A No Gi Knee Mistake Jiu Jitsu Athletes Make (And How to Fix It)

I know what you are all expecting me to say… returning too early after injury, not listening to your body, or not training like every round is ADCC trials. Yes, yes… all of this is true. However, I have a new one today and I truly hope it changes your mindset on how to train leg locks safely, only injecting more risk in competition, when it is sometimes necessary. I have come off the mats after hard no gi training or after a heavy leg entanglement competition with sore knees, which is what prompted this newsletter.

One mistake jiu jitsu athletes make in no gi is repetitively loading the knee during certain positions without understanding what is actually happening. My goal is to explain this concept and help keep more knees healthy for life. 

What Reaping Actually Does To Our Knee

When someone reaps, they place stress on the knee in multiple directions simultaneously. The knee moves in three planes… varus/valgus (think bow-legged vs. knock-kneed), flexion/extension (bend and straighten), and rotation (internal/external). These movements are not equal. Flexion and extension range from roughly -5 to 150 degrees, while the knee only allows about 10 degrees of internal rotation and 30 degrees of external rotation. In addition, rotation occurs primarily when the knee is bent near 90 degrees.

Why does this matter? Reaping drives all three planes of motion at once, rapidly and under load. The knee was not built to resist that combination when performed aggressively. Research confirms it… combined valgus and rotational loading produces significantly greater ACL strain than either force alone. (Shin et al., Journal of Biomechanics, 2011.) That is exactly what repetitive reaping creates.

It Might Not Always Be The Finish That Gets Us

A physical therapist colleague and I were discussing something that comes up more than people realize. Grapplers tearing their ACL during what looks like a subtle, unremarkable movement. No dramatic finish. No loud pop mid-scramble. Just a quiet moment that ends a season.

Our theory is cumulative stress. Rounds and rounds of intense training, repetitive leg entanglements, and a general unawareness of what is happening inside the joint adds up. And it is not just the ligaments. The patella takes significant load during a reap as well, which is typically what happens when we have “sore knees” after no gi competition class. Add in a poor habit of resisting entanglements by turning the wrong direction, uncontrolled training partners, or simply not tapping in training, and the picture becomes clear. The finish may not always cause the injury. The thousand reps may have.

Train Smarter, Not Always Less

After I tore my ACL in a heel hook scramble, I have become more cognizant of both my knees and those of my training partners. There is no need to aggressively reap or kani basami on the people you trust more in the gym. As I always say “don’t break your toys”. 

The gym should be a safe place. Somewhere we train leg locks technically, without adding unnecessary risk to positions that are already inherently dangerous.

What To Actually Do Different

For all you military people out there, I run a “safety brief” before Iive leg lock sparring. My rules are simple: no scissor takedowns, no jumping on our partner's leg from a side body lock, no ripping heel hooks. If your heel is caught, you get one attempt to slip it, then you tap. And we practice catch and release with heel hooks.

Some think I am too cautious. Maybe. But I have seen it happen too many times… and lived it myself. Sometimes there is a surprise pop with zero warning pain. The reckless scramble that ends with a swollen knee and a month off the mat. So yes, I have rules. My goal is to train tomorrow, not win the round. It took me years to figure that out.

Final Thoughts

Leg locks are not the enemy. They are one of the most technical and rewarding parts of modern jiu jitsu. But they carry real risk, and that risk does not always announce itself. The tear that ends your season can come from one bad rep… but it may often come from thousands of reps first.

Train with partners who understand this. Coach athletes who understand this. And remember… the goal is not just to finish the submission. It is to control the position. And to still be on the mat ten years from now.

Protect your knees. They have a lot of rounds left in them.

____

Dr. Megan Lisset Jimenez 

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References:

Shin CS, Chaudhari AM, Andriacchi TP. "Valgus plus internal rotation moments increase anterior cruciate ligament strain more than either alone." Journal of Biomechanics. 2011. PMID: 21266934