Reducing Impact Forces While Running

It is well established that compared to walking, running increases the ground reaction force on our bodies around 2.5 times. This increased impact must be absorbed by our bones, joints, soft tissues, organs, and pelvic floor. Increased impact, when not managed well, can contribute to the development of issues such as pelvic organ prolapse, incontinence, pelvic girdle and/or back pain, joint pain and foot pain among other things. If you are postpartum (even if you’re 30 years postpartum!) it is particularly important to learn different strategies to manage and reduce impact forces, especially for the pelvic floor. 

Fortunately, there are a few ways to reduce impact forces through our bodies while running, some of which can be implemented on your next run! 

The easiest two methods, requiring no extra time, financial cost or footwear changes involves changing your cadence and changing your running posture. 

Cadence

Your cadence refers to the number of steps you take per minute. There isn’t one perfect cadence that everybody should run at, however it has been suggested in the literature that the most efficient running gait happens around 180 steps per minute. You can find your own running cadence using the features on a running watch or your phone, or you can count the number of steps you take as you run for one minute. If your cadence falls well below 180 (let’s say around 150 or so), there has been some research showing that increasing this by 10% substantially reduced hip and knee joint loading (Heiderscheit et al., 2011) [1]. A separate 2012 study by Chumanov et al. [2] found that the heel is more underneath the body’s centre of mass at a 5% to 10% increase in cadence from one’s preferred cadence. The heel landing more underneath the body, vs in front of the body, significantly reduces the braking forces that must be overcome in order to move forward, which in turn reduces the impact through your body. 

If you are going to change your running cadence, try and do it for one minute every few minutes. Changing your cadence for your entire run may actually cause you to develop some discomfort, as your body won’t be used to this new way of moving. Easing your way into it over a number of runs is recommended.

Stride Length

Stride length refers to the distance between one foot touching the ground, and that same foot touching the ground again. Step length is the distance between one foot touching the ground and the opposite foot touching the ground. When our cadence increases as described above, our stride length also tends to decrease. A decrease in our stride length can also contribute to decreased impact and ground reaction forces going through your body. You can change your stride length without changing your cadence, and vice versa, but typically the two go hand in hand.

Running Posture

Next time you’re out running, pay attention to how you are actually moving forward. Are you bending at the hips and leaning your trunk forward, or are you falling forward from the ankles? Leaning forward from the ankles allows the gluteal muscles to participate more (helping absorb some of the ground reaction forces and impact), and allows the ribs to stack over the pelvis, which assists the intra-abdominal pressure system. When the intra-abdominal pressure system is working efficiently, there is a reduction of pressure on the abdominals and pelvic floor. A quick way to practice falling forward from the ankles instead of the hips while running is to stand tall, then let yourself fall forward, making sure only your ankles are moving, not your hips. When you feel like you are about to actually fall, step forward with one foot to catch yourself. Repeat a few times on each leg before heading out for a run.

Footwear

The next way to help manage impact forces while running is by changing the surface underneath your feet. Adding cushion in the form of insoles or sneakers with more shock absorption may help reduce impact forces up your body. This is not my preferred way of reducing impact forces, as there is some debate on how effective this is for different parts of your body. If there is more cushion underneath your foot, you may actually hit the ground harder, which could increase the impact through your body. Joints and tissues absorb impact differently, and extra cushion under your foot could reduce impact at the ankle and knee, but potentially increase it at the pelvis and low back, for example. I like this as a temporary strategy to try, but not a long term solution. 

Strengthening

This is an absolutely amazing way to help your body manage the impact forces from running, but it does take the longest time to have an effect. Why? Strengthening exercises need to be done for a few weeks before there are significant increases in strength. This shouldn’t discourage you from beginning though, it should hopefully motivate you to start strengthening right away! Which areas should you focus on if you don’t have much time to fit a strength training routine into your schedule? The research supports incorporating foot strengthening and hip strengthening for reducing running related injuries. Taddei U.T., et al. (2020) [3] found that recreational runners who completed an 8 week program of foot core strengthening exercises had a 2.42 fold lower rate of running related injuries; and the research from (Fredericson, M. et al., 2000) [4] and (Souza RB, et al., 2009) [5] support hip strengthening for reducing lower extremity injuries. 

My favourite strengthening exercises that provide a lot of benefit while not taking much time to do are full body exercises such as the Bruggers, and Pallof Press variations (examples of these are easily searchable online). 

To summarize, running can put a lot of strain on our bodies, BUT there are many strategies we can try to help manage and reduce the forces from increased impact. Changes in cadence and running posture are quick and easy (and free!), changing your footwear takes a little extra time and trial and error to see if there will be a benefit (and also a financial cost while you try different insoles or shoes), while strengthening takes the longest time to see a benefit, but is also free… and beneficial for almost every area of your health, aside from managing running impact. 

I hope this helps, and happy running!

1. HEIDERSCHEIT, B. R. Y. A. N. C., CHUMANOV, E. L. I. Z. A. B. E. T. H. S., MICHALSKI, M. A. X. P., WILLE, C. H. R. I. S. T. A. M., & RYAN, M. I. C. H. A. E. L. B.

(2011). Effects of Step Rate Manipulation on Joint Mechanics during Running. Medicine & Science in Sports & Exercise, 43(2), 296–302.

https://doi.org/10.1249/mss.0b013e3181ebedf4

2. Chumanov ES1, Wille CM, Michalski MP, Heiderscheit BC.(2012) Changes in muscle activation patterns when running step rate is increased. Gait Posture. 2012

Jun;36(2), 231-235.

3. Taddei, U. T., Matias, A. B., Duarte, M., & Sacco, I. C. (2020). Foot core training to prevent running-related injuries: A survival analysis of a single-blind,

randomized controlled trial. The American Journal of Sports Medicine, 48(14), 3610-3619. doi:10.1177/0363546520969205

4.Fredericson M, et al. Hip abductor weakness in distance runners with iliotibial band syndrome. Clin J Sport Med. 2000;10(3):169–75.

5. Souza RB, Powers CM. Differences in hip kinematics, muscle strength, and muscle activation between subjects with and without patellofemoral pain. J Orthop

Sports Phys Ther. 2009;39(1):12–9.