Too much fluid unsafe in endurance exercise

23 July 2005

Highlights for Saturday July 23 of the Winter Symposium of the Australasian College for Emergency Medicine being held in Queenstown, New Zealand, July 21-23.

Too much fluid unsafe in endurance exercise, particularly in females

Too much fluid during endurance exercise can be hazardous, even resulting in life-threatening seizures and coma, according to a speaker at the Winter Symposium of the Australasian College for Emergency Medicine being held at the Millennium Hotel in Queenstown NZ.

According to Associate Professor Ian Rogers, Director of Postgraduate Medical Education and Research at Sir Charles Gairdner Hospital in Perth, there has been an explosion in participation in endurance sports since the 1980s.

The conventional 42 km marathon is no longer the common limit of endurance competition.

Large numbers of entrants line up for events that may include multiple legs such as running, swimming, cycling, and canoeing over a period of many hours or even days.

"While there is no firm definition of an endurance sport, a useful working definition is moderate-to-high exertion over four or more hours," he said.

"These endurance events have certain associated medical problems.

"The risk of heat stroke, intracranial haemorrhage, or cardiac arrhythmia may seem obvious in the context of prolonged exertion but these are rare.

"The commonest medical problem is exercise-associated collapse, which usually occurs at the end of a race when exertion ceases and the enhanced blood flow to maintain cardiac output is lost."

It is due to simple intravascular volume depletion and usually requires no more than rest in a supine posture and oral fluids, he said.

The most frequently encountered severe medicalproblem is dilutional hyponatraemia - a low level of sodium in the blood due to overhydration

In its most severe form, it is associated with life-threatening seizures and coma.

It is most common in female and slower competitors and has been conclusively shown to be due to excess fluid intake during the event.

Most people can be treated by fluid restriction and close observation.

Severe cases require care in an Emergency Department where sodium will be delivered intravenously .

"Effective prevention is achieved by limiting fluid intake during the race to no more than 500-750 ml per hour," Dr Rogers advised.

"Changing drinking behaviour can be challenging in a setting where the 'if you don't drink you die' mantra has become part of sporting folklore."

Tsunami relief mission exposes a myth

A Tsunami Relief Mission in Sri Lanka has exposed as a myth the belief that infective gastroenteritis is the most common disease after a natural disaster.

Dr Cher-cheong (Wilson) Chong, from Tan Tock Seng Hospital in Singapore, was part of a medical team dispatched from Singapore to Trincomalee in Sri Lanka in January.

The team assisted 1,013 people suffering injuries and health problems as a result of the Boxing Day Tsunami.

Dr Chong will detail his experiences and findings at the Winter Symposium of the Australasian College for Emergency Medicine being held at the Millennium Hotel in Queenstown NZ.

He said of the daily attendance at the medical clinic, 20.4% to 42.4% related to upper respiratory tract infection, not gastroenteritis.

In fact, only 1% to 9.4% related to wounds from injuries and 0.5% to 8.4% related to gastroenteritis.

ENDS

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