The question is no longer “To exercise or not to exercise?” but how much, how often, and with what intensity to exercise in order to maximize fitness and well-being. For most people, the benefits of regular exercise far outweigh the risks. Benefits include a decreased risk for hypertension, diabetes, cardiovascular disease, colon cancer, breast cancer, and osteoporosis as well as improvements in mental health, functional capacity, and quality of life. A majority of medical patients are encouraged to partake in regular physical activity, according to recommendations of the U.S. Preventive Services Task Force, although guidelines continue to be debated. The purpose of this article is to review the cardiovascular and other potential complications of exercise to enable fitness professionals to make sound recommendations to their clients.
The 1996 Surgeon General’s Report on Physical Activity and Health firmly established that regular physical activity prevents the major causes of mortality and morbidity among American adults.) But “activity” does not have to mean running or competing in a major sport. ln fact, the American College of Sports Medicine (ACSM) differentiates physical activity from exercise, and defines physical activity as “bodily movement that is produced by the contraction of skeletal muscle and that substantially increases energy expenditure). In 2007, ACSM and the American Heart Association published updated guidelines for physical activity which state that “all healthy adults aged 18 to 65 years need moderate-intensity aerobic physical activity for a minimum of 30 minutes on 5 days each week or vigorous-intensity aerobic activity for a minimum of 20 minutes on 3 days each week. “Currently, ACSM and AFAA agree that healthy adults should aim to exercise at 64-94% of maximal heart rate intensity (or 40/50-85% heart rate reserve). For those who are previously sedentary, lower levels of intensity should be undertaken at the outset.
This recommendation translates into a strong mandate to counsel clients to introduce exercise slowly and incrementally. There are proven benefits for the cardiovascular system from regular, low-intensity physical activity. Recent research supports the conclusion that regular dynamic exercise has beneficial effects on cholesterol and blood pressure with energy expenditures as low as 40-60% of maximal heart rate. Sedentary subjects over 40 years of age, individuals with coronary heart disease, and those with risk factors at any age should be advised to undergo a physical examination and possibly an exercise electrocardiogram as determined by their health care professional before starting an aerobic exercise program. Once medical clearance has been obtained, exercise should be increased slowly with regard to intensity to avoid musculoskeletal injury and cardiovascular strain.
The acute circulatory effects of dynamic exercise in untrained persons are shown in Table 13-1. Providing low-intensity exercise from moderate-paced walking to a conservative aerobic workout will enhance cardiovascular fitness including the cardiac and skeletal muscle effects as shown. With dynamic exercise, systolic blood pressure is raised, but diastolic pressure usually declines, producing an increase in cardiac output, oxygen delivery, and improved circulatory parameters. In addition to producing beneficial effects on cholesterol, body weight, and body composition, exercise training lowers coronary risk by lowering resting heart rate and blood pressure.
As fitness improves during a regular exercise program, exercise intensity can be slowly increased with reduced injury risk and increased cardiovascular safety. Healthful exercise then becomes a part of an individual’s life, with a positive effect on mental fitness and psychological well-being. Both young and old can obtain these benefits with an exercise program built around consistency and moderation.This approach minimizes the acknowledged increase in cardiovascular risk that may be associated especially with prolonged strenuous exercise in susceptible individuals.
Following the Exercise Prescription
A proper exercise prescription from a client’s physician becomes even more important with advancing years given the underlying risk of cardiac, pulmonary, neurologic, oncologic, or musculoskeletal diseases which may make exercise difficult to initiate and potentially harmful if overexertion prevails. Fitness professionals should make sure the prescription for exercise from the client’s physician includes recommendations for type, intensity, duration, and frequency of exercise.
In some people with coronary artery disease (CAD), a target heart rate of 40- 50% in a cardio-respiratory workout (once medically cleared) can provide cardiac and musculoskeletal conditioning with acceptable, if not dramatic, improvements in functional capacity. A modified Borg Scale of Perceived Exertion may be useful in regulating exercise intensity in low-impact aerobics classes for the elderly with levels of 12-14 corresponding to a 50% of maximal heart rate level. Exercise should be initiated on the light or low end of the Rate of Perceived Exertion Scale so that light conversation can also be conducted during workouts. Consistency over time maintains cardiovascular conditioning and may, with adequate dietary calcium, have a positive effect on bone by preventing postmenopausal osteoporosis. Moderation in intensity and consistency over time are the foundation for an exercise program leading to enhanced well-being at any age and with most underlying medical conditions.
Hazards of Exercise
The professional fitness instructor needs to be fully aware of the following complications or hazards of exercise.
Cardiorespiratory exercise involves the generation of internal heat through performance of muscular work. As the core temperature rises, an increased amount of cardiac output is delivered to the skin so heat can be dissipated in the form of sweating. Heat is lost principally through evaporation of sweat from the body surface, which cools the individual at the price of losing vital circulating fluids. Many extreme hazards can be prevented by knowing ways to avoid dehydration and hyperthermia during exercise. For the over-heated client, moistening the body surface by sponging or spraying to assist in the cooling process is advisable. Fans may aid evaporation. If the client appears week or disoriented or the skin is hot and dry, emergency medical intervention is necessary.
1. Monitor hydration levels. Clients should drink approximately 8-12 oz of fluid shortly before exercise. For more information, see ACSM’s position stand on exercise and fluid replacement. Over-hydration, or exercise associated hyponatremia (EAH), may occur if total fluid intake exceeds losses as may occur especially in slower runners and walkers after 2 or more hours of sustained exercise. Drinking only to thirst is the best preventive measure, which will, for example, keep a runner from going into positive fluid balance. Runners, or others engaged in prolonged workouts, should weigh themselves before and after workouts, adjusting fluid intake to lose 2-3% of initial body weight. While water is optimal for fluid replacement up to 1 hour, salt supplements and sports drinks may assist in preventing dehydration beyond that time frame especially in the heat. As dilute salt solutions, sports drinks do not prevent the onset of EAH if consumed over time in quantities greater than total fluid losses. Drinking to thirst remains the best approach with intake adjusted by changes in body weight if scales are available.
2. Insist on wanning up. The warm-up phase of exercise allows the muscles and tendons to adapt to the biornechanics of exercise while the blood flow increases to the exercising muscles. As body temperature rises, the sweating mechanism kicks into place with the perception of “second wind.”
3. Wear clothing that allows evaporation and ventilation. Appropriate dress during exercise is another important consideration in the prevention of heat stress. This involves dressing in light and loose-fitting clothing during hot weather exercise, especially on humid days when the sweating mechanism is less efficient.
4. Double digit sunscreen should be universally applied to protect exposed skin from ultraviolet injury and risk for neoplasia, including melanoma. Seek shade on very hot days. Utilize head coverings to guard against the sun’s radiant energy and protect against dehydration as well as sunburn.
5. Avoid using saunas and hot tubs after strenuous aerobic exercise, which may enhance fluid depletion. Fainting from orthostatic hypotension and heat-induced vasodilation may occur in saunas after strenuous exercise, especially in warmer weather conditions.
Cardiovascular Complications and Risk Appraisal
In general, except as required by athletic or other sports association type standards, young healthy individuals require no medical clearance prior to undertaking a cardiorespiratory fitness program, but would benefit from a general medical screening. However, all fitness professionals should be aware of the ACSM atherosclerotic cardiovascular disease risk factors and the basic recommendations for medical clearance prior to exercise. The eight risk factors are (a) age, (b) family history, (c) cigarette smoking, (d) hypertension (high blood pressure), (e)dylipidemia (cholesterol abnormalities), (f) prediabetes, (g) obesity, and (h) sedentary lifestyle. A physician’s clearance is recommended if there are two or more risk factors present; or if there are symptoms of cardiovascular, pulmonary, or metabolic disease; or if there is known cardiac, pulmonary, or metabolic disease; or if the individual is male and 45 years of age or over; or if the individual is female and 55 years of age or over.In addition, certain conditions, such as mitral valve prolapse, may run in families and be associated with serious arrhythmias and even with sudden cardiac death. Individuals with any of these factors in their family history should have a systematic medical evaluation prior to undertaking a vigorous exercise program.
If cardiac patients receive clearance from physicians to mend exercise class, an open line of communication should be maintained with them. If a patient is on cardiac or blood pressure medication, such as beta blockers, he or she should adhere to the prescribed target heart rate. Beta blockers will blunt the increase in heart rate and blood pressure, protecting the client from a risk for exercise induced ischemia.
The following are some first-stage actions fitness professionals can take in regard to preventing cardiovascular complications.
1. Complete one or several of the following:
(a) health risk appraisal, and/or (b) fitness assessment.
2. Schedule a counseling session with the client and his or her physician.
3. Teach clients the importance of proper warm-up and cool-down, monitoring them for compliance. Just as the increase in exercise intensity should be gradual during onset, the cool-down should also be progressive to avoid hypotension and fainting due to vaso-vagal syncope. Making sure that clients keep walking slowly after a workout will prevent blood pooling and risk for such complications.
4. Ask symptomatic clients exhibiting irregular heart rate, chest discomfort, or sudden/ severe breathlessness to seek medical consultation before continuing their programs.
Implement an emergency response in cases of collapse or other severe symptomology by calling for help as per the American Heart Association guidelines before initiating basic CPR. Heart patients often describe symptoms such as a dull ache or pressure in the chest. All of these complaints warrant a halt in exercise and immediate referral to a physician or a call to 911, even if the individual does not describe these sensations as “pain.” Awareness and vigilance for these symptoms can be life-saving for helping some clients deal with denial. The exertional sudden death of marathoner Jim Fixx is a case in point.
5. Fitness professionals should also be aware of the potential cardiovascular complications of exercise, including the rare cases of sudden death during exercise. Studies in this area point to silent congenital heart abnormalities in the majority of cases of sudden collapse from heart arrhythmias during physical exertion. Such victims are young (13-35 years of age), and often have a thickening of the heart muscle wall called hypertrophic cardiomyopathy. Individuals with a family history of sudden death during, or even unrelated to, exercise should have medical clearance prior to undertaking a progressive exercise program. Tn contrast, exertional sudden deaths, especially in male clients over 40 years of age, are usually due to underlying coronary artery disease with rupture of an often previously silent atherosclerotic plague. Such individuals may experience sudden cardiac death as the presenting symptom from the onset of ventricular fibrillation, making defibrillation with an automated external defibrillator (AED) the first priority after initiation of cardiopulmonary resuscitation (CPR). This emphasizes the importance of appropriate screening in older patients, especially with risk factors for underlying heart disease. Clients should be continuously assessed for any changes in their physical condition. The warm-up and cool-down phases of an exercise session protect against the risk for such fatal arrhythmias.
Additionally, in 2009 the U.S. Preventive Services Task Force issued guidelines recommending daily aspirin use for the primary prevention of cardiovascular events in low-risk men over 40 years of age and women over 45 years of age up to 90 years of age. Fitness professionals should encourage their clients to discuss this recommendation with their physicians and be supportive of this strategy.
Basic mastery of the concepts of exercise physiology and the role of the cardiovascular system will better prepare the instructor to inform students. This, in turn, will enrich their understanding of the body’s adaptation to regular exercise and the specific changes involved in promoting fitness.
In spite of all its benefits, exercise is a stressor to the body, carrying a degree of risk. The following conditions-asthma, anaphylaxis, and hives-can all be induced by exercise in susceptible individuals.
The process of heat and humidity exchange from the lung space to the outside air can lead to condensation of moisture around the nose and throat, constriction of the bronchial tubes, and symptoms of coughing and wheezing-the definition of exercise-induced asthma (ETA). Such individuals may have a background of allergies or be unaware of any respiratory symptoms except during exercise. Cold weather and dry air can also provoke coughing and the sensation of tightness in the central chest area. Exercise-induced asthma is similar to the bronchial response experienced in “allergic” asthmatic bronchitis, but triggered by the temperature and water exchange mechanisms rather than allergic sensitivity. Symptoms may vary from day to day, may remain stable and then improve, and may worsen during the post-exercise period.
1. Clients should be encouraged to bring a metered dose aerosol inhaler to class and to use this as directed even prior to a workout. Exercise-induced asthma can be blocked and even prevented by pre-exercise inhalers used 20 to 30 minutes prior to exercise with aerosol medication as prescribed and recommended by their health care provider.
2. Persons susceptible to exercise-induced asthma should be examined, treated, and encouraged by their health care providers, to participate in full exercise activity for the benefit of physical conditioning. Lung function is maintained and preserved through such a program. In severe cases of asthma, types of exercise in high humidity environments, such as swimming, may be appropriate. Avoidance of air pollutants, including secondhand smoke, is essential for individuals with reactive airways disease.
Fitness professionals should be aware of a rare, but medically significant, condition known as exercise-induced anaphylaxis. During exercise, some individuals may experience sudden facial swelling or a sense of tightness in the throat with difficulty in breathing. This reaction is similar to the type of reaction that can occur after a bee sting or penicillin exposure in a highly allergic individual. This condition may require emergency medical treatment as injection of epinephrine using a bee-sting kit prescribed by their physician. Exercise-induced anaphylaxis should be considered in any client who develops sudden difficulty breathing, especially if accompanied by facial swelling.
1. Call emergency medical personnel immediately.
2. Keep client as calm as possible until help arrives.
3. If client has a bee-sting kit (epinephrine), give assistance in using it.
Fitness professionals may note that some individuals develop a blotchy red rash, sometimes with itching, at the beginning of a workout. This is called exerciseinduced hives, or urticaria, and results from histamine release in the skin due to rapid superficial temperature changes. The client should be assured that this condition is harmless. Low doses of antihistamines can be helpful in diminishing symptoms as long as the drowsiness side effect is not more bothersome.
1. Determine if client has had this reaction before and knows about it.
2. Reassurance, as this condition is generally harmless.
Other Medical Considerations
Smoking Cessation and Exercise
Exercise training improves the motivation for smoking cessation of becoming an ex-smoker for women participating in smoking cessation programs. Smoking and sports do not mix, including the need to decrease exposure to secondhand smoke.
Exercise and Cancer Risk
While there is a great volume of literature on the beneficial effects of exercise in the primary and secondary prevention of coronary artery disease, research is less conclusive on the relationship of exercise to prevention of cancer. Several studies have demonstrated that exercise has a protective effect against three most common cancers: (a) breast, (b) colon, and (c) prostate. The 2006 American Cancer Society Guidelines on Nutrition and Physical Activity for cancer prevention state that adults should engage in moderate to vigorous physical activity for at least 30 minutes on 5 or more days of the week. This effect is due to the strengthening of the immune system, particularly the NK or Natural Killer cells, which are responsible for the destruction of mutated cells that lead to cancer. The guidelines also emphasize maintaining a healthy weight throughout life, eating a healthy diet with a focus on plant sources, and limiting consumption of alcoholic beverages.
Exercise and Obesity
Exercise is the leading treatment modality in the effort to combat the current virtual epidemic of obesity affecting the U.S. population at all ages. Obesity increases the risk to, and exacerbates the severity of, many of the chronic diseases being treated today, such as cardiovascular disease, diabetes, and cancer. Many studies support the therapeutic benefits of regular participation in physical activity in the prevention and control of syndrome X (also known as metabolic syndrome) and diagnosed diabetes mellitus.
Understanding the basic physiology of exercise and its benefits will enable fitness professionals to guide clients toward sound exercise programs to enhance their physical and emotional health. Knowledge of the potential complications of exercise assists the fitness professional in helping clients to achieve positive outcomes and enhance their overall well-being.