The Art of Drinking & Diving The importance of being well-hydrated while diving

By Mark Brill & well when dehydrated, and your Diving involves work, and your Laura Harris ability to off-gas efficiently is muscles are less effective and more impaired. prone to injury when you’re dehydrated. Sports physiologists When your body loses water, your regard fluid loss as a major factor in blood decreases in volume, becoming sporting performance, so perhaps it’s Diving while your body is thicker and more viscous. It is less time for divers to take hydration more dehydrated, it leads to aching able to carry dissolved gases and its seriously. muscles, fatigue and possibly even flow is slowed, so the speed at which decompression sickness - it’s that you eliminate nitrogen and other Those who consider themselves serious. Technical diver Mark Brill gases is reduced. “serious divers” are concerned about gets together with diver and sports keeping themselves hydrated. physiologist Laura Harris to examine Much of the water in our body is Technical divers, who spend a long how dehydration affects divers and found in lean muscle mass. Getting time in the water on decompression how you can avoid it rid of the excess nitrogen taken on stops, will often avoid alcohol on during any dive requires the body’s their dive trips and take fluids to When you’re preparing for a dive, consume in-water. Nappies and you’re probably more concerned pee-valves are the order of the about your equipment and your day for dry-suited tekkies, dive plan than making sure because they must take on fluids you’ve been drinking enough and they don’t have the option water. In fact, many drysuit of ending their dive early! divers and those who dive from small boats actively avoid That may seem a bit extreme for drinking fluids before diving, for the average diver, but proper fluid fear of needing a pee! regulation is a bit of an art. Unfortunately, this is exactly the Taking on water needs to start the wrong thing to do. day before a dive, because losing fluids is all too easy, even in the Various diving accident reports chillier conditions in colder parts have highlighted dehydration as of the world. a contributory factor in decompression incidents, even How do divers lose fluid? There are among the UK’s drysuit divers. four main ways: through So this isn’t just a warm water sweating; respiration; urination, destination problem. especially when exacerbated by softer tissues to work well, yet it is diuretics; and stomach upsets, It’s not only our planet that is made these tissues that are adversely particularly those which involve up of seven-tenths water. So are our affected by dehydration. diarrhoea and/or vomiting. bodies. Yet a relatively small loss of just 2% of your body mass in water Decompression is not the only stress sweat! will leave you seriously dehydrated on your system. Divers face the As soon as you start exerting and susceptible to a variety of strain of lifting heavy equipment, yourself or heaving yourself into your injuries. Your muscles don’t perform climbing boat ladders and finning wetsuit or drysuit, you’ll be losing against currents.

13 fluids. Putting on a wetsuit or drysuit Whichever type of suit you wear, Don’t think that because beer is like wearing a sweatsuit; your body take it off between dives. contains 95% water it’s any better starts losing moisture even if you’re than drinking spirits. The dehydrating feeling quite cold, and you are breathe! effect of the alcohol far outweighs unlikely to be aware of it. the intake of water in your pint. Breathing dry air causes dehydration. Many divers with “wicking” The compressed air in your cylinder undersuits will notice that they Coffee, tea, cola and chocolate all removes moisture from your body as appear wet after a dive - but not contain caffeine, which acts as a you breathe it. The longer your dive, because their drysuit has leaked. This diuretic. Tempting though it is to the more moisture you’ll have lost. is the result of sweat that has been have a hot cup of tea on a cold day, The impact is greatest in cold water wicked away from their body and in hydration terms it’s inadvisable to diving, where the lungs are warming condensed on the colder outer drink caffeine-based drinks shortly the cold air, and moisture is lost as a surface of the undersuit. Who before a dive. said diving wasn’t glamorous! SPACEMAN SYNDROME Favoured alternatives are soup, You’ve only been in the water for an hour, but now Any work done while suited up, you’re desperate! Why does diving makes you want to hot Ribena, apple juice, fruit such as lifting equipment, makes wee more frequently than you would on land? squashes and isotonic sports you sweat more. Pre-dive Scientists call it “immersion diuresis” and it’s a very serious drinks - but be aware that some adrenalin and emotional stress problem for astronauts. Your body is designed for an fruit juices and soups can work contributes. So avoid putting environment with gravity, and weightless environments against your attempts to keep such as space or the underwater environment confuse your suit on too early, avoid the body’s regulation mechanisms. properly hydrated. Any food or working and - relax! Normally, much of your blood will pool in your drink that has 8 or more grams extremities, slowed by gravity. Take away gravity, and more of carbohydrate per 100ml will Wetsuits are equally problematic blood returns to your centre. Your heart responds to the make your body take water into for hydration in both warm and extra volume by triggering a response in your kidneys to the gut to dilute it. The simple remove fluid. That means you need to pee more, and cold climates, as tight-fitting more often. solution: drink water at the same neoprene will cause you to sweat. In a weightless environment your body is actively working time. It is unpleasant climbing back against you to reduce your blood volume - and as blood into a damp suit for a second is the primary site of gas exchange, this is not good news better out than in! dive, but the loss of fluids caused An upset stomach will often by keeping it on can become result. Breathing is unavoidable, but mean that you are not effectively able dangerous. rebreather divers who are inhaling to absorb fluid across your gut. You warm, moist air have a definite can also lose a considerable amount advantage. of fluid by vomiting or having FIVE KEY FACTS pee! diarrhoea. It’s always best to avoid 1 A 2% loss of body mass through diving if you’re not feeling 100%, and The process of being submerged dehydration reduces your physical diving while dehydrated is likely to seems to make people more inclined performance by 10% make you feel worse. 2 A 5% loss of body mass through to urinate, but diuretics - substances dehydration is the equivalent of heat stroke - that cause you to pee more - have a Many divers suffer from seasickness, you won’t be able to stand. greater effect. 3 You need to drink 2 litres of water every but throwing up before a dive loses day to stay adequately hydrated lots of fluids. If you’ll feel better off Alcohol is a well-known diuretic, and 4 Diving provokes dehydration, so you need the boat and diving, try to replace to drink before and after dives many of the symptoms of a the lost fluid by drinking an 5 Hydration is an important factor in off- hangover, such as headaches, loss of electrolyte fluid. The best option is gassing. Every dive involves decompression, concentration and fatigue, are largely and dehydration can provoke DCI. to use rehydration salts, which are caused by dehydration. available in sachets from chemists,

Alert Diver, SEAP 14 IN-WATER HYDRATION Avoid too much alcohol, coffee, cola, Today’s divers dive deeper and for longer than ever before - not because tea, and chocolate - OK, so you’re we’re braver, but because we have better equipment, computers and human and unlikely to change the thermal protection. habits of a lifetime for the sake of a If you plan to do longer decompression stops, drinking under the water dive, but keep a balance. Sports-style makes sense. Some divers take small foil packs of sports drinks that electrolyte drinks are designed to can be squeezed. Others attach a drinks container to the decompression rehydrate you, providing a balance station. It has a hose and a small tap that can be opened when the diver of water and nutrients; these drinks wants a drink. are especially useful if you suffer There are also some commercial systems such as the SCUDA (Self from seasickness, have a stomach Contained Underwater Drinking Apparatus) or the Weezle Rehydration upset or feel hung-over. System. Whichever type you choose, it’s worth practising your underwater drinking technique. Here are some top tips: Mineral-rich foods such as bananas, • Use a strongly flavoured drink, such as apple juice or fruit squash, so watercress and mushrooms also help that you can easily distinguish it from sea water. your body maintain proper hydration. • Remove the airspace from any container used. If only Pot Noodles came with • Hold your regulator between thumb and first finger and the drinking watercress and mushroom! nozzle between the next two fingers of the same hand. That way you can switch easily between drinking and breathing, and your reg is on- unwell after a dive? hand. If any other diver ever feels unwell • For rebreather divers, closing the loop, drinking, and reopening the after a dive, don’t ignore the signs or loop requires long breath-holding. Many find it easiest to come off the assume that it’s trivial - make sure loop and breathe open-circuit to drink. he or she gets water and oxygen, and contact a DAN hotline immediately. there has been a move towards Let the doctor on call make the but a good alternative consists of aggressive rehydration - taking on a diagnosis and advise you what to do. isotonic drinks such as Lucozade lot of water shortly before a dive. In Sport. hydration terms this doesn’t make If you take it on yourself to make a much sense. If you drink too much diagnosis, for example by deciding Failing that, you can make your own water at one time, your body will that the condition isn’t serious, you rehydration fluid by dissolving six simply flush it through your system, could be liable if the condition turns teaspoonfuls of sugar and half a along with valuable minerals. out to require urgent treatment. teaspoonful of salt into 750ml of Apparently trivial symptoms can be warm water. If you wait until you feel thirsty the first signs of decompression you’re leaving it quite late - you’re illness (DCI). the long-term view already dehydrated. Many divers with DCI will not think It’s not enough to take a few sips of straight and will not want to make a water shortly before a dive and hope You will be most dehydrated in the fuss, but it is far better for all that you’re properly hydrated. The morning, so on the day you dive, drink concerned to react defensively. best approach is a slow, gradual half a litre in the morning and a Rehydration plays a vital role in the intake of fluid, up to two days before further 250ml - a normal-sized mugful treatment of DCI, and nobody diving. Aim to drink at least 2 litres - shortly before the dive to see you comes to harm if made to drink some of water a day.. through your time under water. Immediately after a dive it’s wise to water and breathe oxygen. Avoid over-drinking and getting drink between half a litre and a litre This article, first published in Diver thirsty. In technical diving circles of water to replace the lost fluids. has been reprinted with kind permission of the authors and Diver.

15 DRUGS AND DIVING From previous page ... Diving puts extra and unavoidable stress on your body. If you are taking prescription drugs, check with a doctor about how advisable it is to dive. CHECK YOUR HYDRATION LEVEL If you are taking drugs to control blood Check the colour of your urine. Generally pressure or blood volume, drugs which speaking, the more dehydrated you are, the impact on the functioning of your heart and stronger the yellow and the more potent the kidneys - even drugs to cope with water- smell. Ideally, your urine should be plentiful, retention and bloating - then it’s probably very pale yellow or almost colourless, and best not to dive, (Ed: or at least to ensure odourless. Just bear in mind that first thing that you have been assessed by a diving in the morning your urine will be a stronger physician). yellow colour regardless of your level of If your usual doctor knows nothing about hydration. And if you have been drinking a diving, you can find a specialist diving doctor lot of diuretic fluids (alcohol, tea or coffee) by looking at the South Pacific Underwater be aware that it will tend to be paler, even Medical Society (SPUMS) Website at though you are not properly hydrated. www.spums.org.au.

Alert Diver, SEAP 16