Hamstrings: strength & flexibility 12/18/12
In the last Sports Medicine Corner article, I addressed the importance of taking time this winter to cross train for injury prevention and to enhance running performance. Some of the points I discussed were increasing core strength and dynamic flexibility of the lower extremity. For the next few weeks, I will be talking about specific muscle groups and exercises to train them. Today’s focus is on the hamstrings.
The hamstrings start at the bottom of our hip bone and run the length of the femur before crossing the knee joint to attach on the tibia and fibula. Since they have an attachment at both the hip and knee, they are considered a two joint muscle. Their function is to extend the hip and flex (bend) the knee. When exercising the hamstrings, keep in mind that they cross two joints and focus on exercises that train each of their functions.
Most runners have either very tight or weak hamstrings, or even worse, tight and weak! When the hamstrings are tight, they pull on the hip bone causing a slight rotation, which can affect the natural curvature of the back and cause pain and tightness in the lower back. Weakness in the hamstrings can contribute to knee pain and increase the incidence of a hamstring strain. A lot of people stretch their hamstrings often, but say they can never seem to get more flexible. If this sounds familiar, you might be focusing on the wrong type of stretching exercises. Dynamic flexibility exercises that involve eccentric contractions (muscle lengthening) are the most effective way to increase the flexibility of a muscle.
A good exercise to perform to increase hamstring muscle flexibility & strength is called the Romanian Deadlift, or RDL. Don’t be intimidated by the name, it is not a true deadlift, and you do not have to use a lot of weight to get the benefit of this exercise. The key is to perform it with good form, slowly, through a full range of motion. To start this exercise, grip a straight bar (or a dumbbell in each hand) with your hands at least shoulder width apart or slightly wider. Stand up straight with your feet shoulder width apart. Your knees should be very slightly bent and you should maintain the natural curve of your low back during this exercise. At this point, the bar should be touching the front of your thighs. Maintaining the curve in your low back, slowly lower the bar towards the ground, keeping it close to your body (almost touching your legs). Keep your knees only slightly bent, if you bend them too much, you will not feel this exercise as much in your hamstrings. The motion of this exercise takes place from the hip, not the knees or low back! As you slowly lower the bar towards the ground, you should feel tension in your hamstrings. What you are feeling is an eccentric muscle contraction. The hamstrings are maintaining tension while they elongate. This should feel like a good stretch in the hamstrings. Only go as far down as is comfortable for you. You do not need to touch the weight on the floor. Once you get to the bottom of the exercise, while maintaining the same good form (arch in low back, knees slightly bent), pull the weight back up to the starting position. Remember to keep the bar close to your legs throughout the motion, this will help to decrease unnecessary strain on the low back. As you pull the bar back up to the starting position, your hamstrings will be using a concentric muscle contraction (muscle shortening). The RDL uses both eccentric and concentric muscle contractions, making this a very efficient exercise for increasing both strength & flexibility. Perform this exercise 6-10 repetitions for 2-3 sets, depending on how much weight you are using. Eccentric contraction produces muscle soreness, so start with very light weight and see how you feel 48 hours after you do the exercise. If you are moderately sore, that’s a good thing. If you are very sore or the soreness lasts more than a few days, you did too much! If you are not sore at all, increase the weight you are using. A good guideline is to not increase the weight until you are able to do this exercise through a full range of motion with good form. You can also progress this exercise by doing it on a single leg, which makes it more functional, especially for running.
Another functional exercise to address the two joints that the hamstrings cross (hip & knee) is the physioball hamstring curl. Start by laying on the floor on your back with your legs up on a physioball. Your feet should be shoulder width apart. Make sure your feet are straight and not rotated in or out. To start the exercise, lift your hips up off of the floor while maintaining straight knees (i.e. perform a bridge). Now your hip and core is engaged. Stay in the bridge position and bring your knees towards your chest at the same time. You will be rolling the physioball towards your body at this point. If this is too difficult, you can put your arms out at your side to increase your stability. Slowly straighten your knees back to the starting position. Maintain the bridge position throughout the whole set of 10 repetitions of knee bends. This exercise is more functional and beneficial than doing hamstring curls on a machine because it engages the hamstrings, glutes, and low back to maintain the bridge position while then calling on the hamstrings to perform a concentric knee flexion exercise.
Adding these hamstring strength & flexibility exercises into your cross training routine 1 – 3 times per week will help to prevent injury and improve running performance. Flexible, strong hamstrings translate to a more explosive, efficient running stride! Less injury, better running…double bonus!
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