Have You Hugged Your Hammies Today?

Mother Nature likes balance. Science calls it homeostasis (stability within the body). This Yin and Yang  appears all throughout the various body systems, especially within the muscular system.

Muscles can act as an agonist (the contracting or working muscle) or as an antagonist (the lengthening/stretching muscle) . Usually agonist and antagonist muscles are located direclty opposite one another. For example when doing a dumbbell bicep curl, you're using your biceps as the agonist and the muscle group directly opposite the biceps (the triceps) are the antagonist muscle group.  If the triceps are the "working" muscle group (as in a tricep kickback), then the biceps become the antagonist. In many cases agonist and antagonist muscles are located anterior (front) and posterior (back) on the body (i.e, biceps/triceps, quads/hamstrings, pec/traps, but you can also have medial (close to the midline of the body) and lateral (along the outter sides of the body) agonist and antagonist muscles such as the adductor and abductor muscles in the legs. And you can have agonist and antagonist that are superior (above) and inferior (below) such as delts and lats.

The key "Yin and Yang" muscle groups for runners are the quads and the hamstrings. There are four quadricep muscles (vastus lateralis, rectus femoris, vastus intermedius, and vastus medialis). The quads work as agonist when they contract and flex the hip and further down work with the patellar tendon to extend the knee and pull the lower leg forward. Opposite the four quad muscles are the hamstring muscles (biceps femoris, semimembranosus, and semitendinosus).  As the quads work as the agonist and contract, the hamstrings stretch or lengthen working as the yang to the quads' yin.

However, what goes up has to come down,  or better yet, what contracts has to relax. So, when the quads contract and flex the hip and extend the knee, the hamstrings switch gears  from being the antagonist to becoming the agonist (the working muscle) in order to extend the hip and flex the knee moving both the upper and lower leg backward. When this happens, the quads switch to antagonist mode as they begin to lengthen and relax.

Now this Yin-Yang doesn't always mean a 50/50 relationship. Your quads are a little bigger than your hamstrings and they just get used more throughout the day, so typically your quads are a little stronger than your hamstrings. The normal strength imbalance between the quads and hamstrings is a 3:2 ratio. Women tend to have less of a difference than men.

Runners can have issues with their quads, but more than likely they'll have issues with their hamstrings, especially distance runners. If you haven't had issues, I'm sure you know of a runner who has suffered from a hamstring strain, pull, tendinitis or even worse, a tear. The cause of the hamstring injuries can be from having weak hamstrings, but more than naught, the cause is quad dominance.

When runners log lots of miles they repeatedly load their quads, making them strong. Longer runs can lead to overloading the quads making the quads too strong. This can create an imbalance between the quads and the hamstrings. When this occurs, several things can happen. A worst case scenario would be a hamstring tear. This happens when the hamstrings are too weak to handle the pull of the quads, so they give way or tear. Quad dominance can also wreak havoc on the knees. A healthy counter balance of the hamstrings helps to keep the knees stable. When the quads are too dominant they can pull and tug on the knee joint, muscles, and/or ligaments causing damage. A frustrating result of quad dominance can simply be decreased power causing you to run slower. This happens when the hamstrings kick in sooner than normal to help decrease the overpowering of the quads.

Runners should try very hard to take care of their hamstrings by building up the muscular strength and endurance. Once you get in a quad dominant situation, it's kind of hard to reverse. Also, hamstring injuries usually take a while to heal, so you may be off running for extended periods of time and frustrated.

So, what's a runner to do? Well the first thing that comes to mind is hamstring exercises, right? Right! But hold on, are some exercises better than others? Yep! The typcial hamstring leg lifts, hamstring leg curls, or hamstring roll-ins on a stability ball are all good, but research has shown that eccentric-loading hamstring exercises are even more beneficial, so be sure to throw in some exercises such as eccentric leg slides and hamstring curls. Check out the video below for examples of some great hamstring exercises (including some eccentric exercises) to add to your weekly lower-body or full-body workout routine.