Vertical Tibia Specifics

Utilizing the vertical tibia position in level changes such as the squat and split squat have been a major interest of mine since my tenure with the Philadelphia 76ers.  Utilizing such techniques as the true box squat and rack pull not only have the posterior chain focus, but also I believe there are meaningful changes to knee mechanics that may yield durability long-term compared to movements with an angled tibia.  There is considerable attention afforded this topic on my upcoming DVD, Training = Rehab, Rehab = Training.
The question below came from a D1 Strength Coach looking to gain some more insight to the vertical tibia message.

I have one question on vertical tibia training that I was not able to find an answer for in my research.
When you maintain a vertical tibia in an exercise such as a split squat, there is more of a true roll and less glide of the femur. With this there has to be a greater tensile force in the quad/patellar tendon due to the greater horizontal distance compared to a gliding femur. Have you come across any research that quantifies this tensile force and the relationship is has with patellar compression?

I will do my best to answer your question, but please keep in mind that my application of methodology in regards to the tibia angle is what I would consider science-based.  I believe there are trends and literature to believe what I can explain, but as far as research, there is very little that specifically addesses the same movement pattern within terms of a vertical or angled tibia.
In the vertical tibia, there is a posterior weight shift which leads to a DEloading of the anterior chain, the quad/patella tendon specifically.  It is certainly not slacked, but stress is funnelled to the hip joint much more than the knee.

The arthokinematic position the femoral head is in a more stable position more posterior to the position it would be in an angled tibia technique.  While the femur is still in contact with the posterior aspect of the patella, it is with a graded posterior pull via the posterior weight shift that I mentioned above.

If there were greater anterior chain forces, which I have not read whether this is or isn’t, the translation of those forces through bony stability channels would be much more in the angled tibia position than vertical based on the arthokinematics that you recognize.

Fry et al’s fairly known “Biomechanics of the Squat” yields the trends that I am reporting on here.

There is another study that powers this presentation  demonstrated the natural pattern for a pain-free ACL was with vertical while the non-surgical side descended into angled.  I found this literature after I had actually seen this myself in an athlete, and it looks as bizarre as it seems if you are visualizing it.  The trend that I am reporting on is the natural neuromuscular control that these subjects demonstrated to “get away” for a knee that the brian thought could not buttress any more bony contact(s).  The nociception “memory” was enough to garner the posterior weight shift.

So basically I am not prepared to suggest there is any less patella compression from the anterior chain or from the anterior aspect of the patella.  I am suggesting there is a more stable and posteriorly mediated environment on the other side of the patella.  There may be a strong punch in, but there is less of a punch back, and the retro-patella is spared as is further caudal “grind” of any meniscal wear.

Always to keep in mind in considering my thoughts with the vertical vs. angled tibia is that the angled tibia is real-life.  We operate in ADLs and athletic movement with an angled tibia.  Fundamental movement and most power training utilize the positions.  They can not be avoided.  Strength training is where the vertical positions can be maximized in bringing up the weak link of the posterior chain.

  • October 7, 2010

Leave a Reply 5 comments

Ryan Reply


When you say vertical tibia how “vertical” do you mean—Do you want them to keep it straight as possible or does it angle slightly? Also in your experience with basketball guys with long spines do you see any problems when restricting movement at the knee and placing it on the hip/lower back? I’m guessing you don’t load them unless they have control over the spine. Also do you see this technique in the box squat transfer to a back squat with no box or a body weight squat?

If the weak link isn’t the posterior chain (very rare) do you approach things different?

Thanks for your time

Charlie Reply

Ryan – By vertical, I mean 90 degrees to the floor. A negative shin angle would push the stress even more to the posterior chain.
When you do not use a box, it is pretty impossible to be 100% vertical. There will be some small degree of shin angle I think. And I don’t think that’s a big deal.

The key is actually to break with the hips and sit back as much as possible.
The alternative is to break with the knees, which also results in a technically proficient squat, just a different one with different parameters.

And your assumption on loading is dead on. I think people run into injuries with squatting partly because they simply load them too much or too quickly. Compression and shearing are normal stresses to the spine that can be adaptable via the SAID principle. But getting up and down is not the technical proficiency standard to the squat as I see it.
And in fact, shifting stress to the hips and lumbar spine with proper SAID progression will improve the active buttressing of the loads, not the passive restraints which leads to back injuries from squatting.

The beautiful thing I have found when I was in the NBA and in the real world with degenerative meniscal tears is that yes, hip dominant squatting pain-free absolutely carried over to pain-free or pain-improved quad dominant squatting. The posterior chain tone I THINK changes the neuromuscular control of arthrokinematics during the knee flexion. I THINK this is what happens.

I don’t know that I have ever seen the weak link not fall into the lower-crossed pattern, so I would rarely not work through these thoughts. Also though please consider that prior to attacking the posterior chain, releasing anterior chain tone is mandatory. Before reloading, we need to reset and reinforce.

Steve Falk Reply


Thanks for the fantastic blog and post. Can you expound on “Also though please consider that prior to attacking the posterior chain, releasing anterior chain tone is mandatory. Before reloading, we need to reset and reinforce.”? Are you talking about working anterior mobility and tone right before you hit the posterior chain in a workout (i.e. foam roll, stretch quads and hip flexors then box squat) or not box squatting at all until you have excellent mobility and tissue quality in the anterior chain? Or did I misinterpret altogether? Thanks again for your time. I’m a 6’7 washed up hoopster with old man knees so this topic is near and dear to my heart and it seems you have lots of experience with this. Thanks again,


Charlie Reply

Steve – By all means, you can get into DL and box squat without “perfect” hip extension or internal rotation mobility.
I would like you though to consider them all 1 move. For every set of high box squat you would do, you would also do a hip flexor stretch, a passive leg lowering, and a 1-leg bridge. All 4 of those moves are 1 move. Knock them out for 3-4 times as you warm-up, then continue if you have the need to go heavier with the squats. Just keep form, and progressively lower the box when it’s warranted.

Steve Falk Reply


will do. Thank you so much for the reply and advice.

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