| 61. |
- Ekelund, Ulf, et al.
(författare)
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Alpha 2-adrenoceptor activation may trigger the increased production of endothelium-derived nitric oxide in skeletal muscle during acute haemorrhage
- 1998
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772. ; 164:3, s. 285-292
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Tidskriftsartikel (refereegranskat)abstract
- Our previous studies indicated that acute haemorrhage leads to a pronounced increase in the release of endothelium-derived nitric oxide (EDNO) graded in relation to the magnitude of the blood loss. The EDNO-induced vasodilatation, confined selectively to the arterial 'feeder' vessels, attenuates the concomitant reflex adrenergic constriction and thereby prevents deleterious reduction of blood flow. The present study aimed at investigating whether the reflex release of blood-borne catecholamines might trigger this EDNO release via activation of endothelial alpha 2-adrenoceptors. The study was performed on the sympathectomized vascular bed of cat skeletal muscle with a technique permitting quantitative recordings of resistance (tone) in consecutive vascular sections. Selection alpha 2-adrenoceptor blockade with idazoxan applied at steady state vasoconstriction after a 35% blood loss evoked an initial generalized dilator response (attributable to inhibition of post-synaptic smooth muscle alpha 2-adrenoceptors), followed by a constrictor response selectively in the arterial feeder vessels, the latter compatible with the hypothesis of reduced EDNO release by alpha 2-adrenoceptor blockade. More direct evidence for the hypothesis was obtained from studies of the vascular response to EDNO blockade (L-NAME) after haemorrhage in the presence and absence of alpha 2-adrenoceptor blockade. The constrictor response to EDNO blockade, which is a measure of the pre-existing EDNO dilator influence (EDNO production), was significantly smaller (P < 0.01) in the presence than absence of alpha 2-adrenoceptor blockade. The results indicate that blood-borne catecholamines, via activation of endothelial alpha 2-adrenoceptors, trigger the increase in the EDNO release in acute haemorrhage, implying a functionally important negative feedback in the integrated control of vascular tone in bleeding.
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| 62. |
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| 63. |
- Ekelund, Ulf
(författare)
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Assessment of physical activity and energy expenditure in adolescents
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physical activity (PA) is a complex, multidimensional human behaviour that includes all bodily movement from fidgeting to participation in marathon running. The detailed relationship (i.e. dose - response) between the type and degree of PA and its effects on various aspects of health remains to be elucidated, not least in young people. The development and evaluation of different PA assessment methods is therefore of high priority. Methods of physical activity assessment include both self-report methods, such as activity diaries, questionnaires and activity recalls, and objective assessment techniques. Objective assessment of free-living physical activity can be based on physiological (energy expenditure, heart rate [HR] monitoring) and biomechanical (accelerometry) principles. The overall purpose with the present studies was to increase our understanding of the suitability of different PA assessment methods for use in normally active adolescents m young athletes, and to gain further knowledge about the amount and pattern of physical activity among adolescents. One hundred and fifty-seven randomly selected boys and girls and eight volunteer young athletes participated in the studies. One self-report method (activity diary) and three objective methods (HR monitoring, accelerometry and the doubly labelled water method, [DLW] were applied in the studies. All measurements of PA and total energy expenditure (TEE) were performed under free-living conditions. In addition, the relationship between HR and energy expenditure was individually measured during rest and standardised exercises in the laboratory. In the group of eight young athletes all measurements were performed under two different training conditions. The main findings were that: 1) there was no significant difference for the data on TEE and time spent at PA of moderate intensity or higher between the HR monitoring method and the activity diary; 2) the fitness level of the subjects affected the use of absolute HR when defining PA intensity levels; 3) in a random sample of 14-to-15-year-old adolescents, approximately 30% of the boys and girls did not achieve appropriate levels of PA according to published recommendations; and 4) the relationship between TEE and its derivatives measured by DLW, on the one hand, and the total amount of physical activity measured with an accelerometer, on the other, was influenced by the different training condition, whereas TEE estimated by minute-by-minute HR monitoring seem to be unaffected both by the definition of the FLEX HR and by the training condition. It is concluded that the activity diary method is a valid method for estimating TEE and time spent at PA of moderate intensity or higher in groups of adolescents. With the HR monitoring method, use of absolute heart rates for defining intensity levels reduces the validity of the data interpretation. Individual calibration for the heart rate - oxygen uptake relationship is therefore necessary. A relatively large group of adolescents does not achieve the amounts of physical activity recommended beneficial for health. This seems to be a public health concern. The HR monitoring method is not affected by different training regimens and is therefore a more favourable way of assessing physical activity in young athletes as compared to accelerometry.
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| 64. |
- 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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| 65. |
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| 66. |
- Ekelund, Ulf, 1960-, et al.
(författare)
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Body movement and physical activity energy expenditure in children and adolescents : how to adjust for differences in body size and age
- 2004
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 79:5, s. 851-856
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Physical activity data in children and adolescents who differ in body size and age are influenced by whether physical activity is expressed in terms of body movement or energy expenditure.OBJECTIVE: We examined whether physical activity expressed as body movement (ie, accelerometer counts) differs from physical activity energy expenditure (PAEE) as a function of body size and age.DESIGN: This was a cross-sectional study in children [n = 26; (+/-SD) age: 9.6 +/- 0.3 y] and adolescents (n = 25; age: 17.6 +/- 1.5 y) in which body movement and total energy expenditure (TEE) were simultaneously measured with the use of accelerometry and the doubly labeled water method, respectively. PAEE was expressed as 1) unadjusted PAEE [TEE minus resting energy expenditure (REE); in MJ/d], 2) PAEE adjusted for body weight (BW) (PAEE. kg(-1). d(-1)), 3) PAEE adjusted for fat-free mass (FFM) (PAEE. kg FFM(-1). d(-1)), and 4) the physical activity level (PAL = TEE/REE).RESULTS: Body movement was significantly higher (P = 0.03) in children than in adolescents. Similarly, when PAEE was normalized for differences in BW or FFM, it was significantly higher in children than in adolescents (P = 0.03). In contrast, unadjusted PAEE and PAL were significantly higher in adolescents (P < 0.01).CONCLUSIONS: PAEE should be normalized for BW or FFM for comparison of physical activity between children and adolescents who differ in body size and age. Adjusting PAEE for FFM removes the confounding effect of sex, and therefore FFM may be the most appropriate body-composition variable for normalization of PAEE. Unadjusted PAEE and PAL depend on body size.
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| 67. |
- Ekelund, Ulf, et al.
(författare)
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Criterion-related validity of the last 7-day, short form of the International Physical Activity Questionnaire in Swedish adults
- 2006
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Ingår i: Public Health Nutrition. - 1368-9800 .- 1475-2727. ; 9:2, s. 258-265
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To examine the validity of the short, last 7-day, self-administered form of the International Physical Activity Questionnaire (IPAQ). DESIGN: All subjects wore an accelerometer for seven consecutive days and completed the IPAQ questionnaire on the eighth day. Criterion validity was assessed by linear regression analysis and by modified Bland-Altman analysis. Specificity and sensitivity were calculated for classifying respondents according to the physical activity guidelines of the American College of Sports Medicine/Centers for Disease Control and Prevention. SETTING: Workplaces in Uppsala, Sweden. SUBJECTS: One hundred and eighty-five (87 males) participants, aged 20 to 69 years. RESULTS: Total self-reported physical activity (PA) (MET-min day(-1)) was significantly correlated with average intensity of activity (counts min(-1)) from accelerometry (r = 0.34, P < 0.001). Gender, age, education and body mass index did not affect this relationship. Further, subcomponents of self-reported PA (time spent sitting, time in PA, time in moderate and vigorous activity (MVPA)) were significantly correlated with objectively measured PA (P < 0.05). Self-reported time in PA was significantly different from time measured by accelerometry (mean difference: -25.9 min day(-1); 95% limits of agreement: -172 to 120 min day(-1); P < 0.001). IPAQ identified 77% (specificity) of those who met the current PA guidelines of accumulating more than 30 min day(-1) in MVPA as determined by accelerometry, whereas only 45% (sensitivity) of those not meeting the guidelines were classified correctly. CONCLUSIONS: Our results indicate that the short, last 7-days version of the IPAQ has acceptable criterion validity for use in Swedish adults. However, the IPAQ instrument significantly overestimated self-reported time spent in PA. The specificity to correctly classify people achieving current PA guidelines was acceptable, whereas the sensitivity was low.
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| 68. |
- Ekelund, Ulf, et al.
(författare)
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Criterion-related validity of the last 7-day, short form of the International Physical Activity Questionnaire in Swedish adults
- 2006
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Ingår i: Public Health Nutrition. - 1368-9800 .- 1475-2727. ; 9:2, s. 258-265
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To examine the validity of the short, last 7-day, self-administered form of the International Physical Activity Questionnaire (IPAQ). Design: All subjects wore an accelerometer for seven consecutive days and completed the IPAQ questionnaire on the eighth day. Criterion validity was assessed by linear regression analysis and by modified Bland–Altman analysis. Specificity and sensitivity were calculated for classifying respondents according to the physical activity guidelines of the American College of Sports Medicine/Centers for Disease Control and Prevention. Setting: Workplaces in Uppsala, Sweden. Subjects: One hundred and eighty-five (87 males) participants, aged 20 to 69 years. Results: Total self-reported physical activity (PA) (MET-min day21) was significantly correlated with average intensity of activity (counts min 21) from accelerometry (r ¼ 0.34, P 0.001). Gender, age, education and body mass index did not affect this relationship. Further, subcomponents of self-reported PA (time spent sitting, time in PA, time in moderate and vigorous activity (MVPA)) were significantly correlated with objectively measured PA (P , 0.05). Self-reported time in PA was significantly different from time measured by accelerometry (mean difference: 225.9 min day21; 95% limits of agreement: 2172 to 120 min day21; P , 0.001). IPAQ identified 77% (specificity) of those who met the current PA guidelines of accumulating more than 30 min day 21 in MVPA as determined by accelerometry, whereas only 45% (sensitivity) of those not meeting the guidelines were classified correctly. Conclusions: Our results indicate that the short, last 7-days version of the IPAQ has acceptable criterion validity for use in Swedish adults. However, the IPAQ instrument significantly overestimated self-reported time spent in PA. The specificity to correctly classify people achieving current PA guidelines was acceptable, whereas the sensitivity was low.
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| 69. |
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| 70. |
- Ekelund, Ulf, 1960-, et al.
(författare)
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Does physical activity equally predict gain in fat mass among obese and nonobese young adults?
- 2007
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Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 31:1, s. 65-71
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Differences in energy metabolism and physical activity (PA) may contribute to the long-term regulation of body weight (BW).OBJECTIVE: To examine the associations between metabolic determinants, energy expenditure and objectively measured components of PA with change in BW and fat mass (FM). DESIGN: Prospective (4 years.), case-control study in obese (n=13) and normal weight (n=15) young adults.MEASUREMENTS: At baseline, we measured resting metabolic rate, substrate oxidation, movement economy (ml O(2) kg(-1) min(-1)), aerobic fitness (VO(2max)), total and PA energy expenditure by doubly labelled water, and PA by accelerometry. Fat mass was measured by DXA. At follow-up we repeated our measurements of PA and FM.RESULTS: Fat mass increased significantly (P<0.001) in both groups. Physical activity did not change between baseline and 'follow up'. Change in overall PA (counts per minute) was inversely associated with change in BW and (beta=-0.0124, P=0.054) and FM (beta=-0.008, P=0.04). Post hoc analyses suggested that this association was explained by changes in the normal weight group only (beta=-0.01; P=0.008; and beta=-0.0097; P=0.009, for BW and FM, respectively). Metabolic determinants, energy expenditure estimates and subcomponents of PA (i.e. time spent at different intensity levels) were not significantly associated with change in BW or FM.CONCLUSION: Our results suggest an independent association between PA and FM. However, this association may differ depending on obesity status. The gain in FM, without any change in PA, may suggest that dietary intake is the major contributor to the positive energy balance.
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