EXERCISE PRESCRIPTION IN PRESENCE OF ISCHEMIA / ARRHYTHMIAS
An exercise test and medical supervision are essential for this type of exercise prescription. The manifestations of arrhythmias or ischemia that require such precautions can vary but usually include the following:
Ventricular tachycardia (3-4 beats)
Any arrhythmia that is symptomatic or causes hemodynamic instability
Chest discomfort that is believed to be angina
Significant electrocardiograph (ECG) ST depression
Inappropriate blood pressure responses such as significant hypertension or a decrease in systolic blood pressure of 20 mm Hg from baseline.
Perform exercise testing in the usual fashion, but the conditioning work intensity is derived from the HR associated with the abnormality. If the exercise test continues to a high level of effort, the HR at 50-60% of maximum can be used if it falls at least 10 bpm below the abnormal level.
Otherwise, the recommended peak training HR is 10 bpm less than that associated with the abnormality. These individuals are recommended to have medically supervised cardiac rehabilitation and reevaluation to restratify them to a lower risk. Repeat exercise testing at least yearly.
As the population ages and more elderly persons survive coronary events, increasing numbers need appropriate physical activity. Most of these persons initially demonstrate benefits from supervised exercise for a brief period.
This is performed primarily to introduce the patient to exercise (which the individual may not have performed before) and to evaluate the patient for possible complications of exercise, such as arrhythmias, evidence of heart failure, anginal chest pain, or abnormal ECG ST segments.
On the basis of the evaluation, the person can be categorized as low risk or moderate to high risk, and appropriate cardiac rehabilitation precautions can be taken.
Most individuals in secondary prevention can soon be restratified as low risk and can implement their exercise prescription at home or in a community program. In this setting, the previously mentioned primary prevention guidelines also apply.
The intensity may be much less, and the frequency may be more, with appropriate changes in duration. Interval exercise testing is recommended at least yearly, and coronary risk factor modification should be aggressive.
In summary, implementation of physical activity strategies by physicians for both primary and secondary prevention should consider the dosing effect or expenditure of kilocalories or kilojoules over a unit of time (usually a week).
The guidelines above ideally should entail 5-6 hours of various physical activities weekly if possible. The exercise routine must be individualized (exercise prescription) and should include both aerobic and resistance activities. The benefits of exercise are enhanced with good to excellent compliance with exercise and appropriate lifestyle modifications.
POSTMYOCARDIAL INFARCTION
As the safety of early ambulation was progressively demonstrated in patients after suffering myocardial infarction, other benefits were realized, such as the prevention of the deconditioning effects of bed rest, decrease of anxiety and depression, and improved functional status at discharge.
Early activity
Walking is the recommended mode of activity unless the individual can attend supervised classes where other activities are provided. Begin limited walking and slowly continue, with a gradual increase in duration until 5-10 minutes of continuous movement has been achieved. Active but nonresistive range of motion of the upper extremities is also well tolerated early if the activities do not stress or impair healing of the sternal incision in persons who have had coronary bypass surgery.
The emphasis of exercise in the first 2 weeks after myocardial infarction or coronary bypass surgery should be on offsetting the effects of bed rest or former periods of inactivity. Begin to increase activity when the individual's condition is stable, as measured by ECG tracings, vital signs, and symptomatic standards. Although the prescribed activity is usually well tolerated and safe, certain precautions are recommended, such as awareness of chest discomfort, faintness, and dyspnea.
Supervise the initial activities and record symptoms, RPE, HR, and blood pressure. When safety and tolerance are documented, the activity can be performed without supervision.
Late activity
A symptom-limited exercise test is often performed after the individual's condition has stabilized (as early as 2-6 wk after the coronary event). In secondary prevention, such testing is essential in all patients before beginning a physical activity program. If more studies (eg, echocardiography, angiography) are not indicated, a regular conditioning program can be initiated with a careful prescription of activity based on results of the exercise test.
For conditioning purposes, perform large muscle group activities for at least 20-30 minutes (preceded by a warm-up and followed by cool-down) at least 3-4 times per week. The exercise prescription should be based on the exercise test results.
Supervised group sessions are recommended initially to enhance the exercise educational process, ensure that the participant is tolerating the program, confirm progress, and provide medical supervision in high-risk situations.
Unsupervised home programs are acceptable for persons who are at low risk and who are motivated and understand the basic principles of exercise training.