Fitness and Diving

By Dr. Sawatzky

Last month I started a discussion on fitness and diving. We looked at the various aspects of fitness, how fitness is measured, and some of the many reasons why divers should be fit. This month we will continue with the discussion including the advantages of being fat! Those of you who know me will immediately realize that the last comment was very tongue in cheek.

So why should divers be fit? What difference does it make? There are many advantages to being fit. For Canadian divers one of the most important is increased cold tolerance. When a muscle is working, it generates heat. A diver who is fitter will be able to work harder and generate more heat than a diver who is less fit. I believe I still have the dubious distinction of being the best shiverer ever tested at DCIEM. I can generate eight times as much heat shivering as I do at rest (normal is 3 to 4 times). How do you measure this? Pull on your swimsuit, climb into a water bath up to your neck then relax on a lawn chair for 90 minutes or so. Of course I have not yet mentioned the rectal probe to keep track of your core temperature, the heat flow discs that have been taped all over your body, the periodic measurement of your metabolic activity by having you breathe through a machine nor have I mentioned the temperature of the water, COLD!

A fit diver also has better heat tolerance. Even in Canada this is sometimes a significant factor. Imagine or remember the hot summer day when you were gearing up in your drysuit with lots of underwear, then waiting around for your buddy to get their act together, then getting all your gear on for that long /deep dive. Heat tolerance is important! The fitter diver will generate less heat for a given level of activity than a less fit diver because they will not be working as hard. They will also have an increased ability to generate sweat and tolerate the heat stress better.

Increasing your level of fitness reduces your risk of heart attack and stroke. It also reduces your risk of getting DCS after a dive. As you attain a higher level of fitness, you will have more reserves to call on in an emergency, either because you have had a problem or you have had to help another diver who is in distress. You will have an increased capacity to deal with the unexpected. Anyone who has been diving for a while knows that in diving, the unexpected is expected!

The list of reasons divers should be fit continues. Those diving students who are fitter are more likely to successfully complete the training. Fitness results in less joint problems and less injuries. It delays aging! No, I have not found the fountain of youth but there have been a large number of studies that have shown that maintaining a higher level of fitness reduces the inevitable decline that comes with the passage of time. Regular exercise, especially aerobic exercise for more than 20 minutes, also results in a positive mood. I always thought I felt better after exercising just because I was so glad it was finally over! However, research has shown that regular exercise has a very positive effect on your emotional well-being. For several years now I have been encouraging those patients of mine who are going through an especially difficult time in their lives to exercise on a regular basis. Those who do have almost all found that it makes it much easier to deal with the problems they face. The list could go on almost forever but one last reason that divers should be fit, it changes their body composition. Even if you do not lose any weight, if you exercise you will reduce the percentage of your body weight that is fat and that will have many positive effects including reducing your risk of DCS.

Now, onto the advantages of being fat. Obesity is less important in diving than in many other activities because the diver does not have to support the extra weight while in the water. The increased insulation helps keep a diver warm. Another advantage of excess pounds is that the obese person will have more muscle simply as a result of moving the extra pounds around. Every time they stand up, sit down, walk up a flight of stairs, climb a ladder, or even walk, they are weightlifting the weight of the excess fat they are carrying. Remember, the more obese the person, the more muscle is hidden under all that camouflage! The extra weight will also stress the bones and result in the person having increased bone mass (a good way to prevent osteoporosis). Finally, the increased body fat most women have from the waist down, compared to men, means that they tend to float more horizontally in the water and therefore have more efficient finning. There, I did it, I actually said some good things about obesity. Now, onto the comments I make far more often!

Obesity has many disadvantages in diving. The extra weight is a definite problem when it comes to getting into and out of the water. The extra flotation means that the person will require more lead to become neutrally buoyant, adding even further to the problem of getting into and out of the water. The extra size will increase the diver's cross-sectional area and drag in the water, meaning that they will have to work harder to swim at the same speed as a thinner diver. The obese diver is more susceptible to DCS than the non-obese diver for several reasons including the increased ability of fat to hold nitrogen and the usually lower level of fitness. The obese diver will be more susceptible to hyperthermia (overheating) and is far more likely to have cardiovascular disease (heart attack and stroke), endocrine diseases (diabetes) and orthopedic problems (joint problems). The bottom line for Canadian divers is that a little extra padding is a good thing in cold water diving, as long as the person maintains a high level of fitness.

We have spent a lot of time talking about fitness. How much work is diving anyway? There are surprisingly few well controlled studies. However, diving is much harder work than most of us realize and I once read that the average dive could be compared to playing basketball. The average dive is of course a myth. At one end of the spectrum we have the underwater photographer hanging at 15 fsw in the Caribbean waiting for some creature to come out of its hole so that they can take its picture. At the other end of the spectrum we have the cave diver with multiple tanks and high drag, pulling against a very strong current to move through the cave, often for extensive distances (for example, 3/4 km against a 2-3 knot current). Regardless of the type of diving you do, I believe that there should be some minimal fitness requirement so that you will be able to respond effectively to an emergency, either a problem that you are having or to help another in distress.

What factors influence fitness (other than exercise)? Age. As we get older the maximum fitness level we can attain, regardless how much training we do, declines. The rate of that decline however can be markedly changed by exercise. Lets look at some real real-life examples. Two columns ago, I told the story of going hiking with four men over the age of 65 in the mountains of BC. The most noteworthy point was that the 65 year old had stopped exercising for 10 years from age 50 to 60 because of a move associated with his job. He had retired at age 60 and even 5 years of steady training had not allowed him to catch up with his friends who had not stopped exercising. Most of us know that training at age 60 or 70 does not produce the same results as training at age 20. However, the effect starts long before that age.

For a second example, my wife Dana suggested I use her experiences of the last few years. She has always been an athlete and extremely fit. Just over three years ago she ruptured the anterior cruciate ligament in her left knee while doing martial arts. She was extremely fortunate to see an orthopedic surgeon within a few days and again lucky that he had a cancellation and was able to do the surgery a few weeks later (his waiting list was almost a year at the time). Therefore, she had very little time for deconditioning and should have made a rapid recovery. Unfortunately, she developed extensive scar tissue in the knee and had significant pain whenever she tried to train. It was over two years before the surgeon scoped the knee and removed the scar tissue. Dana's knee now works well and is largely pain free. However, even after several months of training she is finding it extremely difficult to attain a fitness level anywhere close to where she was three years ago. She doubts she will ever get there and her age of 40 is definitely a factor.

Yet again, I have run out of room in this column! When you read this, you should be well into your dive season and if you are diving on a regular basis, diving will help you stay in shape for diving. In the next column, I will look at some exercises you can do to stay in shape for diving when you are not diving on a regular basis.