Yeah, you read that right. Ever since having calf problems 3 years ago, I've been able to crack my hamstrings. It started out lower, but the actual area being cracked has raised to about 3/4 up (closer to the butt than the knee). Basically, several times a day if I stretch my hamstring, I feel a weird resistance, and if I quickly push through it, the hamstring makes a popping sound and I can stretch further. It is definitely not my hip or knee or anything else cracking, it's definitely the muscle. It hasn't bothered me, it's just been kind of weird. I'm curious: does anyone out there have any idea what this is? I've talked to some physical therapists I know, and they're all been baffled.