Head supported mass, moment of inertia, neck loads and stability: A simulation study

Barrett, Jeff M.; Healey, Laura; McKinnon, Colin D.; Laing, Andrew C.; Dickerson, Clark R.; Fischer, Steven L.; Callaghan, Jack P.

doi:10.1016/j.jbiomech.2022.111416

Cited by 3 publications

(2 citation statements)

References 53 publications

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“…For instance, Van Dijke et al (1993) and Newman et al (2022) studied the influence of jet pilot helmets' inertial properties on the risk of neck injury and found that helmets significantly increase the neck joint reaction moments. Barrett et al (2023) showed that the inertial properties (i.e., COM, mass, and moment of inertia) of a military helmet resulted in higher compressive forces in the cervical spine. Other studies on construction (Boschman et al, 2015), mining (Torma-Krajewski et al, 2006), and firefighting (Wang et al, 2021) helmets also emphasized the importance of enhancing the ergonomic aspects (i.e., inertial properties) of helmets in order to reduce neck discomfort and MSDs.…”

Section: Introductionmentioning

confidence: 99%

“…Previous biomechanical studies have linked excessive weight and shifted center of mass (COM) of the helmets and head mounted devices as the cause for cervical spinal disorders and neck muscle fatigue. For instance, Van Dijke et al (1993) and Newman et al (2022) showed that jet pilot helmets significantly increases the neck joint forces and moments, increasing the risk of neck injury; Harrison et al (2016) found that the addition of night vision googles and counterweight increased muscle activation and affected postures, thereby inducing fatigue and cause neck pain; Barrett et al (2023) showed the COM position, mass, and moment of inertia influence the compressive forces in the cervical spine; Baucher et al (2022) found that an increase in weight supported by the head and the restriction of cervical intervertebral motion could be risk factors of degenerative diseases, such as spinal cord spondylosis, degenerative disc disease, and ossification of the ligamentum flavum. In addition, studies on construction (Boschman et al, 2015), mining (Torma-Krajewski et al, 2006), and firefighting (Wang et al, 2021) helmets have emphasized the importance of enhancing ergonomic aspects alongside protective features, as in these domains, the helmets have to be worn for prolonged durations.…”

Section: Introductionmentioning

confidence: 99%

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Firefighter Helmets and Cervical Intervertebral Kinematics: An OpenSim-Based Biomechanical Study

Paulon,

Subramanian,

Chowdhury

2023

Preprint

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Wearing head-mounted devices for prolonged time in occupational settings is one of the leading causes of neck pain. In the case of firefighters, the helmets are designed to provide protection against both fire and impact, making it heavier, thereby increasing the risk of neck pain and musculoskeletal injuries. In this study, we evaluated user adaptability and chances of injury with two different firefighter helmet designs, US-style helmet with a comparatively higher center of mass (COM), and European-style helmet with higher mass, based on cervical intervertebral kinematics. We collected motion data of 18 male and 18 female firefighters while performing static and dynamic flexion-extension and lateral bending with and without the helmets and measured the helmets’ inertial properties. Musculoskeletal simulations were performed by applying the motion data and helmet inertial properties to a modified OpenSim full-body model to calculate cervical intervertebral kinematics. It was found that the US-style helmet, although lighter in weight, significantly increased the maximum neck and intervertebral angles during static flexion, and lateral bending and decreased static and dynamic maximum extension angles. In addition, both helmets affected cervical lordosis, which could potentially increase the risks of musculoskeletal disorders during long-term usage or firefighting operations. This study revealed that the higher lever arm of the helmet COM and moment of inertia about the axis of rotation, especially in the case of US-style helmets, is the reason for variations in neck kinematics. A low-profile helmet design (lower COM) would improve the safety and musculoskeletal health of the firefighters.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Firefighter Helmets and Cervical Intervertebral Kinematics: An OpenSim-Based Biomechanical Study

Paulon,

Subramanian,

Chowdhury

2023

Preprint

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Firefighter helmets and cervical intervertebral Kinematics: An OpenSim-Based biomechanical study

Paulon,

Sudeesh,

Wei

et al. 2024

Journal of Biomechanics

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Muscle short-range stiffness behaves like a maxwell element, not a spring: Implications for joint stability

Barrett,

Malakoutian,

Fels

et al. 2024

PLoS ONE

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Introduction Muscles play a critical role in supporting joints during activities of daily living, owing, in part, to the phenomenon of short-range stiffness. Briefly, when an active muscle is lengthened, bound cross-bridges are stretched, yielding forces greater than what is predicted from the force length relationship. For this reason, short-range stiffness has been proposed as an attractive mechanism for providing joint stability. However, there has yet to be a forward dynamic simulation employing a cross-bridge model, that demonstrates this stabilizing role. Therefore, the purpose of this investigation was to test whether Huxley-type muscle elements, which exhibit short-range stiffness, can stabilize a joint while at constant activation. Methods We analyzed the stability of an inverted pendulum (moment of inertia: 2.7 kg m2) supported by Huxley-type muscle models that reproduce the short-range stiffness phenomenon. We calculated the muscle forces that would provide sufficient short-range stiffness to stabilize the system based in minimizing the potential energy. Simulations consisted of a 50 ms long, 5 Nm square-wave perturbation, with numerical simulations carried out in ArtiSynth. Results Despite the initial analysis predicting shared activity of antagonist and agonist muscles to maintain stable equilibrium, the inverted pendulum model was not stable, and did not maintain an upright posture even with fully activated muscles. Discussion & conclusion Our simulations suggested that short-range stiffness cannot be solely responsible for joint stability, even for modest perturbations. We argue that short-range stiffness cannot achieve stability because its dynamics do not behave like a typical spring. Instead, an alternative conceptual model for short-range stiffness is that of a Maxwell element (spring and damper in series), which can be obtained as a first-order approximation to the Huxley model. We postulate that the damping that results from short-range stiffness slows down the mechanical response and allows the central nervous system time to react and stabilize the joint. We speculate that other mechanisms, like reflexes or residual force enhancement/depression, may also play a role in joint stability. Joint stability is due to a combination of factors, and further research is needed to fully understand this complex system.

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Head supported mass, moment of inertia, neck loads and stability: A simulation study

Cited by 3 publications

References 53 publications

Firefighter Helmets and Cervical Intervertebral Kinematics: An OpenSim-Based Biomechanical Study

Firefighter Helmets and Cervical Intervertebral Kinematics: An OpenSim-Based Biomechanical Study

Firefighter helmets and cervical intervertebral Kinematics: An OpenSim-Based biomechanical study

Muscle short-range stiffness behaves like a maxwell element, not a spring: Implications for joint stability

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