There is a consensus that running biomechanics influences the risk of developing running-related injuries. Treadmill form has been shown to closely resemble overground running form. This makes it possible to use a treadmill form analysis as a proxy for understanding overground running form. It’s quick, easy, cheap, and can help generate some serious insight into treating injuries and becoming a better runner. There’s nothing more frustrating than an injury to keep you from doing what you love. Much of this blog is a summary of this great paper1.
What do you need?
Smartphone
Onform app free (Roger’s PT has no affiliation with the Onform app, I just think it’s great.)
Camera angles
All you’ll need is to capture two views. One from the side and then the other from the rear.
Warm-up and treadmill setup
Before capturing your running footage, warm up for around ten minutes. Because it has been shown that running mechanics deviate from normal within the first 6 – 10 minutes, a warm-up for around 10 minutes will acclimate your form to your normal. Next, set the treadmill speed you ran your longest run in the recent past. The negative result of poor mechanics will accumulate for the longest duration from the longest run, making the longest duration run the one to address first.
The Run
After your ten-minute warm-up, give your cameraman a thumbs up indicating you’re ready to be recorded. Run as you normally would if you weren’t being recorded. A 15-second clip from one side and the back is all you need, but you’re more than welcome to take more footage anywhere else you want a closer look.
The Analysis
Starting with the foot
The analysis will be performed feet to head. Start by observing the moment you make contact with the surface, this phase is known as initial contact. There are three categories of foot strike patterns at initial contact: forefoot strike, midfoot strike, and rear foot strike. Currently, there is not much research to say that one foot strike pattern causes injury more or less than another.
Angle of foot inclination
Applicable only to rear foot strikers, the next point of analysis is the angle of foot inclination. Measured at initial contact, look at the angle your foot makes with the surface of the treadmill. There is research to say that a larger inclination angle can imply larger ground reaction forces, meaning the amount of force traveling from the treadmill to you. This apparent issue can likely be addressed with increasing step cadence. Target cadence around 170 – 180 steps per minute, or 3 steps per second if that helps.
Calf
From the foot we move up to the calf, or tibia. Loading response is the phase of gait right after initial contact when the foot begins to accept load. This phase begins when the shoe begins to deform after initial contact. In this phase, relative to vertical, the tibia can be in three scenarios: flexed, extended, and vertical. When the lateral knee is behind the ankle the tibia is extended, if ahead of the ankle the tibia is flexed, and if they are aligned then the tibia is vertical. Research suggests that a flexed and vertical tibia at loading response is more capable of accepting load than an extended one. Consequently, this reduces overall impact force from the ground and reduces the risks of developing impact-related running injuries.
Knee flexion
Stance phase follows loading response. Stance is when only one foot is in contact with the ground and hasn’t pushed off yet. Scan the frames from your stance phase and find when the knee is maximally bent or flexed. Research points towards max knee flexion of 45 degrees being somewhat normal. The less the knee is bent here, the less it can absorb impact.
Slight trunk lean
Research2 has demonstrated that increasing trunk lean by around 7 degrees can help decrease knee pain. Excessive forward lean can be a problem, so keep it a slight trunk lean.
Overstriding
Measure this by drawing a vertical line from your ankle at initial contact up. Ideally, that line intersects with the pelvis. Overstriding is when the foot lands in front of the COM. A long stride is different than overstriding. Increase your stride length not by overstriding, but instead by increasing hip extension (i.e. how far back your leg reaches before flexing back up). Overstriding has been suggested to predict higher stress demands of the quads and increase the risk of tibial stress fractures. Increasing step cadence can help decrease overstriding.
Bounding
Bounding describes how much your center of mass displaces during running. Using the hip as a proxy for center of mass, during your recorded run, observe the movement of your hip. Measure by comparing the highest point in float to the lowest in stance. Research 3 suggests that more bounding results in higher knee joint loading. This can be addressed by increasing step rate 4.
Pelvic drop
Excess pelvic drop has been linked to many injuries. During stance phase, pause the video and look to see if the pelvis is tilted away from parallel. While some tilt is perfectly normal, more than 5 degrees can be a problem. Usually, this issue comes from weak hip abductors, hip extensors, and core musculature.
Knee Window
As viewed from the back, some space should be always present between the knees during the running cycle. This gives us a quick look at if there is too much hip adduction, hip internal rotation, and/or knee valgus (knock knees). These have been implicated in running injuries. The knee window test is binary; either there is space between your knees or not. Not having a knee window can likely be a sign of gluteal muscle fatigue.
Works Cited
Souza, Richard B. “An Evidence-Based Videotaped Running Biomechanics Analysis.” Physical medicine and rehabilitation clinics of North America vol. 27,1 (2016): 217-36. doi:10.1016/j.pmr.2015.08.006
Vincent, Heather K. PhD, FACSM; Vincent, Kevin R. MD, PhD, FACSM. Healthy Running Habits for the Distance Runner: Clinical Utility of the American College of Sports Medicine Infographic. Current Sports Medicine Reports 21(12):p 463-469, December 2022. | DOI: 10.1249/JSR.0000000000001019
Wille, Christa M et al. “Ability of sagittal kinematic variables to estimate ground reaction forces and joint kinetics in running.” The Journal of orthopaedic and sports physical therapy vol. 44,10 (2014): 825-30. doi:10.2519/jospt.2014.5367
Heiderscheit, Bryan C et al. “Effects of step rate manipulation on joint mechanics during running.” Medicine and science in sports and exercise vol. 43,2 (2011): 296-302. doi:10.1249/MSS.0b013e3181ebedf4