Changing the time spent walking each workout day
• Changing the type of workout by swimming, cycling, or running.

Aerobic activity. Get at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity a week, or a combination of moderate and vigorous activity. The guidelines suggest that you spread out this exercise during the course of a week. Greater amounts of exercise will provide even greater health benefit. But even small amounts of physical activity are helpful. Being active for short periods of time throughout the day can add up to provide health benefit.

The following are guidelines for strength training:

• How often: 2 to 3 days per week, with a day off between sessions to let your muscle recover.
• How long: Begin with 1 exercise set per muscle group, with 8 to 12 repetitions per set. Build up to 3 sets per muscle group. Rest for 30 seconds between sets.
• How hard: Strengthening activities should be done to the point where it's hard for you to do another repetition without help.

The optimal intensity range can be determined by a number of methods: % maximum heart rate (%HRmax), % heart rate reserve (%HRR), talk test and rating of perceived exertion (RPE)

Male, age = 48, active, maximum HR = 180, resting HR = 59. Use 70%–85 %HRR.

Heart rate reserve: 180 – 59 = 121

Low end: (121 × 0.70) + 59 = 144 bpm

High end: (121 × 0.85) + 59 = 162 bpm

Thus, the target heart rate range for this individual is 144–62 bpm

3.   Determine classification, mechanism of action, and adverse effects on exercise testing and training for all medications prescribed.

Ans:-

The purpose of this report is to provide revised standards and guidelines for the exercise testing and training of individuals who are free from clinical manifestations of cardiovascular disease and those with known cardiovascular disease. These guidelines are intended for physicians, nurses, exercise physiologists, specialists, technologists, and other healthcare professionals involved in exercise testing and training of these populations.

Exercise Testing

The Cardiovascular Response to Exercise

Exercise, a common physiological stress, can elicit cardiovascular abnormalities that are not present at rest, and it can be used to determine the adequacy of cardiac function. Because exercise is only one of many stresses to which humans can be exposed, it is more appropriate to call an exercise test exactly that and not a “stress test.” This is particularly relevant considering the increased use of nonexercise stress tests.

Types of Exercise

Three types of muscular contraction or exercise can be applied as a stress to the cardiovascular system: isometric (static), isotonic (dynamic or locomotory), and resistance (a combination of isometric and isotonic).

Isotonic exercise, which is defined as a muscular contraction resulting in movement, primarily provides a volume load to the left ventricle, and the response is proportional to the size of the working muscle mass and the intensity of exercise. Isometric exercise is defined as a muscular contraction without movement (eg, handgrip) and imposes greater pressure than volume load on the left ventricle in relation to the body’s ability to supply oxygen. Cardiac output is not increased as much as in isotonic exercise because increased resistance in active muscle groups limits blood flow. Resistance exercise combines both isometric and isotonic exercise (such as free weight lifting).

Exercise Physiology

In the early phases of exercise in the upright position, cardiac output is increased by an augmentation in stroke volume mediated through the use of the Frank-Starling mechanism and heart rate; the increase in cardiac output in the latter phases of exercise is primarily due to an increase in heart rate. At fixed submaximal workloads below ventilatory threshold in healthy persons, steady-state conditions are usually reached within minutes after the onset of exercise; after this occurs, heart rate, cardiac output, blood pressure, and pulmonary ventilation are maintained at reasonably constant levels. During strenuous exertion, sympathetic discharge is maximal and parasympathetic stimulation is withdrawn, resulting in vasoconstriction in most circulatory body systems, except for that in exercising muscle and in the cerebral and coronary circulations. As exercise progresses, skeletal muscle blood flow is increased, oxygen extraction increases as much as 3-fold, total calculated peripheral resistance decreases, and systolic blood pressure, mean arterial pressure, and pulse pressure usually increase. Diastolic blood pressure may remain unchanged or decrease to a minimal degree. The pulmonary vascular bed can accommodate as much as a 6-fold increase in cardiac output without a significant increase in pulmonary artery pressure. In normal subjects, this is not a limiting determinant of peak exercise capacity. Cardiac output can increase as much as 4- to 6-fold above basal levels during strenuous exertion in the upright position, depending on genetic endowment and level of training. In the postexercise phase, hemodynamics return to baseline within minutes of termination. Vagal reactivation is an important cardiac deceleration mechanism after exercise; it is accelerated in well-trained athletes but may be blunted in deconditioned and/or “medically ill” patients.

Maximum Oxygen Uptake

Oxygen uptake quickly increases when dynamic exercise is begun or increased. During staged exercise testing, oxygen uptake usually remains relatively stable (steady state) after the second minute of each intensity of exercise below the ventilatory threshold. Maximal oxygen consumption (V̇o2 max) is the greatest amount of oxygen a person can take in from inspired air while performing dynamic exercise involving a large part of total muscle mass.

It is considered the best measure of cardiovascular fitness and exercise capacity. V̇o2 maxrepresents the amount of oxygen transported and used in cellular metabolism. It is convenient to express oxygen uptake in multiples of sitting/resting requirements. One metabolic equivalent (MET) is a unit of sitting/resting oxygen uptake (≈3.5 mL of O2 per kilogram of body weight per minute [mL · kg−1 · min−1]). V̇o2 max is influenced by age, sex, exercise habits, heredity, and cardiovascular clinical status. The ventilatory threshold is another measure of relative work effort, and it represents the point at which ventilation abruptly increases, despite linear increases in oxygen uptake and work rate. In most cases, the ventilatory threshold is highly reproducible, although it may not be achieved or readily identified in some patients, particularly those with very poor exercise capacity

• Arterial Blood Pressure Response
• Heart Rate Response
• Myocardial Oxygen Uptake
• Arterial Blood Pressure Response
• Testing Procedures
• Subject Preparation

Preparations for exercise testing include the following.

• The subject should be instructed not to eat or smoke for 3 hours before the test. Water may be taken as needed at any time. Subjects should dress appropriately for exercise, especially with regard to footwear. No unusual physical efforts should be performed for at least 12 hours before testing.
• When exercise testing is performed for diagnostic purposes, withdrawal of medications may be considered because some drugs (especially β-blockers) attenuate the exercise responses and limit the test interpretation. There are no formal guidelines for tapering medications, but rebound phenomena may occur with abrupt discontinuation of β-blockers in patients with a recent acute coronary syndrome. However, most subjects are tested while taking their usual medications. Specific questioning is important to determine which drugs have been taken so that the physician can be aware of possible electrolyte abnormalities and hemodynamic effects of cardioactive drugs.
• A brief history and physical examination should be performed to rule out contraindications to testing or to detect important clinical signs such as a cardiac murmur, gallop sounds, pulmonary “wheezing,” or rales. Subjects with a history of worsening unstable angina or decompensated heart failure should not undergo exercise testing until their condition stabilizes. A cardiac physical examination should indicate which subjects have valvular or congenital heart disease. Because hemodynamic responses to exercise may be abnormal in such subjects, such subjects always warrant careful monitoring and, at times, may require early termination of testing. Special considerations should be made for those with elevated blood pressure and aortic stenosis.
• If the indication for the testing is not clear, the subject should be questioned and the referring physician contacted.
• A resting standard 12-lead electrocardiogram (ECG) should be obtained because it may differ from the resting pre-exercise ECG. The “torso” ECG distorts the standard ECG by shifting the axis to the right, increasing voltage in the inferior lead group. This may cause a disappearance of Q waves in a patient with a documented previous Q-wave inferior myocardial infarction (MI).
• Standing ECG and blood pressure should be recorded (in the sitting position with cycle ergometry) to determine vasoregulatory abnormalities and positional changes, especially ST-segment depression.
• A detailed explanation of the testing procedure should be given that outlines risks and possible complications. The subject should be instructed on how to perform the test, and these instructions should include a demonstration. If musculoskeletal or certain orthopedic limitations are a concern, the testing protocol should be modified.

Indications for Terminating Exercise Testing

Absolute Indications

• ST-segment elevation (>1.0 mm) in leads without Q waves (other than V1 or aVR).
• Drop in systolic blood pressure >10 mm Hg (persistently below baseline), despite an increase in workload, when accompanied by any other evidence of ischemia.
• Moderate-to-severe angina (grade 3 to 4); details descriptions and grades for angina scale.
• Central nervous system symptoms (eg, ataxia, dizziness, or near syncope).
• Signs of poor perfusion (cyanosis or pallor).
• Sustained ventricular tachycardia.
• Technical difficulties monitoring the ECG or systolic blood pressure.
• Subject’s request to stop.

Relative Indications

• ST or QRS changes such as excessive ST displacement (horizontal or downsloping of >2 mm) or marked axis shift.
• Drop in systolic blood pressure >10 mm Hg (persistently below baseline). despite an increase in workload, in the absence of other evidence of ischemia.
• Increasing chest pain.
• Fatigue, shortness of breath, wheezing, leg cramps, or claudication.
• Arrhythmias other than sustained ventricular tachycardia, including multifocal ectopic, ventricular triplets, supraventricular tachycardia, heart block, or bradyarrhythmias.
• General appearance (see below).
• Hypertensive response (systolic blood pressure >250 mm Hg and/or diastolic blood pressure >115 mm Hg).
• Development of bundle-branch block that cannot be distinguished from ventricular tachycardia.

Drugs and Exercise Testing

β-Blockers

Subjects with angina who receive β-blockers may achieve a higher exercise capacity with less ST segment depression and less angina if the drugs prevent them from reaching their ischemic rate-pressure product and therefore translate into a reduction in diagnostic accuracy. Maximum heart rate and systolic blood pressure product may be reduced. The time of ingestion and the dosage of these medications before testing should be recorded. Whether to discontinue β-blockers before testing was discussed under “Subject Preparation.”

Vasodilators

These agents can increase exercise capacity in subjects with angina pectoris. There has been no scientific validation that long-acting nitrates increase exercise capacity in subjects with angina when they are tested after long-term administration.

Digitalis

ST-segment depression can be induced or accentuated during exercise in individuals who are taking digitalis, including both normal subjects and subjects with CAD. A normal QT interval is associated with digitalis-induced ST changes, whereas prolonged QT intervals occur with ischemia, other type 1 antiarrhythmic drugs, electrolyte imbalance, and other medical problems. Exercise-induced ST segment depression may persist for 2 weeks after digitalis is discontinued.

Diuretics

Most diuretics have little influence on heart rate and cardiac performance but do decrease plasma volume, peripheral resistance, and blood pressure. Diuretics can cause hypokalemia, which results in muscle fatigue, ventricular ectopy and, rarely, ST-segment depression.

Obtaining Informed Consent for Exercise Testing

Although obtaining written consent from a subject does not protect a physician from legal action, a signed consent form is nonetheless desirable to provide a written record that documents the informed consent process. A sample consent form is shown below.

Informed Consent for Exercise Testing

To determine my cardiovascular response to exercise, I voluntarily agree to engage in an exercise test. The information obtained about my heart and circulation will be used to help my doctor advise me about activities in which I may engage.

I have been told that before I undergo the test, I will be interviewed and examined by a physician in an attempt to determine if I have a condition indicating that I should not engage in this test. I am told that the test I will undergo will be performed on a (description), with gradually increasing effort until symptoms such as fatigue, shortness of breath, or chest discomfort may appear, indicating to me that I should stop. I have been told certain changes may occur during the test, including abnormal blood pressure, fainting, abnormal ECG showing heart “strain,” disorders of heart beat (too rapid, too low, or ineffective), and, possibly, heart attack and death.

Diabetes Mellitus

Patients with diabetes require special attention, especially if they are using exogenous insulin or oral hypoglycemic medications. Because they are prone to leg and foot wounds that may interfere with or be aggravated by exercise, initial medical evaluation should include an examination of the lower extremities. Patients should be advised to wear thick protective (preferably white cotton) socks and well-fitting supportive footwear during exercise. Patient history should include details regarding type of medication, timing and type of insulin used, and previous episodes of hypoglycemia. Patients should be counseled regarding the effect of exercise on blood glucose levels and the possibility of hypoglycemia, which may occur for several hours after the exercise session. Recognition and treatment of hypoglycemic episodes should be reviewed with diabetic patients.