In a previous article for Muay Thai Scholar, I discussed using strength and conditioning training to discover how your body fails, and working on these weak links – we’ve all got them!

I illustrated with the example of valgus collapse of the knee, where the knee buckles inward under load…

And this is pretty common in fighters.

As far as problems go, it can lead to a lot of nasty injuries if left unchecked, and as a habit contributes to a less than desirable Muay Thai stance and legs that buckle under low kicks.

Numerous people contacted me asking, “That’s me, how do I fix it?” – so here’s how I like to tackle this issue in the gym.


Although valgus knee collapse is more common in women (due to a wider pelvis relative to knee positioning), it affects men too.

I see it a lot, and have to work on this myself too (especially if I become less active through injury).

If you don’t correct it, you can end up with (patellofemoral) knee pain, IT band syndrome or even a dreaded ACL tear.

So a buckling knee doesn’t just look ugly, it’s trouble waiting to happen. There’s more than one reason why your knees cave in under load, and more than one of them may affecting you.

Firstly, poor hip strength or activation will let your knees wander around.

That ball and socket in the hip needs its muscles to do a good job of stabilising a joint that allows a great deal of movement – especially for fighters that can kick head height.

In particular, if your glute medius muscle is weak or underactive, you’ll find it difficult to track your knee correctly and it’ll tend to buckle inward when ‘surprised’ by load.

Just take a look at the difference in the two girls ‘tuck jumping’ in the montage image at the top of the page.

Secondly, you may have poor range of motion in you ankles. If you can’t keep your (bare) foot flat on the floor while flexing your knee beyond your toes by at least 125mm (5”) then you need to work on improving that.

Ankle range of motion test

Thirdly, your ankle mobility and hip strength may be good, but you’re just not coordinating the movement properly and allow your knee to drift inward.

This is a bad habit that needs a conscious effort to re-pattern and correct, demanding repetition with good form.


When it comes to general athletic training, we like to use muscles in coordinated patterns of movement, because that’s how you use your body in real life.

However, when there’s a muscular imbalance, lack of activation in a specific area or an injury for example, we often opt for a more isolated approach to get the lazy bit to ‘tow the line’.

The following exercises go at your glute medius and shout it to attention!

Resistance band squats and hip bridges, and Side Lying Clams are good strengthening and activation exercises to prevent valgus knee collapse, as they operate in a deeper flexed position – where the collapse tends to happen, so are more specific.




The following exercises are also useful but aren’t as specific as the legs are more extended. Crouching lower in the ‘walks’ helps make them more specific…




Foam rolling can be used for self-myofascial release, improving the extensibility of the calf, giving you an increased range of motion.

When foam rolling to improve mobility, move your foot at the ankle (point and flex, or make circles) as you roll to get an even better release.

Mike Reinhold’s video below also shows rolling the arch of your foot with a ball to also release the plantar fascia, which can also help increase ankle mobility.

Stretching the calf both in a knee-bent and straight-knee position will make for the best progress.

Although, the bent-knee stretch is the priority as it’s more specific to the action we need to replicate. Hold each stretch for between 10 to 30 secs (hold the longer time if you’re particularly tight).

Mobilisation involves moving the joint through a full range of motion dynamically in a controlled manner.

If I had to choose between stretches (where you hold an extended position statically) and mobilisation, I’d go for mobilisation every time.

I like the ankle self-mobilisation drill against the wall, heel drops from a step, and knee flexing with your foot on a step – one I call ‘knee breaks’.

Ankle self-mobilisation against the wall – aim to eventually have your toes (barefoot) at a distance of 125mm or more from the wall, and touching you knee to the wall with your heel down.

Heel drops – using both straight and bent leg versions

Knee Breaks – check out the difference in ankle mobility of these two people…

If you want to see my ankle mobility quick-fixes, I’ve dedicated a whole video on releasing the calf and foot here.


If your hips are strong enough and your body knows how to activate the right muscles, you now need to build the habit by practice during ‘live’ movements.

Your body learns movement habits.

If you’ve allowed lazy valgus knee collapse for 1000’s of repetitions, that’ll happen when you’re not thinking about it.

To correct a bad habit typically takes 3000-5000 repetitions of deliberate practice – with your knees out. You can achieve this with constant coached cueing “knees out” during lower body exercises.

I hope that helps you sort out your valgus knees, and gives you an appreciation of how you can target your supplemental strength and conditioning training to improve your athletic potential and reduce injury.

It’s not just about how much you do in training, it’s more about what you do. Think quality not quantity and you’ll get better much quicker, and stay in the game longer.



    Part 1 | The Optimal Performance Pyramid
    Part 2 | Functional Training & Periodisation
    Part 3 | Relentless Endurance & The Optimal 12-Week Fight Camp

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  • Don Heatrick BSc. (Hons) Level 4 Strength & Conditioning Coach, Muay Thai Coach


    Don Heatrick, owner of Heatrick Strength & Conditioning, is a renowned Level 4 Strength and Conditioning coach, Muay Thai coach and former pro Thai boxer from the UK.

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