Explaining Zion’s movement retraining: Knee alignment, jumping/landing mechanics, gait analysis, & more

The Pelicans announced that Zion Williamson will make his season debut on Jan 22nd against the Spurs following surgery on a lateral meniscus tear and extended rehab that focused on modifying Zion’s movement patterns aka movement retraining or re-patterning.

Through reporting from ESPN’s Andrew Lopez, Baxter Holmes, and comments from Pels GM David Griffin and from Zion himself on The Ringer pod, we learned the movement changes focused on things like landing and jumping mechanics, knee alignment, gait (running) analysis, and as Griffin said, “improving Zion’s brakes”.

In the following article, I’ll go through each of those topics with an emphasis on why it’s important, possible changes, and how to assess carry-over to actual games. If you prefer a video format, check out the following:

Clearing up a misconception

First things first, I want to clear up a misnomer that Zion was “re-learning” how to walk. That’s very much an exaggeration and that term is typically associated with patients with acute neurological deficits who are rehabbing post stroke or traumatic brain incident (TBI) and learning how to walk again.

In Zion’s case, the Pelicans were most likely modifying certain higher risk movement patterns that tend to place and accumulate undue stress on specific body regions. With that in mind, let’s get to the first modification!

Reducing knee valgus

-What is knee valgus?

Zion, David Griffin, Andrew Lopez, and Baxter Holmes each mentioned that the team was working with Zion to stop his knee from dropping inwards during movement.

This is biomechanically known as “knee valgus” and results in gapping and tensioning the medial (inside) of the knee while compressing the lateral (outer) aspect of the knee. The latter is especially pertinent in Zion’s case since he’s coming off a lateral meniscus tear. Generally, knee valgus is associated with increased knee injury risk, especially ACL injuries.

Knee valgus can manifest in a number of movement movements including squatting, running, on court cuts and jump-stops, and jumping and landing, to name a few.

-Modifying valgus mechanics

The first task for the Pels rehab staff was to discern the root causes of the knee valgus.

Commonly it’s due to hip abductor weakness that’s addressed with targeted strengthening, ankle dorsiflexion range of motion deficits that’s addressed with targeted mobility, and neuromuscular deficits that are addressed through techniques such as external cueing in which you use a band during movements to enhance proprioception, external feedback with the staff telling Zion what he was or wasn’t doing, film analysis, and reciprocal self-feedback and self-correction with a mirror.

Jumping and landing mechanics

Zion and Baxter Holmes both mentioned that the rehab team was also working with Zion on jumping and landing mechanics.

These mechanics are incredibly important because they’re high force movements. For example, research on athletes indicates landing results in an average ground reaction force (GRF) – think of it like a shockwave traveling upwards through the legs – of 5x body weight.

In Baxter Holmes piece, he wrote that when Zion was tested for landing GRF by biomechanical sports specialists Peak Performance Project – P3 for short – Zion  generated the highest reading they’ve ever seen for any athlete. Therefore, landing mechanics are even more important for him.

In addition to assessing the aforementioned knee valgus during jumping and landing – which is unfortunately all too common in basketball players – there are a multitude of other things the Pels rehab may have been looking for.

-General landing strategy

On a macro scale, athletes tend to bias towards either a knee dominant landing strategy that puts more stress through the anterior (front) part of the knee like the patellar tendon and the quads or towards a hip dominant strategy that puts more stress through the posterior chain – glutes, hamstrings, lumbar extensors.

Typically – and especially in Zion’s case who’s dealing with knee issues – you want to train the athlete to be hip dominant and allow the large, high force muscles of the posterior chain to absorb the huge landing force.

-Dual vs single leg landing

This probably comes as no surprise but landing on one leg puts significantly more force through the joints. Even more concerning is that single leg landing also results in significantly more variability in terms of lower body alignment, with a much higher chance for high risk positions like knee valgus.

-Knee extended vs flexed

The research shows that landing with an extended (straight) knee – a “stiff” landing – vs landing with a flexed (bent) knee – a “soft” landing – results in nearly 20% less force absorption by soft tissue and a much larger load on the joints.

-Ankle angle

The research shows that the specific angle of the ankle at landing significantly varies the amount of landing GRF. In fact, it may be the most critical variable to reducing or increasing force through the body.

To that point, landing with the ankle at 40 degrees of plantarflexion vs landing with 0 degrees of plantarflexion nearly DOUBLES the amount of landing GRF, from 3.24x BW to 6.5x BW.

-How to change it

The key for the Pels rehab staff in altering landing/jumping mechanics is again figuring out the root causes. 

For example, if Zion was lacking hip flexion mobility – extremely common in athletes –  that made it difficult for him to get into that hip dominant position then they would have worked on his hip mobility. 

Additionally, It could also be ingrained neuromuscular patterns. Zion has been jumping and landing in a certain way for years and those patterns became second nature. In that case, like knee valgus, you have to work on breaking those movement patterns via external cueing, movement priming, film analysis and feedback. It’s not easy and takes significant work.

Running gait analysis

Baxter Holmes’ article made mention that the Pelicans rehab staff was analyzing Zion’s running gait, specifically looking at which part of his foot was touching down first – aka Zion’s footstrike pattern during the “initial contact” phase of running.

Footstrike is typically categorized into rear, mid, and forefoot strike – with most individuals falling into rear or mid, even those who claim to be forefoot strikers. For someone coming off injury – like Zion – it can be helpful to transition to a midfoot strike because research shows it can result in decreased peak impact force.

Additionally, the rehab staff may have Zion focus on shortening his running stride length – also referred to as increasing running cadence or increasing running stride rate. There’s consistent evidence showing that a shorter stride results in decreased vertical excursion, ground reaction force (GRF), and energy absorbed at the hip, knee, and ankle joints.

In my opinion, decreasing stride length is the lowest hanging fruit for any recovering athlete in a running sport because it’s relatively easy to change with potentially huge results.

-Modifying stride length

Changing foot strike and stride length is often one and the same process because a shorter stride length biases toward a midfoot strike.

The first step is calculating step rate by counting how many times one foot hits the ground during a minute of medium pace running. Multiply that number by two and that’s your stride rate (aka running cadence). The aim is to increase that number by 5-10% which will result in the aforementioned benefits while not increasing energy expenditure. 

A cue and mantra I found works very well with my patients and clients is “chop your steps”. This will help you shorten your steps and it’ll certainly feel choppy at first but then normalize with practice and familiarity.

“Improving the brakes”

Griffin commented that they were working on “improving Zion’s brakes”. What that likely means is the rehab team is improving what’s known as “eccentric control”.

Eccentric control and contraction occurs when a muscle lengthens while contracting and helps slow down the opposite motion – in other words “braking”. For example, during a controlled descent on a biceps curl, the biceps is lengthening while contracting to “brake” that descent. This braking mechanism results in better movement control and less force into the joints.

Key eccentric muscles for Zion include his quads at the initial contact phase of running, his hamstrings during terminal swing phase, and his quads, hip extensors, and lumbar extensors during jumping and landing. In each of these cases, the muscles serve as brakes and dissipate force.

-Eccentric training

Accordingly, the Pels and Zion were likely working on targeted eccentric strengthening. Eccentric training puts significantly higher stress on a muscle than concentric stress and is typically most associated with developing delayed onset muscle soreness (DOMS) so Zion may have had some really sore days!

The other aspect of eccentric training are parts we already touched on in detail – modifying movement technique. For example, changing to a hip dominant landing strategy shifts eccentric load to the posterior chain which are stronger and better equipped to handle that level of force compared to the quads.

Assessing Zion’s changes

The Pels rehab staff may be using a combination of their own movement observation expertise, video analysis, force plates, and EMG analysis to determine if Zion’s movements are changing. 

When Zion gets back, the main question becomes how well the movement re-patterning is carrying over to the games. A key thing to understand – and I can’t stress this enough – is that Zion will have a natural variance where he’s fluctuating between old and new patterns and somewhere in between.

The research consistently shows that not only is this fluctuation normal for new motor skill acquisition but that these mistakes and variance are a critical part of learning new motor patterns – they’re fuel for the nervous system’s fire – and further, that variance will only increase as intensity and stress levels ratchet up. Therefore, we have to view carry-over and movement re-patterning as a trendline rather than as a straight line.

The upshot

The Pelicans extended approach to Zion’s rehab and cleaning up his movement patterns is an extremely wise decision for Zion’s future and their rare transparency has given us a valuable peak into a generally lesser known sphere of movement science and movement re-patterning.

It’s a long extended process and one that will continue for many months after Zion gets back onto the court. Old habits do indeed die hard but movement quality is critical for Zion’s health moving forward, far more than his playing weight.

That’s a wrap for this article. Thanks for reading. My goal is to provide you with in-depth, evidence based, narrative free analysis and you can always find me on IG and Twitter @3CBPerformance. Make sure to sub to the blog, YouTube channel, and follow along on all social media for the latest updates. 3CB out

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