Exercise-Based Strategies for Chronic Back Pain

Change in Trunk Flexor and Extensor Muscle Function

Trunk Flexor Muscle Strength (Isokinetic Peak Torque): Trunk flexor muscle function will be assessed using an isokinetic dynamometer (Cybex NORM or HUMAC NORM system). The primary outcome will be peak torque during trunk flexion, reported in Newton-meters (N·m) (and, if applicable, normalized to body mass as N·m/kg). Higher values indicate greater trunk flexor strength. Trunk Extensor Muscle Strength (Isokinetic Peak Torque): Trunk extensor muscle function will be assessed using an isokinetic dynamometer (Cybex NORM or HUMAC NORM system). The primary outcome will be peak torque during trunk extension, reported in N·m (and, if applicable, normalized to body mass as N·m/kg). Higher values indicate greater trunk extensor strength.

Short-Form McGill Pain Questionnaire (SF-MPQ) Total Score

Pain intensity and pain-related characteristics will be assessed using the Short-Form McGill Pain Questionnaire (SF-MPQ). The outcome will be the SF-MPQ total score, calculated as the sum of 15 descriptor items rated on a 0-3 scale (0 = none, 1 = mild, 2 = moderate, 3 = severe). Total score ranges from 0 to 45 points, with higher scores indicating worse pain and lower scores indicating improvement.

Change in DNS-Based Functional Postural Stabilization Performance

Abdominal wall tension will be measured during the performance of standardized DNS functional tests using a wearable abdominal wall tension monitoring belt (OHMBelt). The device provides continuous, noninvasive, device-derived estimates of abdominal wall tension, which are related to changes in intra-abdominal pressure. Outcomes will include peak abdominal wall tension and mean abdominal wall tension recorded during each DNS test, reported in device-derived units (arbitrary units, a.u.) (and/or as change from baseline, as applicable). Higher values indicate greater abdominal wall tension during task performance.

Maximal Oxygen Uptake (VO2max) During Treadmill Graded Exercise Test

Maximal oxygen uptake (VO₂max) will be assessed using a graded exercise test (GXT) on a motorized treadmill with breath-by-breath gas exchange analysis (Metalyzer metabolic cart). VO₂max will be defined as the highest 30-second averaged oxygen uptake achieved during the test and reported in mL/kg/min (and, if applicable, also in L/min). Higher VO₂max values indicate greater aerobic capacity.

Quantitative Sensory Testing - Pressure Pain Threshold

Pressure pain threshold will be assessed using quantitative sensory testing with a handheld digital pressure algometer applied at standardized anatomical sites. The outcome will be reported as the pressure at pain threshold in kilopascals (kPa). Higher PPT values indicate lower mechanical pain sensitivity.

Isometric Mid-Thigh Pull

Lower-body maximal isometric force production will be assessed using an isometric mid-thigh pull (IMTP) performed on dual force plates (ForceDecks system). The primary outcome will be peak vertical ground reaction force, reported in Newtons (N) (and, if applicable, also normalized to body mass as N/kg). Higher values indicate greater maximal isometric lower-body force.

Handgrip Strength

Handgrip (kg) is measured by Takei (TKK 5401, Japan).It will be measured for both hands (left and right). Three trials will be performed on each hand and the mean will be calculated. The standard for men over 40 years of age is 47 (±9.5) kg for the right hand and 45 (±9.3) kg for the left hand. The standard for women over 40 is 29 (±5.7) kg for the right hand and 28 (±5.7) kg for the left hand. Higher values are considered to be better.