Sam Osborne

As an aspiring Olympian in his 20s and an amateur mountain bike racer in his 50s, Sam Osborne closely tracked his physical performance. But after a blood clot in his leg led to a life-threatening pulmonary embolism in August, he realized he had a lot to learn about his risks and the dangers of simply pushing through pain.

Osborne’s career as an elite cross-country skier was cut short at 28 when he was diagnosed with Wolff–Parkinson–White syndrome, a condition in which the heart’s electrical system that creates extra conduction pathways and disrupts the normal heart rhythm.

He retired as an athlete and was careful not to overexert himself until the condition was corrected a decade later. Osborne didn’t resume intense training again until his late 50s, when he set his sights on the prestigious Leadville Trail MTB 100, a 100-mile, high-altitude race across the Colorado Rockies.

After a disappointing performance in 2014, Osborne skipped the 2015 race to better hone his training. But in August, less than two weeks before the race, Osborne’s left calf became incredibly painful after an intense training ride.

“It was like someone was driving a nail in my calf,” he said.

Thinking it was a pulled muscle, Osborne, 63,  treated it with stretching, ice and anti-inflammatory medication. The next day, he was getting treatment for a four-week-old knee injury on the same leg, when Osborne’s physical therapist noticed the area around his calf was swollen and hot to the touch.

“She’s the hero in all this because she sent me right to the doctor,” he said

After preliminary testing at his doctor’s office, Osborne was sent to the hospital, where additional tests revealed he was among some 900,000 people in the United States who are affected by blood clots, or thrombosis, each year. Osborne had a deep vein thrombosis, or a clot that formed deep in the body, usually the leg.

He was treated with blood thinners, and, after consultation with a hematologist, cleared to do the Aug. 13 race. Although he’d felt good in training, Osborne experienced cramping in both legs after three hours of racing, failed to make the cut, and returned home to Burlington, Vermont, on an overnight flight.

While unloading his bags from the car, Osborne felt a sharp pain his back and again attributed it to muscle strain. Over the next 24 hours, he also experienced shortness of breath and fatigue.

Osborne returned to the doctor, and was immediately sent to the hospital, where testing revealed that the blood clot had traveled to his lungs, becoming a pulmonary embolism. Together, DVTs and PEs are called venous thromboembolism, a dangerous and potentially deadly medical condition.

VTE is a leading cause of death and disability worldwide. In the United States, there are 100,000 to 300,000 VTE-related deaths each year. Up to 60 percent of VTE cases occur during or after hospitalization, making it a leading preventable cause of hospital death.

But awareness about the risks of thrombosis remains low.

“It’s the third-leading vascular disease after heart disease and stroke, but many people have never heard of it,” said Mary Cushman, M.D., Director of the Thrombosis and Hemostasis Program at the Robert Larner, M.D., College of Medicine at the University of Vermont.

Having surgery, an extended stay in a hospital or being unable to move for a long time, due to bed rest or long-duration travel pose the highest risks for VTEs. But Osborne hadn’t realized that his knee injury, along with his age and the fact that his father had a DVT increased his risk.

“Having a family history of a DVT or PE can basically double your risk,” Cushman said.

Patients undergoing chemotherapy or other treatment for cancer, those who are obese or those using estrogen-based medication, such as contraceptives or hormone-replacement therapy also have increased risks.

Recognizing the signs of a VTE can be difficult because they are often subtle or mistaken for other conditions, Cushman said.

“A pulmonary embolism can be as dramatic as a the sudden onset of chest pain or an inability to breath, but if someone has mild shortness of breath, it might be passed off as an infection,” she said.

For athletes, injuries to the leg, even minor ones such as ankle sprains, can pose risks for developing blood clots, and having more than one factor compounds the risk, Cushman said.

Once you’ve been diagnosed with a DVT or PE, keeping close communication with your medical provider, especially during the first few weeks, to ensure you’re taking your medication correctly, Cushman said.

“If you don’t understand that you can’t miss a dose of medication or don’t take your medication correctly, it can have life-threatening implications,” she said. “Pay attention to any symptoms you may be having and follow-up with your doctor if anything is wrong.”

Osborne has kept in close contact with his medical providers, and is paying closer attention to any changes in his own health. Each morning, he does a body scan, paying careful attention to any swelling or color changes in his legs. While he hasn’t yet returned to intense training, he gets up at least once an hour to walk around, and keep his legs elevated when sitting down.

Osborne is already planning to compete in next year’s Leadville race, but he’ll make several changes to his training and how he schedules his travel, including taking more breaks to walk around and paying more attention to any changes in his body.

“I won’t power through unexpected pain anymore,” he said. “It’s important you watch every detail.”