This was the third year that Irene Davis, the director of Harvard University's Spaulding National Running Center, had volunteered her physical therapy services to the Boston Marathon. A little before 3 p.m. on Monday, she was standing near the back of Medical Tent A, talking to her husband, who questioned whether they were needed any longer.
"It was a beautiful day, not hot like last year when we had so many heat injuries," she said. "It was really quiet in the heat injury section of the medical tent."
She decided to stay in case the next wave of runners coming in needed help. A few minutes later, the bombs exploded.
The first thing she did was look at her husband's face.
"He was in Special Forces for 20 years, so I know he knows what a bomb sounds like," Davis said.
Within five minutes victims with traumatic blast injuries began pouring in, Davis said. The tent, which spanned an entire city block, was set up near the finish line to deal primarily with typical running injuries. In an instant, it was transformed into a mass casualty center.
For several hours, Davis pitched in where needed, wrapping wounds, monitoring vital signs and helping to transport patients in need of greater care to nearby hospitals.
Despite the chaotic scene that unfolded, Davis said she was struck by how calm and focused the medical tent staff remained. She believes that having the bombs go off so close to the race's finish line, where so much medical assistance was readily available, probably helped save lives.
"Everyone jumped into gear and did their part. The medical staff kept cool. That's the part that was so impressive," she said.
Fortunately, most major marathons have a detailed medical plan in place, and the lead medical team is well trained in disaster management. Robert DiGiacomo, a physical therapist at the Hospital for Special Surgery in New York City, has also volunteered at several road races, including the Philadelphia and Pittsburgh marathons. He said that besides several large medical tents set up near the finish line, medical response teams were situated all along the course as well.
"Usually they are staffed by various medical professionals, including physicians, physicians' assistants, nurses, physical therapists and certified athletic trainers," he said.
For a marathon like Boston's, with nearly 30,000 runners, as many as 800 medical volunteers and staff are spread out along the 26.2 mile route, with the greatest concentration of medical help between mile 20 and the finish line, where runners are the most likely to need medical assistance.
Typical injuries range from sunburn to blisters. Dehydration, heat exhaustion and strained muscles are also common. Occasionally, a runner will have a heart attack.
Before the bombings, deaths in the Boston Marathon's 117-year history were few and far between. In 1996, a 62-year-old Swedish man died of a heart attack during the marathon's 100th anniversary race. In 2002, a 28-year-old woman died of hyponatrimia, a severe electrolyte imbalance that usually occurs when an athlete consumes too much liquid.
Most of the medical personnel that staffs marathon routes comes from sports medicine backgrounds and has little trauma experience.
But Capt. Bruce Adams, the medical director of the Marine Corps Marathon, which takes place in Washington, D.C. in October, said that many of the medical professionals at an event the size and scope of Boston's would likely have some level of emergency medical experience and training.
"You see a mix of training and specialties across the board, but it's common practice in medical centers to require at least some training in advanced cardiac life support," he said.
Adams also said that large racing events have medical plans in place that include contingencies for mass casualties such as those seen in Boston.
"In a situation like what happened in Boston we immediately dialog with local emergency medical authorities to figure out what assets are needed and where to mobilize our resources," Adams said. "We defer to local authorities, but we have planned and trained for such events in the same way hospitals do."
Davis said that she, along with the rest of Boston Marathon medical volunteers, was required to attend a meeting before marathon day, where team leaders discussed various roles and plans of action in detail. Yet all her preparation and training did not prepare her for what she witnessed.
"I'm sorry for the people that were hurt. It was really hard to see. I've never experienced anything like that before," she said.
But she said it wouldn't stop her from supporting the race. She loves being part of the marathon, and she loves being there to help the runners.
"It's why we are all in medicine, to transform someone in pain or sickness to feeling better," she said.