If you have ever seen a physical therapist use a specialized metal or plastic tool along a muscle, tendon, or other soft tissue, you may have wondered what they were doing.
This technique is called instrument-assisted soft tissue mobilization (IASTM).
IASTM is a hands-on treatment technique that uses specialized instruments to apply controlled pressure and movement to soft tissues. Physical therapists may use it as part of a broader rehabilitation program to address pain, mobility limitations, and movement restrictions.
But how does IASTM actually work? Does it "break up scar tissue"? And what does the research say about its effectiveness?
The short answer is that IASTM may help improve short-term pain, range of motion, and function in some patients, but the evidence does not support many of the stronger claims sometimes made about the technique. IASTM is best understood as one tool that can complement active rehabilitation rather than replace exercise or other evidence-based treatments.
What Is Instrument-Assisted Soft Tissue Mobilization?
Instrument-assisted soft tissue mobilization, or IASTM, is a manual therapy technique in which a clinician uses a specialized instrument to apply controlled mechanical pressure to soft tissues.
The instruments may be made from stainless steel, plastic, or other materials and come in different shapes and sizes.
A physical therapist may use an instrument over areas such as:
- Muscles
- Tendons
- Fascia
- Ligaments
- Other connective tissues
The clinician typically moves the instrument across the skin using specific strokes and pressures based on the patient's symptoms, movement limitations, and treatment goals.
IASTM is sometimes referred to by other names, including:
- Instrument-assisted soft tissue therapy
- Instrument-assisted manual therapy
- Graston technique
- Gua sha
- Soft tissue mobilization
These terms are related, but they are not necessarily identical. Different techniques use different instruments, treatment methods, and clinical protocols.
How Does IASTM Work?
The exact mechanism of IASTM is still being studied.
Historically, IASTM has sometimes been explained as mechanically "breaking up scar tissue," adhesions, or fascial restrictions.
However, this explanation is likely too simplistic.
Current research suggests that the effects of manual therapy are probably influenced by several factors, including:
- Mechanical stimulation of the tissues
- Changes in sensory input
- Pain modulation
- Changes in muscle tone
- Alterations in movement and range of motion
- Neurophysiological responses
- The patient's perception of pain and movement
IASTM may therefore influence how a person experiences and moves through a painful or restricted area without necessarily physically "scraping away" scar tissue.
A systematic review of IASTM research found that proposed mechanisms include mechanical, neurophysiological, and cellular responses, but also emphasized that the exact mechanisms remain uncertain.
Does IASTM Break Up Scar Tissue?
Not necessarily.
You may have heard that IASTM "breaks up adhesions" or "breaks down scar tissue."
While mechanical forces can influence tissues, there is not strong clinical evidence showing that an instrument physically breaks up scar tissue in the way this phrase often implies.
This is an important distinction.
The sensation of the instrument moving across the skin does not mean that the therapist is literally scraping away scar tissue.
Instead, IASTM may influence pain, movement, tissue loading, and the nervous system in several ways.
A physical therapist should therefore use IASTM based on the patient's clinical presentation rather than promising that the technique will "break up" or "remove" scar tissue.
Why Does the Therapist Use an Instrument Instead of Their Hands?
Physical therapists can apply soft tissue techniques using their hands, but instruments provide another way to deliver pressure.
An instrument may allow the therapist to:
- Apply consistent pressure
- Target a specific area
- Change the angle of contact
- Detect changes in tissue resistance
- Treat a larger area efficiently
- Modify the amount of mechanical input
However, an instrument is not inherently better than the therapist's hands.
The tool is simply another way of delivering manual therapy.
The most important factor is how the technique fits into the patient's overall treatment plan.
What Does IASTM Feel Like?
IASTM can feel different from traditional hands-on massage.
Patients may experience:
- Pressure
- Scraping or gliding sensations
- Mild tenderness
- Stretching
- Warmth
- Temporary sensitivity
The treatment should be appropriately dosed.
More pressure does not automatically mean better treatment.
Some patients may experience mild redness after IASTM. Bruising can also occur, particularly when excessive pressure is used or when an individual is more susceptible to bruising.
Significant pain or excessive bruising should not be considered a requirement for an effective treatment.
Does IASTM Cause Bruising?
It can, but bruising is not necessary for IASTM to work.
Redness or petechiae may occur following some IASTM techniques, but the presence of bruising should not be used as proof that the treatment was successful.
This is particularly important because aggressive treatment can create additional tissue irritation.
A physical therapist should select an appropriate amount of pressure based on the patient, tissue, diagnosis, and treatment goals.
Can IASTM Improve Flexibility and Range of Motion?
One of the more commonly studied effects of IASTM is short-term improvement in range of motion.
A systematic review and meta-analysis published in 2024 found that IASTM produced improvements in range of motion in several populations. However, the authors also noted differences between studies and limitations in the available evidence.
Another systematic review found that IASTM may produce immediate or short-term improvements in range of motion without necessarily causing meaningful changes in muscle performance.
This suggests that IASTM may be useful before movement-based rehabilitation.
For example:
IASTM → improved short-term mobility → exercise → movement retraining → functional activity
The goal is to use any short-term improvement to help the patient actively build lasting changes.
Can IASTM Reduce Pain?
IASTM may help reduce pain in some patients.
A 2024 systematic review and meta-analysis examining IASTM for musculoskeletal disorders found improvements in pain and function across several conditions, although the researchers noted limitations in the available evidence and differences between treatment protocols. (pubmed.ncbi.nlm.nih.gov)
Research has examined IASTM for conditions such as:
- Neck pain
- Low back pain
- Knee pain
- Tendinopathies
- Plantar heel pain
- Sports injuries
- Muscle soreness
However, the evidence is not equally strong for every diagnosis.
A treatment that helps one type of musculoskeletal problem should not automatically be assumed to work for every painful condition.
Can IASTM Help With Muscle Soreness?
IASTM has also been studied as a recovery technique following exercise.
Some research suggests that IASTM may help improve perceived muscle soreness and certain measures of range of motion.
However, evidence is mixed regarding whether it meaningfully improves muscle performance or accelerates physiological recovery.
This means IASTM may be useful when soreness or mobility limitations are affecting movement, but it should not be presented as a guaranteed way to "flush out toxins" or dramatically accelerate muscle recovery.
Can IASTM Help Tendon Problems?
IASTM has been investigated for several tendon-related conditions.
Researchers have examined its use for conditions involving the:
- Achilles tendon
- Patellar tendon
- Rotator cuff
- Elbow
- Plantar fascia
However, tendon rehabilitation is complex.
For most tendinopathies, progressive loading and exercise are important components of rehabilitation. Manual therapy may be incorporated to help manage symptoms or improve movement, but it should not replace appropriate tendon loading.
For example, a patient with Achilles tendinopathy may receive IASTM to address short-term symptoms or mobility limitations while also completing a progressive calf-strengthening program.
Can IASTM Improve Athletic Performance?
There is currently limited evidence that IASTM directly improves athletic performance.
IASTM may improve short-term range of motion or reduce soreness, which could potentially make movement or exercise more comfortable.
But this is different from directly increasing:
- Strength
- Speed
- Power
- Agility
- Endurance
- Sport-specific skill
Those qualities require appropriately designed training.
For athletes, IASTM is therefore better viewed as a supportive recovery or mobility technique rather than a performance treatment by itself.
How Does IASTM Fit Into Physical Therapy?
IASTM is most useful when it is integrated into a broader rehabilitation plan.
For example, imagine a patient who has knee pain and limited knee flexion.
A physical therapist might use IASTM as one part of the session to address symptoms or temporarily improve movement.
The patient might then perform:
- Mobility exercises
- Quadriceps strengthening
- Hamstring strengthening
- Balance training
- Functional movement
- Progressive resistance exercises
This creates a more complete treatment strategy.
The goal is not to repeatedly treat the tissue with an instrument.
The goal is to use manual therapy when appropriate and then help the patient develop lasting improvements in strength, mobility, and function.
Is IASTM Better Than Traditional Manual Therapy?
Not necessarily.
IASTM is one type of manual therapy.
Research comparing IASTM with other forms of treatment has produced mixed findings. Some studies demonstrate improvements in pain or range of motion, while others do not find clear superiority over other interventions.
A 2024 systematic review and meta-analysis found that IASTM can improve pain and function in patients with musculoskeletal disorders, but the certainty and quality of evidence varied across outcomes and conditions.
The important question is therefore not:
"Is IASTM the best treatment?"
Instead:
"Is IASTM appropriate for this patient and this stage of rehabilitation?"
That is where clinical reasoning becomes important.
Is IASTM Evidence-Based?
There is research supporting IASTM, but the evidence should be interpreted carefully.
Systematic reviews have reported potential improvements in pain, range of motion, and function.
At the same time, researchers have identified important limitations, including:
- Small sample sizes
- Differences in treatment protocols
- Different instruments
- Different diagnoses
- Short follow-up periods
- Lack of standardized treatment parameters
- Variation in study quality
A 2019 systematic review noted that the evidence base for IASTM was limited by methodological issues and inconsistent treatment approaches.
Therefore, IASTM should be considered an adjunctive treatment, not a stand-alone solution for musculoskeletal problems.
What Should Patients Expect During an IASTM Session?
Your physical therapist will first evaluate your movement, symptoms, strength, and functional limitations.
If IASTM is appropriate, the therapist may use an instrument over a specific area of the body.
Treatment may last several minutes depending on the area and purpose.
Afterward, your therapist may reassess your:
- Pain
- Range of motion
- Muscle performance
- Movement quality
- Functional ability
IASTM may then be followed by therapeutic exercise or another intervention.
This reassessment is important.
If your movement improves after treatment, the therapist can use that window to work on active mobility, strength, or movement patterns.
Is IASTM Safe?
IASTM is generally considered a relatively low-risk manual therapy technique when appropriately applied.
However, it is not appropriate for every patient.
A physical therapist should consider factors such as:
- Skin integrity
- Active infection
- Open wounds
- Acute injury
- Bleeding disorders
- Medications that increase bleeding or bruising
- Bone injury
- Certain vascular conditions
- Patient sensitivity
- Medical history
Patients should always tell their physical therapist about relevant medical conditions and medications before treatment.
The Bottom Line
Instrument-assisted soft tissue mobilization (IASTM) is a manual therapy technique that uses specialized instruments to apply controlled pressure to soft tissues.
Research suggests IASTM may help improve short-term pain, range of motion, and function in certain patients with musculoskeletal conditions. However, the evidence varies depending on the diagnosis and treatment protocol.
Importantly, IASTM should not be thought of as simply "breaking up scar tissue."
The effects of the treatment are likely more complex and may involve mechanical, sensory, and neurophysiological responses.
For patients, the most important thing to understand is that IASTM is one tool within physical therapy, not a replacement for active rehabilitation.
At Core Performance Physical Therapy, IASTM may be incorporated into an individualized treatment plan alongside therapeutic exercise, strength training, mobility work, movement retraining, and other evidence-based interventions.
The goal is not simply to treat a tissue. The goal is to help you move better, build capacity, and return to the activities that matter to you.
Frequently Asked Questions About IASTM
What does IASTM stand for?
IASTM stands for instrument-assisted soft tissue mobilization.
What does IASTM do?
IASTM uses a specialized instrument to apply controlled pressure and movement to soft tissues. Research suggests it may help improve pain, range of motion, and function in certain musculoskeletal conditions.
Does IASTM break up scar tissue?
There is not strong evidence that IASTM literally breaks up scar tissue. The effects are likely more complex and may involve mechanical and neurophysiological responses.
Does IASTM hurt?
IASTM can cause pressure, mild tenderness, or a scraping sensation. Treatment should be appropriately dosed and should not require significant pain.
Can IASTM cause bruising?
Yes. Some patients may experience redness or bruising, particularly when greater pressure is used. However, bruising is not required for IASTM to be effective.
Does IASTM improve flexibility?
Research suggests IASTM can produce short-term improvements in range of motion in some individuals
Is IASTM the same as Graston Technique?
Graston Technique is a specific branded approach that uses instruments as part of soft tissue treatment. IASTM is the broader category describing instrument-assisted soft tissue mobilization techniques.
Can IASTM replace exercise?
No. IASTM is generally best used as an adjunct to active rehabilitation rather than a replacement for strengthening, mobility exercises, and functional training.
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