Squat Technique: Why Your Build Determines Your Form

Two technically good squats can look completely different.

On one person, the knees travel far forward and the torso stays relatively upright. Another squats with a wider stance and considerably more forward lean. Both can be stable, controlled and sensibly trained.

That does not mean technique is irrelevant.

It only means: a good squat is not a single photo that every body has to copy exactly. Body proportions, mobility, stance, bar position and training goal all change how the movement can look — and which joints take on more of the work.

What a good squat actually has to achieve

Instead of looking for a visually perfect template, four questions are more helpful:

1. Do you stay balanced? The load stays over a stable base of support rather than tipping you forward or backward.
2. Is the movement controlled and reproducible? Under an appropriate load, your technique should look similar from rep to rep.
3. Does the depth suit your goal? A powerlifter needs a different minimum depth from someone using squats purely for muscle growth.
4. Can you load the position sensibly? A movement variation is only useful if you can train it progressively across weeks without symptoms or loss of control limiting your load increases.

That makes technique what it should be: a method for distributing load sensibly — not a beauty contest.

Why your build changes the squat

In a squat, your body has to keep the combined centre of mass of body and barbell over the base of support. How much forward knee travel, hip flexion and forward lean that requires depends among other things on your segment lengths.

A study with 32 adults showed, for instance: people with relatively longer thighs tended to need more knee flexion and ankle dorsiflexion at narrower squat stances. A wider stance particularly reduced the demand on dorsiflexion.

That is an important difference from the simplified rule:

Long femurs = you have to squat exactly like this.

Anthropometry influences your movement but does not automatically dictate one correct technique.

Long thighs

Relatively long femurs can mean you need more forward knee travel, more forward lean or a different stance for the same depth than someone with shorter thighs.

Several adjustments can work in practice:

• a slightly wider stance
• more toe-out angle
• a heel wedge or weightlifting shoes
• a bar position in which you feel more stable

Which of these fits is better found by trying than derived from a photo of your proportions.

Short thighs and a longer torso

With relatively shorter femurs it is often easier to stay more upright at the same depth. Visually, that can look more like the classic “textbook squat”.

But here too: that is not a mark of quality.

A more upright squat is not automatically safer or better. It simply shifts the mechanical demands more towards the knee, while more forward lean tends to increase the hip moment.

Stance width: no universal shoulder-width standard

“Feet shoulder-width apart” is a usable starting point, but not an anatomical rule.

With a wider stance, hip, knee and ankle angles all change. The available research shows, among other things, that a wider position can reduce the ankle dorsiflexion required. Newer biomechanical data also shows that stance width changes how load is distributed across the hip and musculature.

That makes stance a genuine programming lever:

• Too narrow and you cannot get deeper under control because of your ankles? A little wider can help.
• Very wide and you feel uncomfortable in your hips or adductors? Test a little narrower.
• Knees and feet pointing in noticeably different directions? Adjust toe angle and stance together rather than forcing an isolated cue.

You do not need perfect angle values for this. A stable, repeatable position matters more than 15° or 30° on paper.

High bar vs. low bar: what actually changes

Anatomy and bar position often get conflated here.

With high bar, the barbell sits higher on the traps. On average, this variation is performed with more knee flexion, less hip flexion and a more upright torso.

With low bar, the barbell sits lower on the back. That typically means more hip flexion and more forward lean.

This matters, because the common tip “long femurs → low bar so you can stay more upright” does not fit biomechanically. Low bar is characterised precisely by the stronger forward lean.

Low bar can still work very well for someone with long thighs — just for a different reason: the variation allows a more hip-dominant movement strategy and is frequently used in powerlifting to move high loads.

Practical framing:

• High bar: sensible if you want a more upright, more knee-dominant squat, or if carryover to weightlifting movements matters.
• Low bar: sensible if you prefer a hip-dominant variation or if maximum load moved in powerlifting is the priority.
• For general strength training: the variation you train stably and enjoy long-term is often the better choice.

Mobility: relevant — but not the whole explanation

Your ankles and hips need enough freedom of movement for the squat you have chosen.

If ankle dorsiflexion is lacking, the heel can lift on deeper squats or the body has to compensate through other joints. An elevated heel — through weightlifting shoes, for instance — reduces the dorsiflexion required and can make a more upright position easier.

That is not a “shortcut” hiding poor mobility. It simply changes the geometry of the exercise.

Bony hip anatomy also differs between people. But it does not follow that you can reliably diagnose the orientation of your hip socket from a bodyweight squat. If a particular stance repeatedly restricts you earlier or feels uncomfortable, it is more useful to test several positions systematically than to attribute the cause to a specific bone angle without examination.

And mobility is trainable: strength training through large ranges of motion can improve mobility itself.

Knees past the toes: a loading variable, not a red line

Your knees are allowed to travel past your toes in a squat.

The classic study by Fry et al. compared squats with normal knee travel against an artificially restricted variation. Restricting knee movement reduced the torque at the knee but clearly increased the torque at the hip.

That is the decisive insight:

Load does not disappear — it gets redistributed.

More forward knee travel tends to increase the demand on the knees and quadriceps. More forward lean and less knee travel shift more work towards the hips and trunk.

So “knees behind the toes” is not a general safety rule. But “the further past the toes the better” would be just as simplistic.

How the Knees Over Toes / ATG approach fits into this is covered in the ATG/Knees Over Toes review.

How deep should you squat?

For general strength and hypertrophy training, a large, controlled range of motion is a sensible standard.

In healthy, appropriately prepared lifters, deep squats are not inherently more dangerous than partial squats. Knee loading changes in complex ways across the range of motion; “deeper = always more knee pressure” does not represent the biomechanics usefully.

But it does not follow that everyone has to squat ass-to-grass.

Your sensible working depth depends on:

• the squat variation you have chosen
• stance and toe angle
• ankle and hip mobility
• control under load
• your training goal
• any existing symptoms or medical restrictions

For powerlifting, the competition rules matter as well. For muscle growth, what counts is more whether you are training a large and loadable range of motion.

Buttwink: not a usable on/off test for safety

“Buttwink” describes the pelvis tilting backwards in the lower part of a squat. That usually changes the position of the lumbar spine somewhat too.

The old coaching approach often runs:

As soon as the pelvis moves, you are too deep.

There is no convincing scientific threshold for that.

People move their spines when lifting and bending. Even the broader research on lumbar flexion during lifting does not show that more flexion on its own reliably distinguishes people with and without back pain, or predicts back pain. That evidence is limited, though, and not specific to heavy squats.

So the more useful question is:

Does your movement stay controlled under the load you have chosen, and roughly as you planned it?

If your pelvis suddenly changes a lot only under high fatigue, you lose tension, or you develop symptoms in the process, that is a good reason to adjust load or depth. A small, reproducible change of position at the bottom, by contrast, is not automatically a technique fault.

Knees moving inward: not every movement is a “valgus collapse”

Here too, less black-and-white thinking helps.

Dynamic knee valgus plays a role in certain injury mechanisms — particularly in landings and changes of direction. But it does not follow that every visible inward movement of the knee in a bilateral squat is automatically dangerous.

It becomes relevant more when:

• the movement appears suddenly and uncontrolled
• it increases noticeably as load rises
• foot contact or balance is lost
• symptoms develop

A technique cue, less weight or a change of stance can then make sense.

What you do not automatically need: a mini band around your knees or a diagnosis of “weak gluteus medius”. Several factors can influence how the knee visibly tracks.

Trunk bracing: stabilise rather than freeze a spinal shape

Building tension before a heavy squat makes sense.

A strong breath in and bracing increase trunk stiffness and help you transfer forces between barbell and lower body. On heavy reps, many strength athletes use a Valsalva manoeuvre for this.

But the goal is not to reduce every spinal movement to zero.

The more workable goal is: create a robust trunk position that does not change uncontrollably during the rep.

With cardiovascular conditions or other medical restrictions, the breathing strategy should be clarified individually, because hard bracing can raise blood pressure considerably.

Three situations in which you really should adjust your technique

1. You lose balance or foot contact

If your heel lifts, you roll onto the outer edge of your foot, or the barbell visibly drifts in front of or behind your stable base, the movement is hard to reproduce.

Test first:

• less load
• a different stance width
• a changed toe angle
• a heel elevation

2. Your technique changes more under load than planned

A heavy rep is allowed to look slower than a warm-up rep.

But if your squat suddenly turns into a completely different movement under load — noticeably different depth, a strong loss of position, uncontrolled collapse or tipping — that is a sign that load has risen faster than your control.

3. A particular variation repeatedly causes symptoms

“Technically correct” and “currently well tolerated by you” are not the same thing.

If a particular depth, stance or bar position reliably provokes pain, you do not have to prove that the movement should theoretically be safe. Reduce load or range of motion, test a variation, and have persistent or severe symptoms assessed professionally.

How to find your squat systematically

Rather than changing ten cues at once, go step by step.

Step 1: choose the variation by your goal

High bar, low bar and front squat solve different jobs. Start with the variation that suits your training goal.

Step 2: find a stable stance

Start roughly shoulder-width and test slightly narrower and slightly wider from there. Change the toe angle along with it.

Step 3: check whether an elevated heel works better

If a small heel elevation immediately gets you deeper, more stable and more controlled, that is a legitimate technical option — not a cheat.

Step 4: set your working depth

Squat as deep as you need for your goal and can repeat cleanly under a moderate load. The depth does not have to match an internet ideal.

Step 5: film your working sets

A recording from behind at an angle or from the side shows you more than how the rep felt. Watch above all for balance, depth and whether your technique changes as load increases.

Step 6: change one variable at a time

A new stance, new shoes, a different bar position and more weight all at once — after that you have no idea which change helped.

Test systematically and give a position several sessions before judging it.

Conclusion

There is no single squat that has to look the same on every body.

But it does not follow that every execution is equally good.

• Anthropometry changes your joint angles. Segment lengths in particular influence how much knee travel and ankle movement a position demands.
• High bar and low bar are different strategies. High bar is typically more upright; low bar uses more hip flexion and forward lean.
• Knees past the toes are not a technique fault. They change how load is distributed rather than automatically creating injury risk.
• Depth is a training parameter. A large ROM is a good standard but has to suit your goal, variation and tolerance.
• Buttwink and inward knee movement need context. A visible movement is not automatically an injury prediction.
• Progression only works with reproducible technique. When the movement suddenly falls apart under load, less weight is often the more productive decision.

So the best squat is not the one that most resembles a screenshot from a tutorial.

It is the variation whose load distribution suits your goal and that you can train under control, with few symptoms, and progressively over the long run.

Sources

• Glassbrook DJ, Helms ER, Brown SR, Storey AG (2017). A Review of the Biomechanical Differences Between the High-Bar and Low-Bar Back-Squat. Journal of Strength and Conditioning Research, 31(9):2618–2634.
• Demers E, Pendenza J, Radevich V, Preuss R (2018). The Effect of Stance Width and Anthropometrics on Joint Range of Motion in the Lower Extremities during a Back Squat. International Journal of Exercise Science, 11(1):764–775.
• Fry AC, Smith JC, Schilling BK (2003). Effect of Knee Position on Hip and Knee Torques During the Barbell Squat. Journal of Strength and Conditioning Research, 17(4):629–633.
• Hartmann H, Wirth K, Klusemann M (2013). Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load. Sports Medicine, 43(10):993–1008.
• Saraceni N, Kent P, Ng L, Campbell A, Straker L, O’Sullivan P (2020). To Flex or Not to Flex? Is There a Relationship Between Lumbar Spine Flexion During Lifting and Low Back Pain? A Systematic Review With Meta-analysis. Journal of Orthopaedic & Sports Physical Therapy, 50(3):121–130.
• Straub RK, Powers CM (2024). A Biomechanical Review of the Squat Exercise: Implications for Clinical Practice. International Journal of Sports Physical Therapy, 19(4):490–501.
• Schoenfeld BJ (2010). Squatting Kinematics and Kinetics and Their Application to Exercise Performance. Journal of Strength and Conditioning Research, 24(12):3497–3506.