Hamstring injury is very common injury along with athletes who need to be fast. Hamstring is a muscle group located at the back of your tight. In many times reason behind pulled hamstring is imbalance between hamstrings and the quadriceps. Reugular strengthening helps you to prevent it and also makes you faster. You should to 2-3 times a week one of the strengthening exercises show in the video.
Here are great exercises to strengthen your hamstrings:
Articles to get more information about hamstring related information: