In late 2005 I started to take up running. After two winters on a bike trainer in the basement, I was jealous of people who could actually do outdoor things in the winter—in shorts! Running is relatively convenient compared with cycling, especially where I live, so when spring arrived my feet stayed firmly planted on the ground, instead of clipping into pedals. And thus, what began as a winter substitute turned into cross-training and then slowly morphed into something I nearly admitted to liking. (The admission comes hard in part because having been asthmatic into my teens, running is truly harsh on me.) The day before we left for Edinburgh in November 2006, I ran my first sub-7-minute mile.
By spring 2007, the entire length of my left leg felt about twice as old as the rest of me. I had some persistent pain in that foot; then along the thigh; and finally the knee got so bad I couldn't sit with my knee bent for more than fifteen minutes. In restaurants, I had to find a table where I could stretch out my leg, as if fractured and in a cast. I was very close to going in to a doctor, and had begun steeling myself for the inevitable knee surgery.
As an experiment, starting in the beginning of May, I decided to give up running cold turkey and focus solely on cycling. At first all those old pains persisted, and manifested themselves on the bike. But then, about 500 miles later, I noticed that they were...completely gone. My left leg feels as good as my right, both feel excellent, and I write this message having just spent four continuous hours almost motionless on a plane, knees bent, without the slightest trace of pain.
It's well-known that running is usually harder on the knees than cycling (though a badly-configured bicycle can be just as bad or worse). I'm also lazy about warming-up and the like; clearly, people run marathons on end without anything like the problems my feeble efforts engendered. But it still amazes me that cycling can not only be so much less bodily stress, but that it can have helped effectively cure my knee. Maybe I can sink the cost of that surgery into a new bike instead!