Diving and the Aging Diver (Old Farts and Diving)

By Dr. Sawatzky

Today's diving population contains many older members. When recreational diving started it was considered a dangerous, difficult activity and almost all divers where young, fit, males. The divers who started then are no longer young, fit, males! In addition, diving soon expanded to include women and older members of both sexes. In fact, in today's economic climate, many individuals cannot afford to take up diving until they are at least middle aged. In addition, the baby boomers are now in their late 40s and 50s and this bulge in the population curve is also represented among divers. The net effect of all these factors is that there is currently a large number of older divers and the number is increasing rapidly.

There are several general medical factors associated with aging. Maximum performance is reduced with aging, injuries become more common, it takes longer to heal, and that healing is less effective as we get older. It is important to separate the number of years we have lived (chronological age) from our fitness, health, performance, etc. (physiological age) as it is our physiological age that matters.

Performance is actually quite difficult to define or measure (DM-May 1997). Who is fitter? Is it the world class weightlifter, the world class marathon runner or the world class gymnast? There are several different aspects of performance that can be measured and they have to be looked at independently. Cardiovascular endurance is a measurement of aerobic performance (oxygen utilization) while anaerobic capacity measures the work that can be done in 60 seconds, generating energy primarily by chemical reactions that do not use oxygen. Maximum strength measures the force that can be exerted while Power measures a combination of force and speed. Muscular endurance is a measurement of prolonged exercise while flexibility is important to prevent strains and sprains.

These different aspects of performance also peak at different ages. Maximum flexibility is seen in young children while reflexes, balance and coordination peak in the late teens. Strength and power however do not peak until we are in our middle to late 30s! Our best attainable overall fitness level probably occurs when we are in our middle 20s and steadily declines thereafter.

What really matters however is not our maximum attainable fitness level but out actual fitness level. This is almost always less than our potential because of lack of exercise, suboptimal diet, inadequate and/or disturbed sleep and excessive life stresses.

There are several reasons we become more prone to injury as we age. Sometimes it is because we clearly remember what we used to be able to do and try to achieve the same level of performance without appreciating our reduced fitness level. The high school football player, who hasn't touched a pigskin for 20 years, goes out to play football for four hours one Sunday afternoon and is surprised when he pulls a muscle. As we age, our tissues become less strong, our flexibility is usually reduced, and we tend to have more fat and less muscle. In addition, our fitness level tends to decline and we may overexert ourselves trying to keep up with younger companions. Unfortunately, the demands of an activity are not effected by the age of the participant. To climb a mountain, a 60 year old climber has to work just as hard as their 20 year old companion.

The speed and efficiency with which our bodies deal with injuries also declines with age. One factor is that the cells in our bodies seem to be programmed to divide about 50 times and then they are unable to divide again. When we injure ourselves, cells must divide to repair the damage. Therefore, as we get older we are less able to heal damage. In addition, tissue blood flow tends to be reduced with age and it is blood that brings food and oxygen to the healing tissue as well as taking away waste products. As we get older we tend to accumulate more and more scar tissue as well as cumulative damage from injuries we sustain over the years.

Not to be totally negative, there are actually a few advantages to aging. First, increased experience leads to increased effi ciency and increased efficiency leads to increased performance. As we get older we tend to have a better and more realistic appreciation of our personal limitations and usually adopt more conservative behaviour. As we mature (not always in concert with our age) we become less susceptible to peer pressure. The last advantage of aging is that we tend to have more disposable income and can often buy better gear.

There are several physiological changes that occur with aging. We become more susceptible to both hypo and hyperthermia. We have changes in our vision, hearing, percentage body fat (both too much and too little) and generally suffer a reduction in our fitness level.

I keep coming back to fitness so let's look at how much work diving actually is (DM-Sept 1997). There are few well -controlled trials but diving is much harder work than most divers think. Obviously the work of diving depends greatly on the nature of the dive but even for a person doing the most relaxed of dives; there should be a minimum level of fitness required so that they will be able to respond to an emergency. The UK commercial diving fitness standard is 13 METS, independent of age or sex. Dr. Bove (cardiologist and diving medical expert) suggests a minimum fitness level of 13 METS in someone who has had a heart attack before they return to diving. An easy way to think of 13 METS is that it is roughly the fitness level required to run a mile (1.6 km) in eight minutes.

Body fat actually has some advantages. The increased insulation helps keep the diver warm and the increased weight means the person will have increased muscle and bone mass. In addition, obesity is less important in diving, as the diver does not support the extra weight in the water. Finally, women tend to have more fat on their legs than men. This increased leg buoyancy means that they tend to have better trim in the water and therefore more efficient finning. Nevertheless, the disadvantages of obesity far outweigh the advantages. The increased body fat hinders getting in and out of the water. Excessive body fat increases cross-sectional area and drag while swimming. In addition, obesity is often associated with cardiovascular disease, endocrine disease (diabetes), orthopedic problems, lower levels of fitness, and hyperthermia.

There are age specific changes in vision (DM-Dec 96, Feb 97). As we pass through our 20s, almost everyone will become more near-sighted. This can be corrected with lenses in our dive masks, contacts or laser corneal surgery (DM-May 1997). As we pass through our 40s, the progressive decline in the flexibility of the lens in our eyes means that we lose the ability to focus near our eyes and we need reading glasses. We can again get lenses in our masks or mount a small magnifying lens in the mask so that we can read our gauges.

High frequency hearing declines with age and if we are exposed to significant loud noises, we will suffer hearing loss that is maximal around 4,000 Hz. Fortunately, speech tends to be mainly in the 1,000 to 3,000 Hz range and neither type of hearing loss interferes significantly with communication unless it is very severe.

As we get older our sensation of cold declines. At the same time, chronic illness and drugs often reduce our tolerance to cold. Some individuals become too thin, especially losing the subcutaneous fat with aging and therefore suffer more from the cold. In addition, hypothyroidism becomes more common with age and the general decline in fitness all combine to result in increased susceptibility to hypothermia with aging.

How significant is the decline in medical fitness with aging in relation to diving? In Australian commercial diving candi dates, 20% fail to meet the medical standards in their 20s while 45% fail to meet the medical standards if they are older that 35!

What are the specific effects of aging on diving? We have an increased risk of dying while diving. We have an increased risk of developing DCS. We have an increased risk of dysbaric osteonecrosis and of course, we have an increased risk of developing other diseases that might interfere with our ability to dive safely and enjoyably.

As we get older we become more susceptible to DCS (DM-June 1997). Decompression tables and models (computers) are developed and tested on relatively fit, young, healthy divers. The increased body fat, the impaired perfusion, damaged blood vessels and damaged lung function (COPD, smoking) combined with joint degeneration makes the older diver much more likely to get bent. In altitude DCS, a 28 year old person is twice as likely to get bent as an 18 year old. What is the risk for a 75 year old? In aviation DCS, age plus fatness gives the best prediction for DCS. For diving, some authorities have suggested that you should decrease your no-decompression bottom time 10% for each decade older than 30. Another option is to dive nitrox and treat it as air if you are older than 40 or have an increased risk of DCS.

There are many diseases, some of which become more common as we get older, that can effect our ability to dive safely. Hypertension (DM-Apr, May 1998), coronary artery disease, atherosclerosis, multiple sclerosis (DM-Mar 1998), osteoporosis, chronic obstructive pulmonary disease, asthma (DM-Aug 1993), diabetes, renal disease, epilepsy/seizures (DM-May 1995), medical drugs, etc. can all effect your diving. If you have any diseases, you need to find out if and how they effect your diving.

Remember that it is your physiological age, not your chronological age that matters. How can we minimize our physiologi cal age? We need to optimize our diet, obtain a sufficient quantity and quality of sleep, maintain an optimal amount and type of stress, and attain/maintain our maximum fitness level.

What is an optimal diet? In general terms this means no added salt, either at the table or in cooking, as well as minimizing very salty foods. We need to reduce the amount of fats and oils in our diet as well as minimizing simple sugars and processed foods. It is important to eat all three main meals, minimize snacks and not eat complex foods after six p.m. Finally, we need to maximize the amount of insoluble fibre in our diet.

How much sleep do we really require? Generally, young adults need 8-9 hours per night, middle aged adults 7-8 hours and older adults six to seven hours but there are wide individual variations. You should take 10 to 15 minutes to fall asleep. If you fall asleep faster, you are probably chronically fatigued. You should wake up before your alarm most mornings and you should not require nor take long naps during the day.

Stress is a mixed blessing. Both too little and too much result in poor performance and reduced happiness and productivity. There is a wide individual variation to the amount of stress that is optimal but one sure sign is that if you have lost your sense of humour, you probably have too much stress in your life. It has been clearly shown that simply laughing for 20 minutes once per day will extend your life expectancy after a heart attack.

I spent quite a long time talking about fitness. Why is it vitally important? Fitness reduces the frequency of injuries and joint problems. It delays the effects of aging and reduces our physiological age. Exercise results in a more positive mood and an increased sense of well being. Finally, fitness results in fat loss and improved body composition.

If fitness is so important, what can we do to improve our fitness level, especially for diving (DM-Nov 1997)? First, fitness is very activity specific and this becomes even more important as we get older. Before starting an exercise program however, it is important to make sure that you do not have advanced coronary artery disease. Therefore I recommend you get a stress test first if you are male and over 40 or female and over 50 (estrogen protects) or if you have a high risk of CAD (family history, smoking, hypertension, cholesterol, obesity). The best exercise for diving is to dive. Barring that, you should swim lengths in a pool in full scuba gear or at least in snorkel gear including BC. Walking around the house, climbing stairs and ladders wearing your weight belt and tank is also an excellent way to tone up the muscles. It is important to do as a minimum, 45 minutes of aerobic exercise at least three times every week. Running is excellent for the heart and lungs but the leg muscles are used differently in finning. Weightlifting is good but less important unless strength is a problem. It is important to include a wide variety of activities to maintain interest and general fitness.