Yes, and it pushes the number down. A 2025 study of the rectus femoris found that thicker subcutaneous adipose tissue was associated with lower handheld stiffness values regardless of the muscle underneath. That makes raw readings unsafe to compare between patients. It does not stop the same patient's readings from being comparable across visits.
What does the research actually show?
The interference is real and it has a direction. A 2025 study in the Scandinavian Journal of Medicine and Science in Sports compared handheld myotonometry against shear wave elastography in the rectus femoris. It reported a negative relationship between subcutaneous adipose tissue thickness and the handheld stiffness value, and concluded that the two methods are not interchangeable because of that interference.
Read plainly, the layer above the muscle absorbs some of the mechanical impulse before it reaches the muscle. Thicker layer, softer-looking result. The muscle may be identical.
Is the reading measuring fat instead of muscle?
No, and this is where the two findings have to sit together. A 2026 study in Diagnostics used layer-specific shear wave elastography to ask which tissue layer a handheld stiffness value actually tracks. Handheld values corresponded more closely with deeper muscle layers than with superficial ones, at moderate correlations of roughly 0.52 to 0.55.
So the signal originates in the muscle. The overlying tissue scales it. That is a bias in the absolute value, not a reading of the wrong structure.
| Comparison you might want to make | Affected by fat thickness? | Defensible? |
|---|---|---|
| This patient today vs the same site 4 weeks ago | Offset is roughly constant | Yes |
| Left side vs right side in the same patient | Usually similar thickness, not guaranteed | Mostly, with caution |
| Patient A vs patient B, raw values | Directly affected | No |
| Patient vs a published reference range | Directly affected | No |
| Handheld value vs an elastography value | Different scales and interference | No, not interchangeable |
Why does within-patient change survive this problem?
Because the thing causing the bias barely moves between visits. Subcutaneous tissue thickness at one anatomical site in one patient is close to fixed across four to twelve weeks of care. A fixed offset shifts both readings by roughly the same amount, so the difference between them still reflects the muscle.
This is the same logic behind repeating any measurement under the same conditions. The absolute number is contaminated. The change is not, provided the site, the position, and the operator stay the same.
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 these readings otherwise?
Repeatability is good, which is a separate question from accuracy. A 2024 systematic review of 48 studies covering 31 muscles reported intra-rater and inter-rater reliability coefficients frequently in the good to excellent range. A device can be highly repeatable and still carry a systematic offset from body composition. Both statements are true here.
Practically, that combination is what makes tracking work and benchmarking fail. You can trust that the same site measured the same way gives you the same answer. You cannot treat that answer as a body-composition-independent property of the muscle.
What should you do differently?
Fix everything you can control and write down the rest. Mark the measurement site so it is reproduced at the next visit. Keep the patient in the same position. Keep the same operator where staffing allows. Note significant weight change between visits, because that is the one variable that can shift the offset mid-course.
Then interpret narrowly. A drop in a patient's reading across four weeks may reflect a change in the tissue. A patient whose reading is lower than another patient's tells you nothing at all, and presenting it as if it does will not survive the first informed question.
Frequently Asked Questions
Does body fat change a handheld muscle stiffness reading?
Yes. A 2025 study in the Scandinavian Journal of Medicine and Science in Sports reported a negative relationship between subcutaneous adipose tissue thickness and MyotonPRO stiffness values in the rectus femoris, meaning thicker tissue over the muscle produces lower readings.
Does the reading come from the fat layer or the muscle?
Mostly from deeper tissue. A 2026 study in Diagnostics used layer-specific shear wave elastography and found handheld stiffness values corresponded more closely with deeper muscle layers than superficial ones, with moderate correlations around 0.52 to 0.55.
Can you compare stiffness readings between two different patients?
Not usefully for absolute values. Two patients with different body composition can produce different numbers at the same site with comparable underlying muscle, so cross-patient comparison of raw values is not defensible.
Does this make handheld stiffness measurement useless?
No, it narrows what the number is for. Subcutaneous tissue thickness in one patient at one site is essentially constant across a few weeks of care, so it offsets the readings without hiding the change between them.
Is handheld measurement interchangeable with shear wave elastography?
No. The 2025 rectus femoris study concluded the two are not interchangeable, specifically because of adipose tissue interference. They answer related questions on different scales rather than producing the same value.
How reliable are handheld stiffness readings despite this?
Repeatability is generally good. A 2024 systematic review of 48 studies across 31 muscles reported intra-rater and inter-rater reliability coefficients frequently in the good to excellent range, which is about consistency rather than absolute accuracy.
What should you record so fat thickness does not distort a comparison?
Fix the measurement site, the patient position, and the operator, and mark the site so it is reproduced at the next visit. Also note significant weight change between visits, because that is the one thing that can shift the offset.
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.