Pain after dry needling or injection in the muscle is a frequent secondary effect in the treatment of myofascial pain syndrome. In this trial pain and sensitivity will be assessed during a 72 hours follow up period. Factors that may contribute to higher levels of pain or sensitivity will be evaluated.

Inclusion Criteria:

The latent MTrP diagnosis was based upon the following criteria:10

1. presence of a palpable taut band in the muscle
2. presence of a hypersensitive tender spot in the taut band
3. palpable or visible local twitch response with snapping palpation of the tout band
4. referred pain elicitation in response to compression.

Exclusion Criteria:

1. presence of coagulation disorders
2. neck or facial pain
3. previous application of a dry needling technique
4. MTrP therapy in head or neck within the previous 3 months
5. fibromyalgia
6. an insurmountable fear of needles as a reason of refusing the treatment
7. history of surgery in the head or neck area.

Healthy subjetct. Community sample from university.