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releases 08/08/2007 Dont die from ignorance warning to runners Marathon runners across the UK are being warned that they could be putting their lives at risk if they overdose on water while failing to maintain vital supplies of salt.
The “don’t die from ignorance” warning comes as summer finally arrives and the Salt Manufacturers’ Association (SMA) expresses renewed concern that the Government’s blanket advice on salt reduction is leaving large sectors of the population vulnerable to the condition of hyponatraemia, of which many people are ignorant. The thousands of marathon runners who will take to the streets through what forecasters have predicted could be a warmer than average remainder of the summer face particular hazards.
The SMA is writing to marathon organisers urging them to ensure that every runner is given adequate advice about hyponatraemia, which is believed to have been responsible for the death of a male runner in the London marathon this April as well as a number of deaths in other marathons.
Hyponatraemia - defined as a low concentration of sodium in the blood - arises amongst runners during long races when large volumes of water are consumed without adequate sodium intake. The condition has emerged as an important cause of race-related death and life-threatening illness among marathon runners.
Dr Simon Jenkins says in his book Sports Science Handbook: The Essential Guide to Kinesiology, Sport and Exercise Science: “Hyponatraemia is an illness in which there is low concentration of sodium in the blood plasma. Athletes who start already hyponatraemic from excessive drinking in the days or hours before the race are at particular risk of more severe hyponatraemia during the race, because less fluid is required to drop plasma sodium to dangerous levels.”
Marathon running is becoming ever more popular and so is exposing increasing numbers of people to the risk of low blood sodium levels. Research at Loughborough University has also shown the risk to footballers who can lose up 20 grammes of salt through sweating in two daily training sessions. Yet the Government’s blanket advice says that six grammes a day is adequate for everyone.
Dr Emma Ross, from the BASES-accredited Centre for Sports Medicine and Human Performance at Brunel University, said that ‘recreational’ runners (general population rather than well-trained athletes) who participate in long-distance events (over four hours) are the most ‘at-risk’ for exercise-induced hyponatraemia. She said: “The current literature states that this is owing to over-hydration in the face of relatively low sweat rates, but also having a sodium content in sweat twofold higher than fit athletes. ‘Over-drinking’ is not the sole cause of exercise-induced hyponatraemia – indeed warning people not to drink too much during exercise could have catastrophic consequences in terms of dehydration and hyperthermia. Hyponatraemia will develop even without excess fluid intake, unless sweat sodium loss is adequately replaced (which could be by dietary salt during and after prolonged exercise).”
Findings of a number of research projects, involving athletes such as marathon runners, cyclists and footballers, have already caused experts to question the UK government’s blanket advice on reducing salt intake and have drawn attention to one in six people who are ‘salty sweaters’ – in other words they sweat profusely and lose a lot of sodium when they do so.
One study of marathon runners showed up to 13 per cent suffering from some degree of hyponatraemia. Signs can include nausea, extreme fatigue, breathing difficulties, dizziness and coma.
Professor Ron Maughan, of Loughborough University, said: “Dehydration impairs performance in most events, and athletes should be well-hydrated before exercise. Sufficient fluid should be consumed during exercise to limit dehyration to less than about two per cent of body mass. During prolonged exercise the fluid should provide carbohydrate. Sodium should be included when sweat losses are high, especially if exercise lasts more than about two hours.
“Athletes should not drink so much that they gain weight during exercise. During recovery from exercise, rehydration should include replacement of both water and salts lost in sweat.”
Peter Sherratt, General Secretary of the Salt Manufacturers’ Association, said: “With a massive 400 to 500% increase in the number of participants to marathons across the country, we need to ensure that these marathon runners are aware of the risk of not having enough salt in their bodies.
“Experts are increasingly questioning the claim from the Food Standards Agency and the Government that we eat too much salt. The Intersalt study, involving 10,000 people from 52 countries showed that almost everyone with free access to salt eats between six and 12 grammes of salt a day, and we in Britain are right in the middle at nine grammes. The FSA and the Government are ignoring the fact that salt is a life-giver and that too little salt can lead to serious illness or death.
“If runners take part in marathons in hot weather and don’t heed warnings about replacing the salt lost through sweating, their lives could be at risk.”
The Salt Manufacturers’ Association is urging responsible UK sporting organisations to follow the lead of the England Hockey website http://www.englandhockey.co.uk/text.asp?section=0001000100550010#Fluid
The American College of Sports Medicine states that it is important to include sodium in the rehydration solution ingested during exercise lasting longer than one hour since it may help enhance palatability, promote fluid retention, and possibly prevent hyponatraemia in certain individuals who drink excessive quantities of fluid.
Further advice on running in hot weather comes from the Cool Running New Zealand website (http://www.coolrunning.co.nz/articles/2002a011.html), which tells marathon runners that fluid restrictions in hot climates are potentially dangerous and adds: “As long as there is not a medical reason to restrict sodium intake, then increasing your salt intake is perfectly safe. If you consume more sodium than your body needs, then your kidneys simply dump the excess. In summary, eating salty foods, is a very safe, effective treatment and preventive strategy for exercise associated hyponatraemia.”
The Lucozade Sport Science Academy (GlaxoSmithKline) advises runners to consume fluids during training that contain sodium (ie fitness or sports drinks). A spokesperson said: “The benefits of sodium in sports drinks are that: sodium helps stimulate sugar (fuel) and water (fluid) absorption, replaces sodium lost in sweat and helps retain water and encourage drinking.”
View of Dr Sandy Macnair, Medical Adviser to the Salt Manufacturers’ Association:
“Acclimatisation to heat by marathon runners increases the capacity of the sweat glands to produce sweat and also improves their ability to conserve salt by removing most of the salt from the sweat before it reaches the skin surface. Sometimes participants in marathons are also critically lacking sufficient salt to produce the sweat volume required to dissipate the heat generated by running in hot conditions.
“During exercise and in the heat, we often turn to water to avoid dehydration, but that’s only part of the picture. Our bodies must also replace the sodium and other electrolytes lost through sweat, or we can lay ourselves open to hyponatraemia. Poor performance and cramps can follow a lack of salt, but the potentially life-threatening condition of hyponatraemia, which has affected several marathon runners, is caused by drinking excessive amounts of liquid. This dilutes the levels of salt in blood.
“I am surprised that the organisers of marathons don’t hand out salt replacement drinks at the mile posts rather than just water.”
Tips for fluid intake during exercise include using a sport drink containing sodium when high sweat losses are expected, and eating salty foods after training and competition when salt losses are high.
Ends Media contact Susan Tolman, Daybreak Communications 0845 644 3845 mob 07786 543430, e-mail susan.tolman@daybreakcomm.co.uk Notes to editors
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