What motivates runners to tromp through sideways rain, up steep hills and over miles of sun-baked sidewalks has never been fully understood by the general public, beyond the few who spend hours each week laced up in low-top sneakers. However, some experts are trying to better understand the drive to run.

Besides the obvious physical benefits of running, doctors and running specialists recently have been investigating the covert, psychological benefits of the runner’s lifestyle, otherwise known as “runner’s high.” Runner’s high is linked to naturally produced, pain-suppressing, mood-elevating drugs called endorphins.

These endorphins, which are produced by the brain and released into the bloodstream, have the same effects as morphine. Their primary role is to control pain and elevate mood. Stress, either emotional or physical, triggers the release of endorphins into the bloodstream, said Dr. Owen Anderson in Runner’s World magazine.

“It comes as no surprise that running — a physical stress — can bring about a flood of this natural drug through your system,” Anderson wrote. “The result: You feel no pain. On the contrary, you may feel comfortable and relaxed, as though floating along and at peace.”

While the sensations of runner’s high vary from runner to runner, the general euphoric effect is constant.

“It’s total excitement,” said Chris Francois, ISU distance runner and freshman in pre-business. “You don’t feel any pain. You may be really tired, but you don’t feel it.”

ISU distance runner Tait Steines said he gets “high” when all the elements of the run are in sync.

“You feel that everything’s going the way you want it to, like you could run forever and you don’t have any limits,” said Steines, junior in industrial technology. “You want to keep on running because you’re on a roll and it feels good.”

How do runners achieve the magical high? A study conducted by Dr. Edward Colt and his colleagues at Columbia University in New York City suggested the level of the high is proportional to the workout’s level of intensity.

The study, which was reported in Runner’s World, showed that 80 percent of runners had a higher level of endorphins in their blood after a hard session, while only 45 percent benefited following an easy jog.

However, ISU women’s head track and cross country coach Dick Lee said a good performance does not always ensure a high.

“It is not always based on performance,” Lee said. “Your body can be sending you those mixed messages, but when you get done and look at your time, you may realize you didn’t have a great race.”

Although the link between runner’s high and high-tempo running is not clear, many runners say they experience the rush of euphoria after intense running.

“Most likely, I’ll feel it after having a really good race,” Francois said. “When I am proud of what I have done.”

Besides the intensity of the workout, the weather also may have an effect on runner’s high.

“I notice it most when the weather is most inclement,” said ISU distance runner Wade Demmer, senior in computer engineering. “When it’s raining and dark and I am running up a hill and I see a car, I know they think I’m crazy. It makes me pound up the hill as hard as I can.”

As is true with other highs, the runner’s high is, at the very least, psychologically addictive. Since running surges endorphin production, just as alcohol, nicotine and chocolate do, extensive running can have the same effect as addictive substances, according to the Runner’s World study.

“As habits go, it’s a great substitute for smoking or drinking,” Anderson wrote. “Perhaps it’s the endorphin link that has made it easy for so many runners to trade in their Marlboros for running shoes and find a healthy high in running.”

Lee compared the running addiction to a coffee drinker’s dependence on the morning cup.

“There is a physiological addition for distance runners,” Lee said. “It is like a person who drinks three cups of coffee every day. If they don’t get their coffee one morning, they get a craving for it. If [runners] are hurt or they have to miss a few days of running, they miss that feeling.”

Demmer said the absence of runner’s high is more acute than the actual feeling.

“I don’t think it’s something you really notice when you have it,” Demmer said. “But when you don’t have it, you miss it.”