I've been incorporating sprinting into my routine now, but my quads are taking a beating. Today I sprinted and I knew if I pushed it any harder I'd pull my quad muscle.

Looking around online and i found this: http://sportsmedicine.about.com/cs/l...s/a/thigh1.htm

FTA:

A pulled quadriceps is often the result of a strength imbalance between the quadriceps and the hamstring. Strong hamstring muscles in the back of the leg and weak quadriceps muscles in the front of the leg can result in a pull or a tear. Such a muscle imbalance is not uncommon among runners, since running tends to work out the hamstrings much more than the quadriceps.
I do a fair bit of running (5-15km) and am a oly weightlifter, but I'm new to sprinting.

The pull sensation I feel is in the upper region of my quads. Could it be a muscle imbalance?