Physical Fitness and Diving What You Need to Know

Physical fitness and diving go hand in hand. Before diving with any reputable operator, you must fill in a medical form that dives deeply into your overall health and fitness. So how important is physical fitness to diving, and what kind of fitness really matters? Is it better to be a marathon runner or a powerlifter? How fit do you need to be to scuba dive safely? The answers may be a surprise and not what you initially thought!

The Physical Demands of Diving on the Human Body

When you go scuba diving, two separate demands are placed on the human body. The first is to do with the actual physical effort involved with scuba diving. This includes carrying your gear, getting in and out of the water, swimming in the current, and the general physical demands placed on you by diving.

The second demand placed on the human body is much less visible since you have very little control over it except for your dive profile. This is the on-gassing and off-gassing cycle of inert gas out of your tissue and blood. As you dive and breathe, your body is transporting oxygen out of your lungs to your tissues and removing carbon dioxide from your tissues to your lungs. At the same time, your blood is either adding or removing nitrogen from your tissues. Which one depends on whether you are descending and diving or have started your ascend.

The Physical Effort of Diving

Even in relatively benign conditions, diving can require effort. For starters, the equipment is not light. A tank, BCD, Regulator, and weight belt can easily reach around 30kg/66lbs. Not to mention your fins and mask or the restrictive effects of a wetsuit or drysuit. Moving around with this weight comfortably requires a certain level of fitness and strength.

The level of fitness required will vary depending on the type of diving you do. If you only ever dive from liveaboards, then you need a certain level of strength and stamina to take a few steps to the dive deck before dropping into the ocean. If, on the other hand, you regularly shore dive from a rocky coastline, where you have to walk up and down cliffs with your gear to get in the water, let alone fight the waves to get in and out of the ocean, you will need a substantially greater level of strength and stamina.

Training for the Effort of Diving

As we mentioned above, you need a level of physical strength to dive (we will talk about stamina later in the article). This does not mean hitting the gym and starting powerlifting training. Most diving physicians advise against heavy weight training if you are diving regularly. Pumping a load of heavy weights and hitting the ocean is a pretty bad idea.

The micro-tears in muscles caused by heavy weight training (which makes them grow bigger) can cause problems when diving. The tears interfere with proper circulation, meaning your body cannot off-gas properly in the affected areas. This makes those areas more susceptible to a decompression event.

Ideally, you want to develop your core strength and muscles using a lighter form of resistance training. A strong core and back is crucial since they bear all the weight of your gear. Resistance training exercises that strengthen your core and back should be your go-to strength-building exercises for any diver.

After that comes developing good leg strength since they are your primary means of propulsion in the water. Routines incorporating lunges, squats, and calf raises are great and develop your core strengths.

Remember, as a diver; you are not after huge, massive legs; instead, you want supple solid, and flexible legs. So you need to remember to incorporate stretches into your routines to ensure you have supple muscles that can deal with colder waters and the rigors of fining and frog kicking.

Conditioning For the Effort of Diving

In terms of physical conditioning, cardiovascular fitness (stamina) is key to safe diving in two important ways. First, it allows you to cope easier with the rigors of diving. So if you are diving and there is a current, you will be able to swim without getting too out of breath and starting to suffer from your body not being able to oxygenate its muscles and remove the carbon dioxide from your tissues. Increased cardiovascular fitness also lets you stay in control of your breathing since you will not need to breathe much harder in response to the greater physical demands on your body.

The second-way improved stamina enhances your diving is by facilitating on-gassing and off-gassing. Generally, the fitter you are, the better your circulation is, which makes it easier for your body to remove nitrogen from your tissues. Since the process of blood flow bringing oxygen and removing CO2 also adds and removes nitrogen depending on the dive phase.

Any exercise that increases stamina and the body’s ability to transport oxygen to your tissues and remove carbon dioxide is key to improving your condition. Brisk walking, jogging, swimming (longer distances, not sprints), cycling, and more will improve your stamina and make diving easier and safer.

The Effects of Previous Injuries

One thing that needs to be considered when considering the efficiency of circulation and the perfusion of tissues is previous trauma injuries. Whether decompression incidents or physical trauma to your body.

Unfortunately, previous trauma can leave localized scar tissue within the body. So even if you have fantastic oxygen carrying and circulatory capacity, at the local area in the vicinity of the previously injured tissues, circulation can be poor and have a negative impact on the on-gassing and off-gassing cycle.

This is why divers who have taken a decompression hit before are more likely to suffer another hit on a given dive compared to someone who has not had one. That is why being aware of your body and how you feel post and pre-dive is always important.

Exercising Before & After Diving

Exercise Before Diving

There have been a few pieces of research about this particular aspect of exercising before diving. And the data is relatively favorable. Training at moderate to heavy intensity (not heavyweight) up to 24 hours before a dive has been shown to be beneficial in preventing bubble formation after a dive. Essentially if you train up to 24 hours before a dive, you are giving yourself a small level of protection against a decompression event during a dive.

Exercise After Diving

If exercise after diving is a good thing, then the data shows that exercise in the few hours after diving can have a negative impact. Studies have shown that if you exercise after a dive, then you can increase the formation of bubbles in your tissue post-dive. The closer the exercise time is to the end of the dive, the more significant the effect of bubble formation.

Not All Humans Are the Same!

Keep in mind one thing about the above research. The sample population was mostly military divers. So the data may be somewhat skewed, and the effect can be greater in normal individuals. Especially the adverse effects, since regular people are not as physically fit as military divers.

This exact situation occurred early on in the history of scuba diving when the general population started using US Navy dive tables. The US Navy test subjects were predominantly young men in their 20s and 30s who already had a high level of physical fitness. This made their bodies much more capable of tolerating elevated Nitrogen pressures and gradients and resulting in longer no decompression limits.

According to Revision 7 of the US Navy Air table, you have a 5-minute NDL at a depth of 190ft/57m. this NDL is way beyond what any other recreational dive table would produce. Most algorithms developed for a broad spectrum of the population would have a substantial decompression obligation after 5 minutes at 190ft/57m.

Final Thoughts

When it comes to diving, Physical fitness matters. However, there is no need to be a world-class athlete to dive; however, a decent level of strength and stamina is all that is needed to conduct most diving activities safely and comfortably! A general fitness regime that keeps you in good health and listening to your body should be all you need to enjoy a long safe dining adventure.