Muscle imbalances: What they are and why measuring each side of your body matters

Your body is not perfectly symmetrical. It is normal for one arm or leg to be slightly stronger, larger or more developed than the other.

However, when differences become more noticeable, you might begin to wonder whether you have a muscle imbalance and what it means for your health.

Muscle imbalances can develop through everyday habits, physical activity, previous injuries or differences in how you use each side of your body.

Understanding these differences is useful, particularly when monitoring muscle mass and body composition. While body composition measurements cannot diagnose a functional muscle imbalance, they can help you understand how muscle is distributed across your body and how that distribution changes over time.

Key takeaways

• A muscle imbalance refers to differences in muscle strength, size or function between muscles or muscle groups.

• Small differences between your left and right sides are common and do not automatically indicate a problem.

• Segmental body composition measurements can show differences in estimated muscle mass between body regions.

• Muscle mass and strength are not the same thing, so measurements need to be interpreted appropriately.

• Tracking changes over time can provide more useful information than focusing on individual readings.

What is a muscle imbalance?

A muscle imbalance occurs when there is a difference in strength, size or function between muscles or muscle groups.

This can involve differences between the left and right sides of your body or between muscles that work together to support a particular movement.

For example, one leg may have greater muscle mass than the other, or one side may produce more force during certain activities.

Not every difference is clinically significant. Most people naturally favour one side of their body, and some degree of muscular asymmetry is normal.

The important distinction is whether the difference is part of your normal physical variation or is associated with symptoms or changes in function.

What causes muscle imbalances?

Muscle imbalances can develop for several reasons, and there is not always one clear cause.

Common contributing factors include:

• Dominant-side use: Regularly favouring one arm or leg during everyday activities.

• Repetitive movements: Performing the same movement patterns frequently.

• Physical activity: Training or activities that place different demands on particular muscles.

• Previous injuries: Changes in movement or activity during recovery.

• Periods of inactivity: Reduced use of certain muscles during illness, injury or prolonged inactivity.

• Natural differences: Individual variations in muscle development and body structure.

These factors can influence muscle size, strength or both.

However, differences in muscle mass alone cannot establish what caused an imbalance.

Are left-right muscle imbalances normal?

Yes. Small differences between the left and right sides of your body are common.

You may naturally use your dominant hand for writing, carrying objects or performing repetitive tasks. Similarly, one leg may be used more frequently for certain activities.

Over time, these habits can contribute to differences in muscle development.

A left-right muscle imbalance does not necessarily require treatment, particularly when it is not causing pain, weakness or functional difficulties.

There is no single percentage difference that automatically indicates a problem for everyone. Your symptoms, activity levels and individual circumstances matter when considering whether an imbalance is significant.

Why does measuring each side of your body matter?

A standard bathroom scale tells you your total body weight, but it cannot show how that weight is distributed.

Even a single whole-body muscle measurement may not reveal differences between your arms, legs and torso.

Segmental body composition measurement provides additional information by estimating muscle distribution across different regions.

This can help you:

• Compare estimated muscle mass between your left and right arms

• Compare measurements between your legs

• Understand how muscle is distributed across your body

• Monitor changes in individual body segments

• Follow longer-term body composition trends

These measurements provide useful context, although they do not establish whether a difference is affecting strength or movement.

What is segmental body composition measurement?

Segmental body composition measurement involves estimating body composition in separate regions rather than treating the body as one measurement.

These regions commonly include:

• Left arm

• Right arm

• Left leg

• Right leg

• Torso

This allows you to compare estimated muscle distribution across different body segments.

For example, someone might notice that their right leg has a higher estimated muscle measurement than their left.

That information may be useful for monitoring, but it cannot explain the underlying cause or determine whether the difference requires treatment.

How does the Hume Health Pod measure muscle distribution?

Ready Health offers the Hume Health Pod, an at-home body composition device designed to provide more detailed measurements than a conventional scale.

The Pod uses eight electrodes and multi-frequency bioelectrical impedance analysis, commonly known as BIA.

During a scan, you stand barefoot on the device and hold its handles while measurements are taken across the body.

Ready Health states that the scan takes approximately 60 seconds and provides more than 45 body composition metrics.

These include skeletal muscle measurements and a segmental breakdown covering the arms, legs and torso.

This allows users to monitor estimated muscle distribution rather than relying solely on total body weight.

Can the Hume Health Pod detect a muscle imbalance?

The Hume Health Pod can show differences in estimated muscle mass between body segments.

For example, its segmental measurements may show that one arm has a different estimated muscle measurement from the other.

However, this is not the same as diagnosing a functional muscle imbalance.

The Pod cannot directly measure how much force a muscle produces, how well different muscles coordinate or whether a particular movement pattern is causing symptoms.

Ready Health describes the Hume Health Pod as a consumer wellness device rather than a medical device.

Its measurements are intended to support body composition awareness and trend monitoring, not provide a clinical diagnosis.

Muscle mass vs muscle strength: What's the difference?

Muscle mass refers to the amount of muscle tissue in your body.

Muscle strength describes the amount of force a muscle or muscle group can produce.

Although the two are related, they are not interchangeable.

A person with greater muscle mass does not necessarily have proportionately greater strength. Strength also depends on factors such as neuromuscular coordination, training experience and the movement being performed.

This distinction matters when assessing muscle imbalances.

Body composition measurements can estimate differences in muscle mass, but assessing differences in strength requires appropriate functional testing.

Can muscle imbalances affect everyday movement?

Some muscle imbalances may be associated with changes in how a person moves or performs particular activities.

Depending on the circumstances, someone might notice:

• One side feeling weaker during certain movements

• Difficulty performing an activity equally on both sides

• Reduced confidence using a previously injured limb

• Differences in endurance between sides

• Changes in movement following an injury

However, muscle asymmetry does not automatically cause pain or injury.

Many people have measurable differences between sides without experiencing any difficulties.

If weakness, pain or movement problems persist, a healthcare professional can assess whether an underlying condition or functional issue needs attention.

Why tracking muscle imbalances over time can be useful

One measurement provides information about your body at a particular moment.

Repeated measurements can help show whether differences between body segments remain relatively stable or change over time.

For example, you may want to monitor estimated muscle distribution while:

• Following a regular exercise programme

• Increasing physical activity

• Working towards body composition goals

• Returning to normal activity after a period of inactivity

• Monitoring general changes in muscle mass

The aim is not necessarily to make both sides identical.

Instead, tracking can help you understand your personal baseline and identify changes worth exploring.

If you notice a difference between your left and right sides, consider whether it has been present for some time, whether your activity levels have changed and whether you are experiencing any symptoms.

The Hume Health Pod allows you to follow measurements through the Hume Health app, making it easier to review longer-term trends.

How accurate are body composition measurements?

Body composition devices using BIA estimate measurements by analysing how electrical signals pass through the body.

Ready Health cites manufacturer-reported third-party testing comparing the Hume Health Pod with DEXA measurements.

However, this comparison does not mean every individual muscle measurement is exact.

BIA provides estimates that can be affected by hydration, recent food intake and measurement conditions.

Results are therefore best used to monitor trends rather than diagnose muscle-related conditions.

How often should you measure body composition?

There is no need to react to every small change in a body composition reading.

Muscle development and loss generally occur over longer periods, while factors such as hydration can influence measurements in the short term.

Ready Health recommends using the Hume Health Pod under consistent conditions, ideally first thing in the morning, barefoot and on a flat, non-carpeted surface.

The company also recommends focusing on weekly trends rather than daily fluctuations.

Using a consistent approach can make it easier to recognise meaningful patterns and avoid overinterpreting normal measurement variation.

When should a muscle imbalance be assessed?

Small differences in muscle size or strength are not necessarily a cause for concern.

However, medical advice may be appropriate if you notice:

• New or worsening weakness on one side

• Persistent pain associated with movement

• A noticeable change following an injury

• Difficulty completing everyday activities

• Progressive muscle loss

• Unexplained changes in muscle size or function

A clinician can consider your symptoms, medical history and physical function when deciding whether further investigation is required.

Ready Health provides a range of health tests and checks, although body composition measurements alone cannot establish the cause of muscle weakness or functional problems.

Sudden weakness on one side of the body can be a sign of stroke, even without other symptoms. Call 999 immediately if this happens.

Understanding muscle differences over time

Monitoring muscle distribution can provide useful context when tracking changes in body composition, particularly if your activity levels or fitness goals change.

The Hume Health Pod provides segmental measurements across the arms, legs and torso, allowing you to compare estimated muscle mass between different areas and follow longer-term trends.

However, these measurements should be considered alongside your general health, physical function and any symptoms you experience.

Want to understand how muscle is distributed across your body?

Explore Ready Health's Hume Health Pod to track estimated muscle mass across your arms, legs and torso, alongside other body composition measurements.

For persistent weakness, pain or unexplained changes in muscle function, seek appropriate clinical advice.

FAQs

What is a muscle imbalance?

A muscle imbalance is a difference in muscle strength, size or function between muscles or muscle groups. This may involve differences between the left and right sides of the body.

What causes muscle imbalances?

Common contributing factors include dominant-side use, repetitive activities, differences in training, previous injuries and periods of inactivity. Natural variations in muscle development can also play a role.

Is it normal for one arm to have more muscle than the other?

Yes. Small differences in muscle size between arms are common, particularly when one arm is used more frequently. A difference does not automatically indicate a medical problem.

How can you measure left-right muscle imbalance?

Segmental body composition devices can estimate muscle mass in each arm and leg. However, measuring differences in muscle strength or movement requires appropriate functional assessment.

Can the Hume Health Pod identify muscle imbalances?

The Hume Health Pod can show differences in estimated muscle mass between body segments. It cannot diagnose functional muscle imbalances or determine whether a difference is causing symptoms.

Does muscle imbalance always cause pain?

No. Many people have differences in muscle size or strength without experiencing pain. Persistent pain, weakness or movement difficulties should be assessed by an appropriate healthcare professional.