2024-03-29T06:19:49Zhttp://open-archive.highwire.org/handler
oai:open-archive.highwire.org:ageing:35/suppl_2/ii122015-05-19HighWireOUPageing:35:suppl_2
Control of rapid limb movements for balance recovery: age-related changes and implications for fall prevention
Maki, Brian E.
McIlroy, William E.
Mechanistic and Physiological Aspects
<b>Background:</b> balancing reactions that involve rapid stepping or reaching movements are critical for preventing falls. These compensatory reactions are much more rapid than volitional limb movements and can be very effective in decelerating the centre-of-mass motion induced by sudden unpredictable balance perturbation; however, age-related deterioration in the neural, sensory and/or musculoskeletal systems may impede the ability to execute these reactions effectively. <b>Objective:</b> this paper summarises recent research regarding age-related changes in compensatory stepping and reaching reactions and the practical implications of these findings for fall prevention programmes. <b>Results:</b> even healthy older adults experience pronounced difficulties. For stepping reactions, the main problems pertain to control of lateral stability—arresting the lateral body motion that occurs during forward and backward steps, and controlling lateral foot movement so as to avoid collision with the stance limb during lateral steps. Older adults appear to be more reliant on arm reactions than young adults but are less able to execute reach-to-grasp reactions rapidly. <b>Conclusions:</b> it is important for clinicians to assess compensatory stepping and reaching, in order to identify individuals who are at risk of falling and to pinpoint specific control problems to target for balance or strength training or other intervention. More effective use of stepping and reaching reactions can be promoted through improved design and appropriate use of sensory aids, mobility aids, footwear, handrails and grab-bars. It is particularly important to address the problems associated with the control of lateral stability because it is the lateral falls that are most likely to result in hip fracture.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii12
http://dx.doi.org/10.1093/ageing/afl078
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii192015-05-19HighWireOUPageing:35:suppl_2
Obstacle clearance and prevention from falling in the bipedally walking Japanese monkey, Macaca fuscata
Mori, Futoshi
Nakajima, Katsumi
Tachibana, Atsumichi
Mori, Shigemi
Mechanistic and Physiological Aspects
<b>Background:</b> studies are needed which consider CNS-controlled strategies for accommodating perturbed bipedal (Bp) posture and walking. <b>Objective:</b> to demonstrate the suitability of the Japanese monkey, <it>Macaca fuscata</it>, for the above purpose. <b>Setting and subjects:</b> three adult monkeys were operantly trained to use Bp-walking on a moving treadmill belt. On one side of the belt, a rectangular adjustable-height obstacle confronted the ipsilateral leg every 4–6 steps, as determined by belt speed. <b>Methods:</b> animal posture and walking patterns were captured and digitized by two high-speed video systems. Frame-by-frame analyses of side- and back-view kinematics were obtained. <b>Results:</b> the monkeys learned quickly to proactively clear the in-coming obstacles by use of a flexible hip-knee-ankle flexion strategy. This featured an appropriate postural adjustment and leg trajectory. In cases where a monkey failed to clear the obstacle, it promptly adopted a defensive posture to avoid falling. There was then a quick return to a posture that allowed the resumption of a Bp gait. <b>Conclusions:</b> when Bp posture and gait are perturbed in a non-human primate model, the prompt adjustment of a flexible hip-knee-ankle flexion strategy and a defensive postural adjustment act together to prevent a fall and enable the speedy resumption of normal Bp posture and gait.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii19
http://dx.doi.org/10.1093/ageing/afl079
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii242015-05-19HighWireOUPageing:35:suppl_2
The control system for the Honda humanoid robot
Takenaka, Toru
Mechanistic and Physiological Aspects
To avoid tipping over either during walking or on standing up, humans will first push down hard on the ground with a part of the sole of the foot. Then, when the tipping force can no longer be resisted, a change in body position or an extra step (stepping out) may be required to stabilise the posture. Our biped robot’s control system attempts to reproduce and execute the same postural control operations carried out by humans. In this article, we present the history of robot development at Honda, fundamental dynamics for robots and the principles of posture control.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii24
http://dx.doi.org/10.1093/ageing/afl080
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii272015-05-19HighWireOUPageing:35:suppl_2
The role of cortical bone and its microstructure in bone strength
Augat, Peter
Schorlemmer, Sandra
Mechanistic and Physiological Aspects
Bone’s mechanical competence and its fragility in particular depend to a certain extent on the structure and microstructure of the cortical bone compartment. Beyond bone mineral density (BMD) and bone mineral content, a variety of other features of cortical bone contribute to whole bone’s resistance to fracture. Structural properties of cortical bone most commonly employed as surrogate for its mechanical competence include thickness of the cortex, cortical cross-sectional area and area moment of inertia. But microstructural properties such as cortical porosity, crystallinity or the presence of microcracks also contribute to bone’s mechanical competence. Microcracks in particular not only weaken the cortical bone tissue but also provide an effective mechanism for energy dissipation. Bone is a damageable, viscoelastic composite and most of all a living material capable of self-repair and thus exhibits a complex repertoire of mechanical properties. This review provides an overview of a variety of features of cortical bone known to provide mechanical competence and how these features may be applied for fracture risk prediction.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii27
http://dx.doi.org/10.1093/ageing/afl081
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii322015-05-19HighWireOUPageing:35:suppl_2
Low-level mechanical signals and their potential as a non-pharmacological intervention for osteoporosis
Rubin, Clinton
Judex, Stefan
Qin, Yi-Xian
Mechanistic and Physiological Aspects
<b>Background:</b> exercise is recognised as a critical regulatory signal to the skeletal system, but which specific aspects of exercise are responsible for influencing bone mass and morphology and resisting fractures remains unknown. Recent data indicate that extremely low-level mechanical signals are anabolic to bone, and thus may be used, non-invasively, as a form of ‘passive’ exercise to positively influence skeletal status. <b>Objective:</b> to summarise recent experimental studies on the effect of low-level mechanical signals (hypothesised to serve as a surrogate for the spectral content of muscle contractility) as a potential non-pharmacological intervention for osteoporosis. <b>Results:</b> low magnitude mechanical signals are anabolic to bone if applied at a high frequency (15–90 Hz). Long-term animal studies (1 year) show that these low-magnitude mechanical signals can increase cancellous bone volume fraction, trabecular thickness, trabecular number and enhance bone stiffness and strength. Studies in the mouse have shown that these low-level signals will stimulate bone formation rate and labelled surface in cortical and cancellous bone, but the molecular and genetic regulation of this mechanosensitivity is extremely complex. Preliminary studies in children with disabling conditions and post-menopausal women indicate that such signals can be efficacious in reversing and/or preventing bone loss. <b>Conclusions:</b> considering that the strains (deformations) that result from these low-level vibrations are far below (<1/1000th) those which may cause damage to the bone, we believe they represent a unique, non-pharmacological prophylaxis for osteoporosis. Given that so many physiologic systems are tuned to specific frequencies, such as sight, hearing and touch, it should not be entirely surprising that the musculoskeletal system would be responsive to frequency as well.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii32
http://dx.doi.org/10.1093/ageing/afl082
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii372015-05-19HighWireOUPageing:35:suppl_2
Falls in older people: epidemiology, risk factors and strategies for prevention
Rubenstein, Laurence Z.
Clinical Risk Assessment, Interventions and Services
Falls are a common and often devastating problem among older people, causing a tremendous amount of morbidity, mortality and use of health care services including premature nursing home admissions. Most of these falls are associated with one or more identifiable risk factors (e.g. weakness, unsteady gait, confusion and certain medications), and research has shown that attention to these risk factors can significantly reduce rates of falling. Considerable evidence now documents that the most effective (and cost-effective) fall reduction programmes have involved systematic fall risk assessment and targeted interventions, exercise programmes and environmental-inspection and hazard-reduction programmes. These findings have been substantiated by careful meta-analysis of large numbers of controlled clinical trials and by consensus panels of experts who have developed evidence-based practice guidelines for fall prevention and management. Medical assessment of fall risks and provision of appropriate interventions are challenging because of the complex nature of falls. Optimal approaches involve interdisciplinary collaboration in assessment and interventions, particularly exercise, attention to co-existing medical conditions and environmental inspection and hazard abatement.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii37
http://dx.doi.org/10.1093/ageing/afl084
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii422015-05-19HighWireOUPageing:35:suppl_2
Visual risk factors for falls in older people
Lord, Stephen R.
Clinical Risk Assessment, Interventions and Services
Poor vision reduces postural stability and significantly increases the risk of falls and fractures in older people. Most studies have found that poor visual acuity increases the risk of falls. However, studies that have included multiple visual measures have found that reduced contrast sensitivity and depth perception are the most important visual risk factors for falls. Multifocal glasses may add to this risk because their near-vision lenses impair distance contrast sensitivity and depth perception in the lower visual field. This reduces the ability of an older person to detect environmental hazards. There is now evidence that maximising vision through cataract surgery is an effective strategy for preventing falls. Further randomised controlled trials are required to determine whether individual strategies (such as restriction of use of multifocal glasses) or multi-strategy visual improvement interventions can significantly reduce falls in older people. Public health initiatives are required to raise awareness in older people and their carers of the importance of regular eye examinations and use of appropriate prescription glasses.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii42
http://dx.doi.org/10.1093/ageing/afl085
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii462015-05-19HighWireOUPageing:35:suppl_2
Distinguishing syncopal from non-syncopal causes of fall in older people
Brignole, Michele
Clinical Risk Assessment, Interventions and Services
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii46
http://dx.doi.org/10.1093/ageing/afl086
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii52015-05-19HighWireOUPageing:35:suppl_2
Preface
The Prevention of Fall-related Fractures: Emerging Research Dimensions
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii5
http://dx.doi.org/10.1093/ageing/afl101
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii512015-05-19HighWireOUPageing:35:suppl_2
Prevention of hip fracture with hip protectors
Kannus, Pekka
Parkkari, Jari
Clinical Risk Assessment, Interventions and Services
The prevention of fractures amongst older people consists of (i) prevention and treatment of osteoporosis, (ii) prevention of falling and (iii) prevention of fractures using injury-site protection. As the great majority of hip fractures are caused by a sideways fall with direct impact on the greater trochanter of the proximal femur, one approach to prevention is the use of an adequately configured padded, firm-shield external hip protector. With this type of two-part design, the impacting force and energy are, at the time of the fall-impact, first weakened by the padding part of the protector and then diverted away from the greater trochanter by the shield part of the same. Following this line, a series of consecutive studies by the Accident & Trauma Research Center at the UKK Institute, Tampere, Finland, found that a padded, strong-shield hip protector was effective in preventing hip fractures. In the context of the wider literature on hip protectors, these more encouraging results suggest the need for a more rigorous regulation of protector design and characteristics. Alongside inadequacies of design, the other most frequent general problem with hip protectors is compliance. Not all elderly people with a high risk of hip fracture will agree to use hip protectors and in those who do, long-term adherence may decrease. Caregiver motivation and involvement appear therefore to be crucial.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii51
http://dx.doi.org/10.1093/ageing/afl087
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii552015-05-19HighWireOUPageing:35:suppl_2
Home environment risk factors for falls in older people and the efficacy of home modifications
Lord, Stephen R.
Menz, Hylton B.
Sherrington, Catherine
Clinical Risk Assessment, Interventions and Services
Most homes contain potential hazards, and many older people attribute their falls to trips or slips inside the home or immediate home surroundings. However, the existence of home hazards alone is insufficient to cause falls, and the interaction between an older person’s physical abilities and their exposure to environmental stressors appears to be more important. Taking risks or impulsivity may further elevate falls risk. Some studies have found that environmental hazards contribute to falls to a greater extent in older vigorous people than in older frail people. This appears to be due to increased exposure to falls hazards with an increase in the proportion of such falls occurring outside the home. There may also be a non-linear pattern between mobility and falls associated with hazards. Household environmental hazards may pose the greatest risk for older people with fair balance, whereas those with poor balance are less exposed to hazards and those with good mobility are more able to withstand them. Reducing hazards in the home appears not to be an effective falls-prevention strategy in the general older population and those at low risk of falls. Home hazard reduction is effective if targeted at older people with a history of falls and mobility limitations. The effectiveness may depend on the provision of concomitant training for improving transfer abilities and other strategies for effecting behaviour change.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
text/html
http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii55
http://dx.doi.org/10.1093/ageing/afl088
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii602015-05-19HighWireOUPageing:35:suppl_2
Implementation of multifactorial interventions for fall and fracture prevention
Campbell, A. John
Robertson, M. Clare
Clinical Risk Assessment, Interventions and Services
Over 60% of falls experienced by older people result from multiple aetiological factors. Preventing falls in individual patients requires the identification and treatment of these interacting factors. Multifactorial interventions have been successful in some, but not all, fall prevention trials. Preventing falls in populations requires selection of the population most likely to benefit, and selection of the particular interventions shown to have been effective in this group. The implementation of preventive measures has been low despite strong evidence that fall and fractures can be reduced. Misconceptions about the potential for prevention in old age, the time to effect improvement, resource issues and the nature of the interventions contribute to the low uptake. An improved system of delivery of proven preventive measures is needed.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
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http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii60
http://dx.doi.org/10.1093/ageing/afl089
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii652015-05-19HighWireOUPageing:35:suppl_2
The role of medical assessment and intervention in the prevention of falls
Swift, Cameron G.
Clinical Risk Assessment, Interventions and Services
Evidence that falls amongst older people can be prevented now requires researchers and policy makers to elucidate the most comprehensive and cost-effective approach to implementation. The syndrome of falls and fractures in later life reflects the combined age-associated influences of cumulative susceptibility to health problems and reduced adaptive reserve. The major contribution of health factors to falling has long been recognised clinically and has also emerged clearly in epidemiological studies of risk. A fall in an older adult, especially if recurrent, may be a key signal of unmet medical need and should accordingly trigger an in-depth diagnostic process and clinical intervention by an appropriately skilled physician. Although well-designed controlled studies specifying this approach as part of a multifactorial intervention are comparatively few, recent published trials have confirmed the anticipated substantial returns in fall prevention achieved for community-dwelling patients with a history of falling. Larger-scale studies are now required, and further research is needed to achieve effective prevention strategies in institutional care. Combined calcium and vitamin D may act via neuromuscular and skeletal mechanisms in fracture prevention. The requirement for medical assessment has now appropriately been incorporated into national and international guidelines.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
text/html
http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii65
http://dx.doi.org/10.1093/ageing/afl083
en
Copyright (C) 2006, British Geriatrics Society
oai:open-archive.highwire.org:ageing:35/suppl_2/ii72015-05-19HighWireOUPageing:35:suppl_2
Postural orientation and equilibrium: what do we need to know about neural control of balance to prevent falls?
Horak, Fay B.
Mechanistic and Physiological Aspects
Postural control is no longer considered simply a summation of static reflexes but, rather, a complex skill based on the interaction of dynamic sensorimotor processes. The two main functional goals of postural behaviour are postural orientation and postural equilibrium. Postural orientation involves the active alignment of the trunk and head with respect to gravity, support surfaces, the visual surround and internal references. Sensory information from somatosensory, vestibular and visual systems is integrated, and the relative weights placed on each of these inputs are dependent on the goals of the movement task and the environmental context. Postural equilibrium involves the coordination of movement strategies to stabilise the centre of body mass during both self-initiated and externally triggered disturbances of stability. The specific response strategy selected depends not only on the characteristics of the external postural displacement but also on the individual’s expectations, goals and prior experience. Anticipatory postural adjustments, prior to voluntary limb movement, serve to maintain postural stability by compensating for destabilising forces associated with moving a limb. The amount of cognitive processing required for postural control depends both on the complexity of the postural task and on the capability of the subject’s postural control system. The control of posture involves many different underlying physiological systems that can be affected by pathology or sub-clinical constraints. Damage to any of the underlying systems will result in different, context-specific instabilities. The effective rehabilitation of balance to improve mobility and to prevent falls requires a better understanding of the multiple mechanisms underlying postural control.
Oxford University Press
2006-09-01 00:00:00.0
TEXT
text/html
http://ageing.oxfordjournals.org/cgi/content/short/35/suppl_2/ii7
http://dx.doi.org/10.1093/ageing/afl077
en
Copyright (C) 2006, British Geriatrics Society