Author(s): LIAO, J., LIN, P.H., SU, F.C., LIN, C.F., Institution: CHAILI CHI MEI HOSPITAL, Country: TAIWAN, Abstract-ID: 1585

INTRODUCTION:
Chronic non-specific low back pain (CNSLBP) is often linked to posterior-chain dysfunction, characterized by impaired trunk/hip extensor strength, reduced endurance, and altered motor control under load. While resistance training is commonly used, the specific impact of targeted posterior-chain protocols on functional load-regulation remains under-examined. This study evaluated the effects of an 8-week posterior-chain resistance training (PCRT) program on muscle strength, endurance, and load-regulation strategies during functional tasks in individuals with CNSLBP.
METHODS:
Eighteen participants with chronic non-specific low back pain (CNSLBP) (age: 26.1±4.7 yrs; pain duration: 3.5±5.0 yrs) were randomized into three groups: high-intensity posterior-chain resistance training (PCRT-HI, n=6), moderate-intensity (PCRT-MI, n=6), or control (Con, n=6). Training was conducted twice weekly for eight weeks, focusing on multi-joint posterior-chain movements. Primary outcomes included neuromuscular Endurance, such as Biering–Sorensen test (BST) duration and median frequency slope of electromyography (EMG), and Load Regulation, such as center of pressure (COP) path length and Symmetry Indices (SI) for force, mean pressure, and contact area during unloaded barbell squats and deadlifts.
RESULTS:
BST endurance significantly improved in both PCRT-HI (△= 27.1± 14.2 s) and PCRT-MI (△= 23.8±18.4 s) compared to Con (△=17.4±17.3 s; p=0.009), with no difference between intensities. However, PCRT-HI showed a significantly greater reduction in the medial frequency slope of the right gluteus maximus (reflecting improved fatigue resistance) compared to Con (PCRT-HI: 0.10 ± 0.10 Hz/s; PCRT-MI: 0.06 ±0.07 Hz/s; Con: -0.03 ± 0.06 Hz/s; p=0.034). Regarding load regulation, both training groups showed comparable improvements in COP path length and force symmetry (SI) during squats and deadlifts, suggesting enhanced postural control and bilateral loading strategies compared to the control group.
CONCLUSION:
An 8-week PCRT program effectively enhances trunk endurance and load-regulation strategies in individuals with CNSLBP. While both intensities improved functional endurance, high-intensity training may elicit superior neuromuscular adaptations in the gluteus maximus. These findings suggest that targeting the posterior chain improves objective biomechanical markers during fundamental lifting tasks, which is critical for long-term back health.