Feature: Arterial disease and cycling - VeloNews.com

“That offseason, his symptoms worsened. Before, it might have taken 20 minutes of riding at 400 watts to feel the sensation. Now, if he rode for five minutes at 350, he’d be riding with one good leg and one numb, powerless appendage.”

Iliac artery endofibrosis is a circulatory condition affecting the legs and is sending more and more cyclists under the knife.
If you are a bike geek like i am (been watching the Tour de France since i was 15) you may take interest in this. If you are a avid bike rider or triathlete you may take interest in this.
But do not stop at the bike when you have symptoms in front of you that sound vascular. If your leg is doing numb on a long walk or run, dead or heavy during exertion, something is going on that needs evaluated. Get evaluated.