Chronic low back pain (CLBP) is a leading cause of disability worldwide and affects a large proportion of working-age individuals. Cortical reorganization in CLBP, particularly within the sensorimotor cortex, has been shown to negatively influence sensory acuity and motor control. The neuroplasticity underlying this reorganization may enhance the effectiveness of sensorimotor retraining therapies that involve specific stimulus features targeting somatosensory cortical regions.

This randomized controlled trial will include three groups: a device-assisted sensory acuity training group, a manual sensory acuity training group, and a control group receiving conventional physiotherapy. In this study, device-assisted sensory acuity training will be delivered using a standardized vibrotactile interface that presents controlled stimuli and records participant responses. The intervention will be structured to target sensory acuity components similar to those addressed in manual training.

Accordingly, the structured training protocol will include:

• localization training to improve detection of stimulus location,
• orientation discrimination to identify stimulus direction,
• temporal acuity training to distinguish timing differences between tactile stimuli and
• graphesthesia training to improve recognition of shapes or letters drawn on the skin through tactile input.

The primary aim of this study is to evaluate sensory acuity in individuals with CLBP and to determine the effects of a structured manual and technology-based sensory acuity training program, combined with conventional physiotherapy, on pain intensity (VAS), lumbar two-point discrimination, and a composite sensory acuity score.

We hypothesize that adding manual and technology-based structured sensory acuity training (SAT) program to a conventional physiotherapy regimen including motor control exercises will support central nervous system reorganization, improve sensory profiles, and lead to improvements in pain-related variables, disability, and quality of life.

Through this structured SAT program, we aim to provide an approach that evaluates and trains multiple dimensions of sensory acuity in CLBP, including localization, orientation, and temporal discrimination.

This study consists of three research groups: the Technology-Based Sensory Acuity Training Group (T-SATG), the Manual Sensory Acuity Training Group (M-SATG), and the Control Group (CG). All groups will receive conventional physiotherapy for comparison purposes. In addition, a structured technological SAT program will be administered to the T-SATG, and a structured manual SAT program will be administered to the M-SATG, while the control group will receive a patient education (PE) program designed not to provide additional sensory stimulation. This approach will ensure equal session duration across all groups.

All individuals with non-specific chronic low back pain (NCLBP) will receive conventional physiotherapy for 30 minutes per day, three days a week, for four weeks. All patient admissions will be conducted under the guidance of the same physiotherapy team to ensure consistent implementation of the protocol and to maintain patient safety throughout the study. Participants will be asked to refrain from receiving any additional treatments for their lower back during the four-week intervention period, and any changes in medication type or dosage will be recorded.

In this study, the motor control exercise (MCE) program administered as part of conventional physiotherapy will aim to optimize control of the spine and pelvis through appropriate muscle activation, postural alignment, and movement integrity. The program is based on a graded progression system that emphasizes activation of the transversus abdominis and multifidus muscles. It will begin with fundamental exercises involving isolated contractions of these muscles, followed by more complex movements-such as bridging and quadruped exercises-that require coordinated activation of both muscles. During each session, the physiotherapist will guide participants to ensure correct exercise technique and provide necessary adjustments.

Individuals with non-specific chronic low back pain (CLBP) included in the T-SATG and M-SATG will receive sensory acuity training (SAT) for 30 minutes, three times per week, over a four-week period, with the difficulty level progressively increasing each week. This training program comprises four sensory acuity components delivered sequentially: Localization Acuity Training (LAT), Orientation Acuity Training (OAT), Temporal Acuity Training (TAT), and Graphesthesia Training (GT).

The sensory acuity training program will follow a structured weekly progression. During Weeks 1 and 2, participants will complete three core components of the training: Localization Acuity Training (LAT), Orientation Acuity Training (OAT), and Temporal Acuity Training (TAT). In Weeks 3 and 4, the same three components will continue, and Graphesthesia Training (GT) will be added to the protocol, expanding the program to four sensory acuity domains. This stepwise progression is designed to gradually increase training complexity and ensure the systematic development of sensory discrimination abilities across the four-week intervention period.

Localization Acuity Training (LAT) aims to improve the individual's ability to perceive applied stimuli and accurately identify their location. Orientation Acuity Training (OAT) focuses on enhancing the ability to distinguish the direction of two consecutive stimuli. Temporal Acuity Training (TAT) targets the ability to correctly determine the number of stimuli when two successive stimuli delivered to a single point differ in timing. Finally, Graphesthesia Training (GT) involves recognizing letters drawn on the skin and represents a complex process that requires not only tactile acuity but also cortical-level processing and mental representation of the letters.

For both groups, participants will be asked to visually mark their responses to the presented stimuli for each training parameter (LAT, OAT, TAT, GT). Participants in the T-SATG will indicate their responses through a tablet application synchronized with the device (TactiPain). The system will automatically record correct and incorrect responses. Participants in the M-SATG will be provided with a paper template containing designated areas representing the stimulus variables, and they will be instructed to mark the perceived stimulus features on this template. All responses will be collected by the physiotherapist at the end of each session and recorded. This procedure will ensure standardization of the response process and maintain measurement reliability in both training methods.

1. Technology-Assisted Sensory Acuity Training Group (T-SATG): The TactiPain device will be designed as a wearable waist belt containing 16 vibration motors (Pololu - Shaftless Mini Vibration Motor, 10 × 3.4 mm) placed between the last costa and the sacrum. The motors will be aligned in a 4 × 4 matrix according to the distances recommended in the literature. The combination of neoprene and cotton fabric will optimize both comfort and vibration transmission. The device will be integrated with a computer interface for the physiotherapist and a tablet application for the participant. The physiotherapist will be able to adjust the intensity of the vibration motors, the duration of each vibration, and the rest periods between vibrations during the session through the interface. The user screen will be simple and user-friendly, recording only the responses and response times. This innovative system, which offers a structured SAT protocol via vibration motors, aims to contribute scientifically to clinical decision-making processes by retraining sensory interaction mechanisms and reducing pain in individuals with NCLBP. During the training, vibration intensity will be adjusted to correspond to different maximum motor voltage levels. Vibration duration and inter-stimulus intervals will be progressively advanced from easier to more challenging levels based on participant performance. This structured progression is designed to allow the selection of parameters most appropriate to the individual's sensory perception profile and physiological responses, thereby optimizing the development of sensory acuity skills. Perceptual sensitivity to the vibrotactile stimuli and response accuracy will serve as the main progression criteria determining the continuation of training. This method is based on sensory training protocols recommended in the literature to enhance participants' stimulus identification and discrimination abilities.
2. Manual Sensory Acuity Training Group (M-SATG): During this training, the thin and thick tips of the Semmes-Weinstein monofilament will be used to vary stimulus intensity (pressure magnitude) and to provide two different stimulus levels in order to progressively increase difficulty. All SAT parameters (localization, orientation, temporal acuity, and graphesthesia) will be administered using sets generated randomly prior to each training session via the random.org program. This method is intended to prevent the development of habituation in participants. All responses will be recorded by the researcher to monitor weekly progress. During training, an adhesive grid template consisting of 16 holes will be placed on the participant's lumbar region between the last rib and the sacrum. A personalized adhesive grid template will be prepared for each participant, and the grid will be placed directly on the skin before each session.

Inclusion Criteria:

• Age between 25-45 years
• No spinal fracture or acute disc herniation
• Pain duration ≥ 3 months
• Pain intensity ≥ 4/10
• Central Sensitization Scale (CSI) score ≥ 40
• No current psychiatric illness or cognitive impairment
• No contraindications to exercise

Exclusion Criteria:

• Serious spinal pathologies (lumbar stenosis, spondylolisthesis, tumor, infection, metastasis, osteoporotic fracture, severe structural deformities, inflammatory arthritis)
• Conditions with radicular involvement or neurological deficits (sciatica, nerve root compression)
• Systemic or neurological diseases (diabetes mellitus, neuromuscular diseases, serious central or peripheral nervous system diseases, epilepsy)
• Mental disorders
• Pregnancy
• Lower extremity injuries
• Spinal surgery within the last three years
• Chronic generalized pain syndromes (fibromyalgia, chronic fatigue syndrome)
• Individuals receiving other treatment for non-specific chronic low back pain during the study period.