REF-324 · Brandl A, Keiner M, Wilke J, Egner C, Schleip R & Schmidt T, 2024 · Journal of Sports Science and Medicine, · Paper · PubMed

Effects of a Manual Treatment on Lumbar Microcirculation and Tissue Stiffness Following Submaximal Eccentric Trunk Extensor Exercise: A Randomized Controlled Trial

In 21 trained adults, submaximal eccentric trunk extension that caused NO soreness still raised erector spinae stiffness at 24 h (+0.875 m/s) and 48 h (+0.869 m/s); myofascial release lowered it versus sham at 24 h (−0.66 m/s) and raised the pressure-pain threshold at 48 h; connective-tissue stiffness was unchanged

B+moderate evidenceMeasured on trained athletesWritten before October 2026, being re-checked

Participants

n=21 trained healthy participants (31.3 ± 9.6 years; > 4 h exercise per week): manual treatment (MFR) n=11, placebo (sham laser therapy) n=10

Protocol

Submaximal eccentric exercise of the trunk extensors — chosen so as NOT to cause DOMS (the abstract notes severe DOMS is rare in trained individuals)
One group received myofascial release by a therapist; the other sham laser therapy
Measured before (t0), 24 h (t24) and 48 h (t48): stiffness of the extramuscular connective tissue (ECT) and erector spinae muscle (shear-wave elastography), microcirculation (white-light and laser Doppler spectroscopy), palpation pain (100 mm VAS) and pressure pain threshold (PPT, indentometry)

Key Results

Erector spinae stiffness increased after the eccentric exercise: t0 → t24 +0.875 m/s and t0 → t48 +0.869 m/s (shear-wave speed)
After MFR, erector spinae stiffness decreased relative to placebo at t24 (−0.66 m/s); ECT stiffness remained unchanged in both groups
Microcirculation after the exercise: oxygen saturation increased (17-20.93%) and relative haemoglobin decreased (−9.1 to −12.76 AU); MFR differed from placebo at t48 (−3.71 AU)
PPT differed after MFR from placebo at t48 (20.69 N/mm); VAS palpation pain did not change (no soreness was induced)
Multiple linear regression: ECT stiffness and group membership predicted erector spinae stiffness
Authors: MFR "could have" a positive effect on pain, microcirculation and muscle stiffness after submaximal eccentric exercise, to be confirmed by future work

Mechanism

A submaximal eccentric load that produced no soreness still left the muscle measurably stiffer for 48 h — stiffness accumulated below the threshold of perception. The therapist's manual treatment reduced that muscle stiffness at 24 h and shifted microcirculation and pressure-pain threshold at 48 h, while the connective-tissue layer itself did not change.

Inference, not tested: the treatment acted on the muscle (or on the coupling between muscle and ECT, which the regression hints at), not by softening the fascia.

Practical Application

In 21 trained adults, submaximal eccentric trunk work that caused no soreness (VAS unchanged) still raised erector spinae stiffness at 24 h (+0.875 m/s) and 48 h (+0.869 m/s); a single therapist-delivered myofascial release reduced it versus sham at 24 h (−0.66 m/s) and raised the pressure-pain threshold at 48 h (+20.69 N/mm)
Stiffness rose without soreness — the sessions an athlete does not "feel" can still leave a 48-h tissue footprint; this is the one trial in the base that measured it in trained people below the DOMS threshold
Manual therapy changed muscle stiffness here where massage did not after DOMS-level downhill running (Kong 2018 REF-317): a different load level (submaximal, no soreness), a different muscle and a different practitioner protocol — not a contradiction, and neither result generalises to the other setting
Not from this paper; the base's own practice: "silent accumulation" of tissue stiffness across daily threshold sessions, and the need for true rest days, is a coaching inference from this and the other stiffness entries; this trial tested one bout, one treatment, 48 h — foam rolling was not tested

Limitations

Trunk extensors — not lower-limb locomotor muscles
Only 48 h follow-up; single treatment
Small sample (n=21; 11 vs 10)
Submaximal but still eccentric — concentric/isometric cycling loads may differ
How this entry was checked and changed
Why this level

regraded 2026-09-27 from A-: parallel RCT with n=21 (11 + 10)

Content correction 2026-09-27
Added the microcirculation and pressure-pain results from the abstract (SO2 +17-20.93%, rHb −9.1 to −12.76 AU, MFR vs placebo −3.71 AU at t48; PPT +20.69 N/mm) and that VAS pain did not change.
"Myofascial release is the one modality shown to actually reduce stiffness", "strongest evidence for Bakken's muscle tone accumulation", "foam rolling" -> overclaims / not tested; relabelled as house inference; the authors' own hedge ("could have ... needs to be confirmed") added.
Level A- -> B+ (parallel RCT, n=21); Tier 1-2 -> Tier 2 (trained, > 4 h/week); Sport "cycling" -> general.