Bioenergetic pathways in muscle provide high-energy compounds that are required for cellular integrity and function. Increased cellular demand for adenosine triphosphate (ATP) or limitations in the rephosphorylation rate of adenosine diphosphate (ADP) can decrease the total adenine nucleotide (TAN) pool, which may take several days to recover or may not ...

The 5' adenosine monophosphate-activated protein kinase (AMPK) is a member of a metabolite-sensing protein kinase family that functions as a metabolic 'fuel gauge' in skeletal muscle. AMPK is a ubiquitous heterotrimeric protein, consisting of an alpha catalytic, and beta and gamma regulatory subunits that exist in multiple isoforms and are ...

Exercise has diverse effects on metabolic and mitogenic signaling pathways in human skeletal muscle, implying specificity of intracellular signaling cascades. The role of several parallel signaling cascades are discussed in an effort to assign a physiological role for these targets in the regulation of exercise-mediated responses on metabolism and gene ...

In rat skeletal muscle prolonged exercise affects the content and composition of ceramides, but in human skeletal muscle no data are available on this compound. Our aim was to examine the content of ceramide- and sphingomyelin fatty acids and neutral, Mg(2+)-dependent sphingomyelinase activity in skeletal muscle in untrained and trained ...

Decreased dietary protein intake and hemodialysis (HD)-associated protein catabolism are among several factors that predispose chronic hemodialysis (CHD) patients to uremic malnutrition and associated muscle wasting. Intradialytic parenteral nutrition (IDPN) acutely reverses the net negative whole body and forearm muscle protein balances observed during the HD procedure. Exercise has been ...

The skeletal muscle capillary supply is an important determinant of maximum exercise capacity, and it is well known that endurance exercise training increases the muscle capillary supply. The muscle capillary supply and exercise-induced angiogenesis are regulated in part by vascular endothelial growth factor (VEGF). VEGF is produced by skeletal muscle ...

Elevated postexercise amino acid availability has been demonstrated to enhance muscle protein synthesis acutely, but the long-term impact of postexercise protein supplementation on variables such as health, muscle soreness, and function are unclear. Healthy male US Marine recruits from six platoons (US Marine Corps Base, Parris Island, SC; n = ...

OBJECTIVES: To characterize insulin-sensitive glucose-transporter (GLUT-4) protein in equine tissues and determine effects of exercise and glucose administration on content of GLUT-4 protein in equine skeletal muscle. SAMPLE POPULATION: Tissue samples from 9 horses. PROCEDURES: Western blot analyses were performed on crude membrane preparations of equine tissues to characterize GLUT-4. ...

Among persons who do regular exercises, many include abdominal exercises in their customary routine. For this, there are a growing variety of movements being created for strengthening the abdominal muscles. This work aims to know, through electromyography analysis, the action potencies of the supra and infra umbilical of the Rectus ...

Diet can significantly influence exercise performance. Diet alone will not ensure successful performance in sport, but it plays a permissive role in allowing sustained intensive training with limited risk of illness and injury. Diet may also promote adaptations to training by stimulating synthesis and breakdown of the specific proteins that ...

During exercise in human skeletal muscle, the proportion of carbohydrate derived acetyl-CoA is determined at least in part by the activity of the PDH (pyruvate dehydrogenase) complex. Inhibition of the complex is achieved through reversible phosphorylation of the E1 subunit by a family of PDH kinase isoforms (PDK1-4) while dephosphorylation ...

Mitochondrial proteins such as uncoupling protein 3 (UCP3) and adenine nucleotide translocase (ANT) may mediate back-leakage of protons and serve as uncouplers of oxidative phosphorylation. We hypothesized that UCP3 and ANT increase after prolonged exercise and/or endurance training, resulting in increased uncoupled respiration (UCR). Subjects were investigated with muscle biopsies ...

The 5'-AMP-activated protein kinase (AMPK) is proposed to be involved in signaling pathways leading to adaptations in skeletal muscle in response to both a single exercise bout and exercise training. This study investigated the effect of endurance training on protein content of catalytic (alpha1, alpha2) and regulatory (beta1, beta2 and ...

OBJECTIVE: To determine the effect of a single bout of exercise and increased substrate availability after exercise on gene expression and content of the glucose transporter-4 (GLUT-4) protein in equine skeletal muscle. ANIMALS: 6 healthy adult Thoroughbreds. PROCEDURES: The study was designed in a balanced, randomized, 3-way crossover fashion. During ...

Exercise as a therapeutic or prophylactic measure is a topic of particular interest in sarcopenia research. Clearly, exercise can be effectively utilized in the treatment of sarcopenia to recover muscle mass and muscle function in older adults. However, perhaps a more important question is the role of exercise in the ...

The purpose of this study was to elucidate the mechanisms underlying low-intensity exercise-induced peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) protein expression in rat skeletal muscles. Rats (5-6 wk old) swam without a load and ran on the treadmill at a speed of 13 m/min, respectively, in two 3-h sessions separated by ...

There is evidence in rodents that Ca2+-calmodulin-dependent protein kinase II (CaMKII) activity is higher in contracting skeletal muscle, and this kinase may regulate skeletal muscle function and metabolism during exercise. To investigate the effect of exercise on CaMKII in human skeletal muscle, healthy men (n = 8) performed cycle ergometer ...

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors exerting several functions in development and metabolism. The physiological functions of PPARdelta remain elusive. By using a CRE-Lox recombination approach, we generated an animal model for muscle-specific PPARdelta overexpression to investigate the role of PPARdelta in this tissue. Muscle-specific PPARdelta overexpression results in ...

We report a novel nonsense mitochondrial cytochrome b mutation (G15170A) in a 40-year-old woman with progressive exercise intolerance and lactic acidosis. Muscle biopsy showed several cytochrome c oxidase-positive ragged-red fibers, and reduced activities of respiratory chain complexes I and III. This mutation, resulting in the loss of 228 amino acids ...

We studied the effects of exercise without or with a subsequent period on pasture on Ca2+ ATPase concentration in foal skeletal muscle, and compared the results with those previously reported on Na+, K+ ATPase. Ca2+ ATPase was measured in homogenates as Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP. From day 7 after ...

Endurance training leads to many adaptational changes in several tissues. In skeletal muscle, fatty acid usage is enhanced and mitochondrial content is increased. The exact molecular mechanisms regulating these functional and structural changes remain to be elucidated. Contractile activity-induced metabolic perturbation has repeatedly been shown to be important for the ...

Interleukin-6 (IL-6) is produced by many different cell types. Human skeletal muscles produce and release high amounts of IL-6 during exercise; however, the cell source of origin in the muscle is not known. Therefore, we studied the protein expression of IL-6 by immunohistochemistry in human muscle tissue from biopsies obtained ...

The effect of exercise intensity on skeletal muscle AMP-activated protein kinase (AMPK) signaling and substrate metabolism was examined in eight men cycling for 20 min at each of three sequential intensities: low (40 +/- 2% VO(2) peak), medium (59 +/- 1% VO(2) peak), and high (79 +/- 1% VO(2) peak). ...

Emerin and lamins are nuclear proteins, which are missing or defective in Emery-Dreifuss muscular dystrophy (EDMD). The aim of this study was to test the expression of these proteins in skeletal muscles in the X-linked (X-EDMD) and autosomal dominant (AD-EDMD) form. The study group consisted of 11 patients with X-EDMD, ...

We investigated whether acute systemic exercise increases vascular endothelial growth factor (VEGF), VEGF receptor (KDR and Flt-1) mRNA, and VEGF protein in sedentary humans. Twelve sedentary subjects were recruited and performed 1 h of acute, cycle ergometer exercise at 50% of maximal oxygen consumption. Muscle biopsies were obtained from the ...

Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP ...

Cellular adaptations to endurance training are influenced by the intensity and duration of exercise. To examine the impact of exercise intensity and duration on the acute transcriptional regulation of metabolic genes in red (RG) and white (WG) gastrocnemius muscle, rats completed either low-intensity [ approximately 50% maximal O2 uptake (VO2 ...

Insulin resistance increases and muscle oxidative capacity decreases during aging, but lifestyle changes-especially physical activity-may reverse these trends. Here we report the effect of a 16-week aerobic exercise program (n = 65) or control activity (n = 37) performed by men and women aged 21-87 years on insulin sensitivity and ...

Long-chain fatty acids (LCFA) are important sources of energy in contracting skeletal muscle: during the course of endurance exercise the contribution of LCFA in energy metabolism increases whereas when the intensity of exercise increases, the energy need is covered more and more by carbohydrates. Although this has been known for ...

In this study, we quantified the expression of the vascular endothelial growth factor (VEGF) gene in individual muscle fibres at the end of a single 90 min run of 20-25 m min-1, at 10 % incline. In addition, we evaluated the co-ordinated expression of several hypoxia-sensitive genes, including the ORP-150 ...

OBJECTIVES: We sought to determine whether intrinsic mitochondrial function and regulation were altered in heart transplant recipients (HTRs) and to investigate the response of mitochondrial function to six-week endurance training in these patients. BACKGROUND: Despite the normalization of central oxygen transport during exercise, HTRs are still characterized by limited exercise ...

Endurance training elicits profound adaptations of skeletal muscle, including increased expression of several proteins. The 5'-AMP activated protein kinase (AMPK) may be one of these, considering the fact that acute exercise increases AMPK activity. Eight young (26 +/- 1 year) lean, healthy males endurance trained one leg (while the other ...

Angiogenesis, the growth of new blood vessels from existing ones, occurs in the skeletal muscle as an adaptive response to exercise that satisfies the increased requirement of this tissue for oxygen delivery and metabolic processes. Of the factors that have been identified to regulate this process, the endothelial cell mitogen ...

AMP-activated protein kinase (AMPK) is emerging as a key signaling pathway that modulates cellular metabolic processes. In skeletal muscle, AMPK is activated during exercise. Increased myocardial substrate metabolism during exercise could be explained by AMPK activation. Although AMPK is known to be activated during myocardial ischemia, it remains uncertain whether ...

In the present study we examined whether exercise and prostanoids have an effect on the muscle interstitial concentration of vascular endothelial growth factor (VEGF) and on the proliferative effect of muscle interstitial fluid. Dialysate from resting and exercising human skeletal muscle, obtained either during control conditions or during cyclooxygenase inhibition, ...

This review shows the importance of high-glycemic carbohydrates consumed together with protein in enhancing the exercise-induced muscle formation relative to timing of intake. Insulin, which increases in blood after glycemic carbohydrate ingestion, seems to effectively stimulate protein synthesis and inhibit protein degradation right after exercise rather than later. This presents ...

Ca(2+)-ATPase and Ca(2+)-pumping activities by the sarcoplasmic reticulum (SR) and the amounts of sulphydryl and carbonyl groups contained in the SR protein were examined in the superficial portion of the gastrocnemius and vastus lateralis muscles of the rat after high-intensity treadmill runs to exhaustion (average time to exhaustion: 363 s). ...

Our purpose was to determine the effects of gender and exercise training on endothelial nitric oxide synthase (eNOS) and superoxide dismutase (SOD) protein content of porcine skeletal muscle arteries and to evaluate the role of 17beta-estradiol (E2) in these effects. We measured eNOS and SOD content with immunoblots and immunohistochemistry ...

While there is indisputable evidence supporting the beneficial role of aerobic exercise in reducing cardiovascular risk factors, there are few dose-response studies of this relationship. Increasingly, it is thought that the cardiovascular benefits of exercise are significantly influenced by adaptations within skeletal muscle and its vasculature. However, little is known ...

Hormone-sensitive lipase (HSL) catalyzes the hydrolysis of intramuscular triacylglycerols (IMTGs), but HSL regulation is poorly understood in skeletal muscle. The present study measured human skeletal muscle HSL activity at rest and during 120 min of cycling at 60% of peak O2 uptake. Several putative HSL regulators were also measured, including ...

In rodents, acute exercise increases skeletal muscle uncoupling protein (UCP) gene expression and is associated with elevations in serum nonesterified fatty acids (NEFA). To test whether contractions increase UCP mRNA levels in humans, vastus lateralis biopsies were obtained 1 hour postexercise from untrained and trained subjects and analyzed for UCP-2 ...

Animal studies have shown that supra-physiological creatine monohydrate (Cr-mH) supplementation for 3 months reduced skeletal muscle creatine transporter (CRT) content. The doses of Cr-mH (1-2 g/kg/day) used in these studies were between 5 and 10 times those usually used in human studies, and it is unclear whether a down-regulation of ...

Endurance exercise training induces mitochondrial biogenesis in skeletal muscle. The peroxisome proliferator activated receptor co-activator 1alpha (PGC-1alpha) has recently been identified as a nuclear factor critical for coordinating the activation of genes required for mitochondrial biogenesis in cell culture and rodent skeletal muscle. To determine whether PGC-1alpha transcription is regulated ...

Physical exercise increases muscle glucose uptake, enhances insulin sensitivity and leads to fatty acid oxidation in muscle. The AMP-activated protein kinase (AMPK) is an energy-sensing enzyme that is strongly activated during muscle contraction due to acute decreases in ATP/AMP and phosphocreatine/creatine ratios. Accumulating evidence suggests that AMPK plays an important ...

Several different exercise regimens varied in the severity of tissue damage induced. Therefore, this study investigated the effects of a single bout of exercise versus endurance training in heart and skeletal muscles with different predominant fiber types on indices of mitochondrial, endoplasmic reticulum (ER) integrity and protein degradation. Male Wistar ...

The purpose of this investigation was to examine the activation (phosphorylation) and total protein content of MAPK signalling cascade proteins (ERK 1/2, p90RSK, Mnk 1, eIF4E, p38 MAPK, JNK/SAPK, MKP 1) at rest and following exercise, in sedentary young and old men. Eight young (22 +/- 1 years; YM) and ...

Angiogenesis occurs in skeletal muscle in response to exercise training. To gain insight into the regulation of this process, we evaluated the mRNA expression of factors implicated in angiogenesis over the course of a training program. We studied sedentary control (n = 17) rats and both sedentary (n = 18) ...

Skeletal muscle remodeling is a critical component of an organism's response to environmental changes. Exercise causes structural changes in muscle and can induce phase shifts in circadian rhythms, fluctuations in physiology and behavior with a period of around 24 hours that are maintained by a core clock mechanism. Both exercise-induced ...

Behavioural and hereditary conditions are known to decrease mitochondrial volume and function within skeletal muscle. This reduces endurance performance, and is manifest both at high- and low-intensity levels of exertion. A programme of regular endurance exercise, undertaken over a number of weeks, produces significant adaptations within skeletal muscle such that ...

PURPOSE OF REVIEW: In response to decreased usage, skeletal muscle undergoes adaptive reductive remodeling due to the decrease in tension on the weight bearing components of the musculo-skeletal system. This response occurs with uncomplicated disuse (e.g. bed rest, space flight), as a secondary consequence of several widely prevalent chronic diseases ...