Faridah Aghahasni Mahabadi, Abbas Farjad Pezeshk, Mohammad Yousefi,
Volume 12, Issue 2 (Iranian Journal of Ergonomics 2024)
Abstract
Objectives: Using a backpack with a hip belt limits hip movements and prevents disruption in hip and trunk coordination. Therefore, this study aimed to compare the effect of common mechanisms in the design of hip belts in mountaineering backpacks on the coordination between trunk and pelvis organs during walking.
Methods: This semi-experimental research was conducted on 16 men. Three types of backpacks with different hip belts were used. Participants carried backpacks with a load of 13 kg. The continuous relative phase and its variability were used to analyze the coordination. Descriptive statistics of mean and standard deviation and analysis of variance with repeated measures were used to compare variables in four conditions.
Results: According to the results, there was a difference between the level of coordination in two conditions of without a backpack and a normal backpack, with the normal backpack showing a significant decrease in coordination (P<0.05). The results also indicated that the variability in coordination increased after using backpacks with movable hip belts and cross frames compared to walking without a backpack (P<0.05).
Conclusion: Based on the existing findings, backpacks with a cross-movable frame maintain the antiphase coordination between the trunk and pelvis by allowing freedom of movement in these two organs. It also creates more flexibility by increasing variability in coordination.
Saeed Ilbeigi, Zahra Karimi, Abbass Farjad Pezeshk,
Volume 13, Issue 2 (Iranian Journal of Ergonomics-In Press 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.
Abbas Farjad Pezeshk, Saeed Ilbeigi, Mohammad Reza Vafaiee,
Volume 13, Issue 2 (Iranian Journal of Ergonomics-In Press 2025)
Abstract
Background and Objectives: The role of shaft stiffness in military boots is widely recognized, yet most research focuses on quantifying stiffness rather than examining how material composition of boot shaft influences performance. This study explores how different boot materials affect kinetic parameters, comparing conventional leather boots to a hybrid leather-synthetic design to assess their impact on mobility and biomechanical efficiency.
Methods: A repeated-measures experimental design was employed, assessing twenty healthy male participants under four conditions: walking with a formal shoe and three military boot types, each featuring distinct shaft materials (two leather and one a hybrid leather-synthetic design). Ground reaction forces (GRF), rate of force development (RFD), impulse was recorded using a force plate. Statistical analysis involved repeated-measures ANOVA with Bonferroni correction.
Results: Featuring synthetic materials in the shaft, boot 3 showed reduced negative impulse, and elevated positive impulse relative to traditional leather boots during gait.
Conclusions: These findings highlight the biomechanical advantages of hybrid boot designs, suggesting that reduced shaft stiffness improves mobility and motion efficiency. The study underscores the need for optimized traditional boot materials to enhance gait performance while minimizing injury risks, particularly for military personnel.
