Majid Shahbazi, Javad Sarrafzadeh, Saeed Akhlaghi, Hossein Negahban,
Volume 12, Issue 4 (2-2025)
Abstract
Objectives: Balance control is a crucial issue in patients with low back pain. Despite existing studies, the mechanism of balance control in patients with low back pain, especially under different loading conditions at various heights, remains unclear. Therefore, this study aimed to investigate the effect of height on balance during loading.
Methods: In this cross-sectional study, 54 low back pain patients and 20 healthy male individuals participated. Balance control was assessed using a force plate system. The participants were randomly instructed to lower the load from above the head to waist level and from waist level to the ground. The load was approximately 10% of the participants' body weight. The P value was established 5% level of significance.
Results: The results showed that during lifting from above the head to waist level and from waist level to the ground, there were significant differences (P<0.05) in variables such as medial-lateral and anterior-posterior velocity, total mean velocity, and center of pressure displacement in the anterior-posterior direction between the two groups. Intra-group comparisons of variables in healthy individuals and low back pain patients indicated significant differences (P<0.05) in all variables except anterior-posterior velocity in healthy individuals. Both groups exhibited increased postural sway while lowering at a lower height.
Conclusion: The present study demonstrates that both healthy individuals and low back pain patients display less balance when loading at a lower height with a flexed lumbar spine, indicating that considering these findings could contribute to rehabilitation, determining occupational conditions, and preventing workplace-related accidents.
Saeed Ilbeigi, Zahra Karimi, Abbass Farjad Pezeshk,
Volume 13, Issue 2 (9-2025)
Abstract
Background and Purpose: Backpacks with pelvic belts are commonly used for carrying loads during long treks and mountaineering, as they help distribute the load between the upper and lower body and reduce muscular effort. However, they may also restrict movement. This study aimed to compare three common pelvic belt mechanisms in backpacks regarding their effects on postural control and center of pressure (COP) parameters during standing and walking.
Methods: This semi-experimental study was conducted on 20 male physical education students aged 19 to 25. Participants used three types of backpacks (1–with a movable pelvic belt, 2–with a crossed-frame back support, and 3–a regular backpack) while carrying a standard 13 kg load on a flat surface. A walking test without a backpack was also conducted as a control. COP indicators—including area, displacement, velocity, and sway—were measured. Data normality was assessed using the Shapiro-Wilk test, and statistical comparisons were made using repeated measures ANOVA and Bonferroni post hoc tests.
Findings: No significant differences were observed among the backpacks in terms of COP area during standing and walking. However, during eyes-closed standing, significant differences were found in COP displacement and velocity in the anterior-posterior direction (p=0.009), particularly between the regular backpack and the one with a movable pelvic belt. For COP sway (p=0.030), significant differences were found among the three backpacks in the medial-lateral direction, though pairwise comparisons showed no statistical significance.
Conclusion: The backpack with a movable pelvic belt showed superior performance in minimizing COP sway, displacement, and velocity. Differences in pelvic belt designs become more evident under higher complexity postural tasks.
