Yi-Ning Wu

Objective: To investigate muscle activation and movement behavior in the lower back and legs during selected explosive ordnance disposal (EOD) operational tasks to evaluate the impact of EOD personal protective equipment (PPE) on performance and the body. Background: EOD PPE is designed to shield technicians from blast-related threats. However, the protective features make the PPE heavy, and restrictive to movement. It remains unclear how wearers adapt their movement under these constraints. Method: Sixteen participants performed six EOD operational tasks ranked the most challenging and frequently encountered. Electromyography (EMG), force plates, and motion capture system were used to measure the movement while the tasks were performed with and without wearing EOD PPE. Results: EMG results show task-dependent, asymmetrical muscle activation, with greater demands during physically intensive tasks such as bending, lifting, and stair climbing. A trend of decreased ankle muscle activation was observed when carrying a heavy load. Reduced center of pressure displacement was noted during tasks such as bending and rising from kneeling. Conclusion: Wearing EOD PPE amplifies muscle demands, particularly in the thigh muscles during movements requiring postural adjustment and lifting and may increase stiffness or restrict movement. Elevated thigh muscle activity across tasks, together with restricted mobility, increases the hip’s vulnerability to overuse and musculoskeletal injury. Application: Altered motor behavior from wearing EOD PPE has implications for other PPE uses. Understanding human motor adaptation during operations supports prevention strategies such as exoskeletons, ergonomic designs, and targeted training, to reduce musculoskeletal strain, sustain performance, and protect long-term health.

Blood flow restriction (BFR) and body cooling (BC) have been investigated separately during exercise, but little is known about their concurrent use. This study examined acute metabolic responses, respiratory physiology, and rate of perceived exertion (RPE) during interval training (IT) performed with combined BFR and BC (VASPER ON) compared with IT without BFR and BC (VASPER OFF). It was hypothesized that VASPER ON would elicit greater physiological demands. A total of 7 female and 19 male participants (20.2 ± 2.4 years) completed a 21-min IT exercise. In VASPER ON, the participants wore cuffs that simultaneously applied BFR and BC. Total oxygen consumption (TVO₂), total carbon dioxide production (TVCO₂), total breaths (BRTH), and total ventilation (TVE) were measured during exercise (EX) and for 10 min post-exercise (Post-EX). RPE was recorded during EX. During EX, TVE and ventilatory equivalents for both oxygen and carbon were significantly higher in VASPER ON. Post-EX, all variables remained significantly elevated in VASPER ON except for the ventilatory equivalent for carbon dioxide. Sprint interval RPE was significantly lower in VASPER OFF. These findings suggest that concurrent BFR and BC increase post-exercise metabolic and ventilatory demands without attenuating each other’s effect.

Objective: To provide a comprehensive characterization of explosive ordnance disposal (EOD) personal protective equipment (PPE) by evaluating its effects on the human body, specifically the poses, tasks, and conditions under which EOD operations are performed. Background: EOD PPE is designed to protect technicians from a blast. The required features of protection make EOD PPE heavy, bulky, poorly ventilated, and difficult to maneuver in. It is not clear how the EOD PPE wearer physiologically adapts to maintain physical and cognitive performance during EOD operations. Method: Fourteen participants performed EOD operations including mobility and inspection tasks with and without EOD PPE. Physiological measurement and kinematic data recording were used to record human physiological responses and performance. Results: All physiological measures were significantly higher during the mobility and the inspection tasks when EOD PPE was worn. Participants spent significantly more time to complete the mobility tasks, whereas mixed results were found in the inspection tasks. Higher back muscle activations were seen in participants who performed object manipulation while wearing EOD PPE. Conclusion: EOD operations while wearing EOD PPE pose significant physical stress on the human body. The wearer’s mobility is impacted by EOD PPE, resulting in decreased speed and higher muscle activations. Application: The testing and evaluation methodology in this study can be used to benchmark future EOD PPE designs. Identifying hazards posed by EOD PPE lays the groundwork for developing mitigation plans, such as exoskeletons, to reduce physical and cognitive stress caused by EOD PPE on the wearers without compromising their operational performance.

Aim: To assess the neural and non‐neural contributions to spasticity in the impaired ankle of children with cerebral palsy (CP).Method: Instrumented tapping of the Achilles tendon was done isometrically to minimize non‐neural contributions and elicit neural contributions. Robot‐controlled ankle stretching was done at various velocities, including slow stretching, with minimized neural contributions. Spasticity was assessed as having neural (phasic and tonic stretch reflex torque, tendon reflex gain, contraction rate, and half relaxation rate) and non‐neural origin (elastic stiffness and viscous damping) in 17 children with CP (six females and 11 males; mean age [SD] 10y 8mo [3y 11mo], range 4y–18y) and 17 typically developing children (six females and 11 males; mean age [SD] 12y 7mo [2y 9mo], range 7y–18y). All torques were normalized to weight×height.Results: Children with CP showed increased phasic and tonic stretch reflex torque (p=0.004 and p=0.001 respectively), tendon reflex gain (p=0.02), contraction rate (p=0.038), half relaxation rate (p=0.02), elastic stiffness (p=0.01), and viscous damping (p=0.01) compared to typically developing children.Interpretation: Controlled stretching and instrumented tendon tapping allow the systematic quantification of various neural and non‐neural changes in CP, which can be used to guide impairment‐specific treatment.What this paper adds: Ankle spasticity is associated with increased phasic and tonic stretch reflexes, tendon reflex gain, and contraction and half relaxation rates. Ankle spasticity is also associated with increased elastic stiffness and viscous damping.

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[Purpose] This study was performed to examine the relationship between physical performance and muscle properties during police cadet training. The study's hypothesis was that improved physical performance brought about by training, would in turn cause a reduction in muscle flexibility. [Subjects and Methods] Fifty-nine police cadets were included in this study. Standard fitness tests and quantitative assessments of muscular biomechanical properties were conducted before, during and after the 20-week cadet training. [Results] General fitness had improved at the end of the police cadet training. There was no significant decrease in muscle flexibility as measured by the Sit-and-Reach test. However, muscle compliance of the non-dominant leg measured by the relaxation coefficient had decreased at the end of the police cadet training. [Conclusion] The increased sit-and-reach distance could be due in part to strengthening of the abdominal muscles. On the other hand, the biomechanical test, which was specific to muscle extensibility, showed a reduction in the relaxation coefficient of the non-dominant leg. Our data suggests that changes in muscle compliance as a result of lower extremity training should be considered. This data may be useful in the design of a training protocol that prevents the potential injuries caused by reduced muscle flexibility.