Influence of transcutaneous electrical nerve stimulation (TENS) associate with muscle stretching on flexibility gains

Background: Increased pain tolerance caused by stretching is an important factor in flexibility gains. Transcutaneous Electrical Nerve Stimulation (TENS) is therapeutic method for pain treatment, but its use during stretching has not been investigated. Objective: To evaluate the effect of associating TENS with stretching to achieve flexibility gains for the hamstring muscles of healthy women. Methods: Thirty women were randomized into three groups (n=10): one control (C) and two stretching groups (St and St+TENS) The stretching groups underwent static stretching (three repetitions of 30 seconds) for two weeks, and the other (St+TENS) underwent TENS application for ten minutes (100hz, 40 mu s) before the stretching, with the stimulation also being administered during the stretching. Flexibility was evaluated according to the passive knee extension before and after each session, and photographs were taken for analysis using the AUTOCAD software. Pain perception was evaluated on a numerical scale from 0 to 10 points. The data were analyzed using Student's t test for independent samples and analysis of variance, considering p<0.05 as the statistical significance level Results: The St and St+TENS groups increased their range of motion in relation to C, but there were no differences between these two groups, with regard to flexibility gain after two weeks (St+TENS: 17.53 degrees +/- 9.25; St: 12.76 degrees +/- 8.75); daily flexibility gain (St+TENS: 6.00 degrees +/- 1.79; St: 5.20 degrees +/- 3.17): and pain perception during stretching (median of five for both groups). Conclusions: The use of TENS associated with stretching did not provide extra gains in muscle flexibility, in relation to stretching alone.