Effects of burst-type transcutaneous electrical nerve stimulation on cervical range of motion and latent myofascial trigger point pain sensitivity.

OBJECTIVE

To assess the effects of a burst application of transcutaneous electrical nerve stimulation (TENS) on cervical range of motion and pressure point sensitivity of latent myofascial trigger points (MTrPs).

DESIGN

A single-session, single-blind randomized trial.

SETTING

General community rehabilitation clinic.

PARTICIPANTS

Individuals (N = 76; 45 men, 31 women) aged 18 to 41 years (mean ± SD, 23 ± 4y) with latent MTrPs in 1 upper trapezius muscle.

INTERVENTIONS

Subjects were randomly divided into 2 groups: a TENS group that received a burst-type TENS (pulse width, 200 μs; frequency, 100 Hz; burst frequency, 2 Hz) stimulation over the upper trapezius for 10 minutes, and a placebo group that received a sham-TENS application over the upper trapezius also for 10 minutes.

MAIN OUTCOME MEASURES

Referred pressure pain threshold (RPPT) over the MTrP and cervical range of motion in rotation were assessed before, and 1 and 5 minutes after the intervention by an assessor blinded to subjects' treatment.

RESULTS

The analysis of covariance revealed a significant group × time interaction (P < .001) for RPPT: the TENS group exhibited a greater increase compared with the control group; however, between-group differences were small at 1 minute (0.3 kg/cm²; 95% confidence interval [CI], 0.1-0.4) and at 5 minutes (0.6 kg/cm²; 95% CI, 0.3-0.8) after treatment. A significant group × time interaction (P=.01) was also found for cervical rotation in favor of the TENS group. Between-group differences were also small at 1 minute (2.0°; 95% CI, 1.0-2.8) and at 5 minutes (2.7°; 95% CI, 1.7-3.8) after treatment.

CONCLUSIONS

A 10-minute application of burst-type TENS increases in a small but statistically significant manner the RPPT over upper trapezius latent MTrPs and the ipsilateral cervical range of motion.