By Adam St. Pierre
CTS Running Coach and Biomechanist
There are many factors involved in running biomechanics, including body weight, limb length, muscle strength, joint range of motion… and everybody is different in these respects. That’s why there is no singular ideal that defines perfect body mechanics. Rather, each individual must find their own ideal biomechanics. Watch any elite marathon and you’ll see many examples of “perfect” biomechanics – Eliud Kipchoge looks like he’s floating! But you’ll also see examples of elite athletes running amazingly fast with seemingly serious biomechanical flaws. Whether you’re elite or just getting started, here are four areas every runner can optimize to run faster with less effort.
Optimizing the four areas below can lead to faster sustainable paces at a given effort level/power output. It may reduce injury risk by reducing the strain on body tissues – which in turn improves performance by minimizing missed/compromised training.
Running is a weight-bearing sport, so posture is critical to success. In general, you should be upright with a slight forward lean from the ankles. Mid-stance is the point in your running stride where you are standing on one foot, with your knees directly next to each other (when viewed from the side, one knee is hiding behind the other knee). From this side view imagine there is a straight line connecting your ear with the center of your ankle. This line should also go through the center of your shoulder, and the center of your hip. If those points aren’t in alignment, then you could stand to benefit from working on your posture. Planking exercises can be a good way to ingrain proper posture (but only if you do your planks well!).
Your arms and legs will stay in sync while running. While the lower body is responsible for the bulk of power production in running, the upper body is also important because it must rotate counter to the lower body to keep you balanced and moving forward. If your arm carriage is wonky, it may result in compensatory movement in the lower body that could slow you down or lead to injury. Proper arm carriage is compact and relaxed. Elbows should be bent to 90 degrees or less. In this case, “less” means hands higher, and this is okay if it is comfortable. Elbows greater than 90 degrees (hands down) require extra work from the trunk and shoulder musculature to move a longer lever – yay physics! The elbow angle shouldn’t change much throughout the running stride (unless you are sprinting, which is a topic for another day!). You should focus on driving your arms back, and allowing them to relax forward. Your elbow should not come forward of the midline of your body (again, imagine that line running from your ear to your ankle at mid-stance – that’s effectively the midline). Drive back, relax forward, repeat.
The number of steps you take per minute is related to your speed by a simple formula: Steps per minute multiplied by length of each step equals your speed. It is well documented that at a given speed, longer steps (and lower step rates) result in higher impact forces. You may have heard that elite runners run at 180 steps per minute. This may a good target for some runners, but in actuality, appropriate running cadence lies on a spectrum in relation to speed. At 5 miles per hour, 160-170 steps per minute will likely be appropriate. At 5-7mph, 165-175 may be appropriate. At 7-9mph, 170-180 might be best. At 10-15mph a cadence of 190-210+ steps per minute may be necessary. Note: These are just general ranges, not absolute concrete rules. Studies have demonstrated that oxygen demand increases when a runner is asked to utilize a cadence other than their preferred cadence. The body adapts to what it is asked to do, so if you run with a certain cadence, you will become efficient at it. Changing that cadence may require adaptation over a period of time in order to become as efficient as your original cadence. But studies have also shown that increasing cadence 5-10% above your preferred cadence can reduce impact forces, which may decrease stress on tissues and likelihood of injury. Not all runners need to increase their running cadence, but if you find your cadence is often lower than the ranges given above at different speeds, I would encourage you to experiment with increasing it. A caveat: most runners increase speed when they increase cadence, this is not the same as increasing cadence at a set speed. To increase cadence at a set speed you must decrease step length. This is where treadmill running can be very useful, because you can set the speed and practice running at different cadences. You may find you already run at your optimal cadence, or you may find that you feel better with a slightly faster cadence (though some people may actually benefit from slowing their cadence).
I put this one 4th for a reason. If you focus on posture, arm carriage, and cadence, it is very difficult not to have an appropriate footstrike. An appropriate footstrike does not necessarily mean midfoot or forefoot. In fact, depending on terrain, speed, shoes, training, and individual variation, a rearfoot, midfoot, or forefoot landing may be appropriate. There is even some evidence that utilizing a variety of footstrikes helps performance in ultramarathons. Rather than focus on what part of your foot hits the ground first, instead focus on where your foot hits the ground in relation to your center of mass (the center of your hip is pretty much your center of mass). It may be a good drill or cue to think about landing with your foot directly underneath your center of mass, but in practice this is not possible. Ideally your foot lands 4-10 inches in front of your center of mass with a slightly bent knee. The key is to avoid landing with a lower leg that is reaching in front of your body.