Shockwave Therapy for Chronic Muscle Injury and Fibrosis: What Does the Evidence Show?

Clinical evidence supports ESWT as a promising adjunct in selected muscle injuries, while mechanistic studies provide a biologically plausible antifibrotic mechanism. The direct clinical muscle-injury literature is still small, so shockwave is best understood as a tissue-remodeling adjunct within a diagnosis-led plan built on progressive loading, not as a stand-alone fix for an old strain.

Does Shockwave Have an Antifibrotic Effect?

Preclinical evidence says yes. Radial shockwave, combined with diathermy, has reduced fibrosis and profibrotic TGF-β1 signaling in a skeletal-muscle fibrosis model, while other shockwave studies have demonstrated reduced fibrosis-related collagen and myofibroblast signaling in human scar fibroblasts and experimental fibrotic tissue.

Human clinical muscle-injury trials primarily measure pain, function, lesion size and return to activity rather than biopsy-confirmed collagen remodeling. The biological antifibrotic signal is therefore stronger than the current direct human histologic evidence. Both statements are true at the same time, and keeping them separate is the key to reading this literature accurately.

Three levels of evidence

1. Clinical muscle-injury studies. These ask whether people with muscle injuries recover better with ESWT. The best summary is a 2023 systematic review.
2. Mechanistic and histologic studies. These ask what shockwave does to collagen, signaling molecules and fibroblasts, using animal models and cell cultures.
3. Adjacent evidence. Myofascial pain research and broad sports-medicine reviews add context but answer different questions.

Clinical evidence in muscle injury

A systematic review of eight studies involving 143 adults found promising clinical signals for ESWT after muscle injury, including improvements in pain, function, ultrasound lesion size and return-to-play outcomes. The included studies covered indirect and direct muscle injuries and muscular hematomas. Depending on the study, ESWT was associated with lower pain scores, better function, smaller lesions on ultrasound, faster return to play and lower reinjury rates (Mazin, 2023).

However, the evidence base was small, heterogeneous and included only two randomized trials, so definitive treatment protocols cannot yet be established. The remaining studies were one prospective and two retrospective observational studies and three case reports. The authors described the evidence as promising and called for higher-quality studies to define timing, shockwave type and parameters. The review also did not specifically address long-standing post-strain fibrosis, so it cannot by itself show what ESWT does to chronic scar in a calf that was injured years ago.

Experimental muscle fibrosis

The most direct antifibrotic data in skeletal muscle come from an immobilization model. In rabbits whose knees were immobilized in extension for four weeks to induce muscle fibrosis and contracture, researchers then compared untreated animals, natural recovery, radial shockwave, ultrashort-wave diathermy and the two combined. Outcomes included muscle cross-sectional area, collagen deposition, knee range of motion, TGF-β1 and HIF-1α.

In this experimental skeletal-muscle fibrosis model, radial shockwave combined with ultrashort-wave diathermy reduced fibrosis and contracture and downregulated the overexpression of major profibrotic signals including TGF-β1 and HIF-1α. The combined treatment produced the largest effect and the best recovery of joint function, outperforming either therapy alone (Huang, 2021).

Limitations matter here. This was an animal model of immobilization-induced fibrosis, not a strained human calf, and the published abstract reports the clearest result for the combined treatment. It should not be read as direct proof of an identical effect size in chronic human calf fibrosis.

Human scar fibroblasts

Human scar-derived fibroblasts exposed to ESWT showed reduced expression of TGF-β1, alpha-smooth-muscle actin, collagen I and fibronectin—key markers associated with fibrotic tissue formation. In that study, fibroblasts from post-burn hypertrophic scars received 1,000 impulses at several low energy levels. Cell viability was unaffected, migration decreased, the transcription factor Twist-1 fell, and markers of epithelial-mesenchymal transition shifted in an antifibrotic direction (Cui, 2018).

This is human cell evidence. It shows that shockwave can alter the behavior of fibrosis-producing human cells in a dish, but it is not a clinical skeletal-muscle trial, and skin scar fibroblasts are not the same as fibroblasts within injured muscle.

Established fibrous tissue: a non-muscle model

Additional experimental work has shown that repeated shockwave application can reduce established fibrous tissue thickness while shifting profibrotic and matrix-degrading pathways, including TGF-β1 and MMP-2. In rats with silicone implants, multiple ESWT sessions over 14 days had no measurable effect at day 35 but produced a significantly thinner fibrous capsule by day 100, alongside changes in TGF-β1 and MMP-2 (Fischer, 2015).

This was a fibrous-capsule model rather than skeletal muscle, so it serves as mechanistic proof-of-principle rather than direct clinical evidence for calf fibrosis. It is still informative for two reasons: the fibrous tissue was already established, and the change took time to appear.

How Could Shockwave Remodel Fibrotic Tissue?

The evidence does not support a simplistic model in which a shockwave physically shatters collagen. A more biologically plausible model is mechanotransduction: mechanical energy changes fibroblast behavior, profibrotic signaling and matrix turnover, allowing pathologic extracellular matrix to remodel.

Mechanisms proposed in laboratory research include:

• Mechanotransduction: cells convert mechanical stimulation into biochemical signals
• Fibroblast and myofibroblast behavior: reduced migration and lower expression of α-SMA and collagen I, as in human scar fibroblasts
• TGF-β modulation: lower TGF-β1, the central profibrotic growth factor
• Matrix metalloproteinase activity: shifts in matrix-degrading enzymes such as MMP-2
• Extracellular-matrix turnover: a different balance between collagen production and breakdown
• Angiogenic and regenerative signaling: changes in blood-vessel and repair signaling
• Muscle stem-cell activity: effects on satellite cells have been proposed in muscle models

These are proposed pathways rather than effects proven in human calf muscle, and they help explain why shockwave is described here as a remodeling stimulus rather than a mechanical demolition tool. The underlying biology of fibrosis is covered in can muscle fibrosis persist after a strain?

Myofascial pain research answers a different question

ESWT also has a growing myofascial-pain literature, but diagnostic criteria and treatment protocols vary substantially. Myofascial trigger-point studies should not be used as direct proof that shockwave reverses post-strain muscle fibrosis.

A 2025 scoping review of ESWT for myofascial pain syndrome found moderate to good efficacy compared with controls, but identified significant inconsistencies in how myofascial pain was diagnosed, how shockwave was applied and how long patients were followed. Many studies did not follow international society guidelines, energy and impulse settings varied, radial and focused devices were not always distinguished, and one-third of studies followed patients for two weeks or less. The authors called for standardized protocols (Müller-Ehrenberg, 2025). That is useful evidence for muscle pain, but it is not evidence about collagen in a healed strain.

The broader sports-medicine picture

A broader systematic review of 56 studies in physically active populations supports ESWT across several sports-medicine conditions, but those data include many diagnoses and should not be interpreted as calf-muscle-specific evidence. That review included 1,874 athletes and physically active people. Based on its level I studies, ESWT may be effective alone for plantar fasciitis, lateral epicondylitis and proximal hamstring tendinopathy, and as an adjunct to exercise in medial tibial stress syndrome and osteitis pubis, with minimal side effects and athletes generally able to keep training (Rhim, 2024).

Radial or focused?

Both radial pressure-wave and focused shockwave approaches appear in muscle and myofascial research, but current evidence does not establish a universal superior modality or protocol. The skeletal-muscle fibrosis model used radial shockwave, and the clinical muscle-injury review and myofascial literature include both device types with heterogeneous settings. In practice, device choice depends on the depth and extent of the involved tissue and how it responds. The calf adds a practical consideration: the soleus lies beneath the gastrocnemius, so the depth of the involved structure influences how energy is delivered. Treatment is directed to the calf muscles and avoids the back of the knee, where major nerves and vessels run. The general differences are covered in radial vs. focused shockwave.

Diagnosis comes first

None of this evidence applies until the problem has been identified as a muscle injury. Calf pain can come from the soleus, the gastrocnemius, the Achilles tendon, nerves or non-musculoskeletal causes. Calf swelling, warmth or pain accompanied by clot risk factors—or any chest pain or shortness of breath—requires prompt medical evaluation rather than routine soft-tissue treatment, and shockwave is not applied to a suspected deep-vein thrombosis. Telling the calf muscles apart is covered in soleus vs. gastrocnemius injury.

What shockwave does not replace

Progressive loading remains the foundation for restoring muscle capacity after injury. Shockwave does not replace rebuilding strength, endurance and sport-specific force production, and it does not replace imaging when a significant tear or a deep soleus injury is suspected. It also does not address the factors that commonly drive recurrence, such as incomplete strength recovery, inadequate endurance or a rushed return to running. Those are addressed first or alongside any tissue treatment, and progress is judged by function rather than by how the calf feels after a single session.

Why the muscle evidence lags behind tendon evidence

Shockwave for tendinopathy has been studied in many randomized trials. Muscle injury is harder to study. Injuries differ by muscle, by structure within the muscle, by severity and by whether they are recent or long-standing, and return-to-play outcomes depend heavily on the sport and the rehabilitation program. Trials rarely take biopsies, so they cannot show directly whether collagen in a human muscle has changed. These are reasons for caution about effect sizes, not evidence that shockwave is ineffective in muscle.

What better evidence would look like

Useful future studies would enroll people with imaging-confirmed chronic or recurrent muscle injuries, compare progressive loading alone with loading plus shockwave, include sham-controlled designs, report device type, energy and impulse settings in reproducible detail, and track reinjury over months rather than weeks. Imaging measures of tissue structure or stiffness would help connect the clinical results to the tissue-level findings from laboratory research.

Where shockwave fits

Clinical evidence supports ESWT as a promising adjunct in selected muscle injuries, while mechanistic studies provide a biologically plausible antifibrotic mechanism through collagen remodeling, altered TGF-β signaling and extracellular-matrix turnover. The muscle-injury evidence base is still much smaller than the evidence for Achilles, plantar fascia or patellar tendinopathy, so ESWT should be presented as a promising remodeling adjunct rather than as a guaranteed scar-removal treatment.

How Novo uses this evidence

We first confirm that persistent calf pain is a muscle problem and identify the structure involved. When the exam finds restricted, poorly tolerant tissue after a previous strain, radial or focused shockwave may be added to progressive loading and, where appropriate, manual treatment, with strength and function re-measured as care progresses. See how we approach chronic calf pain and muscle injury.

References

• Mazin Y, Lemos C, Paiva C, Amaral Oliveira L, Borges A, Lopes T. The role of extracorporeal shock wave therapy in the treatment of muscle injuries: a systematic review. Cureus. 2023;15(8):e44196. PMID 37767244. (link)
• Huang PP, Zhang QB, Zhou Y, et al. Effect of radial extracorporeal shock wave combined with ultrashort wave diathermy on fibrosis and contracture of muscle. American Journal of Physical Medicine & Rehabilitation. 2021;100(7):643-650. PMID 32969968. (link)
• Cui HS, Hong AR, Kim JB, et al. Extracorporeal shock wave therapy alters the expression of fibrosis-related molecules in fibroblast derived from human hypertrophic scar. International Journal of Molecular Sciences. 2018;19(1):124. PMID 29301325. (link)
• Fischer S, Mueller W, Schulte M, et al. Multiple extracorporeal shock wave therapy degrades capsular fibrosis after insertion of silicone implants. Ultrasound in Medicine & Biology. 2015;41(3):781-789. PMID 25619782. (link)
• Müller-Ehrenberg H, Bonavita J, Sun Y, Stecco C, Giordani F. The state of extracorporeal shockwave therapy for myofascial pain syndrome: a scoping review and a call for standardized protocols. Life. 2025;15(10):1501. PMID 41157174. (link)
• Rhim HC, Shin J, Kang J, et al. Use of extracorporeal shockwave therapies for athletes and physically active individuals: a systematic review. British Journal of Sports Medicine. 2024;58(3):154-163. PMID 38228375. (link)