Instrument Assisted Soft Tissue Mobilisation appears in most serious Achilles rehabilitation protocols — but rarely in the early phase. Understanding what IASTM does, when it is clinically appropriate, and what the research actually supports helps patients engage more meaningfully with their rehabilitation and set realistic expectations for a technique that is frequently misunderstood.
In this article
If you have spent any time in physiotherapy for a tendon injury, you have likely encountered IASTM — the practice of applying stainless steel or similar instruments to the skin over soft tissue, using controlled pressure and specific stroke patterns to mobilise the underlying structures. You may know it by its commercial names: Graston Technique, ASTYM, or simply "scraping" as it is often called colloquially after the muscle scraping videos that circulate on social media.
For Achilles tendon rupture specifically, IASTM is not an early intervention. Clinical rehabilitation protocols from institutions including Massachusetts General Hospital and Stapleton Orthopaedics specify that gentle IASTM may be introduced directly to the repaired tendon from approximately 16 weeks post-surgery — well into the remodelling phase, after the initial healing cascade has completed. Understanding why this timing matters requires understanding what IASTM does at a tissue level.
- What IASTM Is
- What It Does to Tissue
- When in Achilles Recovery
- What the Evidence Shows
- What IASTM Is Not
- The Honest Position
What IASTM Is
IASTM involves applying specialised instruments — typically contoured stainless steel, titanium, or plastic tools — to the skin surface over targeted soft tissue. The clinician applies controlled compressive and shear forces using various stroke techniques: sweeping, fanning, and cross-fibre strokes applied at angles to the tissue. The instrument acts as an extension of the clinician's hands, concentrating force at the contact point and enabling detection of — and treatment of — tissue irregularities that manual palpation alone might miss.
The pressure applied can be varied from very light (neurological stimulation, surface drainage) through moderate (soft tissue mobilisation) to firm (scar tissue remodelling). The appropriate pressure, instrument, and technique depends on the tissue being treated, the phase of healing, and the specific goal of the session. This is not a technique where more pressure equals better results — the research is clear that pressure magnitude is a clinically significant variable that must be appropriately calibrated.
What It Does to Tissue
The mechanisms by which IASTM produces its effects are better understood than its clinical outcomes. Three primary mechanisms have been established through animal and human research.
Fibroblast recruitment and activation. This is the most important mechanism for tendon healing. Fibroblasts are the cells responsible for producing collagen — the structural protein that forms tendon tissue. In the landmark animal studies by Davidson (1997) and Gehlsen (1999), IASTM applied to rat Achilles tendons with enzyme-induced injuries produced a significantly increased number and activation of fibroblasts compared to controls. Gehlsen's work further demonstrated that fibroblast production is directly proportional to the magnitude of IASTM pressure used — establishing a dose-response relationship. More activated fibroblasts means more collagen production, which in theory accelerates and improves the structural quality of tendon repair.
Scar tissue and adhesion mobilisation. The body's acute response to tendon injury produces type III collagen in a disorganised pattern — laying down fibres rapidly rather than in the aligned, longitudinal arrangement of healthy tendon. This disorganised scar tissue is mechanically inferior and can restrict the gliding of the tendon within its sheath. IASTM's compressive and shear forces are thought to break down and remodel these adhesions, promoting more organised collagen remodelling during the late healing phase. This is why IASTM is introduced in the remodelling phase rather than the proliferative phase — it is targeting the reorganisation of existing repair tissue, not the initial healing cascade.
Neurophysiological effects. IASTM stimulates mechanosensitive neurons through skin deformation. This mechanoreceptor activation has two relevant effects: pain modulation through competing sensory input (similar to the gate control theory of pain), and reflexive changes in local muscle tone. The neurophysiological response may partly explain the acute improvements in range of motion observed after single IASTM sessions, which occur too quickly to be explained by structural tissue changes.
"Fibroblast production is directly proportional to the magnitude of IASTM pressure used — establishing a dose-response relationship that has important clinical implications."
When in Achilles Recovery
The timing of IASTM introduction is one of the most important and commonly misunderstood aspects of the technique for Achilles rupture patients. The phases below reflect the consensus position from published clinical rehabilitation protocols for both surgical repair and conservative management.
Weeks 0–6 — Acute / Protective Phase
IASTM: Not appropriate
The tendon is in the inflammatory and early proliferative healing phase. The repair is fragile. IASTM is contraindicated directly over the repair site. Soft tissue work may be appropriate on the calf and surrounding musculature away from the repair — but not on the tendon itself.
Weeks 6–12 — Early Rehabilitation
IASTM: Surrounding tissue only
Boot removal is typically occurring in this phase. IASTM may begin on the gastrocnemius and soleus muscles — addressing the stiffness and adhesions that develop during immobilisation. The tendon repair site itself is still not appropriate for direct IASTM treatment.
Weeks 12–16 — Progressive Loading
IASTM: Scar tissue, cautious approach
Scar tissue around the repair site becomes a clinical target. IASTM may be applied to the peritendinous tissue and surgical scar (if applicable) with clinical judgement. Direct tendon treatment remains cautious. The repair is strengthening but not yet mature.
Week 16+ — Remodelling Phase
IASTM: Direct tendon treatment appropriate
Published protocols specify that gentle IASTM may be initiated directly to the tendon from approximately 16 weeks post-repair, if clinically indicated. This is the phase where fibroblast activation and collagen remodelling benefit most from IASTM stimulation. Progression is guided by tissue response.
Do not self-administer IASTM to a healing Achilles
IASTM instruments are commercially available and frequently used for self-treatment by athletes. For a healing Achilles tendon rupture, self-administered IASTM directly over the repair site is not appropriate. The timing, pressure, technique, and tissue response must be assessed by a qualified physiotherapist. Applied too early or too aggressively, IASTM can disrupt the healing tissue. The instruments in social media "scraping" videos are typically being used on healthy muscle — not on actively healing tendon repairs.
What the Evidence Shows
The evidence for IASTM in Achilles tendon conditions is genuine but not straightforward. It separates into three categories: animal research (strong mechanistic evidence), human research on Achilles tendinopathy (moderate quality, positive signals), and human research on Achilles rupture specifically (very limited).
Animal research. The most compelling evidence comes from rat models. Davidson (1997) and Gehlsen (1999) both demonstrated significantly increased fibroblast activation in IASTM-treated Achilles tendons compared to controls. This is the mechanistic foundation for the technique's use in tendon injury — and it is solid. The limitation is the familiar translation problem: rat tendons are not human tendons, and animal models of Achilles injury do not replicate the conditions of surgical repair or conservative management in humans.
Achilles tendinopathy research. The strongest human clinical data comes from the McCormack and Bovard (2016) randomised controlled trial, which compared eccentric exercise alone to eccentric exercise combined with IASTM in patients with Achilles tendinopathy. The combination group showed significantly greater improvements in VISA-A scores — the validated patient-reported outcome measure for Achilles tendinopathy — at 12 weeks, and these improvements were sustained at 26 and 52 weeks. This is meaningful evidence that IASTM adds value beyond exercise alone in a tendinopathy context.
52wk
The McCormack & Bovard 2016 RCT showed IASTM combined with eccentric exercise produced greater VISA-A improvements than eccentric exercise alone — and these gains were maintained at 52 weeks.
McCormack JR, Underwood FB, Slaven EJ, Cappaert TA. J Sport Rehabil. 2016;25(4):399–402.
Range of motion and flexibility. Multiple studies — including the 2024 Ikeda et al. randomised controlled trial — have shown that IASTM increases ankle range of motion and stretch tolerance. Importantly, Ikeda found that 6 weeks of IASTM increased joint flexibility without changing muscle or tendon stiffness. This suggests the ROM improvements are driven by neurophysiological mechanisms — increased stretch tolerance — rather than true structural tissue changes. This distinction matters: IASTM can help restore range of motion lost during immobilisation, but may not directly remodel the mechanical properties of the tendon itself.
Tendon stiffness and mechanical properties. Here the evidence is less encouraging. Multiple studies, including a systematic review, have reported that IASTM has no significant effect on tendon mechanical or material properties as measured by shear wave elastography. The conclusion from the current evidence base is that IASTM improves ROM, reduces pain, and activates fibroblasts — but direct evidence that it improves the mechanical quality of tendon tissue in humans remains limited.
Achilles rupture specifically. There is limited published research specifically on IASTM in Achilles tendon rupture repair rehabilitation, as distinct from Achilles tendinopathy. The inclusion of IASTM in clinical rehabilitation protocols from major orthopaedic centres reflects the extrapolation from tendinopathy evidence and animal research, combined with clinical experience — not a strong body of rupture-specific RCT evidence. This is worth acknowledging without dismissing the technique.
What IASTM Is Not
A significant amount of misinformation circulates about IASTM, driven partly by its high visibility on social media and partly by marketing from commercial systems.
IASTM does not "break up scar tissue" in the dramatic sense often depicted online. It applies mechanical stimulation that, over a course of treatment, may facilitate remodelling of disorganised collagen — but this is a gradual biological process, not an immediate physical disruption. A single session does not restructure scar tissue.
IASTM is also not interchangeable across all instruments and techniques. The commercial systems — Graston, ASTYM, SMART Tools — differ in instrument design, applied technique, and training requirements. The research is not uniformly applicable across all systems; some studies use specific techniques that cannot be generalised to all IASTM approaches.
And IASTM is not a stand-alone treatment. Every study showing positive outcomes for IASTM in tendon conditions combines it with exercise — typically eccentric loading for Achilles conditions. IASTM without an accompanying progressive loading programme is not a well-supported approach.
The key question to ask your physiotherapist
If your physiotherapist recommends IASTM, the useful questions are: What specifically are you targeting — muscle, peritendinous tissue, or the tendon itself? Where are we in the healing timeline and is this timing appropriate? How does this fit into the overall loading programme? A clear answer to these questions indicates a physiotherapist who is using the technique purposefully rather than reflexively.
The Honest Position
IASTM is a legitimate physiotherapy technique with a credible mechanistic rationale and meaningful clinical evidence in Achilles tendinopathy. For Achilles rupture specifically, its role is best understood as a rehabilitation-phase adjunct — introduced from approximately 16 weeks post-injury when the tissue is in the remodelling phase — targeting fibroblast activation, scar tissue organisation, and restoration of range of motion.
It is not a miracle intervention and not appropriately introduced early in Achilles rupture recovery. The evidence for its effects on tendon mechanical properties in humans is limited. It should always be combined with progressive loading rather than used as a substitute for it.
For a patient working with a skilled physiotherapist who introduces IASTM at the appropriate phase, in combination with a progressive calf loading programme, the evidence supports its value as part of a comprehensive rehabilitation approach. For a patient considering purchasing instruments for home use and self-treating an actively healing Achilles tendon, the evidence does not support this and the risk is real.
References
Davidson CJ, Ganion LR, Gehlsen GM, Verhoestra B, Roepke JE, Sevier TL. Rat tendon morphologic and functional changes resulting from soft tissue mobilization. Med Sci Sports Exerc. 1997;29(3):313–319. Foundational animal study showing IASTM increases fibroblast recruitment in Achilles tendon injury.
Gehlsen GM, Ganion LR, Helfst R. Fibroblast responses to variation in soft tissue mobilization pressure. Med Sci Sports Exerc. 1999;31(4):531–535. Dose-response relationship between IASTM pressure and fibroblast production in rat Achilles tendon.
McCormack JR, Underwood FB, Slaven EJ, Cappaert TA. Eccentric exercise versus eccentric exercise and soft tissue treatment (Astym) in the management of insertional Achilles tendinopathy. J Sport Rehabil. 2016;25(4):399–402. RCT showing IASTM + eccentric exercise superior to eccentric exercise alone at 12, 26, and 52 weeks.
Ikeda N, Hiratsuka K, Isaka T. Effect of 6-week instrument-assisted soft tissue mobilization on joint flexibility and musculotendinous properties. Sports. 2024;12(6):150. Six-week RCT showing IASTM increases stretch tolerance and ROM without changing tendon stiffness.
Cheatham SW, Lee M, Cain M, Baker R. The efficacy of instrument assisted soft tissue mobilization: a systematic review. J Can Chiropr Assoc. 2016;60(3):200–211. Systematic review of IASTM evidence across multiple conditions.
Stapleton Orthopaedics Rehabilitation Protocol for Achilles Tendon Repair, 2024. IASTM introduced from 16 weeks post-repair as per published clinical protocol.
Massachusetts General Hospital Physical Therapy Guidelines: Achilles Rupture Repair Protocol. Specifies IASTM from 16 weeks if clinically indicated, as part of phase-based rehabilitation.