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Effects of the carrier frequency of interferential current on pain modulation in patients with chronic nonspecific low back pain: a protocol of a randomised controlled trial

Juliana Barbosa Corrêa1, Leonardo Oliveira Pena Costa1, Naiane Teixeira Bastos de Oliveira1, Kathleen A Sluka2 and Richard Eloin Liebano1*

Author Affiliations

1 Master’s and Doctoral Programs in Physical Therapy, Universidade Cidade de São Paulo (UNICID), São Paulo, Brazil

2 Graduate Program in Physical Therapy and Rehabilitation Science, University of Iowa, College of Medicine, Iowa City, IA, USA

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BMC Musculoskeletal Disorders 2013, 14:195  doi:10.1186/1471-2474-14-195

Published: 27 June 2013



Low back pain is an important public health problem that is associated with poor quality of life and disability. Among the electrophysical treatments, interferential current (IFC) has not been studied in patients with low back pain in a high-quality randomised controlled trial examining not only pain, but pain mechanisms and function.


A three-arm randomised controlled trial with patient and assessor blinded to the group allocation. One hundred fifty patients with chronic, nonspecific low back pain from outpatient physical therapy clinics in Brazil. The patients will be randomly allocated into 3 groups (IFC 1 kHz, IFC 4 kHz or Placebo IFC). The interferential current will be applied three days per week (30 minutes per session) over four weeks. Primary outcome: Pain intensity. Secondary outcomes: The pressure pain threshold, global impression of recovery, disability, function, conditioned pain modulation and temporal summation of pain, discomfort caused by the current. All outcomes will be measured at 4 weeks and 4 months after randomisation. The between-group differences will be calculated by using linear mixed models and Tukey’s post-hoc tests.


The use of a placebo group and double-blinding assessor and patients strengthen this study. The present study is the first to compare different IFC carrier frequencies in patients with chronic low back pain.

Trial registration

Brazilian Registry of Clinical Trials: http://RBR-8n4hg2 webcite

Low Back Pain; Electric Stimulation; Central Nervous System Sensitization; Central Sensitization; Physical Therapy Modalities