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Dynamic seating

Eunyeong Kim, Mohammad Fard, Kazuhito Kato
Characterizing the coupling between the occupant and vehicle seat is necessary to understand the transmission of vehicle seat vibration to the human body. In this study, the vibration characteristics of the human body coupled with a vehicle seat were identified in frequencies up to 100 Hz. Transmissibilities of three volunteers seated on two different vehicle seats were measured under multi-axial random vibration excitation. The results revealed that the human-seat system vibration was dominated by the human body and foam below 10 Hz...
October 26, 2016: Ergonomics
Michelle Rae, Michelle Girouard, Colin McKinnon, Jack P Callaghan, Wayne J Albert
Police officers have been identified as group at high risk for developing musculoskeletal injuries. The purpose of this study was to determine physical demands differences of patrol officers during day shifts and night shifts. Sixteen participants were recruited (10 males, 6 females) for in-vehicle observation over one full day shift and one full night shift. Dynamic pressure distribution when seated in the vehicle was assessed and compared between the first and last part of each shift. Activity characterization and postural analyses were conducted from video that was recorded continuously for the duration of each shift to determine time spent in each task and corresponding postures...
October 18, 2016: International Journal of Occupational Safety and Ergonomics: JOSE
Gareth D Jones, Darren C James, Michael Thacker, David A Green
Individuals with sensorimotor pathology e.g., stroke have difficulty executing the common task of rising from sitting and initiating gait (sit-to-walk: STW). Thus, in clinical rehabilitation separation of sit-to-stand and gait initiation - termed sit-to-stand-and-walk (STSW) - is usual. However, a standardized STSW protocol with a clearly defined analytical approach suitable for pathological assessment has yet to be defined. Hence, a goal-orientated protocol is defined that is suitable for healthy and compromised individuals by requiring the rising phase to be initiated from 120% knee height with a wide base of support independent of lead limb...
2016: Journal of Visualized Experiments: JoVE
Maryne Cozette, Stéphane Delanaud, Pierre-Marie Lepretre, Thierry Weissland
OBJECTIVE: Shoulder internal (IR) and external rotator (ER) muscles play an important role in the stability of glenohumeral joint. The ratio between the peak torque of ER and IR in concentric (ER/IRPT) and mixed (ER-ECC/IR-CONPT) are usually measured to evaluate the effects of muscle weakness, sport activities, injury and treatment (Greenfield et al., 1990; Scoville et al., 1997). However, ER/IRPT and ER-ECC/IR-CONPT failed to provide some indication on the evolution of the ER/IR torque ratio (ER/IRTorque) and mixed torque ratio (ER-EC/IR-COTorque) during the range of motion (ROM)...
September 2016: Annals of Physical and Rehabilitation Medicine
Kenneth E Games, Joni M Lakin, John C Quindry, Wendi H Weimar, JoEllen M Sefton
INTRODUCTION: Despite significant investment into the development and improvement of military helicopter seat systems, military aviators continue to report seat system related pain and discomfort during prolonged missions. METHODS: Using a factorial repeated measures design, 15 healthy subjects completed the study, in which focal pressure was applied to two locations on the sitting surfaces of the body (ischial tuberosity and middle of the posterior thigh). Pressure was applied using a purpose-built pressure application system allowing subjects to sit in a position mimicking the sitting position in the UH-60 Black Hawk helicopter...
August 2016: Aerospace Medicine and Human Performance
Andréa Gomes Moraes, Fernando Copetti, Vera Regina Angelo, Luana Leonardo Chiavoloni, Ana Cristina David
UNLABELLED: [Purpose] This study evaluated the effects of hippotherapy on seated postural balance, dynamic balance, and functional performance in children with cerebral palsy and compared the effects of 12 and 24 sessions on seated postural balance. [Subjects and Methods] This study included 15 children with cerebral palsy aged between 5 and 10 years. INTERVENTIONS: A hippotherapy protocol was performed for 30 minutes, twice a week, for 12 weeks. Postural balance in a sitting position was measured using an AMTI AccuSway Plus force platform 1 week before initiating the hippotherapy program and after 12 and 24 weeks...
August 2016: Journal of Physical Therapy Science
Paul C Ivancic
Synopsis Head and spinal injuries commonly occur during motor vehicle crashes (MVCs). The goal of this clinical commentary is to discuss real-life versus simulated MVCs and to present clinical, biomechanical, and epidemiological evidence of MVC-related injury mechanisms. It will also address how this knowledge may guide and inform the design of injury mitigation devices and assist in clinical decision making. Evidence indicates that there exists no universal injury tolerance applicable to the entire population of the occupants of MVCs...
October 2016: Journal of Orthopaedic and Sports Physical Therapy
Kristy B Arbogast, Jinyong Kim, Helen Loeb, Jonny Kuo, Sjaan Koppel, Katarina Bohman, Judith L Charlton
OBJECTIVE: Restraint performance is evaluated using anthropomorphic test devices (ATDs) positioned in prescribed, optimal seating positions. Anecdotally, humans-children in particular-assume a variety of positions that may affect restraint performance. Naturalistic driving studies (NDSs), where cameras and other data acquisition systems are placed in a vehicle used by participants during their regular transportation, offer means to collect these data. To date, these studies have used conventional video and analysis methods and, thus, analyses have largely been qualitative...
September 2016: Traffic Injury Prevention
Bengt Pipkorn, Francisco J López-Valdés, Oscar Juste-Lorente, Ricardo Insausti, Christer Lundgren, Cecilia Sunnevång
OBJECTIVES: The objective of this study was to determine the potential chest injury benefits and influence on occupant kinematics of a belt system with independent control of the shoulder and lap portions. METHODS: This article investigates the kinematics and dynamics of human surrogates in 35 km/h impacts with 2 different restraints: a pretensioning (PT), force-limiting (FL) seat belt, a reference belt system, and a concept design with a split buckle consisting (SB) of 2 separate shoulder and lap belt bands...
September 2016: Traffic Injury Prevention
David Poulard, Qi Zhang, Jack Ryan Cochran, Bronislaw Gepner, Jason Kerrigan
OBJECTIVE: The objective of the current study was to evaluate the whole-body kinematic response of the Total Human Model for Safety (THUMS) occupant model in controlled laboratory rollover tests by comparing the model response to postmortem human surrogate (PMHS) kinematic response targets published in 2014. METHODS: A computational model of the parametric vehicle buck environment was developed and the AM50 THUMS occupant model (Ver 4.01) was subjected to a pure dynamic roll at 360°/s in trailing-side front-row seating position...
September 2016: Traffic Injury Prevention
F J López-Valdés, O Juste-Lorente, M Maza-Frechin, B Pipkorn, C Sunnevang, A Lorente, A Aso-Vizan, J Davidsson
OBJECTIVE: The objective of this article is to analyze the kinematics and dynamics of restrained postmortem human surrogates (PMHS) exposed to a nearside oblique impact and the injuries that were found after the tests. METHODS: Three male PMHS of similar age (64 ± 4 years) and anthropometry (weight: 61 ± 9.6 kg; stature: 172 ± 2.7 cm) were exposed to a 30° nearside oblique impact at 34 km/h. The test fixture approximated the seating position of a front seat occupant...
September 2016: Traffic Injury Prevention
Bingbing Nie, Jeff R Crandall, Matthew B Panzer
ABSTRACTS Objective The lower extremity of the occupant represents the most frequently injured body region in motor vehicle crashes. Knee airbags (KABs) have been implemented as potential countermeasure to reduce lower extremity injuries. Despite the increasing prevalence of KABs in vehicles, the biomechanical interaction of the human lower extremity with the KAB has not been well characterized. This study uses computational models of the human body and knee airbags to explore how KAB design may influence the impact response of the occupant's lower extremities...
September 2, 2016: Traffic Injury Prevention
Steven A Romero, Jennifer L McCord, Matthew R Ely, Dylan C Sieck, Tahisha M Buck, Meredith J Luttrell, David A MacLean, John R Halliwill
In humans, acute aerobic exercise elicits a sustained post-exercise vasodilation within previously active skeletal muscle. This response is dependent on activation of histamine H1 and H2 receptors, but the source of intramuscular histamine remains unclear. We tested the hypothesis that interstitial histamine in skeletal muscle would be increased with exercise and would be dependent on de novo formation via the inducible enzyme histidine decarboxylase and/or mast cell degranulation. Subjects performed 1 h of unilateral dynamic knee-extension exercise or sham (seated rest)...
August 25, 2016: Journal of Applied Physiology
K Dipla, A Triantafyllou, N Koletsos, V Sachpekidis, P Poulios, E Gkaliagkousi, A Zafeiridis, S Douma
OBJECTIVE: Masked hypertensives (MH) are at increased cardiovascular risk and target organ damage. Despite a growing number of studies suggesting that early identification of these patients is crucial, a 24 h ambulatory blood pressure (BP) or proper home BP monitoring are not always feasible. An exaggerated BP response during dynamic exercise testing (duration ∼9-15 min) has been used as an additional screening tool to identify suspected systolic MH. However, MH especially in young people, is often characterized by an elevated diastolic BP...
September 2016: Journal of Hypertension
C S Wilhite, W E Field, M Jaramillo
PURPOSE: This feasibility study explored the utility of using a pressure mapping instrument to explore the variable of pressure under subjects sitting on a commonly used tractor seat, and four other cushion interventions. METHOD: A Vista Medical FSA Pressure Mapping System was used as the instrument to gather data and the Braden Scale was used to identify the pressure ulcer risk of each potential subject. Eight subjects with paraplegia participated in the study...
July 22, 2016: Assistive Technology: the Official Journal of RESNA
David Barbado, Luis C Barbado, Jose L L Elvira, Jaap H van Dieën, Francisco J Vera-Garcia
Trunk/core stability is considered a key component of training programs, because it could contribute to prevention of low-back and lower-limb injuries and to sports performance. Based on the specificity principle, sports-related trunk stability tests would be required in elite sports performance. However, there may be some generic qualities underlying trunk stability that can be assessed with nonspecific protocols, which are broadly used in sport and rehabilitation. To assess whether specific tests are needed in a high-performance context, we analyzed the influence of specialization in sports with large but qualitatively different balance control demands (judo and kayaking) on trunk stability and compared high-performance athletes with recreational athletes without a specific training history...
September 2016: Gait & Posture
Hironori Tanoue, Toshitaka Mitsuhashi, Shunji Sako, Ryokichi Goto, Tomohiro Nakai, Ryoichi Inaba
[Purpose] Working while sitting for long periods can cause lumbar pain, fatigue, and reduced work efficiency. How a dynamic chair with a seat that moves three-dimensionally affects pelvic mobility before and after work, work efficiency, and post-work fatigue were examined. [Subjects and Methods] Subjects were 17 healthy adults (10 males, 7 females, mean age 21.8 ± 2.7 years). Subjects performed a 30-min Kraepelin test under two conditions: sitting in a standard office chair and sitting in a dynamic sitting balance chair...
June 2016: Journal of Physical Therapy Science
Maxime T Robert, Laurent Ballaz, Martin Lemay
INTRODUCTION: In the next few years, several head-mounted displays (HMD) will be publicly released making virtual reality more accessible. HMD are expected to be widely popular at home for gaming but also in clinical settings, notably for training and rehabilitation. HMD can be used in both seated and standing positions; however, presently, the impact of HMD on balance remains largely unknown. It is therefore crucial to examine the impact of viewing a virtual environment through a HMD on standing balance...
July 2016: Gait & Posture
Gareth D Jones, Darren C James, Michael Thacker, Eleanor J Jones, David A Green
INTRODUCTION: Sit-to-walk (STW) is a common transitional motor task not usually included in rehabilitation. Typically, sit-to-stand (STS), pause, then gait initiation (GI) before walking is used, which we term sit-to-stand-and-walk (STSW). Separation between centre-of-pressure (COP) and whole-body centre-of-mass (BCOM) during GI is associated with dynamic postural stability. Rising from seats higher than knee-height (KH) is more achievable for patients, but whether this and/or lead-limb significantly affects task dynamics is unclear...
July 2016: Gait & Posture
Liang-Liang Shi, Chen Lei, Kui Li, Shuo-Zhen Fu, Zheng-Wei Wu, Zhi-Yong Yin
PURPOSE: This study aims to explore the biomechanical mechanism of lower limb injuries to the driver by establishing a finite element (FE) simulation model of collisions. METHODS: First a minibus FE model was integrated with a seat belt system. Then it was used to rebuild two collisions together with the total human model for safety (THUMS) provided by Toyota Motor Corporation: a rear-end collision between a minibus and a truck and a head-on collision of a minibus to a rigid wall...
June 1, 2016: Chinese Journal of Traumatology, Zhonghua Chuang Shang za Zhi
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