Arm Flexion Influence on Muscle Reaction Time in Females with Active Myofascial Trigger Point

Aim: To investigate arm flexion effect on reaction time in females with upper trapezius active myofascial trigger point (MTP).

Methods: Fifteen women (aged 24.5±2.7 years) with one active MTP in the upper trapezius and fifteen normal healthy women (aged 23.30±1.6 years) participated in this study. Participants were asked to stand on the force platform for 10 seconds in an erect comfortable standing position. To investigate muscle reaction time, time interval of first stimulus presentation and muscle force generation onset were measured. The target muscles were anterior deltoid (AD), cervical Paraspinal (CP) lumbar Paraspinal (LP), upper trapezius (UT), sternocleidomastoid (SCM), medial head of gastrocnemius (GC). Participants were asked to flex their arms in response to a sound stimulus preceded by warning sound stimulus.

Results: There were significant differences between test and control subjects in reaction and motor time (P < 0.001). There was no significant difference between these groups in premotor time.

Conclusion: The present study showed that patients with active MTP needed more time to react to stimulus. Firstly, patients had less compatibility with environmental stimulations, and secondly, they responded to a specific stimulation with variability in Surface Electromyography (SEMG).