Thoracolumbar Fascia Flexibility and Trunk Proprioception Relationship With Spinal Posture

The "Clinometer" mobile application will be used to assess proprioception. Participants will stand upright with their arms at their sides, heels spaced 3 cm apart, and their gaze fixed on a point at eye level. The phone will be placed in an upright position just above the iliac crest, aligned with the mid-axillary line at the midpoint of the iliac spine, and secured with a belt. The inclination of the clinometer will be calibrated to 0°, which will serve as the starting point. The range of motion will be limited to 0-30°.

The physiotherapist will first passively move the participant's trunk to the target angle, where the participant will remain for 10 seconds to memorize the position. Afterward, the participant will actively return to the starting position. Then, the participant will be instructed to actively replicate the target angle three times with their eyes closed. The mean deviation across the three attempts will be recorded as the proprioception value.

The Spinal Mouse (Idiag, Voletswil, Switzerland, SM) device will be employed to assess spinal posture. Prior to the measurement, the researcher will demonstrate all required positions to the participants. Participants will be instructed to hold each position for 1-2 seconds. They will be asked to remove their clothing to expose all spinous processes, which will be palpated and marked from C7 to S3 using a felt-tip pen by the researcher. The Spinal Mouse will then be guided along the marked points from top to bottom.

Participants will be evaluated in three positions: upright, maximum trunk flexion, and maximum trunk extension.

Pain intensity will be assessed using a 0-10 cm horizontal Visual Analog Scale (VAS). On this scale, a 10 cm line will be anchored with "0: no pain" at one end and "10: unbearable pain" at the other. Participants will be instructed to indicate the intensity of their pain by placing a dot, drawing a line, or marking a specific point along the scale. The distance from the starting point to the participant's mark will represent their perceived pain intensity. Pain levels will be classified as follows: 0-3.4 cm will indicate mild pain, 3.5-7.4 cm moderate pain, and 7.5 cm or more severe pain.

The Oswestry Disability Questionnaire will be widely utilized to assess specific outcomes in individuals with spinal problems. It will consist of 10 items that evaluate various functional aspects, each scored on a scale from 0 to 5. The total score will be calculated by summing the individual item scores, multiplying the result by 2, and expressing it as a percentage. Higher percentages will indicate greater levels of disability.

Scoring classifications will be as follows:

0-20%: Low back pain will not significantly impact the individual's daily life.

20-40%: Low back pain will mildly restrict the individual's daily activities.

40-60%: Low back pain will severely restrict the individual's daily activities.

60-80%: The individual's daily life will be significantly impaired due to low back pain.

80-100%: The individual will be considered bedridden (symptoms may be exaggerated).

This questionnaire will be a standardized tool developed by researchers from multiple countries, supported by the World Health Organization, to assess levels of physical activity. The original version will consist of 27 items, while the short form will include 7 items. Participants will be asked to estimate the duration and frequency of their physical activity over the previous week. The reported durations will be multiplied by known metabolic equivalents values for each activity, and an overall score will be calculated by summing the results for all items. Scores for walking, moderate activity, and vigorous activity will be determined by summing the corresponding item scores. Time spent sitting will be excluded from the calculation.