| 1. |
- Ekman, Carl, et al.
(författare)
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Less pronounced response to exercise in healthy relatives to type 2 diabetic subjects compared with controls
- 2015
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 119:9, s. 953-960
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Tidskriftsartikel (refereegranskat)abstract
- Healthy first-degree relatives with heredity of type 2 diabetes (FH+) are known to have metabolic inflexibility compared with subjects without heredity for diabetes (FH-). In this study, we aimed to test the hypothesis that FH+ individuals have an impaired response to exercise compared with FH-. Sixteen FH+ and 19 FH- insulin-sensitive men similar in age, peak oxygen consumption ((V) over dot(O2 peak)), and body mass index completed an exercise intervention with heart rate monitored during exercise for 7 mo. Before and after the exercise intervention, the participants underwent a physical examination and tests for glucose tolerance and exercise capacity, and muscle biopsies were taken for expression analysis. The participants attended, on average, 39 training sessions during the intervention and spent 18.8 MJ on exercise. (V) over dot(O2 peak)/kg increased by 14%, and the participants lost 1.2 kg of weight and 3 cm waist circumference. Given that the FH- group expended 61% more energy during the intervention, we used regression analysis to analyze the response in the FH+ and FH- groups separately. Exercise volume had a significant effect on (V) over dot(O2 peak), weight, and waist circumference in the FH- group, but not in the FH+ group. After exercise, expression of genes involved in metabolism, oxidative phosphorylation, and cellular respiration increased more in the FH- compared with the FH+ group. This suggests that healthy, insulin-sensitive FH+ and FH- participants with similar age, (V) over dot(O2 peak), and body mass index may respond differently to an exercise intervention. The FH+ background might limit muscle adaptation to exercise, which may contribute to the increased susceptibility to type 2 diabetes in FH+ individuals.
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| 2. |
- McGawley, Kerry, 1978-, et al.
(författare)
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No additional benefits of block-over evenly-distributed high-intensity interval training within a polarized microcycle
- 2017
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 8:JUN, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The current study aimed to investigate the responses to block- versus evenly-distributed high-intensity interval training (HIT) within a polarized microcycle. Methods: Twenty well-trained junior cross-country skiers (10 males, age 17.6 ± 1.5 and 10 females, age 17.3 ± 1.5) completed two, 3-week periods of training (EVEN and BLOCK) in a randomized, crossover-design study. In EVEN, 3 HIT sessions (5 × 4-min of diagonal-stride roller-skiing) were completed at a maximal sustainable intensity each week while low-intensity training (LIT) was distributed evenly around the HIT. In BLOCK, the same 9 HIT sessions were completed in the second week while only LIT was completed in the first and third weeks. Heart rate (HR), session ratings of perceived exertion (sRPE), and perceived recovery (pREC) were recorded for all HIT and LIT sessions, while distance covered was recorded for each HIT interval. The recovery-stress questionnaire for athletes (RESTQ-Sport) was completed weekly. Before and after EVEN and BLOCK, resting saliva and muscle samples were collected and an incremental test and 600-m time-trial (TT) were completed. Results: Pre- to post-testing revealed no significant differences between EVEN and BLOCK for changes in resting salivary cortisol, testosterone, or IgA, or for changes in muscle capillary density, fiber area, fiber composition, enzyme activity (CS, HAD, and PFK) or the protein content of VEGF or PGC-1α. Neither were any differences observed in the changes in skiing economy, VO2max or 600-m time-trial performance between interventions. These findings were coupled with no significant differences between EVEN and BLOCK for distance covered during HIT, summated HR zone scores, total sRPE training load, overall pREC or overall recovery-stress state. However, 600-m TT performance improved from pre- to post-training, irrespective of intervention (P = 0.003), and a number of hormonal and muscle biopsy markers were also significantly altered post-training (P < 0.05). Discussion: The current study shows that well-trained junior cross-country skiers are able to complete 9 HIT sessions within 1 week without compromising total work done and without experiencing greater stress or reduced recovery over a 3-week polarized microcycle. However, the findings do not support block-distributed HIT as a superior method to a more even distribution of HIT in terms of enhancing physiological or performance adaptions.
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| 3. |
- Oskolov, Nikolay, et al.
(författare)
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GWAS OF HISTOLOGICAL PHENOTYPES PROVIDES INSIGHTS INTO THE GENETIC ARCHITECTURE OF HUMAN SKELETAL MUSCLE
- 2015
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Ingår i: ABSTRACT BOOK for the SGGD 2015.
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Konferensbidrag (refereegranskat)abstract
- IntroductionAthlete performance depends to some extent on skeletal muscle fiber-type composition, i.e. athletes practicing endurance sports usually have a higher proportion of slow-twitch type I fibers, while fast-twitch type II fibers are more common for athletes in explosive sports. Insulin sensitivity has also been correlated with proportion of type I fibers, i.e. insulin resistant individuals having reduced muscle oxidative capacity with less oxidative type I and more glycolytic type IIx fibers.AimsHere we aimed to identify genetic variation and corresponding biological mechanisms affecting human skeletal muscle histology.MethodsWe performed a genome-wide association meta-analysis in Swedish males from 3 independent cohorts (n=656) with skeletal muscle histological phenotypes, e.g. capillary density, fibre-type distribution and area (measured by ATPas staining). Skeletal muscle microarray expression data (n=77) were used for an eQTL analysis of associated markers. Follow-up of capillary density was done in Swedish elite cross-country skiers (n=15).ResultsWe identified 11 genome-wide significant (p<5x10-8) independent loci (STEAP, NYAP2, ADRA1B, TNFSF11, FAM155A, SLC22A10, FASLG, RBFOX1, FOXJ2, KCNMA1, RAB3GAP2) associated with 6 skeletal muscle phenotypes. eQTL-genes corresponding to the top associated variants were enriched in metabolic pathways. Using a population differentiation neutrality test we show that some of the fibre-type nominally associated loci (p<1x10-6) fall within regions of positive selection (i.e. FHIT, CRISP and ANXA1). The G-allele of rs115660502 (MAF=0.048) was significantly associated (p=2x10-8) with increased capillary density and also decreased expression of the nearby gene RAB3GAP2 (FDR=0.007). The G-allele also had a significantly higher frequency (MAF=0.122, p=0.029) in the cohort of Swedish elite skiers.ConclusionOur results add to our understanding of skeletal muscle architecture and indicate that there is a genetic component to it and that this might contribute to increased endurance performance in sport athletes.
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| 4. |
- Ström, Kristoffer, et al.
(författare)
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N1-methylnicotinamide is a signalling molecule produced in skeletal muscle coordinating energy metabolism
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Obesity is a major health problem, and although caloric restriction and exercise are successful strategies to lose adipose tissue in obese individuals, a simultaneous decrease in skeletal muscle mass, negatively effects metabolism and muscle function. To deeper understand molecular events occurring in muscle during weight-loss, we measured the expressional change in human skeletal muscle following a combination of severe caloric restriction and exercise over 4 days in 15 Swedish men. Key metabolic genes were regulated after the intervention, indicating a shift from carbohydrate to fat metabolism. Nicotinamide N-methyltransferase (NNMT) was the most consistently upregulated gene following the energy-deficit exercise. Circulating levels of N1-methylnicotinamide (MNA), the product of NNMT activity, were doubled after the intervention. The fasting-fed state was an important determinant of plasma MNA levels, peaking at ~18 h of fasting and being lowest ~3 h after a meal. In culture, MNA was secreted by isolated human myotubes and stimulated lipolysis directly, with no effect on glucagon or insulin secretion. We propose that MNA is a novel myokine that enhances the utilization of energy stores in response to low muscle energy availability. Future research should focus on applying MNA as a biomarker to identify individuals with metabolic disturbances at an early stage.
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| 5. |
- Su, Jing, et al.
(författare)
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A novel atlas of gene expression in human skeletal muscle reveals molecular changes associated with aging
- 2015
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Ingår i: Skeletal Muscle. - : Springer Science and Business Media LLC. - 2044-5040. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although high-throughput studies of gene expression have generated large amounts of data, most of which is freely available in public archives, the use of this valuable resource is limited by computational complications and non-homogenous annotation. To address these issues, we have performed a complete re-annotation of public microarray data from human skeletal muscle biopsies and constructed a muscle expression compendium consisting of nearly 3000 samples. The created muscle compendium is a publicly available resource including all curated annotation. Using this data set, we aimed to elucidate the molecular mechanism of muscle aging and to describe how physical exercise may alleviate negative physiological effects. Results: We find 957 genes to be significantly associated with aging (p < 0.05, FDR = 5 %, n = 361). Aging was associated with perturbation of many central metabolic pathways like mitochondrial function including reduced expression of genes in the ATP synthase, NADH dehydrogenase, cytochrome C reductase and oxidase complexes, as well as in glucose and pyruvate processing. Among the genes with the strongest association with aging were H3 histone, family 3B (H3F3B, p = 3.4 x 10(-13)), AHNAK nucleoprotein, desmoyokin (AHNAK, p = 6.9 x 10(-12)), and histone deacetylase 4 (HDAC4, p = 4.0 x 10(-9)). We also discover genes previously not linked to muscle aging and metabolism, such as fasciculation and elongation protein zeta 2 (FEZ2, p = 2.8 x 10(-8)). Out of the 957 genes associated with aging, 21 (p < 0.001, false discovery rate = 5 %, n = 116) were also associated with maximal oxygen consumption (VO2MAX). Strikingly, 20 out of those 21 genes are regulated in opposite direction when comparing increasing age with increasing VO2MAX. Conclusions: These results support that mitochondrial dysfunction is a major age-related factor and also highlight the beneficial effects of maintaining a high physical capacity for prevention of age-related sarcopenia.
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