Fascia

Fascia is the connective tissue that wraps, separates and links the muscles, organs and other structures of the body. Medical texts agree that it surrounds every structure, but researchers still disagree on a single definition of where fascia starts and stops (Bordoni et al., 2025).

What is fascia, exactly?

It depends who you ask. The anatomists’ definition describes fascia as any dissectible connective tissue under the skin that attaches, encloses and separates muscles and organs. The Fascia Research Society uses a broader idea, the “fascial system”, which treats fasciae, tendons, ligaments and membranes as one continuous network (Bordoni et al., 2025). The society ran a formal expert consensus process to try to settle the terms (Schleip et al., 2019).

The confusion is old. Two fascia researchers warned in 2009 that the word can be so vague it means little more than “some form of connective tissue”, covering loose and dense, superficial and deep layers alike (Langevin & Huijing, 2009). So when someone tells you your fascia is tight, it is fair to ask which tissue they mean.

Fascia and lower back pain

The fascia most studied in back pain is the thoracolumbar fascia, a layered sheet in the lower back. Its dense layers are separated by looser tissue that normally lets them glide past each other as you bend (Langevin et al., 2011).

• It can sense pain. A study of its nerve supply, mostly in rats, found it densely supplied with sensory nerve endings, including fibres thought to carry pain. The innermost layer covers the muscles alongside the spine, the group that includes the erector spinae (Tesarz et al., 2011).
• It glides less in some people with back pain. In 121 adults, ultrasound showed about 20% less shear movement within this fascia during a passive forward bend in the 71 who had had back pain for over a year (Langevin et al., 2011).
• It looks different on scans. A 2026 meta-analysis of 14 imaging studies found it thicker, stiffer and brighter on ultrasound in people with low back pain, and thicker fascia went with higher pain ratings. Whether it glides less was unclear: the two studies on this pointed in opposite directions (Wilke et al., 2026).

What these studies can’t show is which came first. The authors of the 121-person study suggested the reduced gliding could come from people moving their trunk differently, from changes in the tissue itself, or both (Langevin et al., 2011). None of them measured sitting time, so the popular idea that desk work “glues” fascia together hasn’t been tested. Long, unbroken sitting has other reasons to be worth reducing, covered under sedentary behaviour and lower back pain from sitting.

Can you release fascia?

“Fascia release” is often described as stretching or melting tight tissue. A mathematical model of three types of human fascia suggested otherwise: deforming the firm fascia of the thigh or the sole of the foot by even 1% would need forces far beyond the normal range a therapist can apply. The sense of release that therapists feel can’t come from those tissues changing shape, though softer, thinner fascia might deform (Chaudhry et al., 2008).

That doesn’t mean hands-on treatment does nothing:

• In chronic low back pain, a review of eight randomised trials with 375 people found that myofascial release improved pain and function slightly, with no clear effect on quality of life or mobility. The trials were small and of low quality (Wu et al., 2021).
• Across 21 studies, foam rolling before exercise slightly improved flexibility, and after exercise it reduced muscle soreness. The authors judged the effects as minor overall (Wiewelhove et al., 2019).

NICE suggests considering hands-on treatment for low back pain, such as joint mobilisation or massage, only as part of a package that includes exercise (NICE NG59). There is more on hands-on treatment for the neck in Does massage help neck pain?

Are muscles linked by fascial chains?

Some therapists describe “myofascial chains” running the length of the body. A review of 62 dissection studies found strong evidence for three of six proposed chains, including one along the back of the body, and none for a proposed chain down the front. How much these connections matter for movement or pain is still an open question (Wilke et al., 2016). Tender knots in muscle are a separate idea, covered under myofascial pain syndrome.