Why does knee pain occur on the way down in a squat?

Knee pain during squatting is one of the most common complaints seen in our practice. Often, the discomfort appears specifically during the eccentric phase. This is the lowering portion of the squat. This is the phase where the body must control load, maintain alignment and distribute force efficiently across multiple joints. When something in this chain isn’t working well, the knee often ends up taking the stress.

Below we break down why knee pain happens during eccentric squatting, the key contributors (ankle mobility, quad strength, quad length, hamstring function) and how physiotherapy can effectively treat and prevent it.

Why the eccentric phase is a problem for many people:

The eccentric phase demands:

• Controlled deceleration through the quads and hips
• Adequate ankle dorsiflexion and stability
• Good pelvic and trunk control
• Balanced tension between the quads and hamstrings

If one link is off, the knee can become the “victim” joint. This is why you may notice your knees hurt on the way down but not necessarily when standing back up.

Key reasons knee pain appears during eccentric squats:

Poor ankle mobility & stability

One of the biggest contributors to knee pain is insufficient ankle dorsiflexion (the ability to bend the ankle forward). This is often overlooked. During the lowering phase of a squat, the shin needs to travel forward. If the ankle can’t bend enough:

• The knees are forced to track inward
• The torso leans excessively
• The quads take more load
• Stress concentrates at the patellofemoral joint (front of the knee)

Ankle instability can also cause micro-adjustments in the foot, forcing the knee to perform extra stabilisation work it was never meant to do.

Common signs you may have ankle limitations:

• Heels lift when squatting
• Knees collapse inward
• You feel pressure at the front of the knee
• Your squat depth is limited

Limited Eccentric Quadriceps Strength

The quads act as the primary brakes during the lowering phase. If they’re not strong enough
eccentrically:

• The knee collapses into poor alignment
• The patella (kneecap) tracks unevenly
• The body compensates by shifting load forward

This creates irritation around the patellar tendon or behind the kneecap, especially during slow controlled squats or heavy loads.

Eccentric strength is not the same as general quad strength. Many people can squat heavy concentrically (on the way up) but still have poor eccentric control.

Quadriceps Length & Tissue Stiffness

The rectus femoris (one of the quad muscles) crosses both the hip and knee. If it’s tight or
short:

• It increases compressive forces on the patella during descent
• It limits hip flexion, which makes you hinge incorrectly
• It pulls the knee into a slightly forward/loaded position

During the eccentric phase, this extra tension forces the knee joint to absorb more load than
it should.

Hamstring Weakness

The hamstrings help stabilise the knee and pelvis during squatting. If they are weak:

• The quads overpower the movement
• The knee experiences anterior shear forces
• The pelvis may tilt excessively, altering the knee angle

This imbalance is especially common in individuals who sit a lot or train predominantly quad-
based exercises.Hamstrings don’t need to be exceptionally strong for squats but they do need to be working in the right timing and proportion.

How Common Is This Problem?

Extremely common.

Between 60–80% of recreational lifters report some form of knee discomfort, with the
majority of cases occurring:

• During squats
• During lunges
• Or when descending stairs

Most of these issues are movement-based, not due to structural damage. This is why correcting mechanics and strength imbalances is incredibly effective.

Why Knee Pain Happens in the First Place

The knee sits between two highly mobile joints; the hip and the ankle. When either of these joints lacks mobility or control, the knee compensates. Typical causes include:

• Sedentary lifestyle. This leads to reduced ankle mobility & quad tightness
• High training loads without proper eccentric strengthening
• Poor technique learned early and reinforced
• Muscle imbalances from cycling, running or gym training
• Past ankle sprains reducing stability
• Quad-dominant movement patterns

Most people don’t realise they’re compensating during their squat until pain appears. Thiscan even happen months or years later.

How Physiotherapy Helps Fix Knee Pain During Squats

Our practitioners don’t just treat the knee, we aim to restore the full kinetic chain. A physio will typically assess:

• Ankle dorsiflexion range
• Foot mechanics & stability
• Hip strength and control
• Quad flexibility & eccentric strength
• Hamstring activation and balance
• Squat technique and load tolerance

Common treatment components include:

1. Improving ankle mobility: Joint mobilisations, calf lengthening, dorsiflexion-specific exercises & foot stability retraining
2. Building eccentric quad strength: Slow-tempo squats, Spanish squats, decline squats & eccentric step-downs
3. Releasing and lengthening the quadriceps: soft tissue work, hip flexor/quad stretching & strengthening through lengthened ranges
4. Strengthening the hamstrings: nordic regressions, RDLs & hip hinge technique training
5. Technique correction: Once mobility and strength deficits are addressed, the squat pattern can be rebuilt with improved mechanics. Our practitioners guide this process to ensure you return to lifting, training and daily life without pain.

The Bottom Line

Knee pain during the eccentric phase of a squat is common, but it’s rarely because something is “wrong” with your knee. More often, the issue is:

• Limited ankle mobility
• Poor ankle stability
• Inadequate eccentric quad strength
• Tight quadriceps
• Weak or poorly coordinated hamstrings

Knee pain during squatting is common, but it’s highly treatable with the right plan. With targeted physiotherapy, mobility work, strength progression and technique coaching, you can get back to training confidently and pain-free.

At Invigorate Health and Performance, we don’t just treat the knee, we analyse and optimise the entire movement pattern.

Is your knee is painful when squatting? Book an appointment with one of our practitioners today!

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Written by Nick Dimos (Team Leader and Senior Physiotherapist)