spondylitis and rheumatoid arthritis, thus differing from the present study, which did not use placebo for comparisons of possible results.
In a randomized clinical trial, Deyo et al.8 compared the effectiveness of TENS and a stretching program and did not find any significant differences between TENS and placebo after one month of treatment. Over the same period, the groups that performed workouts, whether or not in association with TENS, showed meaningful improvements in their painful state, or in function or pain frequency. Their findings are not in agreement with the present study, which detected significant differences between the treatment groups and the control group.
Cheing and Hui-Chan10 described the effects of a 60-minute TENS session on chronic clinical pain, acute experimental pain and chronic low back pain. In the group that received TENS, there were statistically significant decreases in mean values, by 28% during the application and 37% after the treatment, while in the placebo group the mean values decreased by 4%. Neither TENS nor placebo produced significant changes in experimentally induced pain. Methodological differences, especially relating to the duration of the treatment, make it difficult to correlate their data with the information from the present study.
In a recent systematic review, Khadilkar et al.11 only included two of the 47 clinical trials that had previously been performed to investigate the effects of TENS in cases of chronic low back pain.8,10 Even though the inclusion criteria were stated, the reviewers emphasized that there was a lack of a standardization system, and they did not find enough evidence to justify TENS use in cases of chronic low back pain.
The methodology of the present study sought to use the parameters suggested by the systematic review of Khadilkar et al.11 However, it is important to note that we did not include a placebo group to which switched-off electrical equipment was applied, and it was not possible to monitor long-term results. The suggestion from the present study is that electrotherapy should be used only for an initial period of treatment, so that