Massage, myofascial release, instrument-assisted soft-tissue mobilisation and foam rolling are widely used to reduce stiffness, improve movement and prepare the body for activity. These techniques are often explained in mechanical terms: muscles are said to be loosened, fascia released, adhesions broken down or tendons made more flexible.

But do these treatments actually change the mechanical stiffness of muscle, tendon or the combined muscle–tendon unit?

A research group from Brazil initially examined this question in a systematic review focused specifically on therapist-applied myofascial release techniques. That review included nine randomised controlled trials involving 291 healthy adults. It found no meaningful immediate changes in muscle or muscle–tendon-unit stiffness.

The same group subsequently expanded the investigation to include a much broader range of massage interventions. The updated review included 25 randomised controlled trials and 617 healthy adults and athletes. It examined manual massage, instrument-assisted techniques, roller massage, foam rolling and ball self-massage.

From myofascial release to massage more broadly

The original review focused mainly on manual and instrument-assisted myofascial release. Most studies involved short treatments applied to the calf, thigh or foot muscles.

The expanded review incorporated many of the same studies but added a larger body of evidence on foam rolling and other forms of self-massage. It also included newer studies and, for the first time, a small amount of evidence on Achilles tendon stiffness.

Massage did not significantly change muscle stiffness

The expanded meta-analysis included ten controlled studies with a total of 522 participants.

When the results were pooled, massage produced only a small trend toward reduced muscle stiffness, and the effect was not statistically significant. The certainty of this evidence was rated as moderate.

The result was similar across different forms of treatment:

• manual massage
• instrument-assisted massage
• foam rolling and other self-massage techniques

None produced a reliable reduction in muscle stiffness.

A separate analysis focusing on the medial gastrocnemius, one of the main calf muscles, also found no significant change.

Some individual studies did report small reductions in the stiffness of certain muscles, including the rectus femoris, gastrocnemius and erector spinae. However, these positive findings were inconsistent and were often associated with measurement methods that may be strongly influenced by superficial tissues.

The broader pattern was that isolated positive results did not translate into a consistent overall effect.

Measurement methods may explain conflicting results

One of the major problems in this field is that “stiffness” is measured in several different ways.

Some studies used shear-wave elastography, which uses ultrasound to estimate the mechanical properties of a specific muscle. Others used myotonometers, tissue-hardness meters, durometers or indentometers.

These methods do not measure exactly the same thing.

What about tendon stiffness?

The original review found no eligible studies that directly assessed tendon stiffness after therapist-applied myofascial release.

The expanded review identified only two studies, both examining the Achilles tendon after foam rolling of the calf.

One reported small reductions in stiffness at selected points along the tendon, while the other found no change. The study reporting reductions did not include a proper control condition, making it difficult to know whether the result was caused by the intervention.

The studies also measured different locations along the tendon and used different treatment pressures and durations. These differences may partly explain their conflicting results.

The available evidence is therefore too limited to conclude that massage or foam rolling meaningfully changes tendon stiffness.

The muscle–tendon unit consistently remained unchanged

Nine studies examined the stiffness of the complete muscle–tendon unit.

These studies evaluated the plantar flexors, knee flexors and knee extensors using passive joint torque measurements. Treatment approaches included manual massage, foam rolling, roller massage and instrument-assisted mobilisation.

All nine studies found no significant change in muscle–tendon-unit stiffness.

This is one of the most consistent findings across both reviews.

The muscle and tendon function together as an integrated mechanical system. If massage created a substantial structural change in either component, some change in the behaviour of the complete unit might be expected.

The consistent absence of an effect makes it difficult to support claims that massage acutely lengthens, releases or mechanically softens these tissues.

Does massage create a thixotropic effect?

A common theory is that massage reduces stiffness through thixotropy.

Thixotropy refers to a temporary reduction in viscosity when a material is moved, heated or compressed. Applied to the body, the argument is that massage makes tissue fluids more mobile and causes muscle or fascia to become temporarily less resistant.

This explanation is plausible at a very general level, but the clinical evidence does not show a meaningful reduction in muscle stiffness.

The pressure produced during normal massage may be insufficient to create substantial changes within deeper muscle tissue. Any small fluid-related changes may also disappear rapidly after the treatment ends.

Massage may influence fluid movement, warmth or sliding between superficial layers, but these effects should not automatically be interpreted as structural softening of muscle, fascia or tendon.

Why can range of motion improve without reduced stiffness?

One of the most important clinical findings is that massage and foam rolling can improve range of motion even when tissue stiffness does not change.

This suggests that increased movement is not necessarily caused by physically lengthening the tissue.

A more likely explanation is an increase in stretch tolerance.

After massage, a person may be able to move further before the sensation becomes uncomfortable. The nervous system may interpret stretching, pressure or movement as less threatening, allowing a greater range without any measurable change in tissue structure.

Other possible contributors include:

• altered pain sensitivity
• changes in sensory input
• temporary changes in muscle tone
• relaxation
• expectations and context
• increased confidence in movement
• local changes in blood flow and temperature

These mechanisms are often described as neurophysiological or perceptual rather than mechanical.

They may explain why a patient feels looser even though the tissue itself has not become less stiff.

Limits of the evidence

The reviews mainly included young, healthy adults and athletes. Their findings may not apply directly to people with pain, injury, restricted movement or chronic musculoskeletal conditions.

People with clinical symptoms may respond differently, particularly in outcomes such as pain, confidence and function.

The studies also used highly variable treatment protocols. Duration ranged from seconds to several minutes, and many studies did not accurately measure treatment pressure. Therapist experience, massage speed and the timing of the post-treatment assessment also varied.

These differences make it difficult to determine whether a particular treatment dose or pressure might produce a different response.

Nevertheless, the consistency of the overall findings is notable. Across many techniques, muscles and measurement sites, massage did not reliably alter myotendinous stiffness.