Immediate effects of red (660 nm) and infrared (808 nm) photobiomodulation therapy on fatigue of the orbicularis oris muscle: a randomized clinical study.
Mariana Rodrigues Batista, Ludmila Andrade Estrela, Vanessa Mouffron Novaes Alves and 2 others
PMID 34705999WHAT IT FOUND
Red and infrared laser therapy did not reduce lip muscle fatigue during a sustained lip protrusion task in healthy women.
No immediate effect was found.
Key findings
01The main fatigue measure showed no statistically significant difference before and after photobiomodulation for either lip in any group.
02Muscle signal amplitude and normalized amplitude also showed no statistically significant difference before and after photobiomodulation.
0360 healthy women were randomly distributed into four groups of 15 participants each to compare red 660 nm and infrared 808 nm photobiomodulation.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only healthy women aged 18 to 60 years were tested, with an average age of 25 years, so the results may not apply to men, older adults, children, or people with orofacial problems. The study tested only the immediate effect after laser application and a five-minute rest, not repeated sessions or longer training effects. Lip thickness and other anatomical characteristics were not controlled, and the comparisons were made within groups. The participants were healthy women performing a sustained lip protrusion task, not patients receiving myofunctional therapy for lip weakness.
The easy way to misread this
Do not read the null result as proof that photobiomodulation cannot affect lip muscles in patients. The study tested only healthy women and measured an immediate electromyographic fatigue outcome after application.