I have a blot clot. Until now, any thought I had about blood clots (did I even have any?) would have assumed that clots are reserved for sedentary old people. I’m 40, which as any 50-year-old person will tell you, isn’t old. And while I’m no Olympic athlete, I’m hardly sedentary.

So what happened here? And can it happen to young, fit you? Maybe. Here’s what happened.

I have a history of cramping in my left calf. Sometimes the cramp is on the bike, but usually it’s nocturnal. I’ll be sleeping and will be jolted awake by screaming pain in my calf, which is contracted into a hard, leg-shaped, flesh-covered rock.

I also have a history of being totally stupid about hydration, especially in the summer. A typical day in the summer may start with a strenuous trail ride at dawn, followed by two or three cups of coffee. Commute to work. Work. Commute home the long way with a single water bottle. Run out of water. Have dinner. Have a few beers. Go to bed. Repeat. Altogether, I’m drinking about two quarts of water a day (in addition to coffee and beer). As it turns out, coffee is not the diuretic it’s often accused of being. But beer is a dehydrator for sure.

The point here—and any cyclist who has ridden for a few years has been through this—is that occasional cramping and dehydration happens. So when my calf was killing me during cyclocross “hot lap” training, I didn’t think much of it. But the pain became so bad that I actually had to quit riding. The day had been a typical summer day of inadequate hydration, and I was riding a new bike that didn’t quite fit right, so I chalked up the pain to these obvious factors.

I called a nurse and talked her through the issue. She asked a lot of questions about numbness (none), feelings of “pins and needles” (nope), any traumatic events to the calf (nope), any long flights recently (nope), any sharp pain (not really: a dull pain, but not “sharp”). Looking back on this conversation, she was clearly attempting to figure out if I had a clot. Neither my profile (active, non-sitter) nor my answers pointed to a clot. She said it’s likely a muscle strain and recommended taking ibuprofen, drinking lots of water and applying ice.

The next day, my calf was a bit swollen and the pain had increased a bit. Luckily, Dr. Bob (OTM Health writer) lives right out my back gate. I asked him to look at it. He was also perplexed and was pondering a theory that I may have compartment syndrome, which is when muscles and veins can get compacted, which leads to swelling. He recommended keeping on ice but coming off the ibuprofen.

By the next morning my calf was so swollen that my ankle went missing. My lower leg looked like a giant sausage. When I called Dr. Bob, he had already decided that things just didn’t add up. He took a look at it and got me in the pipeline for a sonogram, which confirmed a blood clot running from my ankle up into my thigh.

There are a few lessons here. The biggest one is not to ignore your wife. My wife was concerned about a potential clot the night I came home from the hot laps. But I didn’t fit the profile. And the nurse didn’t think so. And the doctor didn’t think so. I did know, deep down, that this pain was abnormal. And that’s the real lesson: listen to your body. It’s cliché, but no one knows your body like you do, and our bodies are super loud and clear about laying out the facts for us.

So why did this happen? Until recently, my going theory has been my chronic dehydration, which turns out to be a contributing factor. In addition, I’ve learned that I have a blood deficiency called Factor V Leiden that slightly increases the odds of a clot. That deficiency alone is not enough to cause a clot. But the Factor V Leiden coupled with blood restriction and the dehydration is likely the answer. Until my leg swelled up, I didn’t pay attention to the fact that when I sit at my desk, I typically sit with my left leg folded under my right leg.

The fix for a clot is to take a blood thinner, which both stabilizes the clot and allows blood flow around the clot. Stabilizing the clot is important because if a clot chunk blows off into the blood stream, really bad stuff can happen, like strokes, brain aneurysms and lung failure.

It will probably take about six months of blood thinning treatment for the clot to dissolve away. During this time, I’ll have to be extra careful on my bike, as internal bleeding is more likely with trauma events and much harder to contain with thin blood.

In the end, I’m lucky. I’m lucky I have access to medical care. I’m lucky I didn’t throw a clot into my blood stream. I’m lucky I’ll be back to normal in six months. It could have been much different. I hope I’ve finally learned to respect what my body is telling me. (Read Part 1 here.)

John Speare grew up and lives in Spokane. He rides his bike everywhere. Check out his blog at http://cyclingspokane.blogspot.com.