Optimal intensity of PNF stretching: maintaining the efficacy of stretching while ensuring its safety.
Wootaek Lim
PMID 30154610WHAT IT FOUND
In adults, PNF stretching at 100% of maximum voluntary isometric contraction increased hamstring range more than 40% or 10% but produced more pain. 70% gave range gain similar to 100% and pain levels closer to lower intensities.
Key findings
01The reported flexibility change differed between intensity groups, with P100 different from P40 and P10, and P100 not different from P70.
02Pain differed by intensity group immediately after stretching and on day 1, but not on day 2; the P100 group had a post-stretch VAS score of 4.63 ± 1.63.
03Post-stretch pain was weakly related to target intensity and was not related to flexibility improvement.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study measured only immediate and 2-day pain and one flexibility outcome, so it does not show longer-term range maintenance or injury risk. Pain was self-reported on a visual analogue scale, and the paper notes that this scale can be influenced by subjective characteristics. Participants received real-time intensity feedback and adjusted their own stretching intensity; the paper does not report blinding of participants or assessors. No control or usual-care group was included; all groups received PNF stretching at different intensities. The paper does not describe any clinical condition in the participants, so it is unclear how results apply to patients with pain or injury.
Declared interests
Funded by 2018 Woosong University Academic Research Funding and a Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education. The author declared no conflicts of interest.
The easy way to misread this
Do not assume that 70% intensity is safe for repeated stretching because it gave a similar short-term range gain. The study measured pain and flexibility only immediately and up to day 2, and it did not test tissue injury or longer-term effects.