Health fitness is a must for all divers. Some benefits of fitness are increased heat and cold tolerance, increased diving safety, reduction of injuries, delayed aging and a positive mood.
Good physical condition is important for all divers. This is true even though diving may not always be a physically difficult activity. Being in good physical shape benefits many aspects of scuba diving that are not directly obvious. High physical fitness increases your tolerance to heat and cold. Improving your physical condition reduces your risk of several chronic diseases that affect general health and diving health in particular. High fitness levels seem to be associated with improved diving safety and your ability to comfortably dive more often. How is this all so?
Table of Contents
Increased Heat Tolerance
Exercising in the heat has been described as probably the single greatest stress ever imposed on the human cardiovascular system. With increased physical fitness, your body makes several adaptations to better tolerate heat. Shunting blood to the skin is important for cooling. As there is only a finite amount of blood available, competition problems may develop. The in-shape cardiovascular system is better able to handle this competition for several reasons, including increased total blood volume. The fitter diver can better supply blood simultaneously to muscles for exercise and skin for cooling. The out of shape person can neither supply sufficient blood to the skin, meaning less cooling ability, nor to muscles and the heart to supply oxygen and carbohydrate for energy and to remove waste, reducing ability to exercise safely in the heat. The more in-shape diver will sweat earlier and more and conserve more electrolytes during sweating than an out-of-shape person. Trained muscles hold more water. A fit person’s core temperature will not rise as high at the same exercise intensity as a more out of shape person. Aerobic fitness is one of the most important factors in improving heat tolerance.
Increased Cold Tolerance
Although less than the dramatic influence to reduce susceptibility to overheating, physical fitness improves tolerance to exercise in cold environments. Increased muscle mass through resistance exercise increases heat production and storage. A fit person can generate more heat through shivering and physical exercise. Much discussion seems to concern whether men or women fare better exercising in the cold but your tolerance to cold does not depend on whether you are male or female. It depends instead on many other factors, including state of physical conditioning.
Scientists still debate whether good health is possible without any exercise. But, don’t get your hopes up-evidence continues to build against habitual inactivity and for an active lifestyle to make major positive changes in your health and wellbeing. Many of the most common Western ills such as heart and blood vessel disease, obesity and certain musculoskeletal problems are known as hypokinetic diseases (hypo means less than or not enough and kinetic means activity). Hypokinetic disease is a fancy term for illness related to or even caused by being sedentary and out of shape.
Epidemiologic studies suggest regular exercise lowers colon and reproductive tract cancer risk in men and women and breast cancers in women. Resistance exercise thickens bones, welcome news since osteoporosis affects both men and women, discussed later in this column. Cardiovascular fitness through aerobic exercise reduces your risk of early death from vascular disease, heart disease and high blood pressure, all major killers of both men and women. Sudden death from heart attack is also more common in the out of shape person who exerts past capacity than in those who exercise regularly.
Being in shape is speculated to decrease risk of decompression sickness through circulatory advantages, although the mechanisms and certainty of relation to risk are unclear. Although not firmly established, cardiovascular fitness may give fresh meaning to the phrase, “Don’t get bent out of shape:’
A high degree of muscular strength, cardiovascular endurance and muscular endurance positively affect your capacity for overexertion common to diving. You call on your exercise reserves for extended efforts such as long swims in currents, the transient demands of carrying gear around, getting in and out of the boat regardless of wind and wave action and for emergencies.
A diver with high cardiovascular capacity for kicking with fins can easily find a distance that is work to someone with less cardiovascular adaptation. With high muscular power, strength and endurance you can quickly drag an incapacitated buddy through the water then lift him/her onto the dive deck or up the shoreline, even if the buddy is larger and heavier than you are. Fitter people perceive less exertion at the same exercise intensity so they can dive more before pooping out. When fighting a current, high aerobic capacity can turn a possible near tragedy into an easy jaunt.
Better physical fitness is associated with reduced incidence of joint injury during regular physical activity. Pushing beyond capacity and overtraining, both easy to do with low capacity, often result in pain and overuse injury. Lieutenant Colonel Bruce H. Jones, M.D., Chief of the Occupational Medicine Division of the United States Army Research Institute of Environmental Medicine at Natick, reported on data from army recruits. He found that those of lower physical fitness had consistently higher injury rate than those of higher fitness.
A good range of joint flexibility also seems to be important to reduce injuries. A tight-jointed diver may have a tendency to muscle pulls and strains. A diver with tight back muscles is back pain waiting to happen. Although men usually have less natural flexibility than women, particularly of the lower extremities where injury rates are high, men can attain healthy flexibility with regular stretching. Musculature or exercise do not reduce flexibility. Lack of stretching reduces flexibility.
All divers need physical exercise for general health, diving health and injury prevention. Without it, a vicious cycle of inactivity and injury grows. Sedentary divers should begin to become more active slowly and carefully, working within their safety and comfort zone to make activity a lifetime habit, rather than a chore to endure and avoid if possible. Reduce your injury potential from inflexibility by including stretching in your exercise program, after you’re warmed up. Stretching is not a warm-up. You should be warm enough to sweat before you stretch.
Although not chronologically younger, exercise can leave you functionally younger. It’s difficult to separate the toll of aging from just sitting around too much. However, getting slower and weaker as years pass is not solely an inescapable aging process but a consequence of reduced activity.
Cellular and system functions decline predictably both with aging and without
physical activity. Without exercise intervention, muscular strength, speed and power all drop off sharply as years pass. After about age 30 the deterioration would run about 0.75 to 1 percent per year if you did no exercise to stop it. Without a program of regular aerobic activity, the maximum amount of oxygen your body can use to make energy, an important indicator of fitness, would drop about 1 0 percent each decade from age 20 to 60. Without regular weight lifting or weight bearing activity such as running, walking, skating, skiing and dancing, bones have insufficient resistance to keep them thick. In that case they become increasingly thin and fragile. Regular exercise considerably slows, even reverses all these losses, in some cases making gains equivalent to stopping years of aging. Effectiveness of exercise shows itself in older people who are physically active. They have many of the functional and physical characteristics of a chronologically younger person.
Regular exercise is thought to positively affect your mood in several ways. In the shod term, a vigorously exercising body is thought to manufacture a class of hormones called endorphins, although specifics are far from established. The word endorphin is a contraction of “endogenous (made from within) morphine like substance.” It’s not definitely known, but feasible that endorphins improve mood after hard workouts by releasing chemicals that stimulate your brain’s pleasure center. In the long term and more firmly accepted, exercise increases your overall fitness so you can participate more often and with greater ease in activities you enjoy, such as diving. Regular exercise helps decrease afternoon moodiness and sugar cravings by increasing insulin sensitivity. That means less insulin mobilizes to process a given load of carbohydrate. Your blood sugar remains steadier, reducing the swings that produce food cravings and moodiness. Greater physical ability, body awareness and improving body shape and health with exercise might also make you happy. Overall, specifics of improved emotional state with exercise are not clearly mapped. Still there is support for a relation between long term exercising and increased feelings of well-being and, at least in theory, ability to face emotional stress.
Exercise burns calories so you can eat more without getting lumpy. Regular exercise burns fat and shifts your body to a mode where it burns more fat for fuel in general and during exercise. Preferentially burning fat extends the supply of the carbohydrate stored in your muscles and liver, thereby extending exercise capacity.
In summary, being in good physical condition is beneficial to all divers, even though diving itself is not always physically rigorous. The many health and wellbeing payoffs contribute to safe and healthy diving.
Owing to the high number of inquiries for exercises to help you get in shape for diving, this is the first installment of Exercise of the Month. After each regular column there will be a short description of an easy, safe and hopefully fun stretch, exercise or activity that you can easily work into your daily and weekly routine to improve your diving health and physical happiness.
Exercise Of The Month
The first Exercise of the Month is an easy stretch you can do almost anywhere, even in bed. Back and neck pain are so prevalent and so often result from slouching forward when standing, sitting and bending, that a simple backward leaning stretch is very important to add as a daily exercise for the health of your back. This stretch also feels great.
Lie face down. Put your palms on the floor near your head with your elbows close to your body. Slowly, gently press up into a small arch. Do not force and don’t rise higher than your elbows. Do not do any motion that causes any discomfort. This stretch is beneficial for your back, particularly after bicycling, gardening, cleaning floors, shoveling snow, sitting on dive boats, driving to and from dive sties or any activity where you lean forward for prolonged periods. Also try this one before you even get out of bed in the morning. Unless you already sleep face down, roll over face down and prop up on your elbows very low and gently.
Another variation is to stand up with your hands on your behind and lean back into an easy arch. Do this standing version after every 20 minutes of sitting at your desk or whenever you can’t do the lying down version described above.
For more about back pain and prevention of it, see the February and March 1994 Scuba Fitness columns. With any new exercise, see your physician first.
Why Should Divers Get Fit?
* Increased Heat Tolerance. Being in shape increases your ability to remain cool in conditions that would overheat an out of shape diver.
* Increased Cold Tolerance. Physical fitness improves tolerance to exercise in cold environments.
* Increased Health. Regular exercise reduces incidence of major diseases and may decrease risk of decompression siskness.
* Increased Diving Safety. Fitness positively affects your capacity for overexertion common to diving. it can mean the difference between a diving trip and a diving accident.
* Injury Reduction. Physical fitness is associated with reduced incidence of joint injury during regular physical activity. A good range of joint flexibility also seems important to reduce injuries.
* Delayed Aging. Older people who are physically active have many of the functional and physical characteristics of a chronologically younger person.
* Positive Mood. Regular exercise is associated with increased feeling of well-being.
* Fat Loss. Regular exercise changes body composition.