SYNTH-11 · Guide
Tight or stiff legs
The feeling and the tissue run on different clocks; stretching and rolling buy range of motion and comfort, massage eases soreness without changing measured stiffness, heat raises range of motion but is not shown to lower stiffness, and mostly time brings stiffness down; none of them is recovery between sessions
The question it answers
Default (what to prescribe first)
1
Tight after a hard or unaccustomed session, no pain: it is expected, and it passes with time. After leg curls to exhaustion in 24 subjects, perceived hamstring tightness peaked at 24 h while semitendinosus stiffness peaked at 48 h (+9.7%) and was back at baseline by 96 h (REF-322, B, uncontrolled). The next day follows SYNTH-70.
2
For comfort today (practice; sources in the table): massage or foam rolling, or easy movement (no source in the table) — they change how the legs feel, not the tissue's time course.
3
For range of motion (practice; sources in the table): stretch in a separate session, or roll briefly inside the warm-up.
4
5
Pain, one-sided or localised tightness, or tightness that does not ease → [SYNTH-73].
Decision — what each tool does and does not do
| Tool | Does | Does not | Use |
|---|---|---|---|
| Static stretching | Raises range of motion: acutely, typically for under 30 min (REF-268, A); over 6 weeks ankle range went from 30.9° to 36.3° in the stretching arm of a 49-volunteer trial (REF-382, A-) | Change muscle or tendon stiffness — the 6-week gain was stretch tolerance (REF-382); reduce soreness (REF-385); prevent injury (RR 0.963 for the stretching stratum of a 25-trial meta-analysis in general sport, REF-861, A-); relax the muscle afterwards — reflex excitability fell only while the stretch was held (REF-391, C+, soleus) | Practice: away from hard sessions, for range the sport needs. Before training: under 60 s per muscle, then dynamic work — holds ≥60 s cost −4.6% immediately afterwards vs −1.1% under 60 s, and no clear cost remained when dynamic activity followed (REF-268) |
| PNF (contract-relax) | Large immediate gain in hamstring flexibility vs doing nothing (SMD 1.02 from 6 trials; a review of 39 low-quality trials in adults, REF-383, A-) | Beat static stretching (results conflict, REF-383); it cost −4.4% when tested immediately afterwards (REF-268) | Practice: as static stretching; optimal parameters are unresolved (REF-383) |
| Foam rolling | May lower stiffness and raise range of motion (49 studies, not pooled, REF-378, A-); before exercise, flexibility +4.0%; after, muscle pain eased 6.0% (21 studies, REF-379, A) | Drive recovery — the authors call the effects minor and favour warm-up use (REF-379) | About 90-120 s in total inside a dynamic warm-up (REF-378); afterwards optional (practice) |
| Massage | Most effective technique for soreness and perceived fatigue (99 studies, REF-385; corrected 2026-10-12) | Change passive stiffness: a 16-min massage did no better than sham over 96 h after downhill running in 18 male recreational runners (REF-317, B+); one exception — a single myofascial release lowered trunk-muscle stiffness vs sham at 24 h in 21 trained adults (REF-324, B+) | Practice: for comfort, any time. The benefit is modelled as pain inhibition shaped by context, with small effects (REF-390, C+, commentary on patients — transfer) |
| Percussion gun, vibration | Unverified for range of motion and stiffness: the one verified study counted bench-press repetitions (REF-380, C+); a second entry's results could not be read (REF-558, C+) | Change stiffness on the one test in the base: local vibration did not speed its fall in 11 people (REF-315, B, biceps, 10 min of vibration, followed for 5 min only) | Practice: optional, for comfort |
| Heat: warm shower, hot bath, sauna | Raises range of motion, and heat plus stretching is more effective than stretching alone (systematic review of 36 studies, 1301 healthy participants, high risk of bias across all studies, not pooled; REF-984, A-). A warm muscle is less stiff — a mechanism named in a warm-up review (REF-264, B+, narrative) | Lower measured stiffness: the effects of heat or ice on passive stiffness remain equivocal, and perceived tightness was not addressed (REF-984); the base's older heat-and-tightness entry has no located source (REF-389, C); hot-water immersion for recovery is unclear, the studies conflict (REF-386, B+) | Before or with stretching when the goal is range (REF-984; it gives no temperature, duration or method — those are practice); not a recovery prescription (SYNTH-70) |
| Time and easy movement | Stiffness was back within 10% of baseline by 48 h after one bout in 10 people (REF-327, B, shoulder muscle) and stayed raised up to 96 h after downhill running (REF-317) | An active cool-down showed no clear effect on musculotendinous stiffness or range of motion (REF-913, B+, narrative) | Practice: the default |
Decision (who → what)
"Day two, they feel fine." Feeling better is not tissue recovered: stiffness peaked at 48 h while tightness was already easing (REF-322). Muscle damage lowered sprint and incremental-test peak power but not time-trial performance, with higher RPE at the same power (REF-701, A, meta-analysis in cycling).Not from a study; the base's own practice: after unaccustomed eccentric work (descents, a first heavy lift) keep sprints and maximal tests 72-96 h away; steady riding is fine.
"I feel stiff but nothing was hard." Stiffness can rise without soreness: submaximal eccentric trunk work raised it at 24 and 48 h with no pain (REF-324).
"I want more range for my position." A multi-week static-stretching block raises range through tolerance (REF-382; ankle only — transfer to hips and hamstrings is inference).
How to progress / periodise
A range-of-motion block. Not from a study; the base's own practice: 30-60 s holds per muscle group, most days, for about six weeks (the length of the REF-382 trial), away from hard sessions. Nothing new in race week (practice).
When NOT to use it / red flags
Pain rather than tightness; swelling; a "pop"; numbness or tingling; night pain; one calf tight, warm or swollen → stop and see a clinician (SYNTH-73; the list is the base's own practice).
No percussion, hard rolling or stretching into pain on an acute strain, a bruise, or straight after a muscle-damaging session. Not from a study; the base's own practice.
"Loose" does not mean recovered. After calf raises to exhaustion in 22 active adults, muscle-tendon stiffness had come down by 24 h while contractility had only partly recovered and tendon echo intensity was still falling (REF-326, B).
What the evidence does and does not show
Does not show: that any tool here speeds recovery; that stretching prevents injury (strength programmes did, RR 0.315, REF-861; triage and prevention are SYNTH-73); that heat lowers stiffness or the feeling of tightness (it raises range of motion, REF-984); that percussion changes tightness or range of motion; a lasting drop in "neural tone" from any tool.
Evidence gaps
Candidates are named for the owner; none is in the base.
Heat modality, temperature and duration; heat and perceived tightness or measured stiffness — REF-984 leaves stiffness equivocal and its abstract gives no method.
Long-term stretching and muscle stiffness, pooled — candidate: Takeuchi et al. 2023 (Scand J Med Sci Sports); it may qualify the single-trial result of REF-382.
How this entry was checked and changed
Why this level
(stretching and foam rolling rest on A/A- reviews and one A- RCT; massage on an A meta-analysis and one B+ sham-controlled trial; the time courses on B/B+ studies of 10-24 people; heat on an A- systematic review of studies at high risk of bias, range of motion only; doses and the order of choices are house practice)
Content correction 2026-09-27
Tier 1 for A "foam rolling (REF-324)" -> REF-324 is manual myofascial release; foam rolling now cited to REF-378 ("may reduce stiffness", 49 studies, no pooling). Cryotherapy restated per REF-323's abstract (biomarkers down, stiffness rise confined to the first 48 h).
"Sleep extension (REF-392)" as Tier 1 for perceived tightness, "outperforms most passive modalities combined", ROI #1 -> REF-392 is an unverified C-level composite; sleep re-sourced to REF-384 (30 h deprivation: sprint, glycogen, force, mood) and REF-3500 (single-arm extension), tightness-specific figures labelled practice. REF-384's own "+20-30% soreness / tightness" are not in the Skein 2011 abstract and are not repeated here.
"CWT (REF-386)" for perceived tightness and neural tone -> REF-386's tightness claims were withdrawn; cited only for performance recovery and the CWT / CWI protocol (10-15 °C, 5-15 min; ~1-min alternations, ≤15 min).
Heat / sauna (REF-389) at Tier 2 and ROI #6 -> REF-389 is unverified (Level C); kept as textbook viscosity physiology with the label.
"120 g/h CHO (REF-332 — reduces accumulated damage)" -> REF-332 shows preserved 24-h neuromuscular function; muscle-damage markers (CK, LDH) are REF-331.
"Sauna stacks with heat acclimation per REF-002" -> REF-002 no longer carries sauna protocols; pointed to REF-334b / SYNTH-04. "REF-011 timing 72 h" -> entry shows blunting up to 2 days; 72 h labelled practice. "PNF ≥60 s" decrement -> ~4% (REF-383) / −4.6% for static ≥60 s (REF-268).
Context matrix, ROI ranking, training-plan integration and escalation rules labelled the base's practice; Level B+ -> B (see Level line).
Full-base pass (later 2026-09-27): "REF-391 H-reflex depression lasting 10-15 min after a 10-min stretch" (Tier 1 C, mistake 2, ROI 9) -> REF-391 shows reflex depression only during the stretch (-25% / ~-54%), recovering as soon as the joint returns to neutral.
"Percussion: myotonometry stiffness -5-10% (REF-380)", "H-reflex amplitude reduced (REF-380)", percussion as stiffness-reducing Tier 1 -> REF-380 is a C+ composite; its only verified study is bench-press repetitions (44.6 vs 39.5); moved to Tier 2, dose labelled practice.
"PNF lowers motor-neuron excitability (REF-383)", "REF-383 dose 6-10 s / 20-30 s / 3-5 reps", "~4-5% decrement (REF-383)" -> REF-383 is a flexibility meta-analysis (39 RCTs, SMD 1.02 vs control, conflicting vs static); dose removed from the entry; the -4.4% PNF / -4.6% static ≥60 s figures are REF-268.
"Foam rolling DOMS -4.6% (REF-379)" -> muscle pain perception +6.0%, g = 0.47; authors favour warm-up over recovery use. "Massage across 99 studies (REF-385)" -> top for DOMS and perceived fatigue (the count change to 107 was itself wrong: the paper says 99 studies, corrected 2026-10-12).
"Compression reduces swelling / perceived tightness, worn continuously 24-48 h (REF-387)" -> REF-387 carries DOMS g 0.403 and strength/power/CK recovery, strongest windows 2-8 h and >24 h; swelling, tightness and 24-48 h wear are not in it.
"REF-316 validates SWE and MyotonPRO against each other" -> measured simultaneously, no agreement reported. "Fascial nociceptor activity (REF-318)" -> fascia stiffening associated with later pressure pain (r² = 0.22); nociceptors are inference. "CWI blocks adaptation (REF-011)" -> attenuates. NMES (REF-388) -> limited evidence, active-recovery substitute at best."Placebo and context effects additive (REF-390)" -> context shapes the response; effects small. Level reason updated (Section 20 now B/B+).
Resync 2026-09-28: Tier 1 for A "cryotherapy ... confined the post-exercise stiffness rise to the first 48 h (REF-323)" and ROI 8 "effective for biomarkers and the stiffness time course" -> REF-323 shows lower leukocytes and CK than control; within the cryo group stiffness still rose at 48 h and in two muscles at 72 h, "confined to the first 48 h" is the authors' reading and the abstract has no cryo-vs-control stiffness comparison.Cryotherapy moved from Tier 1 (direct evidence of stiffness reduction) to Tier 2.
Resync 2026-09-28: "tendon structure still changing after muscle stiffness had fallen (REF-326)" -> REF-326 measured muscle-tendon-unit passive stiffness (down by 24 h) and tendon echo intensity (still falling at 24 h).
Resync 2026-09-28: "massage (percussion or manual, REF-385)" -> REF-385 pools massage, not percussion; percussion labelled a house substitute. "FR ~90-120 s total per REF-378" in the post-session stack -> that is REF-378's total dose for flexibility, stated for pre-training use.
Resync 2026-09-28: Derived-from listed REF-393 (the emptied duplicate) -> REF-268.
2026-10-01: rewritten in the decision-framework format and cut to what is unique to tightness and stiffness. Default changed from modality stacks by context to: tightness after hard work passes with time; stretching and rolling are range-of-motion and comfort tools, massage a soreness tool, none of them recovery.Contradictions with SYNTH-70 resolved in its favour: sauna (easy day, base phase, post-illness) and post-session PNF "as recovery" removed; cold water, contrast water, cryotherapy, compression, electrostimulation and sleep rows removed and owned by SYNTH-70; massage kept as comfort only. "120 g/h CHO" removed (→ SYNTH-02).Context matrix, ROI ranking, training-plan integration and neural-tone tiers removed (house constructs); escalation → SYNTH-73. Folded in: REF-861, REF-913, REF-701, REF-264, REF-558.
Verification 2026-10-01: 22 cited REF entries read in full; all level tags next to refIds match the head blocks; no WRONG and no STRETCH that changes advice. Every 'Use' cell and the dose/red-flag lines carry a practice label.
Verification 2026-10-01: Level B is fair — evidence columns rest on A/A- reviews (REF-268, 379, 385, 861, 701) and the stiffness time courses on B/B+ studies of 10-24 people, as the Level line says.
Verification 2026-10-01: consistent with SYNTH-70 (stretching and sauna/hot water 'Not as recovery'; massage 'For comfort'). SYNTH-73 red-flag list matches except 'one calf tight, warm or swollen', which SYNTH-11 labels as its own practice.
Verification 2026-10-01: Evidence gaps names two papers not in the base (Bleakley & Costello 2013; Takeuchi et al. 2023) from memory; they are labelled as candidates, not cited as support, and were not checked here.
'Day two' bullet says 'stiffness peaked at 48 h' without the qualifier that only the semitendinosus stiffened (the other two heads did not change, REF-322); Default 1 states it correctly. Row split counts 5 Default items and 7 tool rows.
Revision 2026-10-01: REF-984 (Bleakley & Costello 2013, A- systematic review, 36 studies, 1301 healthy participants, all at high risk of bias) folded into the heat row: heat raises range of motion and heat plus stretching beats stretching alone; passive stiffness stays equivocal and perceived tightness was not studied.The row's 'nothing verified for tightness or range of motion' was wrong for range of motion and is changed; the Use cell moved from 'if the athlete likes it' to 'before or with stretching when the goal is range', with temperature/duration/method labelled practice. Heat is still not a recovery prescription (SYNTH-70).
Revision 2026-10-01: title fragment 'heat has no verified effect here' contradicts REF-984 — title pair supplied. Level B unchanged; Level parenthetical and Evidence gaps updated.