They are three separate parameters of the same tissue, reported in three different units. Tone is oscillation frequency in hertz. Stiffness is resistance to deformation in newtons per meter. Elasticity is logarithmic decrement, a unitless number. A device can report all three from one measurement, and they do not have to move together.
What does each parameter actually measure?
Each one describes a different feature of how the tissue responds to a small mechanical impulse. A myotonometer taps the tissue and records the oscillation that follows. The shape of that oscillation contains more than one piece of information.
| Parameter | Unit | What it describes | Direction of interest |
|---|---|---|---|
| Tone | Hertz (Hz) | Natural oscillation frequency of the resting tissue | Higher suggests greater resting tension |
| Stiffness | Newtons per meter (N/m) | Resistance to a force that changes tissue shape | Higher means more resistance to deformation |
| Elasticity | Logarithmic decrement (unitless) | How quickly the oscillation dampens out | Lower decrement means more elastic |
| Relaxation time | Milliseconds (ms) | Time for the tissue to recover its shape | Reported by some devices as supporting context |
The elasticity convention causes the most confusion in practice, because the number runs backwards from the word. A lower logarithmic decrement means the tissue dissipates less energy and is described as more elastic. Reading a rising decrement as rising elasticity is the single most common misinterpretation.
Why do clinicians conflate tone and stiffness?
Because everyday clinical language never separated them. A practitioner saying a region feels toned, tight, or stiff is usually describing one palpation impression, not three parameters. The device did not create the ambiguity, it exposed it.
Patients bring their own version of the same problem. A 2022 study in BMC Musculoskeletal Disorders on how patients distinguish discomfort, pain, and stiffness found the terms overlap in patient use, with stiffness described largely through restricted movement and pain described as more severe and limiting. When both sides of the conversation use the same word loosely, a number with defined units is worth having.
Which parameter should you track clinically?
Stiffness, as the headline, with the others as context. Stiffness is expressed in physical units, it maps most closely to what a practitioner means when they describe a region as tight, and it is the parameter with the deepest supporting literature in musculoskeletal work. The 2023 Journal of Athletic Training review on the utility of myotonometry positions these measures as an objective supplement to standard rehabilitation assessment rather than a replacement for it.
Tone and elasticity earn their place when stiffness alone looks flat. A patient whose stiffness has not moved but whose decrement has may be showing a change the headline number missed. Neither result should be read as a diagnosis.
Survey data: In a 2026 survey of 455 patients who stopped chiropractic care, 58% cited perception-based reasons: 36% felt no progress, and 22% felt better and stopped. Neither group was shown that their soft tissue stiffness was still elevated.
How reliable are the three numbers?
Good to excellent in most published work, with site-dependent exceptions. A 2026 study in BMC Sports Science, Medicine and Rehabilitation tested 84 recreational athletes and reported intra-session reliability coefficients of 0.95 or higher and inter-session coefficients of 0.94 or higher across tone, stiffness, elasticity, relaxation time, and creep in the knee extensors and flexors.
The picture is more mixed over a wider set of sites. A 2025 systematic review in the Journal of Bodywork and Movement Therapies pooled 15 studies of neck and back muscles and reported most outcomes as good to excellent, alongside a small number of outcomes that were only moderate or poor. Reliability is a property of the site and the protocol, not a fixed property of the device.
Reference work matters here too. A 2022 paper in Scientific Reports established protocol and reference values for minimal detectable change, which is the figure that separates a real shift from measurement noise. Without it, a small movement in any of the three parameters is uninterpretable.
Does a higher reading mean the patient has a problem?
No, and treating it that way is the fastest route to overclaiming. A single elevated stiffness reading may reflect training history, muscle mass, recent activity, body position, or the site you chose. It does not diagnose, and it does not predict recurrence.
The interpretable signals are narrower: change over time in the same patient at the same site, or a substantial left-to-right difference within the same patient. Both need to clear the minimal detectable change threshold before they mean anything. And stiffness and pain are independent, so a patient can improve on one without improving on the other, without either number being wrong.
Frequently Asked Questions
What is the difference between muscle tone and muscle stiffness?
Tone is the natural oscillation frequency of a resting muscle, reported in hertz. Stiffness is the resistance of that tissue to a deforming force, reported in newtons per meter. They usually move together but they are different measurements and can diverge.
What does elasticity mean in myotonometry?
Elasticity is reported as logarithmic decrement, a unitless number describing how quickly the tissue's oscillation dies away after the device's impulse. A lower decrement means the tissue returns its energy more efficiently, which is described as more elastic.
Which parameter should a clinician actually track?
Stiffness is the most direct answer for soft tissue assessment, because it is expressed in physical units and maps to what a practitioner is trying to describe when they say a region feels tight. Tone and elasticity are useful supporting context rather than the headline.
Are these three numbers redundant?
No. They derive from the same oscillation but describe different features of it, and they do not have to change in the same direction after an intervention. Reporting only one loses information the device already captured.
How reliable are these measurements?
A 2026 study of 84 athletes reported intra-session and inter-session reliability coefficients at or above 0.94 for tone, stiffness, elasticity, relaxation time, and creep in the knee extensors and flexors. A 2025 systematic review of neck and back muscles found most outcomes good to excellent, with some exceptions.
Does higher stiffness mean something is wrong?
Not on its own. A stiffness reading may reflect training history, muscle mass, posture, or recent activity as easily as a problem. The interpretable signal is usually change over time in the same patient at the same site, or a large left-to-right difference.
Is the terminology consistent across the research?
Reasonably consistent in device-based studies, less so in clinical conversation. Patients and practitioners frequently use tone, tightness, and stiffness interchangeably, which is one reason a numeric parameter with defined units is useful in a re-examination.
One approach is to add a second channel of objective data alongside subjective pain reports. Options include soft tissue stiffness measurement (such as MuscleMap), range-of-motion testing, and posture analysis. Each gives you something concrete to show the patient rather than asking them to take your word for it.