It will be hot - hot enough that most locals will have cleared town for cooler havens. But because athletes competing at the 2004 Olympics have no choice but to stay in the sweltering weather, many plan to turn to science to stay cool.

Some will wear vests filled with chilled gel, others will dunk their hands in icewater just before competing and nearly all will be wearing fabrics designed with hot weather in mind.

"Normally we warm up before exercise," said Gordon Sleivert, director of sports science and medicine at the Canadian Sport Center in Victoria, British Columbia. "But in this case we're taking the warm out of warm up. It's like pre-cooling."

Battling heat this summer in Athens could prove as critical a focus as beating record times.

Meteorologists are predicting the average high this August in Athens will be 90 degrees Fahrenheit, with temperatures often reaching above 100 (the average temperature in Sidney for the 2000 summer games was 64).

Humidity will also be a factor, averaging at 41 percent. Although some events, such as the marathon, will start early (7 a.m.) to avoid hot weather, other competitors will be pushing their limits during peak temperatures.

In hot weather, more blood is sent to the skin for cooling so less blood flows to your muscles. This means the heart must beat faster to keep up the pace. By some estimates, as much as 75 percent of the body's energy is used to regulate heat when temperatures peak and only 25 percent to power muscles.

Drinking lots of water will help athletes maintain their cool, but humidity remains a problem. The body's ability to cool down is impaired by damp air since sweat drips off the skin rather than evaporates, resulting in dehydration without the cooling.

"When the air temperature is hotter than the skin temperature, our ability to dissipate heat from the body is impaired," said Sleivert. "Getting hot is a real problem because when our brain heats up, the brain waves are more like when you're really sleepy. Everything feels harder."

(Agencies)