Sore After Treatment? Here's What the Research Suggests Is Happening in Your Fascia

The natural interpretation is that something was damaged, or that the treatment was too forceful. A 2023 narrative review by Stecco and colleagues — published in the journal Life — proposes a specific molecular explanation for this soreness that challenges that interpretation entirely. [1] Rather than a side effect of treatment, the inflammatory response appears to be a necessary phase of the tissue restoration process: the mechanism itself, not a complication of it.

---

The Molecule at the Centre of It

Understanding the soreness requires understanding what Fascial Manipulation is acting on.

In the loose connective tissue between fascial layers — the thin, lubricated interfaces that allow adjacent structures to glide freely during movement — sits a molecule called hyaluronan (HA). HA is a glycosaminoglycan found throughout the body's connective tissues. In its healthy state, it exists as a long, high-molecular-weight polymer that gives the interfascial space its normal lubricating, viscoelastic properties. It allows the layers to slide.

When HA undergoes a shift in molecular weight — fragmenting from its normal long-chain form into progressively smaller pieces — the interfascial space changes character. Medium-molecular-weight fragments increase viscosity. Low-molecular-weight fragments become biologically active in a very different way: rather than lubricating, they trigger an inflammatory response. In the Stecco densification model, the accumulation of self-aggregated, high-viscosity HA in the interfascial loose connective tissue — palpable as the stiff, resistant tissue quality the treating hand works with — restricts gliding and alters load distribution across the fascial system.

Fascial Manipulation applies deep, sustained friction at specific anatomical points to generate the local mechanical and thermal conditions that can disrupt this aggregated HA. The question this 2023 paper addresses is: what happens at the molecular level when it does?

---

The Inflammatory Cascade: What the Research Proposes

Stecco and colleagues reviewed 44 studies examining the relationship between mechanical stress, hyaluronan fragmentation, and the resulting inflammatory response in connective tissues. [1]

Their proposed mechanism proceeds in steps.

Deep friction generates mechanical stress in the interfascial tissue. This depolymerises the self-aggregated, high-molecular-weight HA chains into progressively smaller fragments. The early products of this fragmentation — low-molecular-weight HA (LMW HA, ≤500 kDa) — are biologically active: they bind to TLR-4 and CD44 receptors on local cells, triggering the release of pro-inflammatory mediators including TNF-α, IL-1β, and matrix metalloproteinases. This is the beginning of the inflammatory cascade that patients perceive as post-treatment soreness.

The cascade follows a predictable time course. Inflammatory activity and the associated soreness peak at approximately 12 hours. From that point the cascade becomes self-resolving: the smallest products of HA fragmentation — oligosaccharides (o-HA, <10 kDa) — have the opposite biological effect of their larger predecessors. Rather than amplifying inflammation, oligomeric HA inhibits the inflammatory response and facilitates cellular resolution. By 24 to 48 hours, in most cases, the inflammatory phase has resolved and a new, physiologically appropriate HA environment has been established in the treated region.

This sequence — soreness peaking at around 12 hours, resolving by 24 to 48 hours — matches what patients and practitioners consistently observe in clinical practice.

---

Why the Cascade Appears to Be Necessary, Not Incidental

The significance of this mechanism is not just that it explains soreness. It is that the inflammatory process appears to be required for the durable restoration of normal interfascial tissue properties.

The self-assembled, aggregated HA that characterises a densification cannot simply be cleared from the tissue intact. It must first be fragmented into smaller pieces that can be drained via the lymphatic system and metabolised. Once that clearance has occurred, the fasciacytes — specialised cells in the interfascial loose connective tissue whose primary function is HA synthesis and homeostasis — can replace the fragmented HA with new, correctly sized, physiologically appropriate polymer. Normal interfascial gliding can resume.

Without the fragmentation cascade to initiate this process, the long-chain self-assembled HA remains in the tissue. This is why, Stecco and colleagues propose, the soreness that follows deep friction treatment should be understood as a functional signal — indicating that the restoration process has been initiated — rather than evidence that something has gone wrong.

The intensity and duration of the cascade is not fixed. According to the proposed model, it scales with the degree of pre-existing HA accumulation: the more chronic the densification, the more aggregated HA is present, and the more substantial the inflammatory phase required to clear it. A region that has been restricted for months or years may produce a more noticeable post-treatment response than an acute restriction addressed early.

---

The NSAIDs Question

This mechanism has a direct clinical implication worth stating plainly.

Non-steroidal anti-inflammatory drugs (NSAIDs) — ibuprofen, naproxen, diclofenac — work by suppressing the inflammatory cascade. If the cascade triggered by deep friction treatment is the mechanism through which tissue restoration occurs, then suppressing it with NSAIDs in the post-treatment period may interfere with the durable effect of the treatment.

Paracetamol (acetaminophen) has an analgesic effect without meaningful anti-inflammatory action and is the appropriate choice if post-treatment soreness requires management. [1]

This is not a minor footnote. It directly informs the advice given to patients before and after a session of Fascial Manipulation or any deep friction manual therapy.

---

What the MRI Evidence Adds

The Stecco 2023 paper addresses the molecular mechanism of why soreness occurs. A complementary 2020 study from NYU School of Medicine and Johns Hopkins — examined in detail in our MRI evidence post — captured the structural outcome on imaging: after three sessions of Fascial Manipulation, T1ρ MRI of the deep fascia showed a statistically significant reduction in unbound water concentration, consistent with a reduction in HA viscosity and a shift toward a more physiologically normal interfascial environment. [2]

Together, these papers describe two sides of the same process. The Stecco 2023 mechanism proposes how the change occurs — HA fragmentation drives an inflammatory cascade that clears the aggregated HA and initiates restoration. The Menon 2020 MRI study provides imaging-level evidence that a measurable structural change in the fascia follows treatment. The soreness experienced in between is, on this account, the visible surface of a molecular process with a detectable structural endpoint.

---

What This Means for You

If you feel sore after a session of Fascial Manipulation or deep friction manual therapy, the proposed mechanism suggests this is a functional response to treatment — not damage. The soreness typically peaks at around 12 hours and should begin to resolve within 24 to 48 hours.

If you have had chronic, long-standing restrictions treated, the post-treatment response may be more noticeable. This is consistent with the model: more accumulated HA requires more fragmentation and a more substantial clearing process.

If you need to manage the soreness, paracetamol is appropriate. Ibuprofen and other NSAIDs are best avoided in the immediate post-treatment period, as they may interfere with the inflammatory process that underlies the tissue change the treatment aims to achieve.

If you feel like moving gently after treatment, the research supports it. Light activity generates local heat and promotes lymphatic flow, both of which may support HA fragmentation and drainage. There is no need to rest completely — gentle movement in the treated region is appropriate and encouraged.

If your soreness persists beyond 72 hours or is significantly more intense than expected, let us know. While some variability is normal and expected, marked or prolonged soreness warrants a conversation about treatment parameters.

---

Want to know what to expect from your first session?

---