Abstract Much is known about the sit-to-stand (STS) and its biomechanics. Currently, however, there is little opportunity for instrumented quantification of the STS as part of screening or diagnosis ...in clinical practice. The objectives of the present study were to describe the feasibility of using an automated approach for quantifying the STS using one sensor location and to start testing the discriminative validity of this approach by comparing older and younger adults. 15 older subjects recruited from a residential care home and 16 young adults performed 5 repeated sit-to-stand and stand-to-sit movements. They were instrumented with a small and lightweight measurement system (DynaPort® ) containing 1 triaxial seismic accelerometer and 3 uniaxial gyroscopes fixed in a belt around the waist. Durations of the (sub-)phases of the STS were analyzed and maximum angular velocities were determined. All successful STS cycles were automatically detected without any errors. The STS duration in the older adults was significantly longer and more variable in all phases (i.e., sit-to-stand, standing, stand-to-sit and sitting) compared to the young adults. Older adults also exhibited lower trunk flexion angular velocity. The results of this first fully automated analysis of instrumented repeated STS movements demonstrate that several STS parameters can be identified that provide a basis for a more precise, quantitative study of STS performance in clinical practice.
As falls and fall-related injuries remain a major challenge in the public health domain, reliable and immediate detection of falls is important so that adequate medical support can be delivered. ...Available home alarm systems are placed on the hip, but have several shortcomings. A fall detector based on accelerometers and placed at head level was developed, as well as an algorithm able to distinguish between activities of daily living and simulated falls. Accelerometers were integrated into a hearing-aid housing, which was fixed behind the ear. The sensitivity of the fall detection was assessed by investigation into the acceleration patterns of the head of a young volunteer during intentional falls. The specificity was assessed by investigation into activities of daily living of the same volunteer. In addition, a healthy elderly woman (83 years) wore the sensor during the day. Three trigger thresholds were identified so that a fall could be recognised: the sum-vector of acceleration in the xy-plane higher than 2 g; the sum-vector of velocity of all spatial components right before the impact higher than 0.7 m s(-1); and the sum-vector of acceleration of all spatial components higher than 6 g. The algorithm was able to discriminate activities of daily living from intentional falls. Thus high sensitivity and specificity of the algorithm could be demonstrated that was better than in other fall detectors worn at the hip or wrist at the same stage of development.
Abstract This study aims to determine the length of the gait initiation phase before achieving steady state walking in frail older people. Based on body fixed sensors, habitual walking was analysed ...in 116 community-dwelling older persons (mean age 83.1 years, 84% women). The start of steady state walking was identified using an algorithm taking into account speeds from consecutive strides. On average, participants reached a walking speed of 0.66 m/s after an acceleration phase of 1.43 m (89% after 2.47 m). When spatio-temporal variables were calculated from 4, 6, 8, 10, or 20 consecutive stride cycles after achieving steady state, similar values were observed for mean gait speed and stride length. The variability of these factors differed depending on the number of gait cycles. Assessments of steady state gait in frail elderly people should therefore exclude the first 2.5 m of walking. If gait variability is to be assessed, it is recommended that more than 20 stride cycles be used.
Abstract Most of the knowledge on falls of older persons has been obtained from oral reports that might be biased in many ways. Fall simulations are widely used to gain insight into circumstances of ...falls, but the results, at least concerning fall detection, are not convincing. Variation of acceleration and maximum jerk of 5 real-world backward falls of 4 older persons (mean age 68.8 years) were compared to the corresponding signals of simulated backward falls by 18 healthy students. Students were instructed to “fall to the back as if you were a frail old person” during experiment 1. In experiment 2, students were instructed not to fall, if possible, when released from a backward lean. Data acquisition was performed using a tri-axial acceleration sensor. In experiment 1, there was significantly more variation within the acceleration signals and maximum jerk was higher in the real-world falls, compared to the fall simulation. Conversely, all values of acceleration and jerk were higher for the fall simulations, compared to real-world falls in experiment 2. The present findings demonstrate differences between real-world falls and fall simulations. If fall simulations are used, their limitations should be noted and the protocol should be adapted to better match real-world falls.
Fall detection with body-worn sensors Schwickert, L.; Becker, C.; Lindemann, U. ...
Zeitschrift für Gerontologie und Geriatrie,
12/2013, Letnik:
46, Številka:
8
Journal Article
Recenzirano
Background and aims
Falls among older people remain a major public health challenge. Body-worn sensors are needed to improve the understanding of the underlying mechanisms and kinematics of falls. ...The aim of this systematic review is to assemble, extract and critically discuss the information available in published studies, as well as the characteristics of these investigations (fall documentation and technical characteristics).
Methods
The searching of publically accessible electronic literature databases for articles on fall detection with body-worn sensors identified a collection of 96 records (33 journal articles, 60 conference proceedings and 3 project reports) published between 1998 and 2012. These publications were analysed by two independent expert reviewers. Information was extracted into a custom-built data form and processed using SPSS (SPSS Inc., Chicago, IL, USA).
Results
The main findings were the lack of agreement between the methodology and documentation protocols (study, fall reporting and technical characteristics) used in the studies, as well as a substantial lack of real-world fall recordings. A methodological pitfall identified in most articles was the lack of an established fall definition. The types of sensors and their technical specifications varied considerably between studies.
Conclusion
Limited methodological agreement between sensor-based fall detection studies using body-worn sensors was identified. Published evidence-based support for commercially available fall detection devices is still lacking. A worldwide research group consensus is needed to address fundamental issues such as incident verification, the establishment of guidelines for fall reporting and the development of a common fall definition.
Abstract Objective To investigate construct validity of linear encoder measurement of sit-to-stand performance power in older people by showing associations with relevant functional performance and ...physiological parameters. Design Cross-sectional study. Setting Movement laboratory of a geriatric rehabilitation clinic. Participants Eighty-eight community-dwelling, cognitively unimpaired older women (mean age 78 years). Main outcome measures Sit-to-stand performance power and leg power were assessed using a linear encoder and the Nottingham Power Rig, respectively. Gait speed was measured on an instrumented walkway. Maximum quadriceps and hand grip strength were assessed using dynamometers. Mid-thigh muscle cross-sectional area of both legs was measured using magnetic resonance imaging. Results Associations of sit-to-stand performance power with power assessed by the Nottingham Power Rig, maximum gait speed and muscle cross-sectional area were r = 0.646, r = 0.536 and r = 0.514, respectively. A linear regression model explained 50% of the variance in sit-to-stand performance power including muscle cross-sectional area ( p = 0.001), maximum gait speed ( p = 0.002), and power assessed by the Nottingham Power Rig ( p = 0.006). Conclusions Construct validity of linear encoder measurement of sit-to-stand power was shown at functional level and morphological level for older women. This measure could be used in routine clinical practice as well as in large-scale studies. Clinical Trial Registration Number DRKS00003622.
To determine whether older cognitively impaired people benefit from physical training with regard to motor performance or fall risk reduction and to critically evaluate the methodologic approach in ...identified randomized controlled intervention trials.
Published randomized controlled intervention trials from 1966 through 2004 were identified in PubMed, CINAHL, Gerolit, and the Cochrane Central Register of Controlled Trials according to predefined inclusion criteria and evaluated by two independent reviewers using a modified rating system for randomized controlled intervention trials developed by the Cochrane Library.
There were 11 randomized controlled intervention trials that met the predefined inclusion criteria. There was a large heterogeneity regarding methodology, sample size, type of intervention, study outcomes, and analyses. We found conflicting evidence regarding the effect of physical training on motor performance and falls in older people with cognitive impairment. However, a considerable number of the studies had methodologic limitations, which hampered the evaluation of the effectiveness of training.
The randomized controlled intervention trials showed only limited effectiveness of physical training in patients with cognitive impairment. More studies with adequate sample size, sensitive and validated measurements, and higher specificity for the types of intervention targeting subgroups of patients with different degrees of cognitive impairment are required to give evidence-based recommendations.
the effects of cold on older persons' body and mind are not well documented, but with an increased number of older people with decreasing physical performance, these possible effects need to be ...understood.
to investigate the effect of cold indoor environment on physical performance of older women.
cross-sectional experimental study with two test conditions.
movement laboratory in a climate chamber.
eighty-eight community-dwelling, cognitively unimpaired older women (mean age 78 years).
participants were exposed to moderately cold (15°C) and warm/normal (25°C) temperature in a climate chamber in random order with an interval of 1 week. The assessment protocol included leg extensor power (Nottingham Power Rig), sit-to-stand performance velocity (linear encoder), gait speed, walk-ratio (i.e. step length/cadence on an instrumented walk way), maximal quadriceps and hand grip strength.
physical performance was lower in 15°C room temperature compared with 25°C room temperature for leg extensor power (P < 0.0001), sit-to-stand performance velocity (P < 0.0001), gait speed (P < 0.0001), walk-ratio (P = 0.016) and maximal quadriceps strength (P = 0.015), but not for hand grip strength.
in healthy older women a moderately cold indoor environment decreased important physical performance measures necessary for independent living.
Heat waves increase the morbidity and mortality in Germany, particularly of older patients in need of care. Due to climate change the number of heat waves in Germany will increase threefold by the ...end of the century. In addition, the proportion of patients at risk will grow due to demographic change. Therefore, the Government and the Federal States have developed recommendations for heat action plans, in which the medical profession should also participate in the prevention of heat-related damage to health. Physicians and their team should first become acquainted with the topic. In addition, they should inform patients at risk and their relatives of the risks and preventive measures. In the summer a critical check of drugs is also needed because medications impair cooling mechanisms in heat waves, the pharmacokinetics can change and unwanted side effects of drugs occur more frequently. Lastly, due to their central position in the healthcare system, physicians should participate in the coordination of a good nursing care and intensification of social contacts during heat waves.
Abstract Although mostly negative aspects are reported to be associated with gait variability, irregular walking is needed when walking performance has to be adapted to specific environmental ...conditions. The aim of this study was to evaluate the test–retest reliability and discriminative ability of a measure to assess adaptive walking performance and to identify parameters associated with test performance in young and elderly subjects. Eighteen older (mean age 78.1 years) and 19 young women (mean age 30.8 years) were instructed to walk as precisely as possible over a defined course targeting 26 arbitrarily positioned rectangle boxes fixed on an instrumented walk way with embedded pressure sensors. ICC1,1 of 0.79 demonstrated sufficient reliability in the cohort of older women. Targeting was significantly worse (or deviation was larger) in older women than in young women (mean 3.20 cm versus 2.27 cm, p = 0.005). Mean gait speed of the older women was higher during the test (0.50 m/s versus 0.40 m/s, p = 0.020), but not during unconstrained walking (1.15 m/s versus 1.50 m/s, p < 0.001). The deviation measure classified 78% of the subjects into correct age group (sensitivity 67%, specificity 90%, p = 0.003). Adaptive walking performance was associated with parameters describing physical performance as well as with cognitive executive function. This study shows that this test of adaptive walking performance is a reliable measure of irregular walking with ability to discriminate between young and older subjects. Our results suggest that older persons might try to camouflage their lack of accuracy during adaptive walking by higher gait speed.
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