Hamidreza Barnamehei

Traditional backpacks often cause altered gait, increased joint loading, and discomfort due to poor biomechanical load transfer. This study designed and evaluated a novel backpack featuring a soft polymer fluid-filled bladder as an ergonomic interface, assessing its impact on lower extremity biomechanics across incremental loads. Ten healthy males walked under four conditions: unloaded, and with the backpack loaded at 3 kg, 6 kg, and 9 kg. Motion capture and force plate data informed a subject-specific OpenSim model. Analyses estimated peak joint angles, muscle forces, and joint reaction loads. A repeated-measures ANOVA with Greenhouse-Geisser correction was used to assess the effect of load. Increasing load significantly raised hip, knee, and ankle joint reaction forces along primary weight-bearing axes and major antigravity muscle forces (e.g., quadriceps). Kinematic adaptations included increased hip and knee flexion. Critically, the load transmission pattern suggested the fluid-bladder may provide a dynamic buffering effect, showing a non-uniform force increase between mid and high loads rather than a purely linear rise. While load carriage elevates biomechanical demand, the fluid-bladder interface demonstrates potential as an ergonomic solution by potentially improving force distribution. Future work directly comparing this design to a traditional backpack is required to confirm its ergonomic advantages. This design merges functional hydration with biomechanically-informed load carriage to enhance comfort.

Squat is a closed kinetic chain exercise widely used for strength and conditioning applications. This exercise also supports the preparedness for multiple sports. In Physical rehabilitation, squatting is widely incorporated to strengthen the disorders and activate the muscle extensors. This study collected 3D Motion capture data from 5 healthy, trained individuals. Subjects with a history of injury were excluded. The study aims to examine the difference in kinematic variables between Front and Back squats without load conditions and their postural changes. The Kinematic profile was analyzed using computational musculoskeletal software - OpenSim. Based on the statistical results, it is indicated that there is no significant difference in the lower body joints (p< 0.05), contradicting the upper body joints (p >0.05), especially the spine. The peak joint angle value for the neck, spine, and shoulder in the sagittal plane during the Front squat were -21.53, 16.22, and 22.31 degrees, and during the Back squat were -31.68, 9.19, and 70.90 degrees, respectively. Further statistical test was performed using the Paired sample t-test, indicating a significant difference in knee, neck, spine, and shoulder. Hence, this study differentiates the joint angle variation during the two squat styles. The existence of a dominant component in the squat technique has been identified which potentially adds value and helps in curating the needs of patients requiring rehabilitative techniques. The variables analyzed in this study help identify additional parameters that aid in the qualitative and quantitative analysis of a dedicated posture restoration scheme, including squatting as part of the prescribed exercises.

The goal of the present article is to compare neuromuscular activation patterns among medial-lateral, superior-inferior, and rotational positions of palms for 14 selective muscles during the push-up exercise. Muscle activity and kinematics information of fifteen males (68.35 ± 7.18 kg, 175 ± 3.40 cm, 24.50 ± 7.50 years) were recorded by Myon Electromyographic (EMG) system and Vicon motion capture, respectively. EMG activity in the anterior deltoid, middle deltoid, posterior deltoid, infraspinatus, upper pectoralis major, middle pectoralis major, lower pectoralis major, latissimus dorsi, triceps lateral, triceps medial, biceps brachii, upper trapezius, middle trapezius, and lower trapezius was measured. According to the results, the narrow position of palms increased the infraspinatus, upper pectoralis major, triceps brachii (lateral and medial head), middle trapezius, and lower trapezius muscles, while the wide position of palms enhanced the lower pectoralis major muscle. Superior positions of palms enhanced the upper trapezius, while the inferior positions of palms increased the anterior deltoid, posterior deltoid, infraspinatus, biceps brachii, middle trapezius, lower trapezius, and pectoralis major (lower, middle, and upper) muscles. Internal positions of the palms increased all pectoralis major muscles (lower, middle, and upper), while external positions (lower, middle, and upper) enhanced the middle deltoid, latissimus dorsi, biceps brachii, middle trapezius, and lower trapezius muscles. The information about muscle activation during various types of push-ups can potentially help athletes, coaches, personal trainers, and clinicians to apply modified push-up exercises to make new systematic and useful exercise plans.

(1) Flatfoot is a common malformation in both children and adults, in which a proper arch fails to develop. This study aimed to see how over-the-counter running shoes improved the gait patterns of flatfoot patients. (2) Methods: Three healthy flatfoot subjects were included in the study. Flatfoot was diagnosed by a lateral talometatarsal angle of more than 4 degrees and a talocalcaneal angle of more than 30 degrees. All the patient data were captured using Vicon motion caption cameras. The subjects were allowed to walk at self-selected speeds with and without running shoes. (3) Results: Significant differences in lower limb kinematics were observed between barefoot and running shoe gait. In addition, by wearing the running shoes, the center of mass and lower limb kinematics changed. (4) Conclusion: The improvement in balance and control was clearly indicated, and the change in gait on the entire lower limb influenced normalizing the stresses of the foot with running shoes. These valuable results can be used for rehabilitation programs.

This study is aimed at comparing muscle activations and synergies in badminton forehand overhead smash (BFOS) between elite and nonelite players to clarify how the central nervous system (CNS) controls neuromuscular synergy and activation to generate complex overhead movements. EMG of five upper limb muscles was recorded through surface electromyography (EMG) electrodes from twenty players. Athletics is divided into two groups: elite and nonelite. Eventually, nonnegative matrix factorization (NNMF) was utilized to the calculated electromyography signals for muscle synergy comparison. Similarities between elite and nonelite groups were calculated by scalar product method. Results presented that three muscles synergies could sufficiently delineate the found electromyography signals for elite and nonelite players. Individual muscle patterns were moderately to highly similar between elite and nonelite groups (between-group similarity range: 0.52 to 0.90). In addition, high similarities between groups were found for the shape of synergy activation coefficients (range: 0.85 to 0.89). These results indicate that the synergistic organization of muscle coordination during badminton forehand overhead smash is not profoundly affected by expertise.