As a physical therapist, I have the opportunity to attend courses all over the country to learn from some of the top healthcare professionals in my field. Over the past year, I have gotten to attend a number of lectures given by some of the most prominent researchers/clinicians in the area of running gait analysis. This 3 part series I'm writing entitled, 'The mechanics of running and how it relates to performance and injury' is a synthesis of all that I've learned and studied about this topic over the last year. Part two of this series will focus on the midstance phase of the running cycle.
PART TWO: MIDSTANCE
Midstance refers to the time in the gait cycle when you are supporting all of your body weight on one leg with the foot fully planted. In the first part of this series, I talked about how landing posture can influence how forces are distributed throughout your body and how that can contribute to overuse injuries. While this is important and definitely needs to be considered, a lot more attention should be given to what your body does when you are in the midstance phase of running. Why is this? The body is actually exposed to higher amounts of forces for a longer period of time during this stage of gait . There are two ways that you can visualize this. You can be really scientific about it and look at ground reaction force graphs that quantify the forces absorbed by your legs when you run (see figure 1) or you can simply look at a picture of yourself when you are actually in midstance (see figure 2).
If you ever want a picture of your legs when they have the most muscle definition, have a friend snap a shot of you when you are in midstance! You have much more definition during this phase because it is when your legs are being stressed the most by ground reaction forces. The next time you look at pictures of yourself running, look at how much more defined your leg is when your foot is completely flat on the ground compared to when your foot first hits the ground and/or when the heel starts to rise at the back end of your stride. . . light bulb goes off, now it makes sense!
So what does this have to do with running related injuries? Each time your foot hits the ground, your body absorbs up to 2.6x your body weight (occurs approx. 1,400 times each mile you run, when your cadence is optimal). Midstance is the phase in gait where you take the biggest brunt of these forces and is also when the most biomechanical running flaws tend to occur. During this stage, it is extremely important that your stance leg is stable (i.e. doesn't move when outside forces are acting on it). Being stable requires that the muscles in your legs and core fire very rapidly (in less than 50 milliseconds) and in a very coordinated manner (they have to turn on and off at just the right time and in just the right sequence). What does this mean in terms of how we should utilize resistance training to improve our stability? First off, if you have to support more than 2x your BW in a matter of milliseconds, all while standing on one leg, the last thing you need to be doing is sitting and/or laying on machines that are designed to help you with your 'leg strength'. Exercises that are much better suited to prepare your body for the stresses of running are those that are done in standing positions where one leg is biased at a time. This is an HUGE area that I think we can improve on as endurance athletes. When runners come to me with injury related questions, one of the first things I will ask them is if they incorporate single leg based exercises into their strength training. Over 80% of the time, the reply I get is no (and that is for the 40-50% of those who actually do some type of supplementary strength training outside of running). Even if you think you have perfect running mechanics, I don't think there is a single runner out there who wouldn't benefit from regularly performing these exercises each week. Working on single leg strengthening and balance will help you become more resilient to injury and will also make you a much more powerful runner. So, if machine based exercises can't get the job done, where should I start? Start with you and gravity! Check out my video below for examples of some body weight based exercises that you can do anywhere, anytime, with no excuses. I encourage you to give them a try (or at least exercises that are similar to them. They just might make you better runner.