On an unusually cool summer day, Timothy Olson, 28, rounded the Placer High School track Saturday night for the first sub-15-hour finish in the history of the Western States 100 Mile Endurance Run.

After placing sixth in 2011, Olson came back from Ashland, Ore., with a vengeance this year to shatter Geoff Roes' 2010 course record by more than 20 minutes, finishing in 14 hours, 46 minutes and 44 seconds.

Ellie Greenwood, 33, of Canada set the women's record in 16:47:19, besting the previous mark of 17:37:51 set by Ann Trason in 1994.

An estimated 380 runners are competing in the race, which began at 5 a.m. Saturday in Squaw Valley. The course will remain open until the 30-hour cutoff at 11 a.m. today.

A sea of professional photographers, and iPhone amateurs, captured Olson's celebration as he high-fived fans along the final 60 meters and crossed the finish line under the waving flags of the participating nations.

Alongside all the lenses recording Olson's conquering the grueling run, another set of cameras focused on his feet.

The high school track in Auburn was one of four spots on the course where Dr. Marty Hoffman set up cameras to capture the competitors' gaits for his study on how different foot-strike patterns may reduce muscular damage in ultra-runners.

After crossing the finish line, runners continued moving to the medical tent for final weigh-ins and blood work-ups that help the competitors receive medical attention and provide scientists with relevant data.

For researchers, the endurance race over mountains and across rivers – in which participants lose an average of 3 percent of their body weight while competing for 16 to 30 hours – provides a unique opportunity to study the physiological effects of ultra-running.

"This environment cannot be re-created in a lab," said Hoffman, a member of the Western States Research Committee who ran the race for numerous years before focusing on the studies. "There is a lot of potential research that can be done at the race."

Over the course of the race the competitors ascended 18,000 feet and descended 23,000 feet in the Sierra, teams of researchers coordinated at medical checkpoints along the course to collect scientific data.

The conclusions reached – on everything from dietary practices to limiting muscular damage – will be applied to future Western States events to help the runners enhance athletic performance and to help medical professionals provide care.

"Our job isn't over until the runners have the information," Hoffman said, adding that each year since the early 1980s the research has been presented on the Thursday before the race at a medical clinic.

For researchers, many of whom are able to understand the runners' perspective after winning multiple Western States belt buckles, it is essential that the studies not interfere with the integrity of the race.

At the 62-mile Foresthill Elementary School aid station, runners could grab everything from cookies and chicken soup, to nuts and soda before continuing the descent to Placer High.

Behind the weigh-in scales sat Dr. Jeff Volek from the University of Connecticut, who waited to take cheek swabs from the runners participating in his study.

Volek hopes to better understand how dietary decisions influence the body's inflammatory reaction during ultra-endurance sports by comparing runners with low- and high-carbohydrate diets.

The medical research was sidelined about 2:15 p.m. Saturday when Olson was the first competitor to run onto the scales. He jogged past the cheering fans and proceeded down the course without having his cheek swabbed.

"He's in the lead," Volek said of losing a data point in his study.

Concerns over maintaining control over the research and upholding ethical standards led to the establishment of a formal research committee in 2006.

Past research has included taking biopsies of runners' muscles after the race and measuring the size of their arteries to understand how exercise changes the body.

"We now have funding for research and an internationally recognized committee that reviews the proposals and screens them for their potential likelihood of producing something of value," Hoffman said.

The studies conducted at Western States provide scientists with a greater understanding of the human body and also changed conventional wisdom, said John Medinger, a trustee on the Western States Board of Directors who publishes UltraRunning magazine.

Runners at Western States used to take an abundance of pain relievers, such as ibuprofen, to reduce inflammation, Medinger said.

At the Thursday medical clinic at Squaw Valley Lodge, runners listened as Hoffman explained how Western States research has shown that pain relievers can potentially damage kidneys and decrease muscular recovery.

Seminal work has been done and continues on hydration practices. Cooler temperatures and rain graced Saturday's race, but it is not unusual for temperatures to soar above 100 degrees.

In the 1970s, doctors were primarily concerned with runners' water consumption. Competitors were then encouraged to drink a lot of water before and during the event, Medinger said.

"After the first race in 1977, we noticed that there were some spectacular weight drops and the more weight the runner lost, the more likely it was that they would drop out," said Dr. Bob Lind, a longtime medical director for Western States.

Lind and his team began monitoring runners' weights during the race, and encouraged racers to stay as close to their pre-race weight as possible.

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