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NEWS RELEASE

July 26, 2005
For immediate release

American College of Sports Medicine (ACSM) Offers Guidance to Athletes on
Preventing Hyponatremia and Dehydration during Upcoming Races

Newly Published Roundtable Statement on Hydration and Physical Activity Reinforces
Importance of Managing Both Conditions

Indianapolis, Ind. – July 26, 2005 – A new report, which appears in the June issue of Current Sports Medicine Reports, addresses key issues and reviews research findings on the topics of hyponatremia and dehydration for endurance athletes – a subject that has generated significant media attention this year. The published report, ACSM Roundtable Series: Hydration and Physical Activity, is based on findings from an international panel of hydration experts who conducted an evidence-based analysis on numerous past published studies.

Based on the findings of this report as well as previously published statements, ACSM is issuing the following guidelines to the endurance community:

• Work to Minimize Risk of Both Hyponatremia and Dehydration. Hyponatremia is a dangerous condition that occurs when an athlete consumes too much fluid (either water or other fluids), diluting the body’s sodium levels. Despite heightened media attention to this issue this year, the international ACSM panel concluded that exertional hyponatremia is relatively rare and appears to occur most often in slow-paced athletes (running events lasting longer than four hours or triathlons lasting longer than 9-13 hours). The incidence of symptomatic hyponatremia during endurance exercise events such as the marathon and triathlon is generally low (probably less than one in 1,000 finishers).

  The panel also concluded that especially during hot-weather training, dehydration occurs more frequently and has severe consequences, increasing the risk of heat exhaustion and heat stroke during and immediately after activity. Fluid deficits in athletes can affect physical and mental performance, increase cardiovascular strain and decrease heat tolerance.

  “While hyponatremia has gotten more attention lately, far more athletes are affected by dehydration,” said W. Larry Kenney, Ph.D., FACSM, past president of ACSM and co-chair of the ACSM Roundtable. “However, there are dangers associated with both extremes of behavior -- severe under-drinking and severe over-drinking. Not drinking at all is not a safe option for preventing hyponatremia. The key is ‘drinking intelligently, not drinking maximally’,” he added.

• Drink to Match Fluid Loss and On a Schedule. The experts concluded that appropriate fluid intake (before, during and after exercise) is important to help regulate body temperature and replace fluids lost in sweat. Since fluid and electrolyte needs are widely variable based on the athlete’s genetics and environmental conditions, athletes should know their bodys’ hourly sweat rate (weight lost during exercise per hour + fluid consumed during exercise per hour = hourly sweat rate) and aim to replace the total amount lost during that time.

  According to the previously published ACSM Exercise and Fluid Replacement Position Stand, athletes are encouraged to drink early and at regular intervals rather than rapid fluid replacement. It is noted that perception of thirst, an imperfect index of the magnitude of fluid deficit, cannot be used to provide complete restoration of water lost by sweating. As such, individuals participating in prolonged intense exercise must rely on strategies such as monitoring body weight loss and ingesting volumes of fluid during exercise at a rate equal to that lost from sweating, to ensure complete fluid replacement. Drinking over a set period of time is more effective for complete rehydration as rapid replacement of fluid stimulates increased urine production, reducing body water retention. If athletes are not sweating heavily (such as slow runners) and are not thirsty then their fluid replacement needs are probably modest.

• Consume Salty Foods and Beverages. According to the published roundtable report, research shows foods and beverages with sodium help promote fluid retention and stimulate fluid intake. The report also notes that athletes performing prolonged exercise should ingest snacks or fluids containing sodium to help offset the loss of salt in sweat, in an effort to prevent hyponatremia.

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