| 1. |
- Mascher, Henrik, et al.
(författare)
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Changes in signalling pathways regulating protein synthesis in human muscle in the recovery period after endurance exercise
- 2007
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Ingår i: Acta Physiologica. - : Blackwel. - 1748-1708 .- 1748-1716. ; 191:1, s. 67-75
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Exercise induced alterations in the rate of muscle protein synthesis may be related to activity changes in signalling pathways involved in protein synthesis. The aim of the present study was to investigate whether such changes in enzyme phosphorylation occur after endurance exercise. METHODS: Six male subjects performed ergometer cycling exercise for 1 h at 75% of the maximal oxygen uptake. Muscle biopsy samples from the vastus lateralis were taken before, immediately after, 30 min, 1 h, 2 h and 3 h after exercise for the determination of protein kinase B (PKB/Akt), mammalian target of rapamycin (mTOR), glycogen synthase 3 kinase (GSK-3), p70S6 kinase (p70(S6k)) and eukaryotic elongation factor 2 (eEF2) phosphorylation. RESULTS: The phosphorylation of Akt was unchanged directly after exercise, but two- to fourfold increased 1 and 2 h after the exercise, whereas GSK-3alpha and beta phosphorylation were two- to fourfold elevated throughout most of the 3-h recovery period. Phosphorylation of mTOR was elevated threefold directly after, 30 min and 2 h after exercise and eEF2 phosphorylation was decreased by 35-75% from 30 min to 3 h-recovery. Exercise led to a five- to eightfold increase in Ser(424)/Thr(421) phosphorylation of p70(S6k) up to 30 min after exercise, but no change in Thr(389) phosphorylation. CONCLUSIONS: The marked decrease in eEF2 phosphorylation suggests an activation of translation elongation and possibly protein synthesis in the recovery period after sustained endurance exercise. The lack of p70(S6k) activation suggests that translation initiation is activated via alternative pathways, possibly via the activation of eukaryotic initiating factor 2B.
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| 2. |
- Ekelund, Ulf, et al.
(författare)
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Association of weight gain in infancy and early childhood with metabolic risk in young adults
- 2007
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 92:1, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Early postnatal life has been suggested as an important window during which risks for long-term health may be influenced. OBJECTIVE: The aim of this study was to examine the independent associations between weight gain during infancy (0-6 months) and early childhood (3-6 yr) with components of the metabolic syndrome in young adults. DESIGN: This was a prospective cohort study (The Stockholm Weight Development Study). SETTING: The study was conducted in a general community. PARTICIPANTS: Subjects included 128 (54 males) singletons, followed from birth to 17 yr. MAIN OUTCOME MEASURE: None of these young adults met the full criteria for the metabolic syndrome. We therefore calculated a continuous clustered metabolic risk score by averaging the standardized values of the following components: waist circumference, blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, glucose, and insulin level. RESULTS: Clustered metabolic risk at age 17 yr was predicted by weight gain during infancy (standardized beta = 0.16; P < 0.0001) but not during early childhood (standardized beta = 0.10; P = 0.23), adjusted for birth weight, gestational age, current height, maternal fat mass, and socioeconomic status at age 17 yr. Further adjustment for current fat mass and weight gain during childhood did not alter the significant association between infancy weight gain with the metabolic risk score (standardized beta = 0.20; P = 0.007). CONCLUSIONS: Rapid weight gain during infancy (0-6 months) but not during early childhood (3-6 yr) predicted clustered metabolic risk at age 17 yr. Early interventions to moderate rapid weight gain even at very young ages may help to reduce adult cardiovascular disease risks.
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| 3. |
- Hemmingsson, Erik, et al.
(författare)
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Impact of social support intensity on walking in the severely obese : a randomized clinical trial
- 2008
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Ingår i: Obesity. - : Wiley. - 1930-7381 .- 1930-739X. ; 16:6, s. 1308-1313
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: There are few established methods for promoting physical activity (PA) in the severely obese. Because social support is a potential method for promoting PA, we compared mean steps/day during 18 weeks in severely obese outpatients receiving either standard support (SS) or added support (AS). METHODS AND PROCEDURES: Eighty severely obese outpatients from an obesity clinic were invited; 66 provided written consent, 55 were randomized, and 42 were included in final analyses (9 men, 33 women; age 44.4 +/- 13.1 years; BMI 41.9 +/- 5.5 kg/m(2)). All participants received a pedometer and a walking promotion booklet. In addition to SS, the AS group received ten 2-h group counseling sessions aimed at increasing weekly accumulated steps, every second week during the study. Each participant was asked to complete a 7-day walking diary every second week (10 observations). RESULTS: Baseline steps/day was 6,912 for the AS group and 5,311 for the SS group (P = 0.023). Data at 18 weeks showed that the AS group recorded 10,136 steps/day and the SS group 6,118 steps/day (P = 0.024). There was no allocation x time interaction (P = 0.46). During the follow-up period as a whole, the AS group recorded 1,794 more steps/day than the SS group (P = 0.0074). DISCUSSION: The AS group recorded more steps/day than the SS group, reaching a mean level of approximately 10,000 steps/day. However, the nonsignificant interaction between allocation x time suggests that this difference was present already at baseline and did not increase during follow-up.
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| 4. |
- Hemmingsson, Erik, et al.
(författare)
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Is the association between physical activity and body mass index obesity dependent?
- 2007
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 31:4, s. 663-668
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Most studies indicate an inverse relationship between physical activity (PA) and body mass index (BMI). However, the impact of obesity on this relationship is unclear. OBJECTIVE: To scrutinize the BMI/PA relationship by analysing multiple categories of PA from a sample with a wide BMI range. DESIGN: PA was measured with accelerometry for 7 consecutive days during free-living conditions in 85 severely obese outpatients (mean BMI 42.7 kg/m(2) (s.d. 6.1); age 43.0 year (12.6)) and 193 control subjects (24.0 kg/m(2) (3.5); 41.6 year (13.0)). Six categories of PA were calculated from the accelerometer data (min/day of sedentary time, min/day of light PA, min/day of moderate PA, min/day of vigorous PA, activity counts/day and steps/day). Participants were stratified in obese and non-obese subgroups (BMI=30 kg/m(2) as cutoff). Associations between BMI and PA were examined in the total sample, and in subgroups. The impact of sex and age on the BMI/PA association was tested. RESULTS: In the total sample, the association between BMI and PA was significant in all PA categories except for time spent sedentary (P=0.68). However, in subgroup analyses, the association between BMI and PA in non-obese was only significant for activity counts/day (r=-0.16, P<0.05) and vigorous intensity PA (r=-0.15, P=0.05). After adjustment for age, vigorous PA remained significantly associated with BMI in the non-obese (r=-0.17, P<0.05). In obese individuals, significant associations between BMI and PA were found for all six PA categories (age adjusted), sedentary time (r=0.26, P=0.05), light PA (r=-0.30, P<0.01), moderate PA (r=-0.35, P<0.01), vigorous PA (r=-0.39, P<0.001), activity counts/day (r=-0.50, P<0.001) and steps/day (r=-0.54, P<0.001). CONCLUSION: The association between PA and BMI was weak in non-obese individuals. In contrast, BMI was highly significantly associated with PA in obese individuals. Longitudinal studies are needed to tease out the direction of association between PA and BMI across BMI categories, as the cross-sectional associations seem to be dependent on obesity status.
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| 5. |
- Kadi, Fawzi, et al.
(författare)
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Effects of one bout of endurance exercise on the expression of myogenin in human quadriceps muscle
- 2004
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Ingår i: Histochemistry and Cell Biology. - : Springer Science and Business Media LLC. - 0948-6143 .- 1432-119X. ; 121:4, s. 329-334
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate the cellular localisation of MyoD and myogenin in human skeletal muscle fibres as well as the possible alterations in the expression of MyoD and myogenin in response to a single bout of endurance exercise at 40% and 75% of maximum oxygen uptake (VO(2) max). Twenty-five biopsies (5 per subject) from the vastus lateralis muscle were obtained before exercise, from the exercising leg at 40% and 75% of VO(2) max and from the resting leg following these exercise bouts. The tyramide signal amplification-direct and the Vectastain ABC methods using specific monoclonal antibodies were used to determine the exact location of myogenin and MyoD, to identify muscle satellite cells and to determine myosin heavy chain (MyHC) composition. At rest, myonuclei did not express MyoD or myogenin. Following a single bout of exercise at 40% and 75% of VO(2) max, an accumulation of myogenin in myonuclei and not in satellite cells was observed in biopsies from the exercised leg but not in biopsies before exercise and from the resting leg. The number of myogenin-positive myonuclei varied among individuals indicating differences in the response to a single exercise bout. In conclusion, this immunohistochemical study showed that a rapid rearrangement of myogenin expression occurs in exercised human skeletal muscles in response to a single bout of exercise.
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| 6. |
- Kadi, Fawzi, et al.
(författare)
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The effects of regular strength training on telomere length in human skeletal muscle
- 2008
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Ingår i: Medicine & Science in Sports & Exercise. - : Lippincott Williams & Wilkins. - 0195-9131 .- 1530-0315. ; 40:1, s. 82-87
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The length of DNA telomeres is an important parameter of the proliferative potential of tissues. A recent study has reported abnormally short telomeres in skeletal muscle of athletes with exercise-associated fatigue. This important report raises the question of whether long-term practice of sports might have deleterious effects on muscle telomeres. Therefore, we aimed to compare telomere length of a group of power lifters (PL; N = 7) who trained for 8 +/- 3 yr against that of a group of healthy, active subjects (C; N = 7) with no history of strength training. METHODS: Muscle biopsies were taken from the vastus lateralis, and the mean and minimum telomeric restriction fragments (TRF) (telomere length) were determined, using the Southern blot protocol previously used for the analysis of skeletal muscle. RESULTS: There was no abnormal shortening of telomeres in PL. On the contrary, the mean (P = 0.07) and the minimum (P = 0.09) TRF lengths in PL tended to be higher than in C. In PL, the minimum TRF length was inversely correlated to the individual records in squat (r = -0.86; P = 0.01) and deadlift (r = -0.88; P = 0.01). CONCLUSION: These results show for the first time that long-term training is not associated with an abnormal shortening of skeletal muscle telomere length. Although the minimum telomere length in PL remains within normal physiological ranges, a heavier load put on the muscles means a shorter minimum TRF length in skeletal muscle.
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| 7. |
- Kadi, Fawzi, et al.
(författare)
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The number of satellite cells in slow and fast fibres from human vastus lateralis muscle
- 2006
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Ingår i: Histochemistry and Cell Biology. - : Springer Science and Business Media LLC. - 0948-6143 .- 1432-119X. ; 126:1, s. 83-87
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this investigation was to study the distribution of satellite cells in slow (type I fibres) and fast (type II fibres) fibres from human vastus lateralis muscle. This muscle is characterised by a mixed fibre type composition and is considered as the site of choice for biopsies in research work and for clinical diagnosis. Biopsy samples were obtained from five healthy young volunteers and a total of 1,747 type I fibres and 1,760 type II fibres were assessed. Satellite cells and fibre type composition were studied on serial muscle cross-sections stained with specific monoclonal antibodies. From a total of 218 satellite cells, 116 satellite cells were found in contact with type I fibres (53.6+/-8% of the satellite cells associated to type I fibres) and 102 satellite cells in contact with type II fibres (46.4+/-8% of the satellite cells associated to type II fibres). There was no significant difference (P=0.4) between the percentages of satellite cells in contact with type I and with type II fibres. Additionally, there was no relationship between the mean number of satellite cells per fibre and the mean cross-sectional area of muscle fibres. In conclusion, our results show that there is no fibre type-specific distribution of satellite cells in a human skeletal muscle with mixed fibre type composition.
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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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