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Quick strength for runners : 8 weeks to a better runner's body
\"Poor strength wreaks havoc on a runner's body, leading to slower runs and more injuries. Quick Strength for Runners makes it easy for runners to build a better runner's body. In under an hour a week, runners will strengthen their core and key running muscles to build a better runner's body. Running coach and fitness trainer Jeff Horowitz guides runners through 20-minute workout routines through this 8-week program. With minimal equipment required and no gym membership necessary, runners will build strength without disrupting their everyday running\"-- Provided by publisher.
Book
Moderate-Intensity Exercise and High-Intensity Interval Training Affect Insulin Sensitivity Similarly in Obese Adults
Abstract
Objective
We compared the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on insulin sensitivity and other important metabolic adaptations in adults with obesity.
Methods
Thirty-one inactive adults with obesity (age: 31 ± 6 years; body mass index: 33 ± 3 kg/m2) completed 12 weeks (4 sessions/week) of either HIIT (10 × 1-minute at 90%HRmax, 1-minute active recovery; n = 16) or MICT (45 minutes at 70%HRmax; n = 15). To assess the direct effects of exercise independent of weight/fat loss, participants were required to maintain body mass.
Results
Training increased peak oxygen uptake by ~10% in both HIIT and MICT (P < 0.0001), and body weight/fat mass were unchanged. Peripheral insulin sensitivity (hyperinsulinemic-euglycemic clamp) was ~20% greater the day after the final exercise session compared to pretraining (P < 0.01), with no difference between HIIT and MICT. When trained participants abstained from exercise for 4 days, insulin sensitivity returned to pretraining levels in both groups. HIIT and MICT also induced similar increases in abundance of many skeletal muscle proteins involved in mitochondrial respiration and lipid and carbohydrate metabolism. Training-induced alterations in muscle lipid profile were also similar between groups.
Conclusion
Despite large differences in training intensity and exercise time, 12 weeks of HIIT and MICT induce similar acute improvements in peripheral insulin sensitivity the day after exercise, and similar longer term metabolic adaptations in skeletal muscle in adults with obesity. These findings support the notion that the insulin-sensitizing effects of both HIIT and MICT are mediated by factors stemming from the most recent exercise session(s) rather than adaptations that accrue with training.
Journal Article
Acute exercise increases triglyceride synthesis in skeletal muscle and prevents fatty acid–induced insulin resistance
Fatty acid oversupply is a key mediator of skeletal muscle insulin resistance in obesity, primarily via accumulation of fatty acid metabolites and activation of proinflammatory pathways. Herein, we demonstrate that fatty acid-induced insulin resistance in humans is completely prevented the day after 1 session of endurance exercise. Because skeletal muscle is the primary site for systemic glucose disposal and is highly susceptible to impaired insulin action by elevated fatty acid availability, we obtained skeletal muscle samples to investigate possible mechanisms mediating this protective effect of exercise. Prevention of fatty acid-induced insulin resistance after exercise accompanied enhanced skeletal muscle protein expression of key lipogenic enzymes and an increase in muscle triglyceride synthesis. Partitioning more fatty acids toward triglyceride synthesis within muscle reduced the accumulation of fatty acid metabolites and suppressed the proinflammatory response in skeletal muscle, as evidenced by decreased phosphorylation and activation of JNK and increased abundance of inhibitor of NF-kappaB alpha (I kappa B-alpha) and I kappa B-beta. We believe this is the first study to demonstrate that 1 session of exercise completely reverses fatty acid-induced insulin resistance in humans. Reversal of insulin resistance accompanied enhanced lipogenic capacity within skeletal muscle, reduced accumulation of highly bioactive fatty acid metabolites, and suppressed activation of proinflammatory pathways known to impair insulin action.
Journal Article
Glutaminolysis Epigenetically Regulates Antiapoptotic Gene Expression in Idiopathic Pulmonary Fibrosis Fibroblasts
Fibrotic responses involve multiple cellular processes, including epigenetic changes. Epigenetic changes are sensitive to alterations in the tissue microenvironment such as the flux of tricarboxylic acid (TCA) cycle metabolites. TCA metabolites directly regulate epigenetic states, in part by regulating histone modification–related enzymes. Glutaminolysis is a critical metabolic process by which glutamine is converted to glutamate by glutaminase and then to α-ketoglutarate (α-KG), a TCA cycle metabolite. Idiopathic pulmonary fibrosis (IPF) is a disease characterized by aberrant metabolism, including enhanced glutaminolysis. IPF fibroblasts are apoptosis resistant. In this study, we explored the relationship between glutaminolysis and the resistance to apoptosis of IPF fibroblasts. Inhibition of glutaminolysis decreased expression of XIAP and survivin, members of the inhibitor of apoptosis protein (IAP) family. α-KG is a cofactor for JMJD3 histone demethylase, which targets H3K27me3. In the absence of glutamine, JMJD3 activity in fibroblasts is significantly decreased, whereas H3K27me3 levels are increased. Chromatin immunoprecipitation assays confirmed that JMJD3 directly interacts with XIAP and survivin promoter regions in a glutamine-dependent manner. Exogenous α-KG partially restores JMJD3 function and its interaction with the XIAP and survivin promoter regions under glutamine-deficient conditions. Interestingly, α-KG upregulates XIAP, but not survivin, suggesting differential α-KG–dependent and –independent mechanisms by which glutamine regulates these IAPs. Our data demonstrate a novel mechanism of metabolic regulation in which glutaminolysis promotes apoptosis resistance of IPF fibroblasts through epigenetic regulation of XIAP and survivin.
Journal Article
Ceramides Contained in LDL Are Elevated in Type 2 Diabetes and Promote Inflammation and Skeletal Muscle Insulin Resistance
Dysregulated lipid metabolism and inflammation are linked to the development of insulin resistance in obesity, and the intracellular accumulation of the sphingolipid ceramide has been implicated in these processes. Here, we explored the role of circulating ceramide on the pathogenesis of insulin resistance. Ceramide transported in LDL is elevated in the plasma of obese patients with type 2 diabetes and correlated with insulin resistance but not with the degree of obesity. Treating cultured myotubes with LDL containing ceramide promoted ceramide accrual in cells and was accompanied by reduced insulin-stimulated glucose uptake, Akt phosphorylation, and GLUT4 translocation compared with LDL deficient in ceramide. LDL-ceramide induced a proinflammatory response in cultured macrophages via toll-like receptor–dependent and –independent mechanisms. Finally, infusing LDL-ceramide into lean mice reduced insulin-stimulated glucose uptake, and this was due to impaired insulin action specifically in skeletal muscle. These newly identified roles of LDL-ceramide suggest that strategies aimed at reducing hepatic ceramide production or reducing ceramide packaging into lipoproteins may improve skeletal muscle insulin action.
Journal Article
Investigating Matrix–Fibroblast Regulation of MicroRNAs. A Dice(r)y Proposition
Other studies showed that Yap activation in fibroblasts on stiff substrates also drove profibrotic gene expression and contributed to lung fibrogenesis (8). [...]the investigators postulated that that Yap activation in fibroblasts exposed to an IPF-ECM would suppress miR-29 and promote increased stromal gene expression. [...]the introduction of Dicer1-deficient fibroblasts into zebrafish embryos or into mice promoted the development of lesions with increased procollagen expression suggestive of fibrosis. [...]they can be labor-intensive to produce and difficult to predict (14). [...]the effects of tissue processing on proteoglycans and glycosaminoglycans, on protein conformation, on matrisome protein interactions, and on the enzymes/growth factors harbored within the matrix are all poorly understood.
Journal Article
Discoidin Domain Receptor 2 Signaling Regulates Fibroblast Apoptosis through PDK1/Akt
Progressive fibrosis is a complication of many chronic diseases, and collectively, organ fibrosis is the leading cause of death in the United States. Fibrosis is characterized by accumulation of activated fibroblasts and excessive deposition of extracellular matrix proteins, especially type I collagen. Extensive research has supported a role for matrix signaling in propagating fibrosis, but type I collagen itself is often considered an end product of fibrosis rather than an important regulator of continued collagen deposition. Type I collagen can activate several cell surface receptors, including α2β1 integrin and discoidin domain receptor 2 (DDR2). We have previously shown that mice deficient in type I collagen have reduced activation of DDR2 and reduced accumulation of activated myofibroblasts. In the present study, we found that DDR2-null mice are protected from fibrosis. Surprisingly, DDR2-null fibroblasts have a normal and possibly exaggerated activation response to transforming growth factor-β and do not have diminished proliferation compared with wild-type fibroblasts. DDR2-null fibroblasts are significantly more prone to apoptosis, in vitro and in vivo, than wild-type fibroblasts, supporting a paradigm in which fibroblast resistance to apoptosis is critical for progression of fibrosis. We have identified a novel molecular mechanism by which DDR2 can promote the activation of a PDK1 (3-phosphoinositide dependent protein kinase-1)/Akt survival pathway, and we have found that inhibition of PDK1 can augment fibroblast apoptosis. Furthermore, our studies demonstrate that DDR2 expression is heavily skewed to mesenchymal cells compared with epithelial cells and that idiopathic pulmonary fibrosis cells and tissue demonstrate increased activation of DDR2 and PDK1. Collectively, these findings identify a promising target for fibrosis therapy.
Journal Article
NADPH oxidase-4 mediates myofibroblast activation and fibrogenic responses to lung injury
The mechanisms that lead to idiopathic pulmonary fibrosis, or lung scarring, is not clear. Victor Thannickal and his colleagues have now provided further insight by showing that induction of NOX4, an enzyme that creates reactive oxygen species, is required for the progression of the disease. Their findings suggest NOX4 as a potential target to treat this common ailment that currently has no proven treatment options.
Members of the NADPH oxidase (NOX) family of enzymes, which catalyze the reduction of O
2
to reactive oxygen species, have increased in number during eukaryotic evolution
1
,
2
. Seven isoforms of the
NOX
gene family have been identified in mammals; however, specific roles of NOX enzymes in mammalian physiology and pathophysiology have not been fully elucidated
3
,
4
. The best established physiological role of NOX enzymes is in host defense against pathogen invasion in diverse species, including plants
5
,
6
. The prototypical member of this family, NOX-2 (gp91
phox
), is expressed in phagocytic cells and mediates microbicidal activities
7
,
8
. Here we report a role for the
NOX4
isoform in tissue repair functions of myofibroblasts and fibrogenesis. Transforming growth factor-β1 (TGF-β1) induces NOX-4 expression in lung mesenchymal cells via SMAD-3, a receptor-regulated protein that modulates gene transcription. NOX-4–dependent generation of hydrogen peroxide (H
2
O
2
) is required for TGF-β1–induced myofibroblast differentiation, extracellular matrix (ECM) production and contractility. NOX-4 is upregulated in lungs of mice subjected to noninfectious injury and in cases of human idiopathic pulmonary fibrosis (IPF). Genetic or pharmacologic targeting of NOX-4 abrogates fibrogenesis in two murine models of lung injury. These studies support a function for
NOX4
in tissue fibrogenesis and provide proof of concept for therapeutic targeting of NOX-4 in recalcitrant fibrotic disorders.
Journal Article