| 21. |
- Barnekow-Bergkvist, Margareta, et al.
(författare)
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Prediction of development of fatigue during a simulated ambulance work task from physical performance tests.
- 2004
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Ingår i: Ergonomics. - : Informa UK Limited. - 0014-0139 .- 1366-5847. ; 47:11, s. 1238-1250
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.
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| 22. |
- Barnekow-Bergkvist, Margareta, et al.
(författare)
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Relationships between physical activity and physical capacity in adolescent females and bone mass in adulthood
- 2006
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 16:6, s. 447-455
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates whether physical activity and physical performance in adolescence are positively related to adult bone mineral density (BMD). In 1974, physical activity, endurance, and muscular strength were measured in 204 randomly selected female students, age 16.1 +/- 0.3 year (range 15-17 years). Twenty years later, 36 of the women volunteered to undergo a measurement of their BMD. Women who were members in a sports club in adolescence had significantly higher adult BMD (mean differences of 5% to 17% depending on site) compared with subjects who were not engaged in a sports club. Furthermore, women with persistent weight-bearing activity in adulthood had significantly higher BMD compared with women who had stopped being active or had never been active. The differences ranged between 5% and 19% with the highest difference found in trochanter BMD. Stepwise regression analyses showed that membership in a sports club at baseline was a significant independent predictor of BMD in the total body, lumbar spine, legs, trochanter, and femoral neck, explaining 17-26% of the variation in BMD. Change in body weight was a strong independent predictor of BMD of the total body and arms, explaining 8% of the variation in both sites. In addition, running performance at baseline was an independent predictor of total body BMD, whereas the two-hand lift performance significantly predicted BMD of the total body, legs and trochanter. The hanging leg-lift and handgrip were both significant predictors of arm BMD. In conclusion, membership in a sports club and site-specific physical performance in adolescence together with the change in body weight were significantly associated with adult BMD in premenopausal women
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| 23. |
- Berg, Björn, et al.
(författare)
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Late stage pine litter decomposition : Relationship to litter N, Mn, and acid unhydrolyzable residue (AUR) concentrations and climatic factors
- 2015
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 358, s. 41-47
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to evaluate relationships between decomposition rates of Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta var. contorta) needle litter in the late stage of decomposition (>30% accumulated mass loss), and the progressively changing concentrations of manganese (Mn), nitrogen (N), and acid unhydrolyzable residue (AUR), as well as mean annual temperature (MAT) and mean annual precipitation (MAP). Using available long-term decomposition studies on pine needle litter in a climate gradient in Sweden, we calculated annual mass loss and related to concentrations of Mn, N, and AUR at the start of each one-year period as well as to MAT and MAP. We investigated these relationships for (i) all data on annual mass loss combined and (ii) annual mass loss for five different decomposition categories as defined by accumulated mass loss. We found highly significant, negative, and dominant relationships between annual mass loss and N (R2=0.39) and AUR (R2=0.39), a slight but significant positive relationship to Mn (R2=0.08) and a significant negative relationship to MAT (R2=0.06). The relationships were dynamic, and changed with accumulated mass loss. The rate-dampening effect of N decreased to be a rate-enhancing effect at c. 60-80% accumulated mass loss. A similar trend was found for AUR, becoming rate-enhancing at 70-80% accumulated mass loss. For Scots pine needle litter the effect of MAT on mass loss decreased with increasing accumulated mass loss and changed to a rate-dampening effect at c. 50-70% accumulated mass loss. Mn showed a stimulating effect on mass loss rate in all categories whereas MAP showed no effect in this mainly boreal climatic gradient. The current approach indicates a method for detailed studies of rate-regulating factors for litter decomposition.
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| 24. |
- Berg, Björn, et al.
(författare)
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Manganese in the litter fall-forest floor continuum of boreal and temperate pine and spruce forest ecosystems : a review
- 2015
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 358, s. 248-260
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Forskningsöversikt (refereegranskat)abstract
- We have reviewed the literature on the role of manganese (Mn) in the litter fall-to-humus subsystem. Available data gives a focus on North European coniferous forests. Manganese concentrations in pine (Pinus spp.) foliar litter are highly variable both spatially and temporally within the same litter species and for the genus Pinus we found a range from 0.03 to 3.7mgg-1. Concentrations were related negatively to site mean annual temperature (MAT) and annual actual evapotranspiration (AET) for pine species litter but not for that of Norway spruce (Picea abies) as a single species. Combined data for several species showed a highly significant relationship to MAT.Manganese peroxidase is an Mn-dependent enzyme, found in white-rot fungi, essential for the degradation of lignin and ligninlike compounds. The decomposition rates of lignified litter tissue (late phase) is positively related to the litter’s Mn concentration. Further, the Mn concentration is positively related to the limit value for decomposition - the higher the Mn concentration the smaller the stable litter fraction. Manganese release from decomposing litter appears at least in part to be species related. Thus was release from pine needle litter significantly faster (p<. 0.001) than that from the Mn-richer litter of Norway spruce. Over Northern Europe concentrations of total Mn in mor humus as well as extractable Mn in the mineral soil increase with decreasing MAT and over a climatic gradient the Mn concentrations in Norway spruce mor increase more with decreasing MAT than in a gradient with Scots pine. Higher Mn concentrations in humus appear to decrease its stability and result in a higher release of carbon dioxide (CO2) and dissolved organic carbon (DOC). We conclude that this may explain (i) the lower amount of carbon (C) in mor layers under Norway spruce as compared to Scots pine as well as the higher amount of C in mineral soil under spruce. The increase in nitrogen (N) concentration in humus, following N fertilization resulted in a decrease in that of Mn. We have found four cases - empirical - with negative interaction between Mn and N; (i) in pine foliar litter fall concentrations of Mn decrease with site MAT whereas those of N increase, (ii) in decomposing late-stage litter with N retarding and Mn stimulating decomposition, (iii) for the stable phase, limit values are related negatively to N and positively to Mn, and (iv) Mn concentrations in humus decrease with MAT whereas those of N increase.
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| 25. |
- Bergfors, M, et al.
(författare)
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Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.
- 2005
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 183:4, s. 345-356
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To detennine whether repetitive ann work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity. Methad: Euglycemic clamps (2h) were started in ten healthy individuals 15 minutes after 37 minute periods of: 1) repetitive ann work in a simulated occupational setting; 2) dynamic concentric exercise on a cycle ergometer at 60% OfVO2 max and 3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) wasrecorded continuously. During the clamps, euglycemia was maintained at 5 mmo1/l and insulin was infused at 56 mU/m2/min for 120 min. Results: The insulin-mediated glucose disposal rate (M-value) for the steady state period (60- 120 min) of the clamp, tended to be lower following ann work than for both cycling and resting regimes. When dividing the steady state period into 20-minute intervals, the insulin sensitivity index, (ISI) was significantly lower for ann work compared with the resting control situation between 60-80 minutes (p=0.04) and 80-100 minutes (p=0.01) respectively. Catecholamines increased significantly for ann work and cycling compared with resting regime. .Data from heart rate variability (HRV) me asurements indicated significant sympathetic activation during repetitive ann work test. Canelusian: The results indicate that repetitive ann work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.
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| 26. |
- Berglind, Daniel, et al.
(författare)
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An eHealth program versus a standard care supervised health program and associated health outcomes in individuals with mobility disability : study protocol for a randomized controlled trial.
- 2018
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Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Young adults with mobility disability (MD) are less likely to engage in regular physical activity (PA) compared with their able-bodied peers and inactive adults with a MD are more likely to report one or more chronic diseases compared to those who are physically active. Despite the vast amount of research published in the field of PA interventions over the past decades, little attention has been focused on interventions aiming to increase PA among individuals with MD. Thus, we propose to compare the effects of an eHealth program compared to a usual care supervised health program on levels of PA and other health behaviors.METHODS: The current intervention will use a randomized controlled trial (RCT) design with two treatment groups (an eHealth program and a usual care supervised health program) in young adults with newly acquired MD. In total, 110 young adults (aged 18-40 years) with a MD, acquired within the past 3 years, will be recruited to participate in a 12-week intervention. The primary study outcome is accelerometer-measured time spent in moderate to vigorous PA. Secondary outcomes includes health-related quality of life, depression, stress, fitness, body composition, diet, musculoskeletal pain, motivation to exercise and work ability.DISCUSSION: There is a lack of RCTs investigating effective ways to increase levels of PA in young adults with MD. Increased levels of PA among this physically inactive population have the potential to substantially improve health-related outcomes, possibly more so than in the general population. The trial will put strong emphasis on optimizing exercise adherence and investigating feasibility in the two treatment programs. The Ethical Review Board (EPN) at Karolinska Institutet has approved the study (2017/1206-31/1).TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number (ISRCTN), reference number ISRCTN22387524 . Prospectively registered February 4, 2018.
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| 27. |
- Bergström, Sten Sture, et al.
(författare)
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Concave and convex phases in ambiguous figures showing colour shifts : Mach's figure and the AMBEGUJAS phenomenon
- 2011
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Ingår i: Perception. - : SAGE Publications. - 0301-0066 .- 1468-4233. ; 40:1, s. 30-38
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Tidskriftsartikel (refereegranskat)abstract
- Two ambiguous figures (Mach's book-figure and the AMBEGUJAS phenomenon) have been studied. They show colour shifts synchronised with the shifts of their alternative phases. The perceived concave phase appeared to have chromatic surface colour, but the perceived convex phase can appear to be in coloured illumination and shadow (film colour). The two perceived reversible shapes of the Mach figure (the book and the tent) and the three perceived alternative shapes of the Mondrians used in the AMBEGUJAS phenomenon (a roof, a ceiling, and a tile) all can appear to have chromatic surface colours in their concave phases but appear to have coloured illumination and shadow in their convex phases
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| 28. |
- Björklund, Erika, 1972-
(författare)
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Constituting the Healthy Employee? : Governing gendered subjects in workplace health promotion
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With a post-structural approach and an analytical focus on processes of governmentality and biopower, this study is concerned with how discourses of health are contextualized in educational practice and interaction between educators and participants in workplace health promotion (WHP) interventions. Of concern are issues of the discursive production, regulation and representation of power, knowledge and subjects as gendered beings in workplace health promotion interventions. The methods for generating data are participant observation, interviews and gathering of documentation pertaining to four different workplace health promotion interventions. Based on these data, the thesis offers an analysis of the health discourses drawn on in the interventions and the technologies of power and of the self by which the participants are governed and invited to govern themselves in the name of health. It also asks what practices and positions that thus come to be made available or not to the participants. Two health discourses are identified: the biomedical discourse and the wellness discourse. Both discourses are drawn on in all four studied interventions, the biomedical discourse being the dominating discourse drawn on. The biomedical discourse is informed by scientific ‘facts’ and statistics and is underpinned by a notion of risk. The wellness discourse is informed by an understanding of health as a subjective embodied experience and is underpinned by a notion of pleasure. Drawing on these discourses, the responsibility for health is placed with the participants and the healthy participant/employee is constituted as a rationally motivated risk-avoider and disciplined pleasure seeker who is both willing and able to actively make ‘good’ choices regarding their lifestyle. Furthermore, and informed by essentialist and heteronormative ideas about gender, the ideal healthy person is modelled on a male norm, representing women as the deviant Other.
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| 29. |
- Björklund, Martin, et al.
(författare)
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Acute muscle stretching and shoulder position sense
- 2006
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Ingår i: Journal of athletic training. - 1062-6050 .- 1938-162X. ; 41:3, s. 270-274
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Tidskriftsartikel (refereegranskat)abstract
- Context: Stretching is common among athletes as a potential method for injury prevention. Stretching-induced changes in the muscle spindle properties are a suggested mechanism, which may imply reduced proprioception after stretching; however, little is known of this association. Objective: To evaluate whether acute stretching of the shoulder muscles affects position sense. Design: A crossover design with subjects randomized to 3 groups. Setting: A university human research laboratory. Patients or Other Participants: Nine male (age = 24 +/- 3 years) and 9 female (age = 21 +/- 2 years) healthy volunteers. Intervention(s): Stretching of shoulder (1) agonists or (2) antagonists or (3) nonstretching control. Main Outcome Measure(s): We determined position sense acuity of the right shoulder before and after the interventions by having subjects attempt to reproduce arm positions of 15 degrees and 30 degrees (shoulder adduction) while starting at 45 degrees to the sagittal plane. The outcome variables were response variability (variable error) and overall accuracy (absolute error). Results: The relative change in variable error (ie, variable error after/variable error before) was not significantly different between the interventions ( P = .38). Similarly, no change in absolute error was found ( P = .76). Furthermore, no differences were noted regarding test sequence or the interaction of intervention x sequence for either variable error ( P = .73 and .53, respectively) or absolute error ( P = .71 and .67, respectively). Conclusions: We found no effect on shoulder position sense after an acute bout of stretching of either agonist or antagonist shoulder muscles.
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| 30. |
- Björklund, Martin, 1961-
(författare)
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Effects of repetitive work on proprioception and of stretching on sensory mechanisms : implications for work-related neuromuscular disorders
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of the thesis were (i) to investigate the impact of repetitive low-intensity work exposure on proprioception and (ii) to examine effects of muscle stretching (especially sensory effects and effects on muscle nociception) and to relate its application to the prevention, alleviation and/or treatment of work-related neuromuscular disorders. The effects of low-intensity repetitive work on the shoulder proprioception were tested in healthy subjects. The effect of working time on the retention of subjective fatigue and their relation to changes in proprioception, and the immediate effect of stretching on shoulder proprioception were investigated. A new method to test the stretchability of the rectus femoris muscle was investigated for reliability and validity and used to assess the effects of a two-week stretching regimen on range of motion and on subjective stretch sensation. Finally, the interactions between innocuous muscle stretch and nociceptive chemical stimulation on discharge behavior of nociceptive dorsal horn neurons in the feline spinal cord were explored. The main findings were as follows: 1) The repetitive low-intensity work to fatigue diminished the shoulder proprioception; the working time as well as the retention of subjective fatigue were partly related to the extent of changed proprioception. 2) There was no effect of acute muscle stretching on the proprioception. 3) The new method for testing muscle stretchability proved valid and reliable. A two-week stretching regimen increased the tolerance to stretch torque, but the range of motion remained unchanged. 4) Half of the nociceptive dorsal horn neurons that responded to close arterial injections of bradykinin were modulated by muscle stretching applied directly after the injections. Altogether, the results give credence to the hypothesis of an involvement of sensory information distortion due to repetitive low-intensity work exposure in the development of work-related neuromuscular disorders. Increased tolerance to stretch torque may be an important mechanism in explaining improvements following stretch treatment. The spinal interactions between innocuous stretch and nociceptive muscle afferent inputs indicate a possible mechanism involved in stretching-induced pain alleviation.
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