10,412 research outputs found
Spatio-Temporal Human Grip Force Analysis via Sensor Arrays
No full textThis study describes a technique for measuring human grip forces exerted on a cylindrical object via a sensor array. Standardised resistor-based pressure sensor arrays for industrial and medical applications have been available for some time. We used a special 20 mm diameter grip rod that subjects could either move actively with their fingers in the horizontal direction or exert reactive forces against opposing forces generated in the rod by a linear motor. The sensor array film was attached to the rod by adhesive tape and covered approximately 45 cm(2) of the rod surface. The sensor density was 4/cm(2) with each sensor having a force resolution of 0.1 N. A scan across all sensors resulted in a corresponding frame containing force values at a frame repetition rate of 150/s. The force value of a given sensor was interpreted as a pixel value resulting in a false-colour image. Based on remote sensed image analysis an algorithm was developed to distinguish significant force-representing pixels from those affected by noise. This allowed tracking of the position of identified fingers in subsequent frames such that spatio-temporal grip force profiles for individual fingers could be derived. Moreover, the algorithm allowed simultaneous measurement of forces exerted without any constraints on the number of fingers or on the position of the fingers. The system is thus well suited for basic and clinical research in human physiology as well as for studies in psychophysics
Leren en werken
No full textHet belang van leren en werken wordt steeds nijpender. Als gevolg van de ontwikkeling van een dynamische kenniseconomie is het noodzakelijk om het kennisniveau van de werkenden op peil te houden via leren op het werk. Deze noodzaak wordt versterkt door de vergrijzing van de beroepsbevolking.Het kennisniveau van werkenden kan op peil worden gehouden door middel van scholing, dat wil zeggen cursussen en trainingen. Echter, niet alle werknemers investeren even veel in scholing. In verschillende empirische studies wordt bijvoorbeeld gewezen op het feit dat werknemers met een laag opleidingsniveau minder vaak aan formele training deelnemen dan hoog opgeleiden (zie Fouarge, Schils en de Grip, 2009). Dit is merkwaardig omdat de bereidheid door werkgevers om trainingsdeelname door laag-opgeleiden te financieren groot is (Maximiano en Oosterbeek, 2007). Maar scholing is natuurlijk niet de enige manier waarop kennis wordt vergaard. Leren door te doen wordt in de economische literatuur gezien als een belangrijke bron voor kennisontwikkeling (Arrow, 1962). Onderzoek door ROA heeft laten zien dat een belangrijk deel van de kennis via het informele leren wordt vergaard (Borghans, Golsteyn en de Grip, 2007). Jongeren blijken gemiddeld veertig procent van hun werktijd te besteden aan leerzame werkzaamheden. Hoewel dit percentage negatief gerelateerd is aan iemands leeftijd, is dit percentage voor mensen die de pensioensgerechtigde leeftijd naderen nog steeds gemiddeld 25. Hoewel er geen verschil blijkt te zijn tussen de procentuele tijd die vol- en deeltijders besteden aan het informele leren, is er wel degelijk een verschil in de factoren die van invloed zijn op het informele leren van deeltijders en voltijds werkenden (Nelen en de Grip, 2008). Voltijders worden vooral door feedback van hun leidinggevende op hun functioneren gestimuleerd om informeel te leren op hun werk. Bij deeltijders is dit niet het geval. Zij blijken alleen meer informeel te leren wanneer ze zelf een duidelijk beeld hebben van hun verdere loopbaan.education, training and the labour market;
Comparing the Predictive Power of Subjective and Objective Health Indicators: Changes in Hand Grip Strength and Overall Satisfaction with Life as Predictors of Mortality
No full textSelf-reported measures of health are generally treated as weak measures of respondents' objective health status. On the other hand, most surveys use self-reported health to measure health status and to determine the effects of a range of other socio-economic characteristics of the local environment on individual health. It is therefore of interest to the public health research community to verify the validity of self-reported health data. We do this by analyzing data from a longitudinal household panel survey: the German Socio-Economic Panel Study (SOEP). In 2006, and again in 2008, hand grip strength was measured as part of the SOEP. The hand grip data can be compared with other indicators of health and well-being from the SOEP survey. In a first step, we examine short-term mortality outcomes predicted by changes in hand grip strength. Then we compare the predictive power of the results with those of a subjective indicator of well-being: overall life satisfaction. We find that both measures are related to mortality risk. However, the effects are quite independent. Thus we argue that changes in hand grip strength and overall life satisfaction capture two different aspects of health status and its changes. We therefore test this hypothesis by correlating the indicators with other survey-based health measures that were also taken in the SOEP in 2006 and 2008.grip strength, subjective health status measures, mortality, subjective well-being, SOEP
The scaling of human grip configurations
No full textThe many degrees of freedom of the hand and arm afford the wide range and rich adaptability of human grip configurations in action. Several classification schemes of human grip configurations have been proposed, but none is based on scaling laws of physical biology, which are well established for other categorizations of fundamental physical activities such as locomotion. This study examined the preferred human grip configurations used to displace to a new location cubes that varied systematically in length (L), mass (M), and density (ML-3). The body-scaled equation K = log L + (log M)/h (where h refers to anthropometric measures of the hand) predicted the grip configurations used to displace objects. The findings suggest that information about the dynamic scaling relation is picked up visually and organizes the many degrees of freedom of the hand-arm complex in the coordination of prehensile grip configurations
Are they half as strong as they used to be? An experiment testing whether age-related social comparisons impair older people's hand grip strength and persistence
No full textOBJECTIVE: To assess how age-related social comparisons, which are likely to arise inadvertently or deliberately during assessments, may affect older people's performance on tests that are used to assess their needs and capability. DESIGN: The study randomly assigned participants to a comparison with younger people or a no comparison condition and assessed hand grip strength and persistence. Gender, education, type of residence, arthritis and age were also recorded. SETTING: Age UK centres and senior's lunches in the South of England. PARTICIPANTS: An opportunity sample of 56 adults, with a mean age of 82.25 years. MAIN OUTCOMES MEASURES: Hand grip strength measured using a manual hand dynamometer and persistence of grip measured using a stopwatch. RESULTS: Comparison caused significantly worse performance measured by both strength (comparison =6.85 kg, 95% CI 4.19 kg to 9.5 kg, control group =11.07 kg, 95% CI 8.47 kg to 13.68 kg, OR =0.51, p=0.027) and persistence (comparison =8.36 s, 95% CI 5.44 s to 11.29 s; control group =12.57 s, 95% CI 9.7 s to 15.45 s, OR =0.49, p=0.045). These effects remained significant after accounting for differences in arthritis, gender, education and adjusting for population age norms. CONCLUSIONS: Due to the potential for age comparisons and negative stereotype activation during assessment of older people, such assessments may underestimate physical capability by up to 50%. Because age comparisons are endemic, this means that assessment tests may sometimes seriously underestimate older people's capacity and prognosis, which has implications for the way healthcare professionals treat them in terms of autonomy and dependency
Childhood socioeconomic position and objectively measured physical capability levels in adulthood: a systematic review and meta-analysis
No full text<p><b>Background:</b> Grip strength, walking speed, chair rising and standing balance time are objective measures of physical capability that characterise current health and predict survival in older populations. Socioeconomic position (SEP) in childhood may influence the peak level of physical capability achieved in early adulthood, thereby affecting levels in later adulthood. We have undertaken a systematic review with meta-analyses to test the hypothesis that adverse childhood SEP is associated with lower levels of objectively measured physical capability in adulthood.</p>
<p><b>Methods and Findings:</b> Relevant studies published by May 2010 were identified through literature searches using EMBASE and MEDLINE. Unpublished results were obtained from study investigators. Results were provided by all study investigators in a standard format and pooled using random-effects meta-analyses. 19 studies were included in the review. Total sample sizes in meta-analyses ranged from N = 17,215 for chair rise time to N = 1,061,855 for grip strength. Although heterogeneity was detected, there was consistent evidence in age adjusted models that lower childhood SEP was associated with modest reductions in physical capability levels in adulthood: comparing the lowest with the highest childhood SEP there was a reduction in grip strength of 0.13 standard deviations (95% CI: 0.06, 0.21), a reduction in mean walking speed of 0.07 m/s (0.05, 0.10), an increase in mean chair rise time of 6% (4%, 8%) and an odds ratio of an inability to balance for 5s of 1.26 (1.02, 1.55). Adjustment for the potential mediating factors, adult SEP and body size attenuated associations greatly. However, despite this attenuation, for walking speed and chair rise time, there was still evidence of moderate associations.</p>
<p><b>Conclusions:</b> Policies targeting socioeconomic inequalities in childhood may have additional benefits in promoting the maintenance of independence in later life.</p>
Predicting the consequences of our own actions: the role of sensorimotor context estimation
No full textDuring self-generated movement it is postulated that an efference copy of the descending motor command, in conjunction with an internal model of both the motor system and environment, enables us to predict the consequences of our own actions (von Helmholtz, 1867; Sperry, 1950; von Holst, 1954; Wolpert, 1997). Such a prediction is evident in the precise anticipatory modulation of grip force seen when one hand pushes on an object gripped in the other hand (Johansson and Westling, 1984; Flanagan and Wing, 1933). Here we show that self-generation is not in itself sufficient for such a prediction. We used two robots to simulate virtual objects held in one hand and acted on by the other. Precise predictive grip force modulation of the restraining hand was highly dependent on the sensory feedback to the hand producing the load. The results show that predictive modulation requires not only that the movement is self-generated, but also that the efference copy and sensory feedback are consistent with a specific context; in this case, the manipulation of a single object. We propose a novel computational mechanism whereby the CNS uses multiple internal models, each corresponding to a different sensorimotor context, to estimate the probability that the motor system is acting within each context
Body mass index, muscle strength and physical performance in older adults from eight cohort studies: the HALCyon programme.
No full textObjective
To investigate the associations of body mass index (BMI) and grip strength with objective measures of physical performance (chair rise time, walking speed and balance) including an assessment of sex differences and non-linearity.
Methods
Cross-sectional data from eight UK cohort studies (total N = 16 444) participating in the Healthy Ageing across the Life Course (HALCyon) research programme, ranging in age from 50 to 90+ years at the time of physical capability assessment, were used. Regression models were fitted within each study and meta-analysis methods used to pool regression coefficients across studies and to assess the extent of heterogeneity between studies.
Results
Higher BMI was associated with poorer performance on chair rise (N = 10 773), walking speed (N = 9 761) and standing balance (N = 13 921) tests. Higher BMI was associated with stronger grip strength in men only. Stronger grip strength was associated with better performance on all tests with a tendency for the associations to be stronger in women than men; for example, walking speed was higher by 0.43 cm/s (0.14, 0.71) more per kg in women than men. Both BMI and grip strength remained independently related with performance after mutual adjustment, but there was no evidence of effect modification. Both BMI and grip strength exhibited non-linear relations with performance; those in the lowest fifth of grip strength and highest fifth of BMI having particularly poor performance. Findings were similar when waist circumference was examined in place of BMI.
Conclusion
Older men and women with weak muscle strength and high BMI have considerably poorer performance than others and associations were observed even in the youngest cohort (age 53). Although causality cannot be inferred from observational cross-sectional studies, our findings suggest the likely benefit of early assessment and interventions to reduce fat mass and improve muscle strength in the prevention of future functional limitations
Paddle grip : handgrip size ratio and associated factors contributing to the development of lateral elbow tendinosis and DeQuervains tenosynovitis in K1 marathon paddlers during the 2006 Berg River Canoe Marathon
No full textIncludes abstract.Includes bibliographical references (leaves 98-105).Aim: To determine the relationship between the paddle grip: handgrip size ratio and associated factors contributing to the development of lateral elbow tendinosis and DeQuervains tenosynovitis in K1 marathon paddlers
Clinical effectiveness of grip strength in predicting ambulation of elderly inpatients
No full textMR Beseler,1 C Rubio,1 E Duarte,1 D Hervás,2 MC Guevara,1 M Giner-Pascual,1 E Viosca1 1Physical Medicine and Rehabilitation, La Fe Hospital, Valencia, Spain; 2Statistical Unit, La Fe Hospital, Valencia, Spain Background: Assessing the clinical effectiveness of measuring grip strength as a prognostic tool in recovering ambulation in bed-confined frail elderly patients. Methods: A prospective study was carried out with 50 elderly inpatients (mean age: 81.6 years old). Manual muscle test was used for checking strength of hip flexor muscles, hip abductor muscles and knee extensor muscles. Grip strength was assessed by hydraulic dynamometer. Walking ability was assessed by functional ambulation categories and Functional Classification of Sagunto Hospital Ambulation. Existence of cognitive impairment (Short Portable Mental Status of Pfeiffer) and comorbidity (abbreviated Charlson index) were considered to be confounding variables. Statistical analysis: Simple comparisons and mixed models of multiple ordinal regression. Results: The sample presented generalized weakness in scapular (mean 4.22) and pelvic (mean 3.82) muscle. Mean hand grip values were similar: 11.98 kg right hand; 11.70 kg left hand. The patients had lost walking ability. After treatment, there was a statistically significant for scapular waist strength (P=0.001), pelvic waist strength (P=0.005) and walking ability (P=0.001). A statistically significant relationship in the regression analysis was found between the grip (right and left hands) and walking ability post-treatment (P=0.009; odds ratio 1.14 and P=0.0014 odds ratio 1.113 for each walking scale). The confounding variables showed no statistical significance in the results.Conclusion: Grip strength is associated with walking ability in hospitalized frail elderly. Grip strength assessment by hydraulic dynamometry is useful in patients with poor collaboration. Walking ability training in frail elderly inpatients is useful. Keywords: gait, elderly, hand grip, physical therap
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