| 41. |
- Larsson, Barbro, 1952-, et al.
(författare)
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Surface electromyography and peak torque of repetitive maximum isokinetic plantar flexions in relation to aspects of muscle morphology
- 2006
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Ingår i: Journal of Electromyography & Kinesiology. - : Elsevier BV. - 1050-6411 .- 1873-5711. ; 16:3, s. 281-290
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the relationships between surface electromyography (EMG [Mean frequency of the power spectrum (MNF)]) and peak torque variables obtained during 100 maximum concentric plantar flexions with the right limb at 60 degrees s(-1) and different muscle morphological variables. Surface EMG was recorded from the right gastrocnemius lateralis and muscle biopsies were taken from the same site as the EMG electrodes were positioned. Muscle fibre area and fibre type composition were determined on serial muscle cross sections using both histochemistry (myofibrillar adenosine triphosphatase) and immunohistochemistry (monoclonal antibodies against specific myosin heavy chain isoforms). Forty-three female and nine male students participated in the study. Gastrocnemius lateralis contained predominantly type I fibres (50%) and type IIA fibres (40%) in both sexes and large individual differences were found. Principal component analysis (PCA) was used for the intercorrelation analyses, and projection to latent structures (PLS) was used for the multivariate regression analysis. MNF correlated positively with different fibre areas and with the proportion of type I fibres. Fibre areas and sex were the most important factors in the regression of maximum peak torque. High proportion of type I fibres and sex were the most important regressors of peak torque endurance normalised for lean body mass. More studies are needed to understand the complex interrelationships between intrinsic muscle properties and the frequency content of the surface EMG before theoretical models can be formulated that incorporate both fibre areas and fibre type proportions.
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| 42. |
- Mackey, A. L., et al.
(författare)
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Enhanced satellite cell proliferation with resistance training in elderly men and women
- 2007
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 17:1, s. 34-42
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In addition to the well-documented loss of muscle mass and strength associated with aging, there is evidence for the attenuating effects of aging on the number of satellite cells in human skeletal muscle. The aim of this study was to investigate the response of satellite cells in elderly men and women to 12 weeks of resistance training. Biopsies were collected from the m. vastus lateralis of 13 healthy elderly men and 16 healthy elderly women (mean age 76+/-SD 3 years) before and after the training period. Satellite cells were visualized by immunohistochemical staining of muscle cross-sections with a monoclonal antibody against neural cell adhesion molecule (NCAM) and counterstaining with Mayer's hematoxylin. Compared with the pre-training values, there was a significant increase (P<0.05) in the number of NCAM-positively stained cells per fiber post-training in males (from 0.11+/-0.03 to 0.15+/-0.06; mean+/-SD) and females (from 0.11+/-0.04 to 0.13+/-0.05). These results suggest that 12 weeks of resistance training is effective in enhancing the satellite cell pool in skeletal muscle in the elderly.
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| 43. |
- Mackey, Abigail L., et al.
(författare)
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The influence of anti-inflammatory medication on exercise-induced myogenic precursor cell responses in humans
- 2007
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 103:2, s. 425-431
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Tidskriftsartikel (refereegranskat)abstract
- The consumption of nonsteroidal anti-inflammatory drugs (NSAIDs) is widespread among athletes when faced with muscle soreness or injury, but the effects of NSAIDs on satellite cell activity in humans are unknown. To investigate this, 14 healthy male endurance athletes (mean peak oxygen consumption 62 ml x kg(-1) x min(-1)) volunteered for the study, which involved running 36 km. They were divided into two groups and received either 100 mg indomethacin per day or placebo. Muscle biopsies collected before the run and on days 1, 3, and 8 afterward were analyzed for satellite cells by immunohistochemistry with the aid of neural cell adhesion molecule (NCAM) and fetal antigen-1 (FA1) antibodies. Muscle biopsies were also collected from untrained individuals for comparison. Compared with preexercise levels, a 27% increase in the number of NCAM+ cells was observed on day 8 postexercise in the placebo group (P < 0.05), while levels remained similar at all time points in the NSAID group. No change was seen in the proportion of FA1+ cells, although lower levels were found in the muscle of endurance-trained athletes compared with untrained individuals (P < 0.05). These results suggest that ingestion of anti-inflammatory drugs attenuates the exercise-induced increase in satellite cell number, supporting the role of the cyclooxygenase pathway in satellite cell activity.
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| 44. |
- Maivorsdotter, Ninitha, 1966-, et al.
(författare)
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Aesthetic experience as an aspect of embodied learning : stories from physical education student teachers
- 2009
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Ingår i: Sport, Education and Society. - London : Routledge. - 1357-3322 .- 1470-1243. ; 14:3, s. 265-279
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Tidskriftsartikel (refereegranskat)abstract
- In this article we explore aesthetic experience as an aspect of embodied learning with focus on the moving body. Our theoretical framework is mainly based on the work of John Dewey. In the first part of the article we identify our understanding of central concepts and draw some lines to their implication for physical education (PE). In the second part we then use the theoretical framework in an empirical study inspired by the tradition of pragmatism. The aim is to study how physical education student teachers (PETE students) feel when participating in ball game, and how their feelings are related to the moving activity. Empirical data were mainly generated through observations from two ball game lessons and stories written by 16 PETE students. All stories were subjected to a categorical analysis of content. After analysing the empirical material, four categories emerged built on two pair of words: familiar or unfamiliar, and pleased or displeased. In the discussing section of this article, we put forward that moving activities in PE often are regarded as being technical or instrumental. By using an aesthetic perspective on embodied learning, however, we can go beyond that impression and show other dimensions of participation in ball game. It may become an important shift from exploring performance only to studying learning connected to feelings.
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| 45. |
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| 46. |
- Nilsson, Andreas, 1973-, et al.
(författare)
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Assessing physical activity among children with accelerometers using different time sampling intervals and placements
- 2002
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Ingår i: Pediatric Exercise Science. - : Human Kinetics. - 0899-8493 .- 1543-2920. ; 14:1, s. 87-96
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate (a) the effect of five different time sampling intervals (epoch settings) on different intensity levels when assessing physical activity with an accelerometer (CSA, WAM 7164), and (b) whether the placement of the monitor (on the hip and back) would affect the outcome. Sixteen children (aged 7 yrs) were monitored for four consecutive days. A significant main epoch effect was found for time spent at very high (p < 01) and high (p < 01) intensity activities. No significant difference between the two placements regarding total amount of physical activity (cnts times mm super (-1)) or different intensity levels was observed. In conclusion, different time sampling intervals, but not placement, should be carefully considered when assessing physical activity.
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| 47. |
- Nilsson, Andreas, 1973-, et al.
(författare)
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Between- and within-day variability in physical activity and inactivity in 9- and 15-year-old European children
- 2009
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - Oxford : Wiley-Blackwell. - 0905-7188 .- 1600-0838. ; 19:1, s. 10-18
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Tidskriftsartikel (refereegranskat)abstract
- To examine differences in levels of physical activity (PA), time spent at moderate-to-vigorous intensity PA (MVPA) and time spent sedentary between and within days in children from four European countries, 1954 9 - and 15-year-olds were included. PA was measured during 2 weekdays and 2 weekend days using the manufacturing technology-incorporated (MTI) accelerometer. Average count per minute, time spent sedentary, time spent at MVPA and the proportion of children accumulating > or =60 min of MVPA were calculated. Data were compared between weekdays and weekend days and between school time and leisure-time. Although not entirely consistent across countries, overall PA, time spent sedentary and the proportion of children accumulating > or =60 min of MVPA were higher during weekdays compared with weekend days. Differences in overall PA between school time and leisure-time were highly inconsistent between countries. Few children (4-31%) accumulated > or =60 min of MVPA either during school time or during leisure-time. Differences in activity patterns between weekdays and weekend days are explained by less accumulated time in MVPA during weekend days. Weekend days and leisure-time during weekdays seem appropriate targets when promoting PA in order to increase the proportion of children achieving current recommendations on health-enhancing PA.
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| 48. |
- Nilsson, Andreas, 1973-, et al.
(författare)
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Comparison of equations for predicting energy expenditure from accelerometer counts in children
- 2008
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - Oxford : Blackwell. - 0905-7188 .- 1600-0838. ; 18:5, s. 643-650
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Tidskriftsartikel (refereegranskat)abstract
- Several prediction equations developed to convert body movement measured by accelerometry into energy expenditure have been published. The aim of this study was to examine the degree of agreement between three different prediction equations, when applied to data on physical activity in a large sample of children. We examined 1321 children (663 boys, 658 girls; mean age 9.6+/-0.4 years) from four different countries. Physical activity was measured by the MTI accelerometer. One equation, derived from doubly labeled water (DLW) measurements, was compared with one treadmill-based (TM) and one room calorimeter-based (CAL) equation (mixture of activities). Predicted physical activity energy expenditure (PAEE) was the main outcome variable. In comparison with DLW-predicted PAEE, both laboratory-derived equations significantly (P<0.001) overestimated PAEE by 17% and 83%, respectively, when based on a 24-h prediction, while the TM equation significantly (P<0.001) underestimated PAEE by 46%, when based on awake time only. In contrast, the CAL equation agreed better with the DLW equation under the awake time assumption. Predicted PAEE differ substantially between equations, depending on time-frame assumptions, and interpretations of average levels of PAEE in children from available equations should be made with caution. Further development of equations applicable to free-living scenarios is needed.
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| 49. |
- Nilsson, Andreas, 1973-, et al.
(författare)
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Correlates of objectively assessed physical activity and sedentary time in children : a cross-sectional study (The European Youth Heart Study)
- 2009
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Ingår i: BMC Public Health. - London : BioMed Central. - 1471-2458. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIdentifying leisure time activities performed before and after school that influence time in physical activity (PA) and/or time spent sedentary can provide useful information when designing interventions aimed to promote an active lifestyle in young people. The purpose of this study was to examine associations between mode of transportation to school, outdoor play after school, participation in exercise in clubs, and TV viewing with objectively assessed PA and sedentary behaviour in children.MethodsA total of 1327 nine- and 15-year-old children from three European countries (Norway, Estonia, Portugal) participated as part of the European Youth Heart Study. PA was measured during two weekdays and two weekend days using the MTI accelerometer, and average percent of time in moderate-to-vigorous PA (MVPA) and time spent sedentary were derived. Potential correlates were assessed by self-report. Independent associations between self-reported correlates with percent time in MVPA and percent time sedentary were analysed by general linear models, adjusted by age, gender, country, measurement period, monitored days and parental socio-economic status.ResultsIn 9-year-olds, playing outdoors after school was associated with higher percent time in MVPA (P < 0.01), while participation in sport clubs was associated with higher percent time in MVPA (P < 0.01) in 15-year-olds. No associations with percent time sedentary were observed in either age group.ConclusionFrequency of outdoor play after school is a significant correlate for daily time in MVPA in 9-year-olds, while this correlate is attenuated in favour of participation in sport and exercise in clubs in 15-year-olds. Targeting walking to school or reduced TV viewing time in order to increase time in daily MVPA in children is unlikely to be sufficient. Correlates related to time spent sedentary need further examination.
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| 50. |
- Nyberg, Gisela, et al.
(författare)
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Physical activity in children measured by accelerometry : stability over time
- 2009
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - Oxford : Blackwell. - 0905-7188 .- 1600-0838. ; 19, s. 30-35
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the stability of objectively measured physical activity in Swedish children and to study variables that predicted physical activity and body mass index standard deviation score (BMI SDS) at follow-up. A total of 97 children provided valid repeated measurements of physical activity between 2002 and 2005. The children were on average 7.5 years at baseline (SD+/-0.92) and 9 years at follow-up (SD+/-0.92). The mean follow-up time was approximately 1.5 years (mean 558 days, SD+/-224). An accelerometer (Actiwatch, Cambridge Neurotechnology Ltd., Cambridge, UK) was used to measure physical activity during 7 consecutive days. Yearly weight and height were examined and BMI SDS was calculated. Baseline physical activity was significantly correlated with physical activity at follow-up (r=0.59) with a stronger correlation for boys (r=0.72) than for girls (r=0.51). High physical activity levels were more stable (r=0.74) than low physical activity levels (r=0.55). Physical activity at follow-up was explained by physical activity at baseline and season (R(2)=0.46) whereas BMI SDS at follow-up was explained by BMI SDS at baseline and age (R(2)=0.90). The results of this study suggest that physical activity levels are fairly stable in 6-10-year-old children.
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