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This case of the chills was readily treatable

A runner receives assistance after being taken to the main medical tent at the finish line. "It was a light day," said medical director Pierre d'Hemecourt. (BILL GREENE/GLOBE STAFF)

During the first 10 miles of yesterday's Boston Marathon, Mike Delmore faced a dilemma.

Keep his jacket on to ward off the chill? Or peel it off to prevent overheating?

Delmore chose the former, which the 47-year-old Dallas resident believed to be one reason he headed into the main medical tent next to the Boston Public Library after crossing the finish line.

"Just cramped up," said Delmore, who thought he might have sweated too much because of his jacket. "I know I had enough to drink."

In the main medical tent, the warmers were on full blast. The tarpaulin flaps, usually held open to allow fresh air into the tent, were snapped closed. Unlike previous years, when the tent was cool, it bordered on balmy yesterday, the temperature jacked up to stave off the day's biggest bugaboo: cool, damp weather.

While Delmore didn't think the conditions were particularly nasty ("Where I'm from, this is a summer day," said the Wisconsin native), scores of other runners had to face the same issues: what to wear, what to take off, how to stay dry, how much to drink on a day when weather was the most significant wild card of the 26.2-mile race.

Conditions weren't as drastic as predicted -- the temperature was higher -- but the wind, rain, and cold combined to make it a challenging race for medical personnel, who had prepared for the worst.

However, the fallout wasn't as heavy as projected. At 4:30 p.m., according to medical director Pierre d'Hemecourt, approximately 300 runners had been treated in the main medical tent.

"Better than expected," medical coordinator Chris Troyanos said. "We anticipated concerns with the temperature, wind, and rain. At this point, we thought we'd have a higher casualty rate.

"But I think the forecast changed. And it's nice to have weather forecasts be accurate for a change."

Troyanos credited the Boston Athletic Association for sending e-mails to runners last week, warning them of the conditions and reminding them to dress appropriately. Runners were also cautioned about the weather when they picked up their bibs.

Because of the conditions, the most significant concern was hypothermia (d'Hemecourt reported several cases). Most of the complaints yesterday were for chills, which were treated by removing wet clothing, covering runners with Mylar and cotton blankets, and encouraging them to drink cups of warm broth.

Cramping was also an issue, a result of runners not drinking enough before and during the race.

Before the race, d'Hemecourt thought blisters would be a problem, especially because of the soggy ground in Hopkinton. But he said there weren't many cases of severe blister ailments.

Anticipating hypothermia problems, medical personnel set up tents equipped with warmers along the course. There were also heated buses used as medical stations along the route to transport runners off the course. D'Hemecourt said several runners were treated for hypothermia and were recovering.

For the second straight year, Tent B, set up on Boylston Street beyond the main medical tent, saw heavy traffic. Troyanos explained that after previous marathons, runners bypassed the main tent, believing they did not require medical attention.

But as they walked away from the tent, they started to undergo problems -- severe cramping being the most common affliction -- that had volunteers scrambling to hustle them on wheelchairs back to Copley Square.

"We did that not because Tent A couldn't handle it," said Troyanos. "Our volunteers were being stressed too much, trying to take someone on a wheelchair and transporting them four blocks to Tent A. Boston EMS has a fair amount of golf carts, but there's only so much you can do."

One concern that was lessened yesterday was hyponatremia, the condition that led to the 2002 death of runner Cynthia Lucero. Overdrinking, according to Dr. Charles Siegel, director of internal medicine at McLean Hospital, can lead to water retention and cause acute cerebral edema. But in cooler weather, Siegel said, runners do not drink as much.

Siegel said there was one male diagnosed with hyponatremia-like conditions who was transported to Newton-Wellesley Hospital. According to Siegel, the usual treatment in the medical tent is to give athletes broth to increase their sodium levels, but the runner was too agitated for that and had to be given an IV.

"He was flailing around, his legs were in perpetual motion, and he would kick the staff away," Siegel said. "His sodium was low, which was the main culprit, and he had a high temperature, although it was not high enough for heatstroke."

Despite that case, medical officials were pleased with the lower-than-expected casualty rate.

"It was a light day," said d'Hemecourt.