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Chapter 16 Exercise Risks Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Musculoskeletal Injuries See Figure 16.1 for a summary of emergency room visits for a variety of sports. Running injuries The 1-year injury incidence rate for runners varies from 2-77% or 2.5-12 injuries/1000 hrs running. Figures 16.3 and 16.5 show that injury rates among runners tend to rise with increase in weekly running mileage. Figure 16.4 shows that the knee and foot are the most common injury sites. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Performance Figure 16.7 Overtraining syndrome. See Box 16.1. 1 0.5 0 -0.5 -1 -1.5 -2 -2.5 -3 -3.5 -4 Normal Below normal Poor 1 2 3 4 5 6 7 8 9 10 11 12 Weeks Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Figure 16.10 Management of overuse injuries---also see Box 16.2 for a functional approach to injuries and pain that offers athletes the best chance for recovery from injury. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Female Athlete Triad The syndrome of disordered eating (and excessive exercising), amenorrhea, and osteoporosis is called the female athlete triad (Figure 16.11). See Box 16.3 for a summary. See Figure 16.13 for graph comparing bone mineral mass among different groups. The causes of menstrual dysfunction are still hotly debated but may be related to alterations in sex hormones and energy drain. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Figure 16.11 Female athlete triad Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Figure 16.13 Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise and Pregnancy Moderate amounts of exercise during pregnancy are recommended for the health and fitness of the mother and baby. Debate still centers on whether intense and prolonged exercise by the pregnant mother can cause harm to the growing fetus. See Box 16.4 for ACOG guidelines for exercise during pregnancy. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Heat Injuries See Box 16.5 for risk factors of heat illness. See Box 16.6 for ACSM recommendations for race events. Heat cramps Heat exhaustion Heat stroke Exertional rhabdomyolysis Measuring temperature for exercise risk (see Figure 16.14) Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Environmental Pollution Air pollution and ill health – see Box 16.7 for air quality index standards Primary air pollutants Carbon monoxide Sulfur dioxide Nitrogen oxide Particulate matter Secondary air pollutants Ozone Sulfuric acid Nitric acid Peroxyacetyl nitrate Exercise and ozone – see Figure 16.15 Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Sudden Death From Heart Attack Is there a risk of dying of a heart attack during exercise? Yes, but most people over age 30 who suffer a heart attack during or after vigorous exercise are at high risk for CHD, and then exercise too hard for their fitness level, triggering the final heart attack event (see Figure 16.17). When a young athlete dies during or shortly after exercise, it is most often due to a birth defect of the cardiovascular system (see Figure 16.16). If an individual is at low risk for heart disease, has not experienced any symptoms, and exercises moderately, risk is extremely low, and overall, heart disease risk should be lowered because of the regular exercise program. See Figure 16.19. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise and the Common Cold People who exercise regularly report fewer colds than their sedentary peers. Numerous surveys indicate that 60%-90% of physically active individuals perceive themselves as less vulnerable to viral illnesses than those who are inactive. Several randomized studies support the viewpoint that near-daily physical activity reduces the number of days with sickness. In these studies, subjects in the exercise groups walked briskly 35-45 minutes, five days a week, for 12-15 weeks during the winter/spring or fall, while the control groups remained physically inactive. The results were in the same direction reported by fitness enthusiasts--walkers experienced about half the days with cold symptoms of the sedentary controls. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise Benefits to the Immune System During moderate exercise, several positive changes occur in the immune system. Stress hormones, which can suppress immunity, are not elevated during moderate exercise. Immune cells increase recirculation. Although the immune system returns to pre-exercise levels very quickly after the exercise session is over, each session represents a boost that appears to reduce the risk of infection over the long term. Although public health recommendations must be considered tentative, the data on the relationship between moderate exercise and lowered risk of sickness are consistent with guidelines urging the general public to engage in near-daily brisk walking and other forms of moderate physical activity. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise and Immunity Among elite athletes and their coaches, a common perception is that heavy exertion lowers resistance to colds. The immune systems of athletes have been studied under laboratory conditions before and after exercising intensely for 2-4 hours. A steep drop in immune function occurs which lasts 1 to 3 days. Much of this immune suppression appears to be related to the elevation of stress hormones which are secreted in high quantity during and following heavy exertion. This allows viruses to spread and gain a foothold. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise and Immunity The relationship between exercise, infection, and immune function (often called immunosurveillance) is given in Figure 16.21). This model shows that although the risk of infection may decrease below that of a sedentary individual when one engages in moderate exercise training, risk may rise above average during periods of excessive amounts of high-intensity exercise. Immunosurveillance is enhanced during moderate exercise training, but during unusually heavy training, it is suppressed. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Figure 16.21 Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Concerning exercising when sick: If one has common cold symptoms (e.g., runny nose and sore throat without fever or general body aches and pains), moderate physical activity can be continued. However, wait a few days after the resolution of symptoms before exercising vigorously. With symptoms of fever, extreme tiredness, muscle aches, and swollen lymph glands (e.g., the flu), rest and avoid all exercise. Once the symptoms are gone, gradually return to a regular program of exercise, and allow 2-4 weeks before resumption of intensive training. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. What Is Asthma? Asthma [Greek “to pant”] is an inflammation of the lungs which causes airways to narrow, making it difficult to breathe. See Figure 16.22. Inflammation makes the airways sensitive to allergens, chemical irritants, tobacco smoke, cold air, or exercise. When exposed to these stimuli, an asthma attack can occur, causing the muscles around the windpipes to tighten, making the opening smaller. The lining of the windpipe swells (becomes inflamed), and produces mucus. This leads to coughing, wheezing, chest tightness, and difficulty in breathing, particularly at night or in the early morning. Asthma symptoms come and go; they can last for a few moments or for days. Asthma attacks can be mild or severe and sometimes fatal. Each year in America, more than 5,000 people die from asthma, with rates twice as high among blacks compared to whites. See Box 16.8. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Prevalence of Asthma Asthma is a major public health problem, affecting more than 100 million people worldwide and five percent of Americans (about 17 million). In the United States, about one child in every 15 has asthma. During the 1980s, for unknown reasons, asthma rates rose 49 percent, a problem now recognized in many other nation worldwide. This may be linked to factors including housing with reduced ventilation, exposure to indoor allergens (such as domestic dust mites in bedding, carpets, and stuffed furnishings, and animals with fur, especially cats), tobacco smoke, viral infections, air pollution, and chemical irritants. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Asthma Prevention Guidelines Asthma episodes can be prevented, but it is unknown if development of the underlying inflammatory disease can be averted. Inflammation makes the airways hypersensitive to a wide variety of irritants. Causes of the initial tendency toward inflammation in the airways are not yet known for certain, but one of the strongest risk factors is an inherited tendency to have allergic reactions. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Asthma Prevention Guidelines The common triggers include: House dust mites: These are often a major component of house dust, and feed on human skin sheddings. Hot laundering, airtight covers, removal of carpets, and avoiding fabric-covered furniture are recommended. Animal allergens from animals with fur: These include small rodents, cats, and dogs, and can trigger asthma. Animals should be removed from the home. Tobacco smoke: Is a trigger whether the patient smokes or breathes in the smoke from others. Cockroach allergen: A common trigger in some locations. Infested homes should be cleaned thoroughly and regularly. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Asthma Prevention Guidelines Mold and other fungal spores and pollens: These are particles from plants. Windows and doors should be closed, and those with asthma are recommended to stay indoors when pollen and mold counts are highest. Air conditioning can be helpful. Smoke from wood-burning stoves and other indoor air pollutants: Produce irritating particles. Vent all furnaces and stoves to the outdoors, and keep rooms well ventilated. Colds or viral respiratory infections: Can trigger asthma, especially in children. Give an influenza vaccination every year to patients with moderate to severe asthma. At the first sign of a cold, use asthma medications to control symptoms. Physical activity: A common trigger for most people with asthma. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise-Induced Asthma (EIA) EIA is triggered as the lining cells of the airway are cooled and dried during exercise. As air is taken into the lungs, it is warmed and humidified, resulting in a cooling and drying of the airway lining. Certain chemicals are then released by the lining cells, causing the airways to tighten. This cooling and drying is worsened by several factors, including exercising in cool and dry air, a switch from nasal to mouth breathing, and fast and deep breathing from intense exercise. If pollutants and pollen are in the air, the risk of EIA is increased. EIA symptoms are most severe within five to 10 minutes after exercise. The EIA attack generally lasts five to 15 minutes, and symptoms gradually diminish within 45 to 60 minutes. If the individual exercises again within 30 to 90 minutes of the first bout, the airway tightening is markedly less, and fewer EIA symptoms are experienced. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Figure 16.23 Pattern of EIA EIA goes through at least 3 phases: Early phase response Spontaneous recovery Refractory period Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise Testing In the exercise laboratory, EIA is diagnosed if the ability to exhale a certain amount of air from the lungs quickly (within one second) falls by 15 percent or more following six to eight minutes of high intensity exercise (90 percent of the maximal heart rate). Many asthmatics now use peak flow meters which are small devices that measure how well air moves out of the airways. Asthmatics should avoid exercising vigorously until the peak flow reading returns or exceeds 80 percent of the personal best peak flow reading. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Asthma Treatment Although asthma cannot be cured, it can be controlled by establishing a lifelong management plan with a physician. Individuals who follow their asthma management plans and keep their asthma under control can usually participate vigorously in the full range of sports and physical activities. Proper management of EIA, includes: Monitoring air flow with a peak-flow meter. Avoiding allergic triggers. Using medication before exercise. Modifying exercise habits and practices. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Medication Drugs that relax the muscle spasm in the wall of the airways and help to open them (e.g., bronchodilators) are often the first line of treatment in preventing EIA. Doctors recommend using the medication (typically beta2-agonist) from five minutes to an hour before exercise. Beta2-agonist medications will control EIA in more than 80 percent of asthmatics, and are helpful for several hours. Cromolyn sodium is often prescribed to treat athletes who have EIA. This drug, which is also an inhalant, prevents the lining of the airways from swelling in response to cold air or allergic triggers. Cromolyn sodium can be used up to 15 minutes before engaging in physical activity. Corticosteroids should be used as preventive medicine, usually on an ongoing basis, to help control the underlying inflammation. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise Programming In addition to proper medications, control of triggers, and use of peak-flow meters, several modifications to the exercise program have proven valuable: Adequate warm-up and cool-down periods: These help prevent or lessen episodes of EIA. Type of exercise: Outdoor running is closely linked with EIA, followed by treadmill running, cycling, and walking. Swimming rarely leads to EIA because warm and humid air near the surface of the water prevents cooling and drying of the airways. Length of exercise: Long, intense, continuous exercise (e.g., running and cycling) causes more EIA than repeated short bursts of exercise (generally less than five minutes each). Stop-and-go sports like tennis, volleyball, or football may lead to less EIA for some asthmatics. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Exercise Programming Intensity of exercise: High intensity exercise (above 80-90 percent of the maximum heart rate) causes more EIA than does exercise at more moderate levels (e.g., walking). Nasal breathing: Nasal breathing warms and humidifies the air better than breathing through the mouth. Wear a mask or scarf in cold weather: This can increase the temperature and humidity of the inhaled air, reducing cooling and drying of the airway lining. Monitor the environment for potential allergens and irritants: Examples include a recently mowed field, refinished gym floor, smoke in the air, or high pollen counts during a spring morning. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Benefits of Exercise Training Despite the fact that exercise may trigger asthma, the benefits that come from regular physical training are so important that most asthma experts urge that it be included as an important part of the management strategy of the asthmatic. Regular exercise improves the overall physical fitness level of the individual with asthma, improves psychological mood state, decreases the risk for other chronic diseases, and improves heart and lung function. Also, several researchers have shown that as the individual with asthma becomes physically fit, EIA attacks are less frequent. Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved. Figure 16.24 Nieman DC. Exercise Testing and Prescription: A Health-Related Approach. 6/e. Copyright ©2007 McGraw-Hill Higher Education. All rights reserved.