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. Before getting into Part 1, lets talk briefly about the gait cycle .
Gait Cycle 101
To keep it simple, there are basically two main phases of gait: stance and swing. When we refer to the 'gait cycle', this includes the time when one foot hits the ground to the next time that same foot hits the ground again. In running, approximately 40% of that cycle is spent in stance phase (when the foot is on the ground) while 60% of that cycle is spent in swing phase (when the same foot is airborne). As you run faster, this ratio changes with more time being spent in swing and less in stance. The phase of gait that this 3 part series will focus on is stance phase. Within the stance phase, there are 3 main subphases: initial contact, midstance and propulsion (take off) (figure 1). For now, we'll leave it at that and get into Part 1 of the series.
Initial contact refers to the moment at which your foot first hits the ground. A lot of research has recently come out about the injury risk implications of lower limb positioning at initial contact. There has been quite a bit of hype in the media about this, which has focused mostly on what occurs from the ankle down and how that relates to barefoot running vs. shod running (i.e. running with shoes). The consensus seems to be that landing on your heel (heel-striking) is bad , which is what most people do in traditional running shoes, while landing on the middle or front of your foot (midfoot/forefoot striking) is good, which is what barefoot running promotes. This is partially true, but not the whole story. To get the whole story, you've got to look at more than just the foot. What ultimately matters is not the angle at which your heel hits the ground, but where your foot lands relative to your center of mass (COM). When your foot lands further out in front of your COM, you load your limb more rapidly, which results in more stress to your tissues (bones,ligaments,muscles,tendons,etc). This type of a landing posture also puts a lot more stress on your knees, (which just so happens to be the location where most running injuries occur). So here's where the rest of the story comes in: say you get a brand new pair of Vibrams (or minimalist shoes, which function very similarly), and they do, in fact, help you adopt more of a midfoot/forefoot striking pattern. What happens if your foot lands how it is 'supposed to', but your low back arches backwards when you make ground contact? In this case, the backwards arching of your trunk causes your COM to shift backwards and thus diminishes one of the benefits that the new shoes are supposed to give you. I'm not saying that Vibrams and minimalist shoes aren't beneficial (in some cases), just that there's more you've got to invest in than just shoes if you want to reduce your chances of getting a running related injury. What I'm referring to is posture and core strength. Is this an issue in runners? You bet! Can it be improved? It can through both cueing to 'stay tall' (i.e. another way of thinking about it is to 'keep your spine long' which helps automatically engage the muscles that stabilize your back and keep it from arching) and through supplemental neuromuscular training that helps prepare your core to work more efficiently when you run.
So, now that we've covered the foot and the trunk, is there still more to the story? Research is showing that yes, there may be. It turns out that how stiff you keep your knees can also affect how much stress you place on your tissues when you run. When your knees are really stiff (i.e. less bent) at landing, this increases stresses to your limbs, whereas decreasing stiffness at the knee (i.e. landing with more bend in the knee) can help reduce stresses. When I refer to stiffness in this case, I'm not talking about 'tight hamstring' stiffness, but more to how your brain recruits and activates your muscles prior to landing on the ground. One cue that can help promote less knee stiffness at landing is the cue to 'land soft' when you run.
So, there you have it. Don't just focus on the foot; look above at what it's connected to as well.
Take Home Message
Don't get caught up in the debate of heel vs. midfoot or forefoot striking and whether or not you should run barefoot or with shoes. Just remember to 'land soft', 'stay tall' and 'land close to your body'.