| 41. |
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| 42. |
- Halvorsen, Kjartan, et al.
(författare)
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The concept of mobility in single- and double handed manipulation.
- 2014
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 47:14, s. 3569-3573
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Tidskriftsartikel (refereegranskat)abstract
- The concept of mobility describes an important property of the human body when performing manipulation tasks. It describes, in a sense, how easy it is to accelerate a link or a point on the manipulator. Most often it is calculated for the end-link or end-point of the manipulator, since these are important for the control objective of the manipulator. Mobility is the inverse of the inertia experienced by a force acting on the end-point, or a combined force and torque acting on the end-link. The concept has been used in studies of reaching tasks with one arm, but thus far not for bi-manual manipulation. We present here the concept for both single-handed and double-handed manipulation, in a general manner which includes any type of grip of the hands on the object. The use of the concept is illustrated with data on the left and right arm in a golf swing.
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| 43. |
- Halvorsen, Kjartan, et al.
(författare)
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Tracking the Motion of Hidden Segments Using Kinematic Constraints and Kalman Filtering
- 2008
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Ingår i: Journal of Biomechanical Engineering. - : ASME International. - 0148-0731 .- 1528-8951. ; 130:1, s. 011012:1-9
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Tidskriftsartikel (refereegranskat)abstract
- Motion capture for biomechanical applications involves in almost all cases sensors or markers that are applied to the skin of the body segments of interest. This paper deals with the problem of estimating the movement of connected skeletal segments from 3D position data of markers attached to the skin. The use of kinematic constraints has been shown previously to reduce the error in estimated segment movement that are due to skin and muscles moving with respect to the underlying segment. A kinematic constraint reduces the number of degrees of freedom between two articulating segments. Moreover, kinematic constraints can help reveal the movement of some segments when the 3D marker data otherwise are insufficient. Important cases include the human ankle complex and the phalangeal segments of the horse, where the movement of small segments is almost completely hidden from external observation by joint capsules and ligaments. This paper discusses the use of an extended Kalman filter for tracking a system of connected segments. The system is modeled using rigid segments connected by simplified joint models. The position and orientation of the mechanism are specified by a set of generalized coordinates corresponding to the mechanism’s degrees of motion. The generalized coordinates together with their first time derivatives can be used as the state vector of a state space model governing the kinematics of the mechanism. The data collected are marker trajectories from skin-mounted markers, and the state vector is related to the position of the markers through a nonlinear function. The Jacobian of this function is derived. The practical use of the method is demonstrated on a model of the distal part of the limb of the horse. Monte Carlo simulations of marker data for a two-segment system connected by a joint with three degrees of freedom indicate that the proposed method gives significant improvement over a method, which does not make use of the joint constraint, but the method requires that the model is a good approximation of the true mechanism. Applying the method to data on the movement of the four distal-most segments of the horse’s limb shows good between trial consistency and small differences between measured marker positions and marker positions predicted by the model.
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| 44. |
- Heiland, Emerald G, et al.
(författare)
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ABBaH: Activity Breaks for Brain Health : A Protocol for a Randomized Crossover Trial
- 2020
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Ingår i: Frontiers in Human Neuroscience. - : Frontiers Media S.A.. - 1662-5161. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Extended periods of sitting may have detrimental effects on brain health. However, the effects of breaking up prolonged sedentary periods with frequent, short physical activity bouts on mechanisms to improve brain health remain unclear. Therefore, this study aims to investigate the immediate effects of uninterrupted sitting and frequent, short bouts of physical activity on cerebral blood flow and cognitive function in the prefrontal cortex in middle-aged adults. Methods: This is a protocol article to describe a randomized crossover study. We will collect data from 13 healthy adults, aged between 40 and 60 years old, with a body mass index <35 kg/m(2). Participants will be required to come into the laboratory on three occasions, sit for 3 h, and perform a different type of break for 3 min every 30 min at each visit in a random order, being either: (1) a social break; (2) brisk walk on a treadmill; or (3) simple resistance activities. Before and after each experimental condition, cerebral blood flow (primary outcome) will be measured using functional near-infrared spectroscopy (fNIRS), with short-separation channels, and working memory (1-, 2-, and 3-back on the computer) will be assessed. The following additional secondary outcomes will be collected: psychological factors (questionnaires); arterial stiffness; salivary cortisol levels; and blood glucose levels. Conclusion: The results from this randomized crossover study will determine the effects of uninterrupted sitting and frequent, short bouts of physical activity on cerebral blood flow and cognitive performance. Publication of this study protocol emphasizes the importance of registration and publication of protocols in the field of sedentary behavior research.
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| 45. |
- Heiland, Emerald G, et al.
(författare)
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Association of mobility limitations with incident disability among older adults : a population-based study.
- 2016
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Ingår i: Age and Ageing. - : Oxford University Press (OUP). - 0002-0729 .- 1468-2834. ; 45:6, s. 812-819
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: mobility-related limitations predict future disability; however, the extent to which individual and combined mobility tests may predict disability remains unclear.OBJECTIVES: to estimate the odds of developing disability in activities of daily living (ADL) according to limitations in walking speed, balance or both; and explore the role of chronic diseases and cognitive function.DESIGN: a prospective cohort study.SETTING: urban area of Stockholm, Sweden.SUBJECTS: one thousand nine hundred and seventy-one disability-free persons (age ≥60 years, 63% women) from the Swedish National study on Aging and Care in Kungsholmen (SNAC-K), who underwent baseline examination in 2001-04 and follow-up assessments for 6 years.MEASUREMENTS: mobility limitation was defined as a one-leg balance stand <5 s or walking speed <0.8 m/s. ADL disability was defined as the inability to complete one or more ADL: bathing, dressing, using the toilet, transferring and eating.RESULTS: during a total of 11,404 person-years (mean per person 5.8 years, SD 0.30) of follow-up, 119 (incidence 1.5/100 person-years) participants developed ADL disability. The demographic adjusted odds ratios (OR) (95% confidence intervals, CI) of incident ADL disability related to balance stand and walking speed limitations were 3.8 (2.3-6.3) and 8.4 (5.2-13.3), respectively. The associations remained statistically significant after controlling for number of chronic diseases and cognitive status. People with limitations in both balance and walking speed had an OR of 12.9 (95% CI 7.0-23.7) for incident disability compared with no limitation.CONCLUSION: balance and walking speed tests are simple clinical procedures that can indicate hierarchical risk of ADL dependence in older adults.
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| 46. |
- Heiland, Emerald G, et al.
(författare)
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Bi-Directional, Day-to-Day Associations between Objectively-Measured Physical Activity, Sedentary Behavior, and Sleep among Office Workers.
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 18:15
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Tidskriftsartikel (refereegranskat)abstract
- The bi-directional, day-to-day associations between daytime physical activity and sedentary behavior, and nocturnal sleep, in office workers are unknown. This study investigated these associations and whether they varied by weekday or weekend day. Among 324 Swedish office workers (mean age 42.4 years; 33.3% men), moderate-to-vigorous physical activity (MVPA), and sedentary behaviors and sleep (total sleep time (TST) and sleep efficiency (SE)) were ascertained by using accelerometers (Actigraph GT3X) over 8 days. Multilevel linear mixed models were used to assess the bi-directional, day-to-day, within-person associations. Additional analyses stratified by weekend/weekday were performed. On average, participants spent 6% (57 min) of their day in MVPA and 59% (9.5 h) sedentary, and during the night, TST was 7 h, and SE was 91%. More daytime sedentary behavior was associated with less TST that night, and reciprocally, more TST at night was associated with less sedentary behavior on the following weekday. Greater TST during the night was also associated with less MVPA the next day, only on weekdays. However, daytime MVPA was not associated with TST that night. Higher nighttime SE was associated with greater time spent sedentary and in MVPA on the following day, regardless if weekday or weekend day. Sleep may be more crucial for being physically active the following day than vice versa, especially on weekdays. Nevertheless, sedentary behavior's relation with sleep time may be bi-directional. Office workers may struggle with balancing sleep and physical activity time.
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| 47. |
- Heiland, Emerald G, et al.
(författare)
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Cardiovascular Risk Burden and Future Risk of Walking Speed Limitation in Older Adults
- 2017
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 65:11, s. 2418-2424
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To explore the association between cardiovascular risk factor (CRF) burden and limitation in walking speed, balance, and chair stand and to verify whether these associations vary according to age and cognitive status.DESIGN: Longitudinal population-based study.SETTING: Urban area of Stockholm, Sweden.PARTICIPANTS: Individuals aged 60 and older who participated in the Swedish National Study on Aging and Care in Kungsholmen and were free of limitations in walking speed (n = 1,441), balance (n = 1,154), or chair stands (n = 1,496) at baseline (2001-04).MEASUREMENTS: At baseline, data on demographic characteristics, CRFs, other lifestyle factors, C-reactive protein, and cognitive function were collected. CRF burden was measured using the Framingham general cardiovascular risk score (FRS). Limitations in walking speed (<0.8 m/s), balance (<5 seconds), and chair stand (inability to rise 5 times) were determined at 3-, 6-, and 9-year follow-up. Data were analyzed using Cox proportional hazards models stratified according to age (<78, >= 78).RESULTS: During follow-up, 326 persons developed limitations in walking speed, 303 in balance, and 374 in chair stands. An association between the FRS and walking speed limitation was evident only in adults younger than 78 (for each 1-point increase in FRS: hazard ratio (HR) = 1.09, 95% confidence interval (CI) = 1.02-1.17) after controlling for potential confounders including cognitive function (correspondingly, in adults aged >= 78: HR = 0.98, 95% CI = 0.92-1.03). Also, higher FRS was significantly associated with faster decline in walking speed (P<.001).CONCLUSION: A higher FRS is associated with greater risk of subsequent development of walking speed limitation in adults younger than 78, independent of cognitive function. Interventions targeting multiple CRFs in younger-old people may help in maintaining mobility function.
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| 48. |
- Heiland, Emerald G, et al.
(författare)
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Cardiovascular Risk Factors and the Risk of Disability in Older Adults : Variation by Age and Functional Status.
- 2019
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Ingår i: Journal of the American Medical Directors Association. - : Elsevier BV. - 1525-8610 .- 1538-9375. ; 20:2, s. 208-212.e3
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We aimed to quantify the increased risk of disability associated with cardiovascular risk factors among older adults, and to verify whether this risk may vary by age and functional status.DESIGN: Longitudinal population-based cohort study.SETTING: Urban area of Stockholm, Sweden.PARTICIPANTS: Community-dwelling and institutionalized adults ≥60 years in the Swedish National study on Aging and Care in Kungsholmen free of cardiovascular diseases and disability (n = 1756) at baseline (2001-2004).MEASURES: Incident disability in activities of daily living (ADL) was ascertained over 9 years. Cardiovascular risk factors (physical inactivity, alcohol consumption, smoking, high blood pressure, diabetes, high body mass index, high levels of total cholesterol, and high C-reactive protein) and walking speed were assessed at baseline. Data were analyzed using Cox proportional hazards models, stratifying by younger-old (age 60-72 years) and older-old (≥78 years).RESULTS: During the follow-up, 23 and 148 persons developed ADL-disability among the younger- and older-old, respectively. In the younger-old, the adjusted hazard ratio (HR) of developing ADL-disability was 4.10 (95% confidence interval [CI] 1.22-13.76) for physical inactivity and 5.61 (95% CI 1.17-26.82) for diabetes. In the older-old, physical inactivity was associated with incident ADL-disability (HR 1.99, 95% CI 1.36-2.93), and there was a significant interaction between physical inactivity and walking speed limitation (<0.8 m/s), showing a 6-fold higher risk of ADL-disability in those who were both physically inactive and had walking speed limitation than being active with no limitation, accounting for a population-attributable risk of 42.7%.CONCLUSIONS/IMPLICATIONS: Interventions targeting cardiovascular risk factors may be more important for the younger-old in decreasing the risk of disability, whereas improving physical function and maintaining physical activity may be more beneficial for the older-old.
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| 49. |
- Heiland, Emerald G, et al.
(författare)
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Cerebral small vessel disease, cardiovascular risk factors, and future walking speed in old age : a population-based cohort study.
- 2021
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Ingår i: BMC Neurology. - : BioMed Central. - 1471-2377. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The purpose of this study was to examine the associations between combined and individual cerebral small vessel disease (cSVD) markers on future walking speed over 9 years; and to explore whether these associations varied by the presence of cardiovascular risk factors (CRFs).METHODS: This population-based cohort study included 331 adults, aged ≥60 years, without limitation in walking speed (≥0.8 m/s). At baseline, cSVD markers, including white matter hyperintensities (WMH), lacunes, and perivascular spaces (PVS), were assessed on magnetic resonance imaging. The modifiable CRFs (physical inactivity, heavy alcohol consumption, smoking, hypertension, high total cholesterol, diabetes, and overweight/obese) were combined into a score. The association between baseline cSVD markers and the decline in walking speed was examined using linear mixed-effects models, whereas Cox proportional hazards models were used to estimate the association with walking speed limitation (defined as < 0.8 m/s) over the follow-up.RESULTS: Over the follow-up period, 76 (23.0%) persons developed walking speed limitation. Participants in the highest tertile of the combined cSVD marker score had a hazard ratio (HR) of 3.78 (95% confidence interval [CI] 1.70-8.45) for walking speed limitation compared with people in the lowest score tertile, even after adjusting for socio-demographics, CRFs, cognitive function, and chronic conditions. When investigating the cSVD markers individually, having the highest burden of WMH was associated with a significantly faster decline in walking speed (β coefficient - 0.020; 95% CI -0.035-0.004) and a greater HR of walking speed limitation (HR 2.78; 95% CI 1.31-5.89) compared with having the lowest WMH burden. Similar results were obtained for the highest tertile of PVS (HR 2.13; 95% CI 1.04-4.36). Lacunes were associated with walking speed limitation, but only in men. Having ≥4 CRFs and high WMH volume simultaneously, showed a greater risk of walking speed limitation compared with having ≥4 CRFs and low WMH burden. CRFs did not modify the associations between lacunes or PVS and walking speed.CONCLUSIONS: Combined cSVD markers strongly predict walking speed limitation in healthy older adults, independent of cognitive function, with WMH and PVS being the strongest contributors. Improving cardiovascular health may help to mitigate the negative effects of WMH on future walking speed.
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| 50. |
- Heiland, Emerald G, et al.
(författare)
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Frequent, Short Physical Activity Breaks Reduce Prefrontal Cortex Activation but Preserve Working Memory in Middle-Aged Adults : ABBaH Study.
- 2021
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Ingår i: Frontiers in Human Neuroscience. - : Frontiers Media S.A.. - 1662-5161. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged sitting is increasingly common and may possibly be unfavorable for cognitive function and mood. In this randomized crossover study, the effects of frequent, short physical activity breaks during prolonged sitting on cognitive task-related activation of the prefrontal cortex were investigated. The effects on working memory, psychological factors, and blood glucose were also examined, and whether arterial stiffness moderated prefrontal cortex activation. Thirteen subjects (mean age 50.5 years; eight men) underwent three 3-h sitting conditions, interrupted every 30-min by a different 3-min break on separate, randomized-ordered days: seated social interactions (SOCIAL), walking (WALK), or simple resistance activities (SRA). Arterial stiffness was assessed at baseline. Before and after each 3-h condition, psychological factors (stress, mood, sleepiness, and alertness) were assessed through questionnaires and functional near-infrared spectroscopy (fNIRS) was used to measure changes in prefrontal oxygenated hemoglobin (Oxy-Hb), indicative of cortical activation, while performing working memory tasks [1- (baseline), 2-, and 3-back]. Blood glucose levels were continuously measured throughout the conditions. Results revealed no significant changes in Oxy-Hb during the 2-back compared with the 1-back test in any condition, and no time-by-condition interactions. During the 3-back test, there was a significant decrease in Oxy-Hb compared with the 1-back after the WALK condition in the right prefrontal cortex, but there were no time-by-condition interactions, although 3-back reaction time improved only in the WALK condition. Mood and alertness improved after the WALK condition, which was significantly different from the SOCIAL condition. Arterial stiffness moderated the effects, such that changes in Oxy-Hb were significantly different between WALK and SOCIAL conditions only among those with low arterial stiffness. Blood glucose during the interventions did not differ between conditions. Thus, breaking up prolonged sitting with frequent, short physical activity breaks may reduce right prefrontal cortex activation, with improvements in some aspects of working memory, mood, and alertness. Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT04137211.
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