Effects of SIS Therapy in Individuals With Chronic Nonspecific Low Back Pain

This study is a prospective, assessor-blinded, two-arm, parallel-group randomized controlled trial designed to investigate the effects of SIS Therapy in individuals with chronic nonspecific low back pain and to compare its effects with conventional physiotherapy.

Individuals aged 18-65 years with chronic nonspecific low back pain lasting for at least three months will be screened for eligibility. Individuals with a Visual Analog Scale (VAS) pain intensity score of 4 or higher, who are able to walk independently and who voluntarily agree to participate in the study by providing written informed consent will be included.

After enrollment, participants will be randomly allocated to one of two intervention groups in a 1:1 ratio using a computer-generated randomization sequence. Allocation concealment will be achieved using sequentially numbered, opaque, sealed envelopes prepared according to the randomization sequence by a researcher independent of the study. The researcher responsible for outcome assessments will be blinded to group allocation.

Participants allocated to the SIS Therapy group will receive SIS Therapy together with a standard exercise program consisting of lumbar stabilization and stretching exercises. Participants allocated to the conventional physiotherapy group will receive a conventional physiotherapy program consisting of heat application, transcutaneous electrical nerve stimulation (TENS), therapeutic ultrasound, and therapeutic exercise. Both groups will receive treatment twice per week for four weeks, resulting in a total of eight treatment sessions. In addition, the same home exercise program will be provided to participants in both groups.

Outcome assessments will be performed at baseline before the intervention and after completion of the four-week intervention period by the same assessor under standardized conditions.

Pain intensity will be assessed using the Visual Analog Scale (VAS). Participants will indicate the intensity of their current low back pain on a 10-cm horizontal line ranging from 0, representing no pain, to 10, representing the worst or unbearable pain.

Pressure pain threshold (PPT) will also be assessed to provide a quantitative measure of mechanical pain sensitivity. A pressure algometer will be applied perpendicular to standardized measurement sites in the lumbar paraspinal region, and pressure will be gradually increased. Participants will be instructed to indicate the moment when the sensation of pressure first becomes painful. The pressure value at this point will be recorded as the pressure pain threshold. Measurements will be repeated at the predetermined sites, and the mean value will be used for analysis. Higher PPT values will indicate a higher pressure pain threshold and lower mechanical pain sensitivity.

Lumbar flexion mobility will be evaluated using the Modified Modified Schober Test (MMST). The participant will stand in an upright position, and standardized anatomical landmarks will be identified. The change in distance between the marked points during maximal forward trunk flexion will be recorded as an indicator of lumbar flexion mobility.

Static endurance of the lumbar extensor muscles will be evaluated using the Sorensen Back Extensor Endurance Test. During the test, the pelvis and lower extremities will be stabilized while the participant maintains the upper trunk in a horizontal position for as long as possible. The duration for which the position can be maintained will be recorded in seconds, with longer durations indicating greater back extensor endurance.

Functional disability related to low back pain will be evaluated using the Oswestry Disability Index (ODI). The ODI will be used to determine the degree to which low back pain affects participants' daily activities and functional status.

A total of 60 participants are planned to be enrolled in the study, with 30 participants allocated to each group. The sample size was determined based on an alpha level of 0.05, statistical power of 80%, and an anticipated effect size of Cohen's d = 0.80. The target sample size was increased to account for an anticipated dropout rate of approximately 15%.

The primary objective of the study is to determine whether SIS Therapy, when combined with an exercise program, produces changes in pain intensity compared with conventional physiotherapy in individuals with chronic nonspecific low back pain. Secondary objectives include investigating changes in pressure pain threshold, functional disability, lumbar mobility, and back extensor muscle endurance following the intervention.