EDS: Study shows intravenous and oral rehydration have similar effects on athletic performance
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March 10, 1998
STORRS, Conn. ó When NHL goalie Sean Burke stepped on the ice in Miami Arena in March of 1995 the outside temperature was 85 degrees. At ice level, the arena was hot and extremely humid. Throughout the game Burke lost a lot of fluid and found it difficult keeping himself hydrated.
He ended up in the hospital for two hours receiving an intravenous solution to replace lost fluid.
If Burke had received intravenous fluids between periods, would that have made a difference in his performance?
"Many coaches, trainers and athletes believe so because i.v. fluid administration is commonly used to treat heat-related illnesses," said Carl Maresh, a professor of exercise science at the University of Connecticut. "They believe that if lost fluid is replaced by going directly into the circulation, athletes will recover more quickly and probably perform better, but there has been very little research to substantiate these claims."
Maresh and his colleague Larry Armstrong, an associate professor of exercise science at UConn, conducted a study with cyclists to determine if oral or intravenous hydration has a better effect on an athlete's performance once they become dehydrated.
After five months of carefully examining the cyclists, Maresh and Armstrong found there was no difference. In their first study, the cyclists were dehydrated to minus four percent of their body weight because endurance performance is affected at minus three percent. Once the cyclists were dehydrated, they were given two hours to rehydrate intravenously or orally. The cyclists were then put into a heat chamber at 95 degrees to exercise at 50 percent of their maximum capability. "We had them ride as lonas they could before exhaustion," Maresh said.
A week later, the two professors put the cyclists through the same regiment. "What was interesting," Maresh said, "is that the cyclists exercised for a longer period of time . . . 84 minutes following oral rehydration but only 77 minutes after i.v. rehydration. That was a surprise to us."
So Maresh and Armstrong decided to test a different group of cyclists using a different approach. This time they gave the cyclists only 30 minutes to rehydrate and had them exercise at 70 percent of their maximal capacity. Results showed that those who had their body fluids replenished orally were able to exercise for 34 minutes as where the intravenous users went only for 29 and a half minutes.
"These results speak against what all people would expect," Maresh said.
At halftime, you can go into NFL or professional soccer locker rooms and see players being administered i.v. infusions. Once during a New England Patriots game against the New York Jets in September of 1989, Armstrong witnessed a lineman being administered an i.v. on the sideline in 98 degree heat.
"He was near heat exhaustion," Armstrong said. One person inserted the i.v., while the second squeezed i.v. fluid into a left forearm vein. Gauze and tape were placed on the lineman's forearm and he entered the game on the next play.
"You don't normally squeeze i.v.'s," Armstrong said. "You drip them. The concern about i.v. rehydration has been the capability of those who are administering the i.v.'s. Are they phlebotomists, athletic trainers or possibly untrained managers?"
Maresh believes another risk associated with i.v. administration -- hitting a nerve or missing a vein -- may be adverted since the research he and Armstrong conducted shows that i.v. rehydration does not have a better impact on performance than drinking.
"The cyclists felt better exercising after consuming water than after i.v. treatment," Maresh said. "They also reported that their thirst and heat sensations were diminished if they were able to drink, so there may also be a psychological component to this."
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