Neurophysiological reflex mechanisms' lack of contribution to the success of PNF stretches.
Level 3 - non-randomized controlled study
Non-randomized repeated-measures laboratory physiological study
PubMed 19827499 · doi:10.1123/jsr.18.3.343
What was done
Eighteen subjects aged 17–44 years performed two proprioceptive neuromuscular facilitation (PNF) stretching protocols: contract-relax (CR) and contract-relax, agonist contract (CRAC). Electromyographic (EMG) data were recorded from medial hamstring muscles using surface and indwelling wire electrodes to evaluate reciprocal inhibition, autogenic inhibition, and successive induction.
What was found
The abstract reports directional findings without numerical values. Reciprocal inhibition was not observed; instead, antagonist contraction produced elevated hamstring EMG activity suggestive of cocontraction. Autogenic inhibition was also not observed, with post-contraction EMG remaining higher than baseline. Successive induction was confirmed.
Why it matters
These findings challenge traditional explanations attributing the effectiveness of PNF stretching to spinal reflex inhibition mechanisms in healthy individuals.
Limits
The sample size is small (n = 18), and the abstract omits quantitative EMG data, statistical effect sizes, and range-of-motion measurements. Findings in healthy individuals may not generalize to populations with neurological impairment.
Cited by
- contradicts Contracting the glute activates reciprocal inhibition, causing the opposing hip flexor to relax and allowing greater hip range of motion.