What Causes a Pulled Hamstring?

I'm a track and field sprinter. Though I warm up and do at least 30 minutes of stretching before running, I still have hamstring pulls. Do you think a vitamin or mineral deficiency could be causing my problem?

I am not aware of vitamin or mineral deficiencies that would put you at increased risk of chronic muscle pulls. A deficiency in protein intake could potentially do that since healing and muscle growth is dependent on protein, but most Americans, and even athletes, get enough protein in their diet. I recommend that you post specific questions or concerns that you have about your diet or nutrition deficiencies to Betty Kovacs, our MedicineNet registered dietitian (RD), or consult with an RD in your area. Your doctor can refer you.

As for hamstring pulls, they are typically caused by overstretching or overcontracting fatigued muscles and are generally considered an overuse injury. The basic causes are the following:

1. Overtraining. If you push hard every day, there is no time for muscles to rest and recover. Sprint training causes micro-trauma to the muscle fibers and is as tough as leg exercises in the gym. If you train hard every day, or even every other day, then there may not be enough time for your muscles to recover. Give your muscles time to rest, recover, and grow.
2. Muscle imbalance. There could be a muscle imbalance between your quadriceps and hamstrings. The normal quadriceps/hamstrings ratio is 60:40; that is, the quadriceps should be no more than 1.5 times as strong as the hamstrings (lift 60 pounds with quads and 40 pounds with hams). Some coaches believe the ratio should be closer to 1:1 to prevent hamstring pulls, although this has not been proven. What is clear is that quadriceps that are more than 1.5 times as strong as hamstrings puts you at greater risk for injury. Speak with your running or strength coach about knee flexion exercises (the leg curl machine in the gym) to help strengthen your hamstrings if there is an imbalance.

Here are some guidelines for treatment of hamstring pulls:

1. Rest and ice is the first line of treatment. You can ice for 10 minutes every two to three hours to reduce inflammation.
2. Do not run through pain. You should stop running until it heals.
3. Check with your doctor about medications like nonsteroidal antiinflammatories, and use a compression sleeve, wrap, or brace for your thigh.
4. Ask your doctor about physical therapy. Modalities like ice, massage, ultrasound, and electric stimulation can speed up healing. A physical therapist is trained to use these modalities and get you back on your feet.

Start back slowly and make sure to regularly strengthen and stretch once you heal (it can take three to six weeks to heal and up to 10 weeks if not treated properly). An effective method for stretching is to warm up with an eight to 10 minute jog, then take your time stretching, then build up slowly to faster and faster training sprints, then cool down gradually with more jogging and gentle stretching, taking care not to overstretch (no pain) after your workout.