“Muscle pulls and strains are what I see the most,” McLean says. The most common causes of hamstring strains are strength imbalances and improper form. Runners are especially susceptible when they run their fastest. The quicker you go, the more pressure you put on the hamstrings because you extend your stride. This kind of injury takes at least four weeks to heal. It can often be longer because we walk every day, putting more pressure on the muscles. The best way to avoid the injury is through strength training. Standing deadlifts are recommended.