protective measures against a Hamstring repetition

Some vigorous, superficial massage to your quads/hamstrings before you exercise should be beneficial, as well as dynamic stretching before workouts.

The massage you can do yourself. Just sit down and grab your quads/hams and squeeze and release, like kneading. Also striking the soft tissue with soft hands (the chopping you see in a swedish massage, otherwise known as tapotement) will stimulate muscle contraction and is an excellent warm-up technique for sports application.

1-2 minutes of massage per body part is enough, 5-7 minutes will actually sedate the area affected.