How fit are you?
Are you ready to dive?
When you wish to dive, you should be ready to do so in a manner that allows maximum comfort. To be ready entails adequate knowledge and appropriate physical skills. A psychological, medical and physical fitness is also required. Fitness is achieved if you regularly exercise at an intensity that keeps your heart rate above 70% of the maximum, for around 90 minutes per week. If you can do this you are physically fit enough to dive at recreational level, 40 meters maximum. Just scuba diving activities alone, however, does not deem you fit and does not constitute as regular physical exercise. Anyone who takes exercise close to, in-between dives or shortly after the last dive, may jeopardise their safety.
What are the guidelines?
In our environment, the diver should have sufficient strength and aerobic capacity reserves to meet the demands of the chosen dive site. This includes the entry and exit points. Sometimes these points demand a lot of strength to climb out with a heavy weight belt or cylinder. Surfaces are not always easy to negotiate, so aerobic skills and strength is often required after the dive. Just diving will not give you that physical fitness, and it is often not sufficient to be able to just manage!
Physical fitness for diving:
To maintain physical fitness, the intensity and frequency of exercise should be sufficient to protect the bodies capabilities. There are both biochemical and physiological capacities that determine a fitness limit. The physical fitness will improve when the exercise load exceeds the body’s current capacity. If this work load is slowly increased we form a work out pattern. As the work out increases the body will become fitter and stronger.
Does carrying equipment and cylinders count?
Sadly, the answer is no. Although the divers physical strength may be tested, the duration of effort is too short to count as a workout. A well-planned dive has even less physical and aerobic demand than a poor planned dive. Entry and exit points make a challenge, but the aerobic and physical demand is not intense enough to protect even a moderate aerobic capacity. This means that a diver should undertake some form of physical activity outside of diving to improve or maintain good physical levels.
Physical fitness is not granted!
Sometimes we think we can just go and do whatever we wish. Often this will lead to a surprise when the capacity to cope is clearly not there to do the task in hand. If we do not exercise, experts maintain that our strength and aerobic capacity peaks around the early 20s for most people. To maintain fitness at a young age is easier than later in life. Fitness work-outs later in life require dedicated time and effort. The burden of fitness in our 20s was no problem, but the burden increases as age increases. With the increase of age-related medical issues, it is paramount that health and fitness needs to be addressed early on.
Although data is still incomplete, physical fitness amongst divers has been associated with fewer post-decompression bubbles. Although silent bubbles are present in divers after each dive, the fact that a lower bubble count indicate a reduced degree of decompression stress. As we all know, a stress-free dive is mentally and physically a big plus. It is clear that a sound physical fitness is desirable for safety, decompression safety, physical competence and the ability to meet the demands of certain situations, foreseen or otherwise.
When should you exercise and dive?
What is the correct time to do physical exercise work-outs and dive? This can be quite difficult if you are a frequent diver. Apart from time management, consideration must be given to the time frame of how far apart the diving activity and intense physical activity will be. Too close a time frame can cause problems for the diver!
Bubble formation as we know it is not equal to or a guarantee of DCS, but can indicate an increased risk for it. A work-out with intense physical activity, such as joint loading, muscular forces or force on joints is believed to transiently increase the activity of micro-nuclei. Both intense physical activity before or after a dive can increase and stimulate additional bubble formation. We are given to understand that a combination of increased joint forces and increased micro-nuclei activity may increase bubble formation. Increased in micro-nuclei activity is thought to be agent for bubble formation within our body.
24 hours before the dive?
Some work has shown that intense exercise 24 hours before the dive may reduce bubble presence in the human body. It is possible that a good work out may inhibit micro-nuclei activity. Exercise taken closer to the dive time did not show this protective effect. Although these studies require more work, they do suggest that intense exercise should not be scheduled within 24 hours before or after a dive.
Low intensity activities are better performed closer to the dive time. Anyone who takes part in high-powered physical exercise should dive on training rest days if possible. The overall risk of DCS is increased when taking exercise to close to the diving activity.
Timing the exercise during diving sessions.
Anyone who participates in physical activity while on a dive puts themselves at risk. It has a direct impact on decompression safety. If strenuous exercise is done whilst at depth the diver will have an increased inert gas uptake. This will increase any values of a dive table or computer. We need to remember that a computer or RDP table can only assume what the dive was like, but it cannot actually read what activities the diver undertakes.
A safety stop with light exercise increases gas elimination and reduces DCI risks. A decompression stop with light exercise may look a little different. Too much or too intense exercise at the decompression phase can stimulate bubble formation. If bubble formation is stimulated, this leads to inhibited gas elimination and an increased risk of decompression sickness.
More research and final recommendations.
Work still has to be done on this subject and there is still insufficient data to come to a conclusion. Important is, we must understand that moderate time-depth profiles are your best defence against decompression. Slow ascent rates and stop phases with light exercise is acceptable. Exercise that is intense and stimulates substantial joint-loading in unacceptable at any point near or during a dive. Exercise post-dive is also not recommended due to the stimulation of micro-nuclei and bubble formation.
Physical fitness is important for divers physical and decompression safety. Intense exercise should be scheduled on non diving days. Intense physical exercise should not take place 24 hours either side of diving activity. If exercise is taken, it will be low impact with minimal possible joint forces.