Why Does Your Knee Hurt When the Problem May Be Somewhere Else? The Science of the Kinetic Chain

Your ankle affects your knee. Your knee affects your hip. Your hip affects your pelvis. Your pelvis affects your spine. Your body doesn't move as isolated parts—it moves as a connected system.

Have you ever noticed that one knee moves differently from the other when you squat?

Perhaps you shift your weight to one side.

Maybe your knee clicks when climbing stairs.

Your ankle feels stiff during a squat.

Your hip feels tight when you lunge.

Or your movement becomes less controlled when you get tired.

It is tempting to focus only on the area that hurts.

But movement is rarely that simple.

Your body operates through an interconnected system often described as the kinetic chain. When one part of that system has limited mobility, reduced strength, poor stability, pain, or reduced motor control, other areas may contribute differently to complete the movement.

That does not mean the painful joint is always being affected by another joint, nor does a movement difference automatically indicate an injury.

It means the entire movement deserves to be understood.

At Sports2Science, this is the foundation of biomechanical and functional movement assessment:

Assess the movement. Understand the contributing factors. Build capacity. Then progress.

What Is the Kinetic Chain?

Think of your body like a chain made up of interconnected links.

The foot connects with the ankle.

The ankle influences the lower leg.

The lower leg connects with the knee.

The knee connects with the hip.

The hip works with the pelvis.

The pelvis interacts with the spine.

The spine influences the position and movement of the upper body.

When you walk, run, squat, lunge, jump, land or change direction, these regions don't work independently.

They coordinate.

For example, during a squat, you need appropriate contributions from the:

• Ankle
• Knee
• Hip
• Pelvis
• Trunk
• Foot
• Nervous system

If one area has a limitation, the body may find another movement strategy to complete the task.

This is called compensation.

Compensation is not automatically bad. In fact, it is an important part of human movement.

The concern arises when a movement strategy becomes excessive, inefficient, painful, poorly controlled, or difficult to tolerate under increasing demands.

Functional Movement Is More Than Flexibility

When people hear "movement assessment," they often think about flexibility.

But functional movement involves much more.

A useful movement assessment considers several qualities:

Mobility

Can the joint or body segment move through the range required for the task?

Stability

Can you control the available movement?

Strength

Can your muscles produce and sustain the force required?

Balance

Can you maintain control while your body moves?

Coordination

Can different body segments work together efficiently?

Proprioception

Can your nervous system accurately sense where your body is in space?

Motor Control

Can you consistently organise movement according to the demands of the task?

Therefore, functional movement is not simply:

"How flexible are you?"

A better question is:

"Can you access the movement you need, control it, produce force through it, and adapt it to the demands of your activity?"

Why Can an Ankle Problem Change a Squat?

Consider the deep squat.

To squat comfortably, the body requires coordinated movement from the ankle, knee, hip and trunk.

Ankle dorsiflexion is particularly relevant because the lower leg needs to move forward over the foot as the body descends.

If ankle movement is restricted, the body may modify the movement strategy.

You might see:

• Reduced squat depth
• Heels lifting
• Increased trunk movement
• A change in weight distribution
• A shift toward one side
• Altered knee movement

But here's an important point:

A movement observation does not automatically identify the cause.

A squat shift could have multiple contributors, including mobility differences, strength differences, balance, pain, previous injury, motor control, or individual anatomy.

That's why simply seeing a movement pattern is the beginning of assessment—not the end.

Your Hip Is a Major Link in the Chain

The hip plays an important role in walking, running, squatting, lunging and changing direction.

It needs a combination of:

• Mobility
• Strength
• Stability
• Rotation
• Control

Consider running.

During running, the hip contributes to controlling the pelvis and producing movement through the lower limb.

If a person's hip function is limited, other body segments may contribute differently to complete the task.

This can influence movement around the:

• Pelvis
• Knee
• Foot
• Lumbar spine

Again, this doesn't mean that every knee or back problem originates from the hip.

It means the hip is one part of a system worth examining.

The Thoracic Spine: The Forgotten Link

Movement assessments often focus heavily on the lower body.

But the thoracic spine—the middle section of your spine—is also an important part of movement.

Thoracic mobility contributes to:

• Rotation
• Overhead movement
• Upper-body positioning
• Throwing
• Reaching
• Running posture
• Breathing mechanics

For someone spending many hours at a desk, movement variety can become limited.

That does not automatically mean sitting has "damaged" the spine.

A more useful way to think about it is:

The body adapts to the demands you repeatedly place upon it.

If a movement is rarely practiced, that range may become less familiar or less well controlled.

Mobility and Stability: You Need Both

One of the most common movement-training mistakes is assuming:

"I'm stiff, so I need to stretch."

Sometimes that is appropriate.

But stiffness can have multiple contributors.

It may involve:

• Reduced joint range
• Muscle tightness
• Previous injury
• Pain
• Reduced strength
• Poor motor control
• Protective responses
• Limited movement exposure
• Reduced confidence in a particular position

Think about standing on a narrow bridge.

If you feel unstable, you may naturally restrict your movement.

Your body is trying to maintain control.

A similar strategy can occur during exercise.

Mobility asks:

Can I get there?

Stability asks:

Can I control myself when I get there?

Functional movement asks:

Can I get there, control it, produce force, and return safely?

That distinction is extremely important.

The SAID Principle: Your Body Adapts to What You Practice

The **SAID Principle—Specific Adaptation to Imposed Demands—**provides a simple way of understanding training adaptation.

Your body adapts to the demands you repeatedly expose it to.

If you regularly train resistance, your body adapts to resistance.

If you practice running, your body adapts to running.

If you train single-leg balance, your nervous system becomes more practiced at controlling your body on one leg.

If you spend most of your day sitting, sitting becomes one of the movements your body repeatedly practices.

This is why movement variety matters.

The goal isn't to avoid sitting, resting or repeating movements.

The goal is to give your body an appropriate range of demands.

Why Sitting Isn't Necessarily the Enemy

Modern life involves a lot of sitting.

You may sit:

• At work
• During travel
• While eating
• While using your phone
• While watching television
• While studying

Sitting for a period of time does not automatically mean you are damaging your body.

The bigger issue can be too little movement variety for too long.

Your body adapts to the environment you give it.

That's why regular movement breaks, walking, resistance training, mobility work and varied physical activity can all be useful components of a healthy movement routine.

What Does It Mean If You Shift to One Side?

Imagine you squat and consistently shift toward your right side.

What does that mean?

It means something about the movement deserves investigation.

It does not automatically mean:

• Your right knee is injured
• Your left hip is weak
• Your ankle is the problem
• Your pelvis is "out of alignment"

There could be several contributing factors.

For example:

• Mobility differences
• Strength differences
• Balance
• Pain
• Previous injury
• Motor control
• Fear or apprehension
• Individual anatomy

This is why a good assessment asks:

What are we seeing?

Then:

Why might it be happening?

Then:

Does it actually matter for this person's symptoms, function or performance?

What About Knee Clicking?

Knee clicking and other joint sounds are extremely common.

A sound by itself does not automatically mean that something is damaged.

Instead, consider the larger picture.

Ask:

• Is there pain?
• Is there swelling?
• Is the joint giving way?
• Has movement become restricted?
• Did the sound begin after an injury?
• Is function getting worse?
• Is the symptom persistent or worsening?

If joint sounds are accompanied by concerning symptoms, appropriate professional assessment is warranted.

The objective is not to panic about every sound.

It is to understand whether the sound is associated with a meaningful functional problem.

Why "Stretch More" Doesn't Always Work

Imagine someone has poor single-leg control.

They are given more stretching.

Their flexibility improves.

But their balance and control remain poor.

The original problem hasn't necessarily been addressed.

This is why corrective exercise should not mean:

"Find a tight muscle and stretch it."

Instead, the intervention should match the assessment finding.

For example:

Limited ankle mobility → progressive ankle mobility work

Poor single-leg stability → balance and single-leg strengthening

Reduced hip strength → progressive hip strengthening

Poor trunk control → core stability and integrated movement

Reduced thoracic mobility → thoracic mobility exercises

Poor movement coordination → movement re-education

The exercise should have a reason.

Mobility Without Control Isn't Enough

Imagine you can move your leg into a very large range.

But you cannot control that range.

Is more flexibility automatically the answer?

Not necessarily.

Useful movement requires both:

Available range + control of that range

This is why mobility and stability should often be trained together.

A person may need to first access a movement, then learn to control it, then strengthen it, and eventually integrate it into their activity.

What Happens When You Add Heavy Load Too Early?

Imagine someone struggles to control a bodyweight squat.

Then they immediately add a heavy barbell.

The additional load does not automatically correct the movement.

It increases the demand.

A useful progression is often:

Movement → Control → Capacity → Load → Performance

This doesn't mean everyone must master a perfect bodyweight movement before lifting weights.

It means training load should be appropriate to the person's current capacity and goal.

Movement Quality Before Movement Quantity

Training is often measured by numbers:

How many repetitions?

How much weight?

How many kilometres?

How fast?

But another question matters:

How well could you perform the movement under the current demand?

Ten controlled repetitions may be more useful than twenty repetitions performed with progressively deteriorating technique.

This doesn't mean every repetition must look identical.

Human movement naturally varies.

The goal is to maintain movement within a range appropriate for the individual's:

• Goal
• Capacity
• Symptoms
• Fatigue level
• Training experience

Don't Chase Perfect Symmetry

Perfect human symmetry does not exist.

People have:

• Dominant sides
• Different sporting histories
• Anatomical variations
• Different movement preferences
• Previous injuries
• Different training adaptations

Therefore, the goal of movement assessment should not be:

"Make both sides exactly identical."

Instead, the more useful question is:

"Is the difference meaningful for this person's function, symptoms or performance?"

That is a much more practical approach.

Pain Changes Movement

Pain and stiffness are not the same thing.

Stiffness can feel like restricted or difficult movement.

Pain is a complex sensory and emotional experience associated with actual or potential tissue threat.

When someone experiences pain, their movement strategy can change.

They may:

• Reduce movement
• Move more slowly
• Shift weight
• Guard an area
• Reduce muscle activation
• Avoid certain positions

This is why movement assessment should always be interpreted alongside symptoms and history.

A movement pattern observed during pain may not represent how that person moves when symptoms are absent.

Should You Push Through Pain?

The phrase:

"No pain, no gain."

is often used in fitness.

But it isn't universally appropriate.

Training can sometimes involve normal exertion or manageable exercise discomfort depending on the situation.

However, sharp, worsening, unfamiliar or concerning pain deserves attention—particularly when accompanied by:

• Swelling
• Instability
• Significant weakness
• Loss of function
• Trauma
• Rapid deterioration

The goal of training isn't to ignore warning signals.

It is to understand them and respond appropriately.

What Does a Functional Movement Assessment Actually Look At?

A structured movement assessment can examine different movement tasks to understand how the body currently performs.

Depending on the individual's needs, this may include:

Squatting

Can the person maintain appropriate mobility and control through the lower limb and trunk?

Hurdle-Type Movement

Can the person control single-leg movement while maintaining appropriate alignment?

Lunging

Can the body maintain mobility, stability and coordination during a split stance?

Shoulder Mobility

Can the upper limb move through the required range?

Active Straight-Leg Movement

Can the person demonstrate the required lower-limb mobility and control?

Trunk Stability

Can the trunk maintain appropriate control while the limbs move?

Rotary Stability

Can the body coordinate movement across multiple planes?

The objective isn't to collect scores simply for the sake of scoring.

The objective is to turn observations into useful decisions.

From Assessment to Action

A useful assessment should answer four questions.

1. What is happening?

For example:

The person shifts during a squat.

2. What might contribute to it?

Possible contributors could include:

• Mobility
• Strength
• Balance
• Pain
• Motor control
• Previous injury

3. What does it affect?

Potentially:

• Exercise technique
• Movement efficiency
• Load tolerance
• Sport-specific performance
• Confidence in movement

4. What should we do?

Depending on the findings, the strategy may involve:

• Mobility training
• Stability training
• Strength training
• Balance training
• Coordination
• Movement re-education
• Progressive loading
• Sport-specific training

This is the difference between testing movement and using an assessment to guide training.

How Sports2Science Approaches Movement

At Sports2Science, the goal isn't simply to tell you:

"Your movement is poor."

The goal is to help answer:

What is happening?

What factors may be contributing?

How does it relate to your activity?

What should we train?

How should we progress?

Our assessment approach can incorporate multiple layers of information.

Posture Analysis

Posture assessment provides information about alignment and body positioning from different views.

Depending on the assessment, this may include observations involving:

• Head
• Shoulders
• Spine
• Pelvis
• Knees
• Feet

Posture is not treated as a diagnosis by itself.

It is one piece of the movement puzzle.

Functional Movement Assessment

Movement assessment looks at how the body behaves during specific tasks.

It can help identify relevant observations involving:

• Mobility
• Stability
• Asymmetry
• Balance
• Coordination
• Motor control
• Compensatory strategies
• Pain during movement

A static posture photograph cannot tell the entire story.

The body also needs to be observed while it moves.

Biomechanical Analysis

Movement becomes even more meaningful when it is related to the person's actual activity.

For a runner, assessment may focus on:

• Single-leg control
• Lower-limb alignment
• Running mechanics
• Foot and ankle function
• Pelvic control

For a badminton player, relevant demands may include:

• Lunging
• Deceleration
• Change of direction
• Single-leg stability
• Rotational control

For an office worker, assessment may consider:

• Thoracic mobility
• Shoulder movement
• Hip mobility
• Movement capacity
• Prolonged-position-related movement limitations

The assessment should reflect the person's real-world demands.

Where EMG Can Fit In

Where appropriate, EMG and muscle-activation assessment can provide additional information about muscular contribution during movement.

It may help examine how activation changes under different movement conditions.

However, EMG should not be treated as a magic "cause detector."

It is another piece of information.

It becomes more meaningful when considered alongside:

• Movement assessment
• Strength testing
• Symptoms
• Training history
• Functional demands
• Clinical reasoning

Corrective Exercise: What Happens After Assessment?

The word "corrective" can make exercise sound complicated.

In practice, corrective exercise means selecting exercises that address a specific movement limitation or capacity deficit.

For example:

Limited thoracic mobility → thoracic mobility work

Reduced ankle mobility → progressive ankle mobility

Poor single-leg stability → balance and single-leg strengthening

Reduced hip strength → progressive hip strengthening

Poor trunk control → core stability and integrated movement

Poor coordination → movement re-education

The objective is not to collect dozens of exercises.

It is to select the right exercise for the relevant finding.

Mobility → Stability → Strength → Integration

A simple training progression may look like:

Mobility

↓

Stability

↓

Strength

↓

Integration

↓

Sport or Activity

For example:

Ankle mobility

↓

Single-leg balance

↓

Calf and lower-limb strengthening

↓

Running drills

↓

Running performance

The exact progression depends on the individual.

But the principle is important:

Build the capacity before demanding more from it.

Movement Re-Education

Sometimes the body doesn't need more strength.

It needs more practice.

Movement re-education can involve:

• Slow controlled repetitions
• External cues
• Mirror feedback
• Tempo changes
• Balance challenges
• Progressive resistance
• Sport-specific drills

The objective isn't to make every movement robotic.

Human movement should remain adaptable.

The goal is to improve control where control is currently limited.

When Should You Consider a Movement Assessment?

Consider having your movement assessed if you repeatedly experience:

• Significant movement shifts during squats or lunges
• Recurrent loss of balance
• Persistent stiffness
• Repeated joint instability
• Pain during movement
• Significant side-to-side differences
• Difficulty reaching certain positions
• Recurrent injuries
• Movement that deteriorates rapidly with fatigue
• Difficulty returning to activity after an injury

These signs do not automatically mean something is seriously wrong.

They simply indicate that understanding the movement may be more useful than continually working around it.

Movement Assessment Isn't Just for Athletes

You don't need to be a professional athlete to benefit from understanding how you move.

Movement matters when you:

• Walk
• Climb stairs
• Sit down
• Stand up
• Pick something up
• Carry groceries
• Work at a desk
• Exercise
• Run
• Play badminton
• Train in the gym

Your body is moving throughout the day.

Biomechanics therefore applies to everyday life—not just sport.

Common Kinetic Chain & Movement Myths

Myth 1: Joint clicking always means damage.

Fact: Joint sounds can occur for many reasons. Pain, swelling, instability and loss of function are more important contextual factors.

Myth 2: Every stiffness problem needs stretching.

Fact: Stiffness can involve mobility, strength, stability, pain or motor control.

Myth 3: An asymmetry means you are injured.

Fact: Human movement is naturally asymmetrical. The importance of an asymmetry depends on context.

Myth 4: The painful joint is always the cause.

Fact: Movement involves multiple connected regions, so assessment should consider the broader system.

Myth 5: More flexibility always means better movement.

Fact: Functional movement requires both adequate range and control.

Myth 6: Heavy training automatically improves movement.

Fact: Training load should match the person's current capacity and objective.

Myth 7: You need perfect symmetry.

Fact: Appropriate, controlled and adaptable movement is generally a more useful goal than absolute symmetry.

Myth 8: More exercises will fix movement faster.

Fact: The appropriate exercise, performed consistently and progressed appropriately, is generally more useful than simply adding more exercises.

Frequently Asked Questions

Why do I shift to one side when I squat?

A squat shift can have multiple contributors, including mobility, strength, balance, pain, previous injury and motor control. The movement should be investigated rather than automatically attributed to one joint.

Can poor ankle mobility affect my squat?

Yes. Ankle movement contributes to how the body descends and maintains balance during a squat. A limitation may influence movement elsewhere in the chain.

Does stretching always fix stiffness?

No. Stretching can be useful when reduced mobility is relevant, but stiffness may also involve strength, stability, pain or motor control.

Do knee clicks mean I have an injury?

Not necessarily. Joint sounds are common. If clicking is accompanied by pain, swelling, instability or loss of function, appropriate assessment is recommended.

Is a low movement-screening score dangerous?

A screening score is not a diagnosis. It provides information about movement performance that should be interpreted alongside symptoms, history and other assessment findings.

Should I stop exercising if I have movement restrictions?

Not necessarily. Training can often be modified to an appropriate level while specific movement limitations are addressed.

Can movement patterns improve?

Yes. Mobility, strength, balance, coordination and motor control can all be trained progressively.

Do I need to be an athlete for biomechanical assessment?

No. Biomechanics applies to everyday movement as well as sport.

Can posture be the only cause of pain?

Pain is complex and rarely explained by a single observation alone. Posture can be one factor, but it should be considered alongside symptoms, movement, history and other relevant factors.

How long does it take to improve movement?

It depends on the individual, the limitation being addressed, training consistency, starting capacity and the demands of the activity. Some changes may be noticed quickly, while meaningful improvements in capacity generally require consistent practice over time.

Your Body Doesn't Need Perfect Movement

There is no single movement pattern that every human being must perform.

A recreational runner doesn't need to move exactly like an Olympic athlete.

An office worker doesn't need the movement capacity of a professional athlete.

A badminton player doesn't need to move like a marathon runner.

Your movement needs to match your life, your sport, your goals and your current capacity.

The objective isn't perfect movement.

It is movement that is:

Controlled.

Adaptable.

Strong enough.

Mobile enough.

Appropriate for your demands.

The Sports2Science Approach

At Sports2Science, we believe assessment should lead to action.

Rather than simply identifying a movement difference, we aim to understand the broader picture and use the findings to guide an appropriate training or rehabilitation strategy.

The process can be thought of as:

Assess → Understand → Correct → Strengthen → Integrate → Progress

Whether you're a runner trying to improve performance, a badminton player returning to sport, a gym-goer dealing with movement limitations, or an individual who simply wants to move better, understanding your movement can help make your training more purposeful.

Final Thought: Don't Just Treat the Symptom

Your body doesn't move as separate pieces.

Your ankle doesn't know that your knee is supposed to handle everything.

Your hip doesn't know that your back is supposed to compensate.

Your nervous system simply tries to find a way to complete the task.

That is why a movement problem can sometimes appear far away from where a limitation or contributing factor exists.

Instead of only asking:

"Where does it hurt?"

also ask:

"How is the entire movement being performed?"

Instead of only asking:

"How can I stretch this tight muscle?"

ask:

"Why is this movement restricted, and what does my body need to control it?"

And instead of asking:

"How much weight can I lift?"

also ask:

"Can I control the movement and tolerate the load?"

That is the foundation of intelligent movement training.

Assess the movement. Understand the contributing factors. Build the capacity. Then progress.

Sports2Science

Assess Better. Move Better. Train Smarter. Live Stronger.

Biomechanical & Movement Assessment | Physiotherapy | Strength & Conditioning

KK Nagar & Porur, Chennai

Call / WhatsApp: 9677715990 | 7401187466

Website: www.sports2science.com