Flexibility vs Range of Motion

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Flexibility vs Range of Motion

Abstract

Flexibility and range of motion are closely related but not identical. Both concern how far a joint can move, but each depends on different factors and leads to different results. Flexibility refers to capacity of joints to change position, which is influenced by the mechanical and sensory properties of muscles, tendons and connective tissues that determine how much these structures can lengthen. Range of motion, on the other hand, is the measurable movement of a joint that results from the combined effects of tissue extensibility, joint structure, ligament and capsule limits, muscle activity and pain perception. Confusing the two conceals key mechanisms and leads to errors in testing or training design.

Medical disclaimer

This content is for education purposes only. It does not replace medical advice. Do not start or change exercise or rehabilitation programmes without consulting a qualified healthcare provider.

Last updated: 19th October 2025.

Change log: Article reformatted.

Key points (TL;DR)

Flexibility is a motor ability that shows how well a joint, or several joints working together, can move through their range to assume positions required by varying conditions.
Many people use the terms “flexibility” and “range of motion” as if they mean the same thing, but they do not.
Flexibility is a capacity of the body to change its shape (by altering the position of its joints) and range of motion is a way to measure that capacity.
Other methods for measuring flexibility include stretch tolerance, passive stiffness, maximum voluntary force and rate of motion.
It is more precise to use the term “flexibility” only when referring to the motor ability itself, and to reserve “range of motion” for describing the measurable degrees of a joint’s angle during testing.

Table of contents

1. Introduction

Many clinicians treat flexibility and range of motion as the same thing. They are related, yet not identical. Flexibility is a motor ability showing how freely joints can change position. Range of motion is the actual joint angle measured during testing. Confusing these terms conceals key differences in how they work, how they are measured and how they guide clinical decisions.

2. Definitions and scope

For clarity in this article:

Flexibility is a motor ability that allows a joint to move through different positions. Clinicians assess it as static passive, static active, dynamic passive or dynamic active flexibility.

Range of motion is the measurable angle of movement, recorded with a goniometer, inclinometer, camera-based system or wearable sensors.

The capacity of tissues to lengthen is called extensibility. It is not flexibility. Range of motion shows the result of extensibility, neuromuscular control and how the test is done, while flexibility is the ability that makes such movement possible.

3. Background and theory

Flexibility, as a motor ability, results from the coordinated interaction of several factors: the extensibility of tissues, the level of neural drive, modulation of reflexes, tolerance to stretching and the ability to control movements specific to the task. The measurement of range of motion depends greatly on the posture used for testing, the external load applied, the measuring device, the examiner’s method and the subject’s tolerance to discomfort at the end of the range.

Analyses of mechanisms show that an increase in range of motion after static passive stretching comes mainly from a reduction in the overall stiffness of the muscle–tendon unit and from a higher tolerance to stretching. In most studies, changes in muscle fascicle length are minimal or negligible. This shows that most improvements in range of motion result from altered perception and passive mechanical characteristics rather than from significant structural changes within the tissues. ^[1,2]

4. Evidence Synthesis

A 2023 systematic review and meta-analysis of 47 trials confirmed that one properly executed session of stretching brings small yet statistically significant increases in range of motion across several standard tests. Within normal clinical limits, there were no consistent differences between stretching methods or intensities. The outcome depends on the muscle group: hamstrings and triceps surae show clearer and more reliable gains than the hip adductors. ^[3] Dynamic and ballistic stretches, when performed with the same total workload as static stretching, also produce immediate range of motion improvements of comparable size. ^[4]

A 2024 systematic review showed that consistent stretch training, maintained for at least two weeks, reliably increases joint range of motion. When comparing methods, static passive stretching and proprioceptive neuromuscular facilitation (static active stretching) often produce large gains, while dynamic active stretching gives moderate results when the total training volume is the same. ^[5] A 2025 multivariate meta-analysis examined how different mechanisms produce these outcomes. Static passive stretching lowered overall stiffness after both single and repeated sessions and improved stretch tolerance after repeated sessions. The increase in range of motion correlated both with reduced stiffness and with greater tolerance to stretch. Average changes in muscle fascicle length were not statistically significant. ^[1]

Reviews of muscle architecture show small increases in fascicle length only when stretching uses high volumes and strong intensities. However, there are no consistent changes in pennation angle or muscle thickness. These findings confirm that improved perception and passive mechanical properties explain most of the range of motion increase. ^[2]

Measurement methods greatly affect the recorded range of motion. Recent clinical research confirms that both intra- and inter-rater reliability for active and passive knee range of motion can be high when using universal goniometers, medical inclinometers or smartphone applications. Among these, inclinometers usually give the best combination of reliability and efficiency. Even so, differences in technique still lead to device-dependent absolute values and standard errors within 1-4° under controlled conditions. ^[6,7] Earlier reviews of devices used for measuring cervical range of motion showed the same pattern. Several instruments can give reliable and valid results if used with standardised procedures, but variations in methods continue to make pooled analysis unreliable. ^[8]

Resistance exercises done through a full range of motion can increase joint flexibility as much as conventional stretching in healthy adults. Meta-analyses and controlled studies show that when resistance movements challenge the end positions of a joint, the resulting gains in flexibility match those from stretching. ^[9-11] This confirms that flexibility develops through specific control of movement and muscle tension in given tasks, not just by lengthening tissues.

5. Practical Implications

Although “flexibility” and “range of motion” are commonly used interchangeably, ensure you do not confuse them. Flexibility is the ability of joints to change position and allow movement; range of motion is simply the measurable angle achieved in a given test. A person may display limited range of motion in a specific assessment because of the testing method, their tolerance at the end of the range or the torque applied by the examiner, but still have the neuromuscular capacity to move through greater ranges in other actions.

You must match each assessment to its specific flexibility sub-type. Use static passive, static active, dynamic passive and dynamic active tests according to the functional demands you want to evaluate. Understand that different sub-types will show different ranges of motion because their neural control and stretch tolerance are not the same.

Standardise how you measure flexibility. Always use the same anatomical landmarks, end-feel criteria, torque and movement speed. When possible, use inclinometers or validated smartphone tools for accuracy. Record the device and exact testing protocol so you can interpret any change scores in relation to known standard errors.

To improve range of motion quickly before activity, use brief static passive or dynamic active stretches. These bring only small, short-term gains. For lasting improvement, you must use a consistent stretching programme that increases your tolerance to the stretch and reduces passive stiffness. Another effective method is strength training through the full range of motion, loading the end positions and building control in every part of the movement.

Be precise and consistent in your use of terminology. When referring to the ability of tissues to lengthen, use the term “extensibility.” Keep “flexibility” for describing the motor ability that depends on extensibility, strength and coordination. Use range of motion only when you refer to the measurable degree of movement in a joint.

6. Counterarguments and limitations

Insisting on rigid terminology may overlook how athletes and therapists already use these words in real life. Many coaches and clinicians treat flexibility as a practical result: a mix of tissue extensibility, neural tolerance and joint mechanics. A narrow motor definition can fail to describe what happens in real training. In everyday speech, people think of flexibility as “how far you can move”, so people opposed to the definitions I have used in this article may argue that I am splitting hairs with technical language that only confuses students and clients. In research, authors often report flexibility and range of motion as if they mean the same thing. If we draw a strict line between them, we could make systematic reviews and meta-analyses harder to interpret. Measurement cannot be pure either. Goniometry shows tolerance, skill and context, not only joint angle. Dynamic work adds more noise: speed, force and coordination all change available motion. Dividing terms into silos has the potential to weaken teaching that should connect physiology, biomechanics and rehabilitation. Precision matters, but when definitions become too strict, we can lose clarity, transfer, ecological validity and sound decision making in practice.

However, my position on the subject is that precise terminology brings clarity instead of confusion. When we use flexibility to describe the capacity of the motor system and range of motion to describe the measured joint angle, we can clearly link cause and effect. Mixing these terms in casual language hides the real mechanisms and weakens understanding. In teaching, we can keep familiar expressions but still explain the exact definitions needed for testing and research. The old habit of using both terms interchangeably is a reason for change, not for keeping the confusion; scientific language must evolve to remove bias and make meta-analyses sharper. Variation in measurement does not mean we should blur the concepts. We can standardise our testing, note the conditions and still name the variable correctly. Dynamic tasks differ, which is exactly why range of motion should describe the actual angle measured under specific conditions, while flexibility should refer to the underlying ability shaped by muscles, connective tissues and neural control. Clear definitions unite fields rather than dividing them. When physiologists, biomechanists and clinicians use the same language, they can better compare findings, refine training and improve treatment. Precision strengthens communication, study design and practical application.

7. Conclusion

Flexibility and range of motion are related but not identical. Both concern how far a joint can move, but they describe different phenomena. Flexibility is a motor ability, i.e., it is the capacity to reach and control positions in varied conditions. Range of motion, on the other hand, is a measured angle taken under defined testing protocols. Mechanistic and clinical research shows that changes in range of motion usually reflect altered stretch tolerance and passive stiffness, not major structural elongation. Range of motion can be measured reliably when procedures are standardised, but the measurement does not equal the motor ability itself. Practitioners must choose assessment types and methods that serve the functional aims of training or therapy. When tissue lengthening is discussed, the correct term is “extensibility.” Range of motion values should be understood as context-dependent indicators of flexibility, not as flexibility itself.

Read the next article: The Anatomy of Flexibility

Medical disclaimer

This content is for education purposes only. It does not replace medical advice. Do not start or change exercise or rehabilitation programmes without consulting a qualified healthcare provider.

References

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