Should Backward Walking be standard of care for knee pain?

What would you say if I told you there was one thing you could do right now to ease knee pain and set the building blocks for strength improvements and muscle growth? What if I said this one thing requires zero equipment and was scientifically proven to work? Would you believe me? What if all it took was 10 minutes per day? Would you start today? Well, such a thing exists, and it’s as simple as doing the exact opposite of what you’ve always done.

The prevalence of knee pain has skyrocketed in recent years. More than 24% of all Americans will report some form of knee pain in 2022, a number that has increased by more than 65% in the last 20 years or so. Research has ruled out obesity and the fact that we just live longer than we used to, as primary causes of knee pain and arthritis. The same research is inconclusive as to what exactly is behind this dramatic rise in knee pain and arthritis(Nguyent et al., 2011). This isn’t to suggest that just because we don’t understand the cause we can’t understand a solution.

Here’s another thought experiment for you: is it possible that the emergence of the notion of walking as exercise and the rise of fitness trackers such as fitbits, which encourage 10,000 steps per day, are in part responsible for the recent increase in the incidence of knee pain and knee arthritis?

Let me explain. In the normal gait cycle, the hamstrings, gluteals, and calf are the muscles primarily responsible for forward movement. The quadriceps and hip flexors play a minor role of controlling knee bend as your foot hits the ground. In an unhealthy knee, the quadriceps contraction is often avoided entirely. Therefore, reliance on walking for exercise and strengthening likely doesn’t provide enough stimulus to even maintain a healthy level of quadriceps musculature. Put another way, walking may actually be responsible for some of the quadriceps atrophy we see in folks with knee pain and arthritis.

The problem here is that increased quadriceps size and strength has been shown to be protective against knee pain and cartilage loss (Amin et al., 2009). Conversely, increased knee pain has been associated with decreased quadriceps size, strength and activation (Doxey, G., 1987).

Current guidelines for addressing knee pain and arthritis with exercise are somewhat vague and inconclusive as to which exercises should/shouldn’t be utilized (Doormaal et al., 2020). For example, it is recommended that an exercise program should address major muscle groups of the leg including the knee extensors (quadriceps), but a knee extension machine should be avoided entirely. Forward walking as well as cycling and swimming are suggested for low-load aerobic conditioning, but as discussed and hypothesized above, forward walking is less helpful and is perhaps detrimental to knee health in the presence of osteoarthritis.

So what can we do now that one of our most basic functions is at best not helpful, and at worst detrimental for knee pain and arthritis? Simple. Walk backward.

Backward walking reduces knee pain (Chen et al., 2021). As mentioned above, forward walking involves primarily the posterior musculature of the leg, none of which help attenuate the forces you encounter when your foot hits the ground. Backward walking is the exact opposite (Winter, D. 2013). Each component of backward walking (from your toes, through your ankle and up to your knee) acts as a shock absorber (Roos et al., 2012), helping to decrease the forces your knee joint experiences with every step and is therefore protective against knee pain and deterioration.

Backward walking improves quad recruitment and activation. In the injured or arthritic knee, quadriceps activation and strength are reduced (Wada et al., 2018). Your body likely does this as a way to protect your knee from further injury and overload. While this protective mechanism may sound practical, it’s not super helpful when trying to rehab an injured or arthritic knee.

In these cases, we need a gentle, targeted, and scalable method of quadriceps loading to help wake the muscle up and prepare it for further strengthening.

Backward walking has been shown to be superior to forward walking when it comes to quadriceps activation and strengthening (Abdelraouf et al., 2019). In a healthy knee, quadriceps activation is balanced equally between medial and lateral components. In the injured or arthritic knee, this ratio can skew to 0.5:1 -meaning the medial quad is only working half as well as the lateral portion. Backward walking has even been shown to improve forward walking speed to a greater degree than forward walking (Balasukumaran et al., 2019)!

Should backward walking be used as standard of care for knee pain and knee arthritis? Given the large volume of research on the subject of the effects of backward walking on knee pain and knee arthritis, it is surprising that this intervention is not included in clinical practice guidelines and standards of care for either condition. Instead, forward walking and vague support for leg strengthening continues to be championed as the best we have address the injured or arthritic knee. This essay does not seek to diminish the benefits of forward walking. Indeed, the benefits of walking for cardiovascular health are well established and thoroughly researched. However, perhaps the narrative for the benefits of forward walking in the presence of knee pain and arthritis should end here, and backward walking should take its place in research and rehabilitation.

References

Nguyen, U S, Zhang, Y, Zhu, Y, et al. Increasing prevalence of knee pain and symptomatic knee osteoarthritis: survey and cohort data. 2011 https://doi.org/10.7326/0003-4819-155-11-201112060-00004

Amin S, Baker K, Niu J, et al. Quadriceps Strength and the Risk of Cartilage Loss and Symptom Progression in Knee Osteoarthritis. 2009;60(1):189–198. doi:10.1002/art.24182.

Doxey GE. Assessing Quadriceps Femoris Muscle Bulk with-Girth Measurements in Subjects with Patellofemoral Pain. 1987.

Doormaal MCM Van, Peter WF, Vlieland TPMV. A clinical practice guideline for physical therapy in patients with hip or knee osteoarthritis. 2020;(May):1–21. doi:10.1002/msc.1492.

Chen Z, Ye X, Wang Y, et al. The Efficacy of Backward Walking on Static Stability , Proprioception , Pain , and Physical Function of Patients with Knee Osteoarthritis : A Randomized Controlled Trial. 2021;2021.

Winter DA. Backward Walking : A Simple Reversal of Forward Walking ? Department of Kinesiology University of Waterloo Waterloo , Ontario University of Alberta. 2013;(July 2014):37–41. doi:10.1080/00222895.1989.10735483.

Roos PE, Barton N, Deursen RWM Van. Patellofemoral joint compression forces in backward and forward running. J Biomech. 2012;45(9):1656–1660. doi:10.1016/j.jbiomech.2012.03.020.

Wada O, Kurita N, Kamitani T, Nakano N, Mizuno K. Influence of the severity of knee osteoarthritis on the association between leg muscle mass and quadriceps strength : the SPSS-OK study. 2018.

Abdelraouf OR, Abdel-aziem AA, Ahmed AA, Nassif NS, Matar AG. Backward walking alters vastus medialis oblique / vastus lateralis muscle activity ratio in females with patellofemoral pain syndrome. 2019;65(2):169–176. doi:10.5606/tftrd.2019.2445.

Balasukumaran T, Olivier B, Ntsiea MV. The effectiveness of backward walking as a treatment for people with gait impairments : a systematic review and meta-analysis. 2019. doi:10.1177/0269215518801430.