Neurophysiological reflex mechanisms' lack of contribution to the success of PNF stretches
Two pages on PainSci cite Mitchell 2009: 1. Quite a Stretch 2. Reciprocal inhibition invalidated (15 years ago)
PainSci commentary on Mitchell 2009: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.
This 2009 experiment probably definitively invalidated the phenomena of antagonist inhibition and autogenic inhibition, contradicting Etnyre et al.’s 1988 result, which had been the most credible evidence pointing the other way, but confirming a variety of other early experiments (like Osternig et al and Condon et al).
They studied eighteen adult subjects doing proprioceptive neuromuscular facilitation (PNF) stretches, collecting EMG from the medial hamstring muscles via both surface and indwelling wire electrodes.
Not only was “reciprocal inhibition was not evident,” but they found an “elevated rather than an inhibited EMG during the antagonist contraction, possibly representing co-contraction.” They also could not detect autogenic inhibition (relaxation after contraction in the same muscle), and again the result was actually the opposite: EMG values were “higher than baseline.”
“Previous neurophysiological explanations for mechanisms of PNF stretching appear to be inadequate,” they concluded. “This study corroborates previous findings that a muscle’s tone increases during its antagonist’s contraction. Other explanations should be considered regarding the mechanism for the effectiveness of the CRAC and CR PNF techniques in a nonneurologically impaired population.”
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
BACKGROUND AND PURPOSE: Proprioceptive neuromuscular facilitation (PNF) stretches are widely used in athletics and rehabilitation. Although it has been shown that they produce better range-of-motion (ROM) increases than the slow or static stretch, the mechanisms responsible remain an enigma. This study was conducted to determine whether the previously proposed neurophysiological mechanisms of reciprocal inhibition and autogenic inhibition are responsible for the success of PNF stretches. In addition, the authors assessed the existence of the phenomenon of successive induction because it is used to strengthen reciprocal inhibition.
METHODS: Eighteen subjects 17-44 y performed the PNF stretches contract-relax (CR) and contract-relax, agonist contract (CRAC). EMG data were collected from the medial hamstring muscles via surface and indwelling wire electrodes and analyzed for reciprocal inhibition and successive induction, as well as autogenic inhibition (surface electrodes only).
RESULTS: Reciprocal inhibition was not evident. The results indicated an elevated rather than an inhibited EMG during the antagonist contraction, possibly representing cocontraction. The authors did confirm the presence of successive induction. Autogenic inhibition was also not evident, and the expected inhibition and therefore lower EMG values after muscle contraction were not observed; instead, they were higher than baseline.
CONCLUSION: Previous neurophysiological explanations for mechanisms of PNF stretching appear to be inadequate. This study corroborates previous findings that a muscle's tone increases during its antagonist's contraction. Other explanations should be considered regarding the mechanism for the effectiveness of the CRAC and CR PNF techniques in a nonneurologically impaired population.
related content
- “Soleus muscle electromyographic activity and ankle dorsiflexion range of motion during four stretching procedures,” Condon et al, Physical Therapy, 1987.
- “Muscle activation during proprioceptive neuromuscular facilitation (PNF) stretching techniques,” Osternig et al, Am J Phys Med, 1987.
- “Antagonist muscle activity during stretching: a paradox re-assessed,” Etnyre et al, Medicine & Science in Sports & Exercise, 1988.
- “The Effectiveness of PNF Versus Static Stretching on Increasing Hip-Flexion Range of Motion,” Lempke et al, Journal of Sport Rehabilitation, 2018.
- “Immediate Effects of Proprioceptive Neuromuscular Facilitation Stretching Programs Compared With Passive Stretching Programs for Hamstring Flexibility: A Critically Appraised Topic,” Hill et al, Journal of Sport Rehabilitation, 2017.
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Placebo analgesia in physical and psychological interventions: Systematic review and meta-analysis of three-armed trials. Hohenschurz-Schmidt 2024 Eur J Pain.
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