Chronic Low Back Pain
Conditions
Keywords
Chronic nonspecific low back pain, Office workers, Sensory stimulation, Lumbar vibration, Wearable device, Lumbar multifidus, Sensorimotor control, Somatosensory cortex, Proprioception
Brief summary
This randomized, double-blind, sham-controlled trial will evaluate the effectiveness of a sensory stimulation belt in office workers with chronic nonspecific low back pain. Participants will first complete baseline clinical and sensorimotor assessments and will then be randomly assigned in a 1:1 ratio to receive either an active sensory stimulation belt or a sham belt. Participants will wear the assigned belt during their usual office work for at least 4 hours per day, 5 days per week, for 4 weeks. Daily belt use, pain intensity, adherence, skin reactions, and device-related problems will be recorded in a study logbook, with weekly follow-up by the research team. Clinical outcomes will include pain intensity, frequency and intensity of low back pain or discomfort episodes, low back pain-related disability, work-related musculoskeletal discomfort, tactile acuity, and pressure pain threshold. Mechanistic outcomes will include corticospinal excitability, somatosensory cortical responses during unstable sitting, postural control, lumbar multifidus motor-unit behavior, and lumbar multifidus contractile response. The primary objective is to determine whether 4 weeks of active lumbar sensory stimulation produces greater improvements in clinical outcomes than a sham intervention and whether clinical changes are accompanied by changes in sensorimotor and neuromuscular outcomes.
Detailed description
Phase III is a prospective, double-blind, sham-controlled randomized clinical trial designed to evaluate the clinical effectiveness and potential sensorimotor mechanisms of a wearable sensory stimulation belt in office workers with chronic nonspecific low back pain. After eligibility screening and written informed consent, participants will undergo a baseline laboratory assessment. Baseline clinical assessments will include pain intensity, low back pain-related disability, work-related musculoskeletal discomfort, movement-control testing, tactile acuity, and pressure pain threshold. Baseline mechanistic assessments will characterize corticospinal, cortical, postural, motor-unit, and lumbar multifidus function. Corticospinal excitability will be assessed using single-pulse transcranial magnetic stimulation (TMS), with motor-evoked potentials recorded from the lumbar multifidus and erector spinae muscles. Somatosensory cortical and postural responses will be assessed during unstable sitting using functional near-infrared spectroscopy (fNIRS) over the bilateral primary somatosensory cortex together with inertial measurement units (IMUs). Participants will also perform a repeated loaded forward-bending task while lumbar multifidus motor-unit behavior is recorded using decomposition electromyography (dEMG) and trunk movement is recorded using IMUs. Lumbar multifidus morphology and contractile response will be assessed using rehabilitative ultrasound imaging (RUSI) at rest and during contralateral arm lifting. Following completion of the baseline assessment, participants will be randomly allocated in a 1:1 ratio to an active sensory stimulation belt group or a sham belt group using a computer-generated block randomization sequence. Allocation will be concealed using sequentially numbered, opaque, sealed envelopes prepared by a research assistant who is not involved in outcome assessment. Participants assigned to the active intervention group will receive a sensory stimulation belt programmed with the lumbar vibration parameters identified during the preceding Phase II parameter-optimization study. Participants assigned to the sham group will receive a belt designed to have similar appearance, weight, sound, and user interface. The sham belt will provide only a brief, low-level surface vibration at the beginning of use and will subsequently cease active stimulation so that it does not provide the intended sustained sensory stimulation. Participants and outcome assessors will be blinded to group allocation. Device programming and allocation management will be performed by research personnel who are not involved in clinical or mechanistic outcome assessment. Participants will be instructed to wear their assigned belt during their usual office working hours for at least 4 hours per day, 5 days per week, for 4 consecutive weeks. Participants may continue their usual occupational activities while wearing the belt. Throughout the 4-week intervention period, participants will complete a daily study logbook documenting belt-wear duration, number of wear sessions, pain intensity before and after belt use, local discomfort or skin reactions, technical or device-related problems, and reasons for missed use when applicable. A member of the research team will conduct weekly follow-up to review adherence, identify technical problems, reinforce study procedures, and document adverse events. At the end of the 4-week intervention, participants will return to the laboratory for post-intervention assessments using procedures comparable to the baseline assessment. Clinical assessments will include pain intensity, low back pain-related disability, work-related musculoskeletal discomfort, movement-control testing, tactile acuity, and pressure pain threshold. Mechanistic assessments will include corticospinal excitability using TMS, somatosensory cortical and postural responses during unstable sitting using fNIRS and IMUs, lumbar multifidus motor-unit behavior during loaded forward bending using dEMG, and lumbar multifidus contractile response using RUSI. The primary efficacy analysis will compare changes in clinical outcomes between the active and sham groups over the 4-week intervention period. Linear mixed-effects models will be used to evaluate group, time, and group-by-time interaction effects for continuous outcomes. Repeated daily pain or discomfort measurements will also be evaluated using mixed-effects models. The frequency of pain or discomfort episodes may be analyzed using Poisson or negative-binomial regression, depending on the distribution of the data. The primary analysis will follow the intention-to-treat principle. A complementary per-protocol analysis will be performed for participants who complete at least 75% of the prescribed belt use. Treatment effects will be reported with 95% confidence intervals. Safety, adherence, comfort, usability, and device-related problems will be monitored throughout the intervention. Belt use will be discontinued if a participant requests discontinuation, develops clinically important symptom aggravation, experiences a significant adverse event, or develops a device-related problem that makes continued use inappropriate.
Interventions
DEVICEActive Sensory Stimulation Belt
The active sensory stimulation belt is a wearable device designed to deliver controlled mechanical sensory stimulation to the lumbar region during prolonged office work. The belt will be programmed using the optimized vibration parameters identified during the preceding Phase II neurophysiological optimization study. Participants will wear the active belt during usual office work for at least 4 hours per day, 5 days per week, for 4 weeks.
DEVICESham Sensory Stimulation Belt
The sham sensory stimulation belt is designed to resemble the active belt in appearance, weight, sound, and user interface. The sham device will provide a brief, low-level surface vibration at the beginning of use and will subsequently cease active stimulation. It will therefore not provide the sustained lumbar sensory stimulation delivered by the active device. Participants will wear the sham belt during usual office work for at least 4 hours per day, 5 days per week, for 4 weeks.
Sponsors
Mahidol University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
Participants and outcome assessors will be blinded to group allocation. The active and sham belts will be designed to have similar appearance, weight, sound, and user interface. Device allocation and programming will be performed by research personnel who are not involved in outcome assessment. The sham belt will provide a brief, low-level surface vibration at the beginning of use but will not provide the sustained stimulation delivered by the active belt.
Intervention model description
Participants will be randomly assigned in a 1:1 ratio to either an active sensory stimulation belt group or a sham belt group. Both groups will use the assigned belt during usual office work for at least 4 hours per day, 5 days per week, for 4 weeks. Clinical and mechanistic outcomes will be assessed at baseline and after the 4-week intervention.
Eligibility
Sex/Gender
ALL
Age
20 Years to 60 Years
Healthy volunteers
No
Inclusion criteria
1. Office workers who currently sit for at least 6 hours per workday. 2. Age between 20 and 60 years. 3. Chronic nonspecific low back pain for at least 3 months. 4. Current pain intensity of at least 2/10 on the Numeric Pain Rating Scale.
Exclusion criteria
1. History of seizure in the participant or a family member. 2. Implanted pacemaker. 3. Contraindications to TMS or fNIRS, including relevant open wound, infection, skin lesion, or other condition preventing safe measurement. 4. Acute cerebral hemorrhage. 5. History of major spinal surgery, fracture, or traumatic injury to the lumbar spine. 6. Evidence of neurological deficits, including radiculopathy, loss of sensation, or motor weakness in the lower limbs. 7. Diagnosis of a systemic inflammatory condition, including ankylosing spondylitis or rheumatoid arthritis. 8. Allergy to adhesives or history of severe skin sensitivity to vibration or mechanical pressure. 9. Body mass index greater than 30 kg/m2 because of potential effects on RUSI, dEMG, and fNIRS signal quality. 10. Pregnancy.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in low back pain intensity | Baseline and 4 weeks | Pain intensity will be measured using the 11-point Numeric Pain Rating Scale (NPRS), ranging from 0 (no pain) to 10 (worst imaginable pain). Current pain and average pain during the previous 7 days will be recorded. Change in pain intensity from baseline to the end of the 4-week intervention will be compared between the active and sham groups. |
| Frequency of low back pain or discomfort episodes | Daily during the 4-week intervention | Participants will record the occurrence of low back pain or discomfort episodes in a daily study logbook throughout the 4-week intervention. The number of episodes will be summarized over the intervention period and compared between the active and sham groups. |
| Daily change in low back pain intensity associated with belt use | Before and after belt use on each study day for 4 weeks | Participants will rate low back pain intensity using the 0-10 Numeric Pain Rating Scale immediately before the first belt-wear period and after the final belt-wear period of each study day. Repeated daily pain responses will be compared between the active and sham groups. |
| Change in low back pain-related disability | Baseline and 4 weeks | Low back pain-related disability will be assessed using the Oswestry Disability Index (ODI). The questionnaire score is expressed as a percentage, with higher scores indicating greater disability. Change from baseline to 4 weeks will be compared between groups. |
| Change in work-related musculoskeletal discomfort | Baseline and 4 weeks | Work-related musculoskeletal discomfort will be assessed using the Cornell Musculoskeletal Discomfort Questionnaire (CMDQ), which evaluates the frequency, severity, and interference with work associated with musculoskeletal discomfort during the previous working week. The lower-back score and total CMDQ score will be analyzed. |
| Change in lumbar tactile acuity | Baseline and 4 weeks | Lumbar tactile acuity will be assessed using a three-point aesthesiometer to determine two-point discrimination threshold over the lumbar region. Lower discrimination thresholds indicate greater tactile spatial acuity. |
| Change in pressure pain threshold | Baseline and 4 weeks | Pressure pain threshold will be measured using a digital pressure algometer at predefined local lumbar and remote anatomical sites. Pressure will be gradually increased until the participant first reports pain. Change in pressure pain threshold from baseline to 4 weeks will be compared between groups. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in oxygenated hemoglobin concentration in the bilateral primary somatosensory cortex during unstable sitting | Baseline and 4 weeks | Oxygenated hemoglobin concentration will be recorded from the bilateral primary somatosensory cortex using functional near-infrared spectroscopy during unstable sitting. The primary fNIRS metric will be the baseline-corrected change in oxygenated hemoglobin concentration during the unstable sitting condition. |
| Change in deoxygenated hemoglobin concentration in the bilateral primary somatosensory cortex during unstable sitting | Baseline and 4 weeks | Deoxygenated hemoglobin concentration will be recorded from the bilateral primary somatosensory cortex using functional near-infrared spectroscopy during unstable sitting. |
| Change in total hemoglobin concentration in the bilateral primary somatosensory cortex during unstable sitting | Baseline and 4 weeks | Total hemoglobin concentration will be calculated from oxygenated and deoxygenated hemoglobin signals recorded using functional near-infrared spectroscopy during unstable sitting. |
| Change in lumbar resultant angular velocity during unstable sitting | Baseline and 4 weeks | Inertial measurement units positioned over the lumbar and pelvic regions will record trunk movement during unstable sitting. Resultant angular velocity will be calculated in degrees per second as a quantitative measure of postural-control behavior. |
| Change in number of lumbar multifidus motor units during loaded forward bending | Baseline and 4 weeks | Decomposition electromyography will be used to identify lumbar multifidus motor units during repeated 45-degree trunk flexion-extension while holding 5% of body weight. The number of motor units meeting predefined decomposition quality criteria will be recorded. |
| Change in lumbar multifidus percentage thickness change during contraction | Baseline and 4 weeks | Lumbar multifidus thickness will be measured using B-mode rehabilitative ultrasound imaging at the L4-L5 level at rest and during contralateral arm lifting against standardized resistance. Percentage thickness change will be calculated as \[(contracted thickness - resting thickness) / resting thickness\] × 100 and used as an estimate of lumbar multifidus contractile response. |
| Change in lumbar multifidus absolute thickness change during contraction | Baseline and 4 weeks | Absolute lumbar multifidus thickness change will be calculated as contracted thickness minus resting thickness using rehabilitative ultrasound imaging at the L4-L5 level. |
| Belt-wear adherence | Daily throughout the 4-week intervention | Adherence will be determined from the participant daily logbook using recorded belt-wear duration and frequency. The prescribed use is at least 4 hours per day, 5 days per week, for 4 weeks. Adherence will be summarized as the number and percentage of prescribed study days completed and the proportion of prescribed belt-wear time completed. |
| Change in lumbar multifidus motor-unit firing rate during loaded forward bending | Baseline and 4 weeks | Lumbar multifidus motor-unit firing rate will be quantified using decomposition electromyography during repeated loaded forward bending and expressed in pulses per second. |
| Number of participants with device-related adverse events | Throughout the 4-week intervention | Device-related adverse events will include increased low back pain, local discomfort, skin redness or irritation, excessive warmth, numbness, dizziness, or other symptoms judged to be related to use of the study belt. Events will be recorded in the participant daily logbook and reviewed during weekly follow-up contacts. The number of participants experiencing at least one device-related adverse event will be reported for each group. |
| Change in lumbar multifidus motor-unit action-potential amplitude during loaded forward bending | Baseline and 4 weeks | Lumbar multifidus motor-unit action-potential amplitude will be derived from decomposition electromyography during the loaded forward-bending task and expressed in microvolts. |
| Change in lumbar multifidus and erector spinae motor-evoked potential amplitude | Baseline and 4 weeks | Corticospinal excitability of the lumbar multifidus will be assessed using single-pulse transcranial magnetic stimulation with surface electromyographic recording. Motor-evoked potential amplitude will be quantified as peak-to-peak amplitude in millivolts. |
| Change in active motor threshold of lumbar multifidus and erector spinae measured by transcranial magnetic stimulation | Baseline and 4 weeks | Active motor threshold of lumbar multifidus and erector spinae will be determined during standardized submaximal contraction and expressed as a percentage of maximum stimulator output. |
| Change in motor-evoked potential latency of lumbar multifidus and erector spinae | Baseline and 4 weeks | Motor-evoked potential latency of lumbar multifidus and erector spinae will be measured as the time in milliseconds from the transcranial magnetic stimulation pulse to the onset of the electromyographic motor-evoked potential. |
| Change in cortical motor map volume of lumbar multifidus and erector spinae | Baseline and 4 weeks | Cortical motor map volume of lumbar multifidus and erector spinae will be derived from motor-evoked potential amplitudes recorded across the standardized transcranial magnetic stimulation scalp grid. |
| Change in cortical motor map area of lumbar multifidus and erector spinae | Baseline and 4 weeks | Cortical motor map area of lumbar multifidus and erector spinae will be calculated from the number and spatial distribution of responsive stimulation sites within the standardized transcranial magnetic stimulation grid. |
Countries
Thailand
Contacts
CONTACTPeemongkon Wattananon, PhD
CONTACTApinkarn Jaroenlarp, PhD Candidate
PRINCIPAL_INVESTIGATORPeemongkon Wattananon, PhD
Mahidol University
Outcome results
None listed