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Are You Fit To Dive? 

Keeping yourself in good working order is as important as maintaining and servicing your dive kit

From basic ear problems to serious heart and circulation issues, there are various ailments that can stop us being fit to dive. Dr Peter Larkin scans the body from head to toe and points out the areas divers should look after to get the all-clear 


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Heart disease is certainly one of the biggest causes of health-related dive fatalities, which is why we should be aware of the following: 

Blood vessels in the heart can be affected by diabetes, kidney problems – and most of all, smoking, which can cause angina and heart attacks. Both angina and heart attacks normally will end a diver’s time underwater, unless they show no evidence of heart damage. Bypass operations, which are generally the result of more widespread disease, are less likely to allow continued diving than angioplasty. 

High blood pressure can lead to heart disease, but if there are signs that the blood pressure has caused damage to the heart, kidneys or circulation, then there is a risk of fluid in the lungs developing underwater (even in the swimming pool), which can be fatal. 

Palpitations – sudden awareness of heartbeat, or an irregular heartbeat – are, for the most part, an irritation; but if they make you feel unwell, you should not dive. Remember that Warfarin or blood-thinning agents used to treat some heart irregularities can increase the severity of damage in decompression illness (DCI) – particularly spinal bends. 

Valve disease may or may not cause difficulties with diving, depending on the type and severity of the disease involved. 


Most people with circulation problems are smokers. When circulation becomes poor, it results in a lack of oxygen to the leg muscles. This can be aggravated by cold water, and can result in cramp of the legs with exercise – not great in a strong current! 

There is also a condition called Raynaud’s, where the circulation to the fingers and toes becomes closed off with a slight temperature drop. Usually it is a nuisance, but occasionally can be a marker of significant disease. It will be more pronounced when diving in UK waters, and cold, numb, painful hands make using equipment difficult. 


You use your legs to propel you through the water, so regular exercise is a good idea to keep up your stamina. Swimming, running and cycling will all increase your stamina and cardiovascular fitness and will keep your legs in good shape for diving. There is also evidence to suggest that divers who are fit are less likely to develop DCI. 


Mental fitness: stress, anxiety and, more seriously, depression will interfere with your ability to make sound, safe judgements underwater, putting you and your buddy at risk. This is more likely if your condition means that you have to take medication, which may aggravate nitrogen narcosis. In this case, diving should cease until the problem is fully resolved. Don’t dive if you are suffering from panic attacks. 

Eyes: if you have sight problems, you may rquire corrective lenses fitted to your mask. 

Ears: see Ear problems below. 

Neck: swimming along horizontally with your neck extended can cause neck pain and discomfort spreading into the shoulders. On occasion, this can mimic the symptoms of DCI. 


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There are two main areas of concern when diving: 

Asthma, if not well controlled, can result in pockets of air becoming trapped in the lungs – these will expand with ascent and possibly rupture the lungs. In order to prevent this, asthmatics must undergo periodic exercise testing to exclude those who are more likely to have problems. Asthmatics with exercise- or cold-induced asthma are not safe to dive. 

The other concern is chronic obstructive pulmonary disease (COPD), which is a catch-all term for conditions such as emphysema and chronic bronchitis. This is almost exclusively due to smoking and causes a reduction in lung function, air trapping and development of bubbles (bullae) in the lung tissue that can burst on ascent, resulting in similar dangers as described above. 


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Dive kit is heavy, and hauling it about in cramped, unstable conditions is a good way to strain your back – or slip a disc. Regular back exercises, and taking care with lifting (for example, get someone to help you put your kit on) should keep the risk to a minimum. 


Arms and hands are useful underwater, so making sure fingers don’t get trapped between pieces of kit, snagged on ropesm and so on is generally a good idea. In warm waters, corals and toxic creatures can cause stings – some severe and life-threatening – so keep your hands to yourself. 



Regular cardiovascular exercise is recommended as it improves breathing and fitness for diving. Jogging, cycling and swimming a few times a week will help to increase cardiovascular fitness. Building up muscle strength in legs and arms is also important. 


A well-balanced diet will help maintain energy levels, reduce fatigue, control weight and provide a good balance of vitamins and minerals for a healthy body. Avoid food that’s high in saturated fats, such as biscuits, cakes and crisps. For energy between dives, try to swap the greasy bacon sandwich for foods that slowly release energy, such as pasta and fruit. 


Outer Ear 

outer ear

The outer ear conducts sound waves to the eardrum via a small tube leading down to the eardrum. The outer third produces wax, which traps debris and has some antibacterial properties. 

Water can be retained in this tube by surface tension, which can lead to infection in the ear canal, causing pain and itching in the ear (otitis externa or swimmer’s ear). A buildup of wax can also trap water behind it, and otitis externa can develop. 

To prevent this, you can have your earwax syringed at your doctor’s surgery – but this can occasionally cause problems, so get it done a few weeks before your dive holiday! Regularly adding a couple of drops of olive or almond oil to the ear canal can help to reduce wax buildup and may help to lessen water retention if used just before a dive. 

There are also chemicals such as Swim Ear that you put down your ear after diving or swimming – these work by reducing surface tension and thus allowing water drainage, but if you can manage without them, so much the better. DO NOT put cotton buds (or anything else for that matter) in your ears to clear wax. They will push the wax further down and could perforate the eardrum. Some divers will get ear infections so regularly that it can put them off diving – they may benefit from using a ProEar mask, which encloses the ear completely and keeps water out. Occasionally, patients will have a foreign body in their ears – a bead or a chunk of cotton wool, for example. Every now and again, we’ll spot a mosquito trapped down the canal! 

Those who dive or swim regularly in cold water can develop bony growths in the ear canal called exostoses – they can almost block the canal but don’t often cause problems, though occasionally can result in reverse ear (see Middle ear). 

Middle Ear 

middle ear

The middle ear transmits the sound waves from the eardrum to the cochlea (the hearing part of the ear) and is the part that most causes ear problems in divers. 

The middle part of the ear is basically a box within bone, with the eardrum at one side and the round and oval windows on the other. There are three tiny bones that transmit sound waves from the eardrum to the oval window and then to the cochlea. 

From the lower side of the box drops the Eustachian tube, which leads to the back of the nasal cavity and allows equalisation of the ear during a dive. This area is lined by tissue that constantly absorbs oxygen from the space, and so the space is normally at a slight negative pressure compared to the outside environment. 

The end of the Eustachian tube acts as a flap valve, and can lock closed at a depth of as little as 2m. If the Eustachian tube is closed, discomfort can develop with a descent of just 0.3m. So, if you haven’t cleared your ears by 2m, you will find it very difficult, if not impossible, to do so. A result of this is increasing pain, and the eardrum might rupture anywhere between 2m and 10m. 

If you can’t get air into the middle ear cavity on descent, then, as the volume of air present shrinks, something needs to take its place. The lining of the middle ear becomes swollen and may bleed, with the blood filling the cavity instead of air, along with inward bulging of the eardrum (barotrauma of descent). When the eardrum ruptures, cold water will then fill the space and can lead to vertigo and nausea. 

On the way up, the reverse happens: the air inside the middle ear expands as you ascend, and if you can’t clear this excess pressure via the Eustachian tube, the eardrum bulges outwards and becomes painful. Alternobaric vertigo (caused by differing middle-ear pressures) can develop, and occasionally the eardrum will rupture. Generally, though, there is much less of a problem with barotrauma when ascending than when descending, as the pressure can equalise more easily on ascent. Both types of barotraumas are more likely if you dive with a head cold, which causes congestion of the Eustachian tubes and interferes with the function of the flap valve. 

Reverse ear is caused when the ear canal is blocked – by, for example, a tight hood or earwax – and air in the outer ear becomes trapped. It will then compress in volume as you descend, and if the middle ear is inflated normally, the eardrum will painfully bulge outwards, and congestion of the tissues of the outer ear will occur with swelling and sometimes bleeding. Normally, it is not severe, and can be eased quickly by removing the blockage: pulling the hood away from the ear, for example. 

Inner ear 

inner ear

The inner ear consists of the cochlea for hearing and the vestibular apparatus (the semi-circular canals) for balance. 

If you struggle to clear your ears on descent – particularly if you have to try hard and use excessive force to clear them, instead of ascending until you are able to do so – then you are at risk of inner ear barotrauma, in which a high-pressure wave is transmitted through the fluid surrounding the brain into the cochlea and bursts the round window. A leakage of fluid called perilymph will result, causing deafness, ringing or roaring in the ear (tinnitus), and vertigo, which may vary from mild to incapacitating. 

Usually, the symptoms will start within a short time of surfacing (these may be mild but will be aggravated by physical activity such as pulling up an anchor) or even during ascent, but the key feature is difficulty with clearing the ears. If this occurs to you once, you are more likely to have further episodes, and the symptoms may be long-term. 

Decompression illness (DCI) can develop in the inner ear, and the symptoms are very similar to those of inner ear barotrauma. This tends to emerge a short time after surfacing (say, between 15 and 20 minutes) and much later than barotrauma symptoms, so symptom-timing is important. DCI is treated by recompression, but barotrauma is remedied by rest and avoiding strain – recompression may aggravate it. It is sometimes necessary to have an operation to repair the round window if the symptoms do not subside. 



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