REF-391 · Guissard, Duchateau, Hainaut, 2001 / Magnusson et al., 1996 · Experimental Brain Research · Paper · PubMed
Mechanisms of decreased motoneurone excitation during passive muscle stretching: H-reflex falls 25% at a small stretch and about 54% at a larger one, and recovers as soon as the joint returns to neutral
Protocol
Soleus EMG responses of two reflex pathways sharing one motoneurone pool were compared during passive ankle dorsiflexion: the Hoffmann (H) reflex, which is subject to presynaptic inhibition, and the exteroceptive (E) reflex, which is not
Tibial nerve stimulation at the popliteal fossa (H reflex) and at the ankle (E reflex) at different dorsiflexion angles; the M wave in soleus and abductor hallucis controlled stimulation stability
Additional experiments recorded motor-evoked potentials (MEP) from magnetic stimulation of the motor cortex
Sample size is not stated in the abstract
Key Findings
Small stretch (10° dorsiflexion): Hmax/Mmax fell significantly (-25%, P < 0.05) with no significant change in Emax/Mmax — a presynaptic (premotoneuronal) mechanism
Larger stretch (20° dorsiflexion): the E reflex fell (-54.6%, P < 0.001) to a similar extent as the H reflex (-54.2%) — postsynaptic mechanisms now dominate
MEPs behaved like the E reflex
As soon as the ankle returned to neutral (90°), both reflex responses recovered their initial values — the inhibition is present during the stretch, not after it
Conclusion: reduced motoneurone excitation during stretching is caused by pre- and postsynaptic mechanisms; presynaptic ones dominate at small amplitude, postsynaptic ones at larger amplitude
Practical Application
During a passive calf stretch, soleus motoneurone excitability drops — the H-reflex by 25% at 10° of dorsiflexion and by about 54% at 20° — but it returns to baseline the moment the ankle comes back to neutral. The "neural relaxation" of stretching is real and graded with stretch amplitude, and in this experiment it did not outlast the stretch itself.
Inference, not tested: this is the spinal side of why a stretch "feels like it lets go" without changing tissue stiffness (REF-382); it says nothing about a lasting post-stretch window
Not from this paper; the base's own practice: use static or PNF stretching in the evening or on recovery days as a relaxation ritual and ROM tool; do not schedule it expecting a carry-over of reduced neural tone into the next session — this study shows recovery of excitability on return to neutral
Limitations
Experimental / physiology lab setting; soleus only; passive stretch, not a stretching programme
Single-session measurements; no performance outcome
Sample size not in the abstract; the Magnusson 1996 half of this entry is unverified
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B+: mechanistic lab study with no performance outcome; sample size not given in the abstract
Content correction 2026-09-27
"H-reflex decreases significantly after 10 min static stretch — effect lasts 10-15 min", "passive stiffness returns to baseline within 15-30 min", "~10-20 min window of reduced neural tone", "stress-relaxation over a 30-60 s hold" -> not in the abstract, which reports reflex depression at 10° (-25%) and 20° (-54.6% / -54.2%) of dorsiflexion during the stretch and immediate recovery when the ankle returns to 90°. Direction corrected (no lasting window), numbers replaced.
"Do stretching in the evening (parasympathetic-dominant state amplifies the effect)" -> not from this paper; relabelled as house practice without the mechanism claim.
Level B+ -> C+ (mechanistic study, no performance outcome).