Exercise Training With Chronic Heart Failure

INTRODUCTIONChronic heart failure (CHF), also called congestive heart failure, is a lifelong condition in which the heart muscle cannot pump enough blood to meet the body’s needs for oxygenated blood (1,2). The heart cannot keep up with its workload. When this happens, blood often backs up and fluid can build up in the lungs, causing symptoms such as shortness of breath. Certain heart conditions gradually cause the heart to weaken and/or stiffen (1). This leads to insufficient ventricular filling and reduced cardiac output. These conditions include hypertension and narrowed coronary arteries. The heart will try to compensate by enlarging itself, increasing cardiac muscle and pumping faster. These changes usually help initially but not long term. CHF can become life threatening and is associated with high morbidity and mortality levels (1). Individuals with CHF may have severe symptoms. Some may need a heart transplant or a device (left ventricular assist device) to help the heart pump sufficient blood throughout the body. Proper treatment can improve the symptoms of CHF and may help some people live longer (2). Lifestyle changes also can help manage CHF and improve quality of life. These changes include losing weight (if needed), physical activity/exercise, consuming less sodium (salt), managing substance abuse, and managing stress levels (2,3).There are three types of CHF, such as right-sided heart failure, left-sided heart failure, and biventricular heart failure. According to the pumping ability, there are two types of heart failure, such as heart failure with preserved ejection fraction and heart failure with reduced ejection fraction, also known as diastolic and systolic heart failure, respectively (4). The primary focus of this column will be heart failure with reduced ejection fraction. EPIDEMIOLOGY AND PATHOPHYSIOLOGY It is estimated that approximately 6.7 million Americans over the age of 20 have CHF. The prevalence is predicted to increase to 8.5 million Americans by the year 2030. The lifetime risk of CHF is approximately 24% with one in four individuals developing CHF in their lifetime. The prevalence of CHF is greater among Black individuals compared with other racial and ethnic groups (5). Interestingly, a greater annual increase in CHF-related mortality rates has been noticed in younger adults (35 to 64 years) compared with older adults (65 to 84 years). The greatest CHF death rates have been reported in the Midwest, Southeast, and Southern states. Rural areas have displayed greater CHF mortality rates for both younger and older age groups when compared with urban areas. This recent data on CHF epidemiology comes from a report from the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines (6).There are several risk factors for developing CHF. Some of the more common risk factors include the following (1,4): Hypertension Diabetes Coronary artery disease Heart attack Kidney disease Overweight and obesity Cardiomyopathy Arrhythmias Tobacco use Substance abuse (alcohol and recreational drugs) Individuals with CHF can have mild symptoms and sometimes no symptoms at all. CHF can vary from mild to severe and may be intermittent (6). However, CHF symptoms typically get worse over time. As CHF progresses, the signs and symptoms usually increase or become more severe (2,7). Some of the more common signs and symptoms of CHF include the following (1,4,7): Shortness of breath Chest pain Heart palpitations Edema in the ankles, legs, and abdomen Weight gain Frequent urination at night Dry cough Loss of appetite Bloated abdomen The most common medications used to treat CHF aim to delay detrimental effects such as increasing heart rate and constriction of blood vessels, resulting in reduced blood flow to important organs. These medications are shown in brief in Table 1. TABLE 1 - Pharmacological Treatment Options for Chronic Heart Failure Drug Class Side Effects Effects on Exercise Antiarrhythmics Dizziness, syncope, tachycardia,bradycardia, arrhythmia No adverse effects β-Blockers Dizziness, wheezing, fatigue, depression, impotence, ↓ HDL ↓ Blood pressure, ↓ heart rate, ↓ V˙O2max in hypertension Diuretics Weakness, confusion, potassiumdepletion, fatigue, thirst, gout ↓ Blood pressure, especially postexercise if not appropriately hydrated ACE inhibitors Cough, rush, fluid retention, hypotension, orthostatic intolerance ↓ Blood pressure, ↓ heart rate Calcium channel antagonists Constipation, headache, dizziness, nausea, tachycardia, fatigue, swelling of feet ↓ Blood flow to working muscles, ↓ lactate threshold, ↓ heart rate Aldosterone receptor blockers Nausea, vomiting, stomach cramps, diarrhea, hyperkalemia No adverse effects ACE, angiotensin-converting enzyme; HDL, high-density lipoprotein cholesterol; V˙O2max, maximal oxygen uptake (6). EXERCISE BENEFITS Individuals with CHF have low exercise capacity, demonstrating fatigue and dyspnea when engaging in physical activity or structured exercise training. This is common due to impaired vasodilation capacity and various side effects of medications, resulting in reduced inotropic and chronotropic responses to exercise. Thus, people with CHF present with low functionality and several physical limitations adversely affecting activities of daily living and quality of life (6). Regular exercise has been reported as a vital tool for improving numerous psychophysiological indicators in patients with CHF. Specifically, physical exercise increases exercise capacity (10% to 30%), peak oxygen uptake (17%), cardiovascular efficiency, skeletal muscle function, and quality of life (8–10). EXERCISE TESTING Symptom-limited exercise testing has been considered safe for persons with CHF with reduced ejection fraction, especially when combined with the indirect measurement of expired gases (11). However, clinical exercise physiologists should pay attention to several special exercise training considerations; in particular, this population demonstrates lower heart rate peak, stroke volume, and peak cardiac output response to exercise, resulting in significantly reduced exercise capacity. Importantly, exercise tolerance may be <50% of age-predicted normal or a volume of oxygen consumed per minute (<12 mL/kg/min) (12,13) in people with CHF being considered for cardiac transplant. Thus, the modified Naughton treadmill protocol or a 10 W/min ramp ergometer protocol are the most suitable exercise testing options for people with CHF. Also, regional and local blood flow are limited due to reduced vasodilation of the large vessels and resistance vasculature, while oxidative capacity also is limited due to abnormalities in skeletal muscle histochemistry (14). In general, exercise testing results may support cardiologists to further evaluate cases for a continuous flow left ventricular assist device or cardiac transplants (11,13). EXERCISE RECOMMENDATIONS Given that exercise intolerance and increased risk of subsequent risk for a cardiac event seem to critically be the weakest links among people with CHF, cardiorespiratory fitness activities are considered a top priority for inducing functional and clinical benefits. Also, habitual physical activity levels are important for increasing daily energy expenditure while engaging this population in regular bodily movement. In general, low- to moderate-intensity continuous aerobic exercise for most days of the week is recommended. It is worth mentioning that high-intensity interval training (work intervals: 30 seconds to 4 minutes at 85% to 95% of heart rate reserve [HRR]; rest intervals: 1 to 3 minutes at 50% to 70% of HRR; total duration: 20 minutes, including warm-up and cool down) can be implemented with caution and, only for those who have higher exercise capacity, have completed a maximal exercise test, and have been medically screened and approved for such a demanding training modality (15,16). On the other side, muscle-strengthening activities have been reported safe and effective, and thus they can be performed on a few nonconsecutive days per week using light-to-moderate loads in a circuit fashion. Lastly, flexibility training also is recommended for individuals with CHF primarily characterized by sedentary behavior and lack of structured physical activity and exercise (Tables 2 to 4). TABLE 2 - Aerobic Training Recommendations for Individuals With CHF Training Parameter Recommendation Frequency 3 to 4 days per week and progressively increase to 5 to 7 days Intensity 40% to 50% and progressively increase to 60% to 70% HRR (RPE 11 to 14 on a 6 to 20 scale) Time 20 to 60 minutes per day Type Treadmill or free walking and stationary cycling HRR, heart rate reserve; RPE, rating of perceived exertion (17). TABLE 3 - Resistance Training Recommendations for Individuals With CHF Training Parameter Recommendation Frequency One to three nonconsecutive days per week Intensity 40% to 50% 1 RM (progressively increase to 60% to 70%)OMNI-RES 2 to 3 on a 0 to 10 scale Time 1 to 2 sets × 10 to 15 repetition1 to 2 exercises per muscle group30 to 60 s rest between sets Type 6 to 10 exercises in a circuit format using stationary weight machines, dumbbells, elastic bands, and/or bodyweight movements 1 RM, one repetition maximum; OMNI-RES, OMNI-resistance exercise scale of perceived exertion (18). TABLE 4 - Flexibility Training Recommendations for Individuals With CHF Training Parameter Recommendation Frequency 2 to 3 days per week Intensity Stretch to the point of feeling tightness or slight discomfort Time 10- to 30-second hold for static stretching2 to 4 repetitions of each exercise Type Static, dynamic, and/or PNF stretching PNF, proprioceptive neuromuscular facilitation (19). SPECIAL CONSIDERATIONS - Extensive warm-up and cool down are necessary for individuals with CHF since they are struggling with temperature extremes due to the use of medication affecting thermoregulation. - The peak heart rate should be measured during a symptom-limited, maximal exercise test to determine the target heart rate during supervised exercise. - If the peak heart rate is not available, the target heart rate should be estimated as follows: resting heart rate + (20 to 30 beats) and a rate of perceived exertion (RPE) of 11 to 14 (6 to 20 scale). - Initially, gradual increases in frequency and duration and not intensity should be implemented weekly. - Once individuals with CHF have adjusted to aerobic training after at least 4 weeks, muscle-strengthening activities can be added (17,18). - Left ventricular assist devices are becoming more and more common for individuals with CHF since the Doppler use for blood pressure and other considerations need to be carefully taken into account.