Chapter 4- Diving Physiology Diving Physiology 139 FITNESS FOR SCUBA DIVING Diving fitness has many interrelated components including health and medical conditions, nutritional status, and physical fitness. Problems in any of these areas can affect your ability to meet the physical and problem solving demands of diving. This section explains the medical exam, identifies health conditions believed to raise health risks of diving, discusses effects of smoking, drugs, and alcohol, very briefly reviews nutrition guidelines, and presents information for improving selected components of physical fitness. Health and Medical Considerations The Diving Medical Exam. Some of the health conditions accepted as contraindications to diving are based on reliable evidence. Others are based on plausible, though theoretical objections. Conditions are generally considered contraindications if they: • Cause incapacitation or loss of consciousness • Greatly restrict physical exertion • Prevent your lungs, middle ears, or sinuses from equalizing pressure You need to identify possible risks before beginning a diving program, so that you can make informed decisions about what risks you are willing to assume. Determining medical fitness for diving typically begins with a general medical history form reviewed by the diving instructor, who refers applicants with problematic histories for a complete medical exam and physician recommendation. The physician’s medical history is important to determine your health in the past, past injuries such as serious head injury, medications you take regularly, alcohol or drug abuse, mental attitude, tendency to habitual air swallowing, accident-proneness, impulsive behavior, and risk of panic. Discussing these issues with your physician does not necessarily mean you will be disqualified for diving. It can help determine how risky diving may be for you, and start the process of correcting the problems, thereby improving your diving health and personal health. Cases of near miss accidents have involved medical problems, past or present, not revealed on the diving medical. A comprehensive diving medical exam may include chest x-rays and pulmonary function tests to determine lung health, blood and urine tests for infectious and metabolic disorders, examination of your central nervous system, and examination of your eyes, ears, nose, and throat. Resting and exercise electrocardiograms (ECGs) that screen for cardiovascular disease and exercise tolerance are commonly recommended for males over age 40 and females over 50. Exercise ECGs may reveal abnormalities that would not show up at rest. In an exercise treadmill test, your heart, blood pressure, and sometimes oxygen consumption and other variables are monitored to see the effects of exertion on your cardiovascular system. Several types of heart murmurs and ECG abnormalities show up in routine medical exams but do not rule out diving. A history of rheumatic fever or heart valve prolapse, for example, are of some concern, but the resulting cardiovascular effects may not prevent diving. Your physician will make the judgment on the basis of whether or not there is risk of dangerous heart rhythm or limitation of exercise tolerance. Your physician may recommend an annual stress test, even if you do not have several known risk factors. For repeat medicals, your diving history is important. For example, if you have done much decompression diving, long bone x-rays might be useful to determine if bone changes such as dysbaric osteonecrosis are occurring. An initial screening medical exam, then annual exams, are a good idea for all divers, particularly for those over age 35 and those with personal or family histories of conditions of concern in diving. Some of these conditions are briefly covered next. Cardiovascular Disease Cardiovascular disease, which includes heart attack and stroke, is the number one noninjury cause of death for men over thirty and women over forty. Nearly half of all deaths in the United States each year are from cardiovascular disease. Cardiovascular disease kills twice as many people as cancer. The combination of the physical exertion of diving and cold water adds to the normal demands on your cardiovascular system. Most people dying a sudden death during physical activity had under
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