Objective: To determine whether latent myofascial trigger points (MTPs) can be identified in healthy infants and in healthy adult subjects.
Design: Blind comparison.
Participants: A convenience sample of 60 healthy adults and 60 infants (age range, 0-12mo).
Interventions: Not applicable.
Main outcome measures: An algometer was used to measure the pressure pain threshold (PPT) on 3 different sites, including a midpoint (assumed to be the MTP site) in the brachioradialis muscle.
Results: The mean PPT values at the MTP site were significantly lower than the other sites in the adult muscles. However, no significant differences in PPT values among these 3 sites were found in the infants. Taut bands were found in all the adult muscles but none in the infants.
Conclusions: In the adult subjects, the midpoint of brachioradialis muscle was significantly more irritable than other sites and the midpoint was probably a latent MTP. However, in the infants younger than 1 year old, such a phenomenon could not be observed in this study. It is very likely that the latent MTPs might not exist in early life, but develop in later life.