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- Danielsson, P, et al.
(författare)
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Importance of age for 3-year continuous behavioral obesity treatment success and dropout rate
- 2012
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Ingår i: Obesity facts. - : S. Karger AG. - 1662-4033 .- 1662-4025. ; 5:1, s. 34-44
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Tidskriftsartikel (refereegranskat)abstract
- <i>Objective:</i> To assess whether first year weight loss, age, and socioeconomic background correlate with the success rate of continuous long-term behavioral obesity treatment. <i>Methods: </i>In a 3-year longitudinal study, obese children (n = 684) were divided into three groups based on age at the start of treatment, age 6–9 years, 10–13 years, and 14–16 years. <i>Results:</i> The mean BMI standard deviation score (BMI-SDS) decline was age-dependent (p = 0.001), independently of adjustment for missing data: –1.8 BMI-SDS units in the youngest, –1.3 in the middle age group, and –0.5 in the oldest age group. SES and parental BMI status did not affect the results. 30% of the adolescents remained in treatment at year 3. There was only a weak correlation between BMI-SDS change after 1 and 3 years: r = 0.51 (p < 0.001). Among children with no BMI-SDS reduction during year 1 (n = 46), 40% had a clinically significantly reduced BMI-SDS after year 3. <i>Conclusion:</i> Behavioral treatment should be initiated at an early age to increase the chance for good results. Childhood obesity treatment should be continued for at least 3 years, regardless of the initial change in BMI-SDS.
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- Larsen, Filip J, et al.
(författare)
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Dietary nitrate reduces maximal oxygen consumption while maintaining work performance in maximal exercise.
- 2010
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 48:2, s. 342-7
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Tidskriftsartikel (refereegranskat)abstract
- The anion nitrate-abundant in our diet-has recently emerged as a major pool of nitric oxide (NO) synthase-independent NO production. Nitrate is reduced stepwise in vivo to nitrite and then NO and possibly other bioactive nitrogen oxides. This reductive pathway is enhanced during low oxygen tension and acidosis. A recent study shows a reduction in oxygen consumption during submaximal exercise attributable to dietary nitrate. We went on to study the effects of dietary nitrate on various physiological and biochemical parameters during maximal exercise. Nine healthy, nonsmoking volunteers (age 30+/-2.3 years, VO(2max) 3.72+/-0.33 L/min) participated in this study, which had a randomized, double-blind crossover design. Subjects received dietary supplementation with sodium nitrate (0.1 mmol/kg/day) or placebo (NaCl) for 2 days before the test. This dose corresponds to the amount found in 100-300 g of a nitrate-rich vegetable such as spinach or beetroot. The maximal exercise tests consisted of an incremental exercise to exhaustion with combined arm and leg cranking on two separate ergometers. Dietary nitrate reduced VO(2max) from 3.72+/-0.33 to 3.62+/-0.31 L/min, P<0.05. Despite the reduction in VO(2max) the time to exhaustion trended to an increase after nitrate supplementation (524+/-31 vs 563+/-30 s, P=0.13). There was a correlation between the change in time to exhaustion and the change in VO(2max) (R(2)=0.47, P=0.04). A moderate dietary dose of nitrate significantly reduces VO(2max) during maximal exercise using a large active muscle mass. This reduction occurred with a trend toward increased time to exhaustion implying that two separate mechanisms are involved: one that reduces VO(2max) and another that improves the energetic function of the working muscles.
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- Larsen, Filip J, et al.
(författare)
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Dietary nitrate reduces resting metabolic rate : a randomized, crossover study in humans.
- 2014
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 99:4, s. 843-50
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Nitrate, which is an inorganic anion abundant in vegetables, increases the efficiency of isolated human mitochondria. Such an effect might be reflected in changes in the resting metabolic rate (RMR) and formation of reactive oxygen species. The bioactivation of nitrate involves its active accumulation in saliva followed by a sequential reduction to nitrite, nitric oxide, and other reactive nitrogen species.OBJECTIVE: We studied effects of inorganic nitrate, in amounts that represented a diet rich in vegetables, on the RMR in healthy volunteers.DESIGN: In a randomized, double-blind, crossover study, we measured the RMR by using indirect calorimetry in 13 healthy volunteers after a 3-d dietary intervention with sodium nitrate (NaNO3) or a placebo (NaCl). The nitrate dose (0.1 mmol · kg(-1) · d(-1)) corresponded to the amount in 200-300 g spinach, beetroot, lettuce, or other vegetable that was rich in nitrate. Effects of direct nitrite exposure on cell respiration were studied in cultured human primary myotubes.RESULTS: The RMR was 4.2% lower after nitrate compared with placebo administration, and the change correlated strongly to the degree of nitrate accumulation in saliva (r(2) = 0.71). The thyroid hormone status, insulin sensitivity, glucose uptake, plasma concentration of isoprostanes, and total antioxidant capacity were unaffected by nitrate. The administration of nitrite to human primary myotubes acutely inhibited respiration.CONCLUSIONS: Dietary inorganic nitrate reduces the RMR. This effect may have implications for the regulation of metabolic function in health and disease.
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- Schiffer, Tomas A, et al.
(författare)
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Dynamic regulation of metabolic efficiency explains tolerance to acute hypoxia in humans.
- 2014
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 28:10, s. 4303-11
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Tidskriftsartikel (refereegranskat)abstract
- The maximum power principle dictates that open biological systems tend to self-organize to a level of efficiency that allows maximal power production. Applying this principle to cellular energetics and whole-body physiology would suggest that for every metabolic challenge, an optimal efficiency exists that maximizes power production. On exposure to hypoxia, it would be favorable if metabolic efficiency would rapidly adjust so as to better preserve work performance. We tested this idea in humans by measuring metabolic efficiency and exercise tolerance under normoxic (Fio2=20.9%) and hypoxic (Fio2=16%) conditions, where Fio2 is fraction of inhaled oxygen. The results were compared with respirometric analyses of skeletal muscle mitochondria from the same individuals. We found that among healthy trained subjects (n=14) with a wide range of metabolic efficiency (ME), those with a high ME during normoxic exercise were able to better maintain exercise capacity (Wmax) in hypoxia. On hypoxic exposure, these subjects acutely decreased their efficiency from 19.2 to 17.4%, thereby likely shifting it closer to a degree of efficiency where maximal power production is achieved. In addition, mitochondria from these subjects had a lower intrinsic respiration compared to subjects that showed a large drop in Wmax in hypoxia An acute shift in efficiency was also demonstrated in isolated mitochondria exposed to physiological levels of hypoxia as P/O ratio increased from 0.9 to 1.3 with hypoxic exposure. These findings suggest the existence of a physiological adaptive response by which metabolic efficiency is dynamically optimized to maximize power production.-Schiffer, T. A., Ekblom, B., Lundberg, J. O., Weitzberg, E., Larsen, F. J. Dynamic regulation of metabolic efficiency explains tolerance to acute hypoxia in humans.
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