A pile of leaves forever changed 50-year-old Rob Pernick's sense of vulnerability.
But despite a crippling accident caused by those leaves, Pernick's commitment to exercise never wavered.
On Nov. 14, 1998, the avid cyclist and runner dropped his wife, Diane, and daughter Sarah at school for Sarah's clarinet competition. He drove home, and then rode his bike to the network of paths near his Columbia house.
It was a cool, dry day, and Pernick was not alarmed when his tire crossed a pile of dry leaves on the trail. But the leaves were wet underneath, and the bike skidded out from under him.
"I hit with such force," Pernick recalls. "Nothing broke my fall -- not the handlebars, or my elbow or my wrist."
What did break was his hip. Residents raking leaves nearby saw the accident and called 911.
Pernick's first thought was, "Oh, God, will I be able to run again?"
In the emergency room, Pernick, a management consultant who holds a degree in organizational behavior, tried to tell himself he wasn't injured that badly.
The next morning, doctors placed a metal plate on his femur to allow the hip to heal properly.
During the next five days in the hospital, "I was having severe withdrawal symptoms from exercise," Pernick remembers.
He had been running since the 1960s. His typical workout was six miles several times a week. In 1985 he decided to add cycling to his regimen to avoid overuse injuries from running.
"At some level," he recalls, "I was aware that I was breaking down my body with all this running."
He bought a stationary bike -- a bike that now has more than 33,000 miles on it -- and would pedal for an hour at a stretch.
He also mapped out a 20-mile loop near his house, and rode his mountain bike on the C&O; Canal towpath and the Northern Central Railroad Trail.
Three weeks after surgery, Pernick spotted his old pal, the exercise bike. He climbed on awkwardly, placing his bad leg over the handlebars, and pedaled for 30 minutes with one leg.
The exercise felt good. Every day he rode the stationary bike, and after a week, he found a more comfortable way to prop his injured leg on a book on top of a chair.
He routinely clocked about 8 miles using one leg. Although he wasn't outdoors, "the exercise experience was almost as satisfying."
Pernick started doing sit-ups, keeping his bad leg flat, and modified push-ups, allowing him to work his triceps.
Six weeks after the accident, he was allowed to take a shower -- instead of sponge baths -- and to swim. He began using free weights about the same time.
Pernick's injuries are now mostly healed, and he hopes to start running again this spring. In late February, he ran three-tenths of a mile, but it was painful.
And while he's moved his exercise bike onto his deck to enjoy the weather, that's as close as he's come to riding a bike outside.
"I just don't feel comfortable," he says. "The accident was a very sobering experience for me."
One way or the other, though, he will find a way to work out. "What has sustained me my whole life," he says, "has been exercise."