Cardiorespiratory exercise has traditionally been the emphasis of cardiac rehabilitation programs. However, resistance training (RT) has gradually become a critical component of cardiac rehabilitation because of its significant health benefits and positive effects on cardiac comorbidities (1). There are safety concerns that need to be considered when implementing a RT program for the cardiac patient. As a result, specific RT guidelines have been established for cardiac rehabilitation (2,3). This article will address the benefits of RT in cardiac rehabilitation. In addition, safety concerns and guidelines and how to develop, implement, and monitor an RT program for patients in cardiac rehabilitation and after cardiac rehabilitation will be presented.
RT BENEFITS FOR CARDIAC PATIENTS
The benefits of RT for persons with cardiovascular disease are numerous. The most well-known benefit of RT is increased muscular strength and endurance (1,4-10). Overall muscle strength improvements of 25% to 30% are typically seen (4,8-10). In addition, a 46% improvement in muscle power has been observed in frail individuals who perform RT (4).
This is important for cardiac patients because many activities of daily living require more muscular strength and endurance than what is developed from cardiorespiratory exercise. In addition, the requisite force to complete these activities may exceed medically imposed lifting restrictions placed on this patient population (11). These activities include rising from a chair, carrying groceries, climbing stairs, and holding/carrying children and grandchildren. Many cardiac patients also lack the confidence to perform many tasks of daily living (1,2). Resistance training can provide them with both the muscular strength and confidence to live a more active and independent lifestyle (1,4-6,10,11).
For cardiac patients returning to work after rehabilitation, RT will be of particular interest, especially for those with physically demanding occupations. Resistance training reduces cardiac demands at given workloads by reducing the rate-pressure product (RPP) (systolic blood pressure × heart rate) (2,4,6-10,12) and can make tasks such as lifting heavy objects safer to perform. Combined cardiorespiratory exercise and RT have been shown to improve aerobic fitness more than cardiorespiratory training alone (8,13), further enhancing functional capacity and quality of life (1,4,10).
Resistance training helps manage and prevent a number of coronary risk factors (5,6,12) and other chronic diseases (5,6,10,12). These include type 2 diabetes, hypertension, overweight/obesity, arthritis, frailty/sarcopenia, and osteoporosis. Given that many cardiac rehabilitation patients are of increased age, maintaining or enhancing functional independence is a noteworthy benefit obtained from RT (1,4,5,11). See Table 1 for a summary of RT benefits for cardiac patients.
RT PRECAUTIONS AND SAFETY ISSUES FOR CARDIAC PATIENTS
Resistance training was once thought to be dangerous for the cardiac patient. Cardiac patients were (and sometimes still are) told not to lift anything heavier than 5 to 10 lbs for an indefinite time period after a cardiac event or procedure (11). This, if anything, will encourage less physical activity (1,11). However, research has shown RT to be safe in selected cardiac patients (6-8,11-18). Many studies have shown that low-risk (e.g., functional capacity, ≥7 metabolic equivalents [METs]) and moderate-risk (e.g., mild to moderate silent ischemia during exercise testing or recovery) cardiac patients can engage in RT without excessive myocardial strain (6-12). This includes certain individuals with congestive heart failure who have demonstrated the ability to tolerate RT (14,19,20). However, high-risk cardiac patients (e.g., presence of complex ventricular dysrhythmias) should not perform RT. Circuit RT can induce lower myocardial strain than an 85% effort on a treadmill test (10,21,22) or stationary bicycling at 70% of oxygen consumption at peak effort (7).
Many cardiac patients have other cardiac- (e.g., hypertension, diabetes, implantable cardiac defibrillators [ICDs], and pacemakers) and noncardiac-related (e.g., osteoarthritis, osteoporosis, and shoulder impingement) conditions that should be considered when developing an RT program. Most cardiac patients take a number of medications for their heart condition. The sidebar describes some of the more common medications taken by cardiac patients.
It is prudent that the fitness professional knows the cardiac history of the patient/client before initiating RT (1). Table 2 outlines the time course for initiating RT in low- to moderate-risk cardiac patients.
Resistance training is contraindicated and/or requires physician clearance for certain higher risk patients (2,3,10). Absolute and relative RT contraindications have been established for cardiac patients (Table 3). Special RT precautions need to be taken with patients who have had myocardial infarction (MIs), coronary artery bypass surgery (CABG), implantable defibrillators (ICDs), pacemakers, diabetes, and hypertension (1-3,8-11). Exercises involving significant shoulder girdle involvement and elevation are generally restricted for 4 and 6 weeks for patients having ICDs/pacemeakers and CABGs, respectively (2,3,11). Adams and colleagues (11) examined 13 commonly used RT exercises for safety, efficacy, and overall usefulness for patients who had a history of MI, CABGs, and ICDs/pacemakers. They developed a list of appropriate exercises and a timeline for specific movement/exercise restrictions. Upper-body RT should be restricted until the sternum has healed sufficiently (e.g., generally 3 months) in patients receiving CABGs and until physicians clear recipients of ICDs and pacemakers (2,10,11). Repetitive motion activities such as weight lifting can result in pacing lead fractures and dislodgement (2,10,11). Resting BP values should be less than 160/100 mmHg (3), and an exercise BP cutoff of 220/105 mmHg may be prudent (2). Monitor rate-pressure product in patients with hypertension (10) by taking and paying attention to both heart rate and systolic blood pressure (11). Consider using single-limb (instead of double limb) upper-extremity training in patients who have an exaggerated rise in blood pressure or RPP during RT (1). This also can be helpful in those patients with congestive heart failure (8).
Additional RT safety precautions and suggestions for specific conditions include the following:
- Combine RT with aerobic training (3,6,10,12).
- Use lighter weights (≤50% of 1-repetition maximum) (3,6,10,12).
- Select 8 to 10 exercises for the major muscle groups (3).
- Select a resistance allowing performance of 12 to 15 repetitions (3).
- Avoid tight gripping and breath holding (Valsalva maneuver) (3).
- Use a BP cutoff of 220/105 mmHg during RT (2).
- Avoid rapid changes in body position to prevent dizziness and falls. Some individuals with diabetes have autonomic neuropathies (a nervous system disorder) that can negatively effect circulation and balance.
- Use the RPE scale (Borg) if autonomic neuropathies are present.
- Encourage fluid replacement during exercise, and avoid dehydration.
- Start with RT loads of between 40% and 60% of 1RM and perform 10 to 15 repetitions.
- Avoid momentary muscle fatigue.
- Avoid tight gripping and the Valsalva maneuver (2,10).
Implantable Defibrillators (ICDs) and Pacemakers
- Repetitive motions like RT can result in pacing and lead fractures and dislodgement.
- Persons with ICDs and pacemakers should follow their physician's guidelines concerning raising their arms above shoulder height.
- Upper-extremity strength may be decreased from lack of use. Return to or begin upper-body RT gradually (2,10).
- Avoid spinal flexion (bending forward), twisting, running, and jumping to reduce the risks of vertebral fractures.
- Perform exercises in an upright posture, and emphasize activities like scapular retraction and depression (scapular rows), and hip and knee extension (partial squats and leg presses.
- Start with 1 set of 8 to 10 repetitions of exercises for all major muscle groups.
- Use an RPE range of 13 to 15.
- Exercise 2 days/week.
- Avoid painful activities.
- Avoid rapid changes of body position, and provide close supervision (some persons with osteoporosis may have postural changes that may negatively affect their balance).
- Progress to 2 to 3 sets, if tolerated (2,23).
- Avoid RT during periods of worsening pain and swelling.
- Avoid RT in the early morning in persons with rheumatoid arthritis.
- Some persons with arthritis may only tolerate 2 or 3 repetitions at a time with brief rest periods. Repetitions should be added as tolerated.
- Select 8 to 10 exercises (1 exercise for each major muscle group).
- Eliminate exercises that worsen or cause additional pain.
- Exercise within a pain-free range of motion.
- Isometric exercises and resistance bands and machines are all acceptable options, if tolerated.
- Avoid repetitive exercises in persons with unstable joints (2).
Continuous breathing during RT is particularly important for cardiac patients, to avoid the Valsalva maneuver. Exhaling during the exertion (lifting) phase is recommended. Avoiding tight gripping and sustained static (isometric) contractions also will help prevent excessive increases in blood pressure during RT (1-3,8,10,11). Exercise professionals should stop RT sessions immediately if any of the following adverse responses occur including:
- diastolic BP of 110 mmHg or higher
- decrease in systolic BP of 10 mmHg or higher
- significant ventricular or atrial dysrhythmias (Dysrhythmia means an abnormal cardiac rhythm. It can be either a single beat or sustained beats and can come from either the atria or ventricles.)
- second- or third-degree heart block (Two types of obstructions or delays in the conduction of electrical activity between the atria and ventricles.)
- signs/symptoms of exercise intolerance, including angina (chest pain), marked dyspnea (labored breathing), light-headedness or dizziness, and electrocardiogram changes suggestive of ischemia (insufficient oxygenated blood flow to the heart muscle or myocardium) (2,3)
Not all fitness facilities will have electrocardiogram or blood pressure equipment to monitor these vital signs. However, many ACSM certified professionals (i.e., exercise specialist, registered clinical exercise physiologist, and program directors) have the skills to monitor blood pressure, take a pulse, and calculate RPP. It is prudent that fitness professionals working with this population possess or acquire these skill sets.
RT PROGRAMMING FOR CARDIAC PATIENTS
Once a patient has been medically cleared to begin RT, a personalized program should be developed. It is important to consider other health conditions that may alter the RT program design. A cardiac patient with osteoporosis should perform all exercises with an upright posture and avoid spinal flexion (forward and lateral) and spinal rotation (twisting) (2,23). A patient with a shoulder impingement should keep movements below 90 degrees of shoulder abduction and flexion and keep arms slightly in front of the body in the scapular plane. Emphasis should be placed on scapular retraction and depression and on shoulder internal and external rotation. Rows are an appropriate choice for patients with a shoulder impingement (24).
There should be a balance among major muscle groups trained (5,6,10,12,25,26). This will prevent strength imbalances between opposing muscle groups, which could result in musculoskeletal injury. Both lower- and upper-body muscle groups should be trained on the same day to preserve time (5,10,26). Because of their efficiency and functional effects, multijoint exercises should be emphasized and use single-joint exercises to compliment the RT program (1,2,5,10,26). Not all cardiac rehabilitation programs have the time, space, and equipment to develop extensive RT programs. This amplifies the importance of performing multijoint exercises. When a variety of RT equipment is available, select modes that will be most comfortable for the patient (1).
Although there are recommended 1RM percentages for lower- and upper-body exercises for cardiac patients (Table 4), 1RM testing often is not performed because of safety concerns and a lack of RT experience that is common in cardiac patients. An RPE of 11 to 13 (fairly light to somewhat hard) on the Borg Scale is an appropriate method for determining initial loads for RT exercises (2,3). A gradual increase in resistance (5%) should occur once the patient can complete 12 to 15 repetitions with ease (3). A few training tips include the following:
- Perform a warm-up before the start of all RT sessions; a general warm-up would consist of light aerobic exercise for 5to 10 minutes; a specific warm-up would include gentle stretching and/or active range of motion exercises with light or no resistance (2).
- Resist the desired movements/synergies while keeping resistances (weights, bands, tubes, medicine balls, etc.) parallel to the plane of motion and opposite the intended direction of their movement(s).
- Avoid "throwing" or "dropping" the resistance; always maintain control of the resistance.
- Use a rest interval duration, which allows the patient to recover enough to produce the desired repetitions/work for the following set or exercise.
- Maintain proper body and joint alignment at all times (e.g., ankles, knees, and hips in line during a leg press or squat) (26).
- Machines typically allow for more time-efficient RT sessions, are easier to perform with proper technique, and stabilize the body, reducing balance requirements (more muscle isolation) (1,26).
- Free weights typically use more muscles for balance and stabilization, offer a variety of technique manipulations (e.g., various hand positions), and work the muscles in a more functional manner (1,26). See Table 4 for a summary of RT programming guidelines for cardiac patients.
RT FOR PATIENTS WHO COMPLETED CARDIAC REHABILITATION
The RT program design for the patient after cardiac rehabilitation will depend on where the patient plans on exercising upon completion of their allotted cardiac rehabilitation sessions and what RT equipment (e.g., variable dynamic resistance machines, free weights, and variable resistance [or color] bands/tubing) an individual will have access to. In an ideal situation, upon completion of the monitored phase of cardiac rehabilitation (often referred to as phase II), an individual will be offered the opportunity to continue exercising in the same facility as a member of their maintenance program (often referred to as phases III to IV). Remaining in a familiar environment will increase both an individual's comfort and confidence level in moving forward with their exercise program, particularly RT. However, as is often the case, many patients must find a new place to exercise with different equipment and, just as important, a new staff.
With the various modes of RT and exercise equipment available to the health and fitness professional, each cardiac patient must be evaluated on an individual basis. Understanding the new client's medical history (e.g., MI, CABG, and angioplasty) is essential. In a phase IV environment, the health and fitness professional in conjunction with the clinical program director would be charged with developing the client's exercise prescription. However, in a nonclinical setting (e.g., local health club or gym), the fitness professional must contact and work with the client's physician or health care provider in designing the client's exercise prescription (Table 4). For example, a cardiac patient who had open-heart surgery and participated in only 4 weeks of supervised cardiac rehabilitation (phase II) would not be ready to perform the same RT exercises that an individual who had an angioplasty with stent placement 4 weeks prior would be ready to perform. In this particular case, both the open-heart surgery patient and the health and fitness professional must be cognizant of sternal precautions (healing usually takes 12 weeks), which would primarily include limiting upper-body RT exercises (Table 2).
Health and fitness professionals working in the clinical environment also must be comfortable with preparing cardiac patients for exercising in their homes. As is the case with many cardiac patients, they do not transition into another formal setting, thus they must be prepared to continue their strength-training program at home. Many cardiac rehabilitation programs will incorporate the use of colored tubing or resistance bands (different colors indicate a different level of resistance) into their RT programs. As well as being a safe and effective form of strength training, using this type of RT equipment is easy for the patient to learn. In addition, cardiac rehabilitation programs can usually accommodate distributing these resistance bands and colored tubing for use by their client's at home upon completion of their program.
The number of cardiac patients is not going to decrease in the years ahead, thus the cardiac rehabilitation programs and fitness facilities are charged with the following: facilities must have the essential equipment (e.g., treadmills, upper-body ergometers, variable dynamic resistance machines, free weights, and colored tubing/bands) to elicit expected outcomes; and staff must be properly trained/educated (e.g., degreed, certified) to work not only with cardiac patients but also with the increasing numbers of various special populations.
Resistance training is safe for selected cardiac rehabilitation patients and provides a number of health and fitness benefits. It is important for each cardiac patient to follow the proper time course for initiating RT and adhere to specific RT programming and safety guidelines. Cardiac patients should have their RT program adapted to their specific needs and abilities. This will allow them to achieve the benefits of RT, while minimizing the risk of adverse events or injury. Resistance training, like cardiorespiratory exercise, should be continued after the completion of a cardiac rehabilitation program to maintain or further enhance muscular fitness.
CONDENSED VERSION AND BOTTOM LINE
Evidence now clearly demonstrates that cardiac rehabilitation patients should be performing RT. The benefits obtained from RT will compliment the cardiorespiratory component of cardiac rehabilitation. Once a cardiac patient has been deemed safe and ready to initiate RT, specific safety and programming guidelines should be followed to maximize RT safety and efficacy. In addition to maintaining their cardiorespiratory training after cardiac rehabilitation, cardiac patients should continue to engage in RT to improve their quality of life.
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