Killer Hills:  Don't be macho. This is the firm warning from Roger Minkow, M.D., to any rider who even remotely suspects a heart problem. He's not speaking only as a medical professional. He's speaking as a victim.

 Minkow, 59, is the designer of the Specialized Body Geometry seats that revolutionized the saddle industry in the late 1990s. He rides for fitness, and that's what he was doing in 2003 when he began noticing tingling and numbness in his left pinkie and the front of his left shoulder. He'd feel it during a gradual climb on his training route, and then it would subside on the descent.

 Rather than ignore this odd condition, Minkow went to a cardiologist. A battery of tests found nothing wrong. But on subsequent climbs and descents of the hill, the same thing happened. This time he demanded an arteriogram.

 Result: 99% blockage of one artery and 85% blockage of two others. He was that close to having a heart attack. The next day he underwent triple bypass surgery.

 "When you have symptoms going up a hill versus going down, it indicates a cardiovascular problem," Minkow says. "You're not okay and you need to find out why. You can't be macho about it.''