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NAUI Master Scuba Diver 142 Diving Physiology overviewed next. Coffee, tea, and several soft drinks contain the stimulant caffeine. People differ in how they react to caffeine. In most people, caffeine increases alertness. In some, too much caffeine may also cause anxiousness, trembling, heartburn, and irregular heart rhythm. Like alcohol, caffeine increases fluid loss by increasing urination, increasing your need to drink water to offset possible dehydration. Stimulant drugs such as amphetamines are dangerous enough on land and can dangerously alter heart rhythm, depending on the dose. They have also been found to reduce coordination, judgment, and problem solving ability under hyperbaric conditions. Cocaine is dangerous enough for divers at the surface, more so at depth. Cocaine alters perceptions and judgment, and elevates blood pressure and heart rate, sometimes lethally. People in their 20s and 30s have had serious heart irregularities, even fatal heart attacks following use of cocaine. Marijuana has many of the combined effects of alcohol and tobacco smoking, for example, producing both impaired judgment and reactive airways, both of which increase the health risks of diving. Impaired judgment and slowed reaction time have been reported to be more pronounced with increased diving depth. Long term risk of lung cancer is real. Consult your diving physician about side effects or interactions which might occur with the medication you take or plan to take. Dive only when your personal condition is appropriate to the demands of your planned dive. Ask yourself if you should be diving when you feel like you need medication. Alcohol. Drinking alcoholic drinks impairs alertness, coordination, and judgment, and is associated with increased risk of accidents. Alcohol can increase dehydration. Alcohol dilates vessels to your skin, increasing heat loss and risk of chilling. The effects of cold, nitrogen narcosis, and other diving factors magnify the negative effects of alcohol on judgment and performance. If you drink after diving, you may be unaware of DCS or other symptoms which may develop after the dive. These are just the effects of a few drinks. Chronic alcohol abuse produces an entire number of physical and emotional conditions incompatible with diving. NUTRITION General nutritional advice to divers is the same as to anyone else for good health and reduction of risk for heart disease, cancer, stroke, diabetes, hypertension, obesity, and other health problems. A healthy diet is high in complex carbohydrates (grains, legumes, fruits, and vegetables) and high in fiber. Fiber is found only in grains, vegetables, fruits, nuts, and legumes, not in meat, poultry, fish, eggs, or dairy. A healthy diet includes lots of water, as needed but not excessive levels of protein, vitamins, and minerals, and has limited amounts of alcohol, caffeine, salt, saturated fats (prima-rily from animal fats), and sugar. Previous nutritional advice relied heavily on meat and dairy and were found to be far too high in fat and far too low in fiber and many vitamins. Current guidelines emphasize fruits, vegetables, legumes, and grains as the largest part of your meals, rather than meats and dairy. Beans and legumes are included as protein sources. Simple sugar and fats should be eaten sparingly. PHYSICAL FITNESS A high level of physical fitness reduces your risk of diving accidents and allows you to more easily enjoy a variety of diving experiences. Physical fitness has many components. You may be in great shape for one task, like casual underwater swimming, and unable to perform another, such as getting yourself or a buddy out of the surf or up a diving ladder in full gear. Playing tennis, or only going scuba diving or golfing, is exercise but will not work all the various components you need for all of you to be in shape. Being in shape is more than just being strong or able to touch your toes. This section covers aerobic fitness, muscular strength, muscular endurance, and flexibility, although there are many other important components of physical fitness.


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