Fifteen days of 3200m simulated hypoxia marginally regulates markers for protein synthesis and degradation in human skeletal muscle

Chronic hypoxia leads to muscle atrophy. The molecular mechanisms responsible for this phenomenon are not well defined in vivo. We sought to determine how chronic hypoxia regulates molecular markers of protein synthesis and degradation in human skeletal muscle and whether these regulations were related to the regulation of the hypoxia-inducible factor (HIF) pathway. Eight young male subjects lived in a normobaric hypoxic hotel (FiO2 14.1%, 3,200 m) for 15 days in well-controlled conditions for nutrition and physical activity. Skeletal muscle biopsies were obtained in the musculus vastus lateralis before (PRE) and immediately after (POST) hypoxic exposure. Intramuscular hypoxia-inducible factor-1 alpha (HIF-1α) protein expression decreased (-49%, P=0.03), whereas hypoxia-inducible factor-2 alpha (HIF-2α) remained unaffected from PRE to POST hypoxic exposure. Also, downstream HIF-1α target genes VEGF-A (-66%, P=0.006) and BNIP3 (-24%, P=0.002) were downregulated, and a tendency was measured for neural precursor cell expressed, developmentally Nedd4 (-47%, P=0.07), suggesting lowered HIF-1α transcriptional activity after 15 days of exposure to environmental hypoxia. No difference was found on microtubule-associated protein 1 light chain 3 type II/I (LC3b-II/I) ratio, and P62 protein expression tended to increase (+45%, P=0.07) compared to PRE exposure levels, suggesting that autophagy was not modulated after chronic hypoxia. The mammalian target of rapamycin complex 1 pathway was not altered as Akt, mammalian target of rapamycin, S6 kinase 1, and 4E-binding protein 1 phosphorylation did not change between PRE and POST. Finally, myofiber cross-sectional area was unchanged between PRE and POST. In summary, our data indicate that moderate chronic hypoxia differentially regulates HIF-1α and HIF-2α, marginally affects markers of protein degradation, and does not modify markers of protein synthesis or myofiber cross-sectional area in human skeletal muscle

Hepatic steatosis in n-3 fatty acid depleted mice: focus on metabolic alterations related to tissue fatty acid composition

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Protein supplementation in strength and conditioning adepts: knowledge, dietary behaviour and practice in Palermo, Italy

Background: It is known that supplement use is a widespread and accepted practice by athletes and people who attend commercial gyms. Little is known about protein supplement amongst people undertaking strength training in commercial gyms in Italy when compared to the US. Objective: The purpose of this study was to examine the use of protein supplementation, alone or in association with other supplements, and dietary behavior amongst regular fitness center attendees in Palermo, Italy. Design: Resistance training information have been collected from 800 regular fitness center attendees for the initial analysis. A specific questionnaire was generated for the experimentation. Data were collected using a face-to-face interview method. Supplement users were then compared to the non users and analyzed using a one-way ANOVA, Kruskall-Wallis, chi-square test or exact test of Fisher when appropriate. Results: 30.1% of the respondents use dietary supplements during their training as a believe it is the "way to gain muscles and strength". Whey protein shakes (50.0%) mixed with creatine and amino-acids (48.3%) were the most frequent choices amongst the users. A majority of the subjects (34.0%) appeared to rely on their gym instructors' advice for their intake; a lower proportion (13.0%) consulted physicians, while none of them consulted nutritionists. A high consumption of milk has been noticed in both users (67,7%) and non-users (52,8%); supplement non-users consumed significantly more snacks and bakery products than users per week (P < 0.001), while users consumed significantly more protein-rich foods (P < 0.01) with a particular preference for meat (48.0%). Conclusions: A considerable number of regular strength training adepts consume protein supplements mixed with other products (mainly creatine and amino-acids). Limited numbers consult "dietary specialists" and rely mainly on their instructors. We emphasize on the importance of the dissemination of scientifically based information about supplementation in this environment and the promotion of updated educational programs for the instructors

Creatine ingestion augments dietary carbohydrate mediated muscle glycogen supercomposition during the initial 24 hrs of recovery following prolonged exhaustive exercise in humans

Muscle glycogen availability can limit endurance exercise performance. We previously demonstrated 5 days of creatine (Cr) and carbohydrate (CHO) ingestion augmented post-exercise muscle glycogen storage compared to CHO feeding alone in healthy volunteers. Here we aimed to characterise the time-course of this Cr-induced response under more stringent and controlled experimental conditions and identify potential mechanisms underpinning this phenomenon. Fourteen healthy, male volunteers cycled to exhaustion at 70% VO2peak. Muscle biopsies were obtained at rest immediately post-exercise and after 1, 3 and 6 days of recovery, during which Cr or placebo supplements (20g.day-1) were ingested along with a prescribed high CHO diet (37.5 kcal.kg body mass-1.day-1, >80% calories CHO). Oral-glucose tolerance tests (oral-GTT) were performed pre-exercise and after 1, 3 and 6 days of Cr and placebo supplementation. Exercise depleted muscle glycogen content to the same extent in both treatment groups. Creatine supplementation increased muscle total-Cr, free-Cr and phosphocreatine (PCr) content above placebo following 1, 3 and 6 days of supplementation (all P<0.05). Creatine supplementation also increased muscle glycogen content noticeably above placebo after 1 day of supplementation (P<0.05), which was sustained thereafter. This study confirmed dietary Cr augments post-exercise muscle glycogen super-compensation, and demonstrates this occurred during the initial 24 h of post-exercise recovery (when muscle total-Cr had increased by <10%). This marked response ensued without apparent treatment differences in muscle insulin sensitivity (oral-GTT, muscle GLUT4 mRNA), osmotic stress (muscle c-fos and HSP72 mRNA) or muscle cell volume (muscle water content) responses, such that another mechanism must be causative

ER Stress Induces Anabolic Resistance in Muscle Cells through PKB-Induced Blockade of mTORC1

Anabolic resistance is the inability to increase protein synthesis in response to an increase in amino acids following a meal. One potential mediator of anabolic resistance is endoplasmic reticulum (ER) stress. The purpose of the present study was to test whether ER stress impairs the response to growth factors and leucine in muscle cells

The creatine kinase system and pleiotropic effects of creatine

The pleiotropic effects of creatine (Cr) are based mostly on the functions of the enzyme creatine kinase (CK) and its high-energy product phosphocreatine (PCr). Multidisciplinary studies have established molecular, cellular, organ and somatic functions of the CK/PCr system, in particular for cells and tissues with high and intermittent energy fluctuations. These studies include tissue-specific expression and subcellular localization of CK isoforms, high-resolution molecular structures and structure–function relationships, transgenic CK abrogation and reverse genetic approaches. Three energy-related physiological principles emerge, namely that the CK/PCr systems functions as (a) an immediately available temporal energy buffer, (b) a spatial energy buffer or intracellular energy transport system (the CK/PCr energy shuttle or circuit) and (c) a metabolic regulator. The CK/PCr energy shuttle connects sites of ATP production (glycolysis and mitochondrial oxidative phosphorylation) with subcellular sites of ATP utilization (ATPases). Thus, diffusion limitations of ADP and ATP are overcome by PCr/Cr shuttling, as most clearly seen in polar cells such as spermatozoa, retina photoreceptor cells and sensory hair bundles of the inner ear. The CK/PCr system relies on the close exchange of substrates and products between CK isoforms and ATP-generating or -consuming processes. Mitochondrial CK in the mitochondrial outer compartment, for example, is tightly coupled to ATP export via adenine nucleotide transporter or carrier (ANT) and thus ATP-synthesis and respiratory chain activity, releasing PCr into the cytosol. This coupling also reduces formation of reactive oxygen species (ROS) and inhibits mitochondrial permeability transition, an early event in apoptosis. Cr itself may also act as a direct and/or indirect anti-oxidant, while PCr can interact with and protect cellular membranes. Collectively, these factors may well explain the beneficial effects of Cr supplementation. The stimulating effects of Cr for muscle and bone growth and maintenance, and especially in neuroprotection, are now recognized and the first clinical studies are underway. Novel socio-economically relevant applications of Cr supplementation are emerging, e.g. for senior people, intensive care units and dialysis patients, who are notoriously Cr-depleted. Also, Cr will likely be beneficial for the healthy development of premature infants, who after separation from the placenta depend on external Cr. Cr supplementation of pregnant and lactating women, as well as of babies and infants are likely to be of benefit for child development. Last but not least, Cr harbours a global ecological potential as an additive for animal feed, replacing meat- and fish meal for animal (poultry and swine) and fish aqua farming. This may help to alleviate human starvation and at the same time prevent over-fishing of oceans

Short Term Creatine Loading Without Weight Gain Improves Sprint, Agility and Leg Strength Performance in Female Futsal Players

Summary Objectives Futsal game requires players to perform frequent bouts of high-intensity activity with limited rest periods that are not sufficient for full recovery. Therefore, creatine supplementation may enhance performance by improving recovery rate. Along with this, the number of studies conducted to determine the effects of creatine on performance in the females is scarce. Thus, the main aim of this study is to identify the effects of short-term (7/day) creatine supplementation on leg strength, velocity and agility in young female futsal players. Equipment and methods A total of thirty of young female futsal players (aged: 19.83±1.13 years) participated in the study which was designed as randomized and double-blind, on a voluntary basis. Participants were randomly assigned either to creatine (n=15) or placebo (n=15) group. Over 7 days, creatine group received 0.25g/kg/day micronized pure creatine monohydrate (Creapure, Hardline Nutrition, Kavi Gıda Istanbul, Turkey) and placebo group did not take any supplements, apart from maltodextrin (Fantomalt, Nutricia, United Kingdom). Before and after 7 days of loading creatine supplementation, body weight, leg strength, velocity and agility performance of the participants were determined. The data obtained were analysed with ANCOVA statistical model. Results Creatine supplementation significantly improved 10m, 20m and 30m speed performances (P0.05). The data obtained provide that 7 days low dose creatine supplementation may be an effective approach for improving exercise capacity in female futsal players without an associated increase in body weight. Résumé Objectifs Le jeu de futsal exige que les joueurs effectuent de fréquentes périodes d’activité de haute intensité avec des périodes de repos limitées qui ne sont pas suffisantes pour une récupération complète. Par conséquent, la supplémentation en créatine peut améliorer les performances en améliorant le taux de récupération. Parallèlement à cela, le nombre d’études menées pour déterminer les effets de la créatine sur la performance chez les femmes est rare. Ainsi, le but principal de cette étude est d’identifier les effets de la supplémentation en créatine à court terme (7/jour) sur puissance des jambes, la vélocité et l’agilité chez les jeunes joueuses de futsal féminines. Équipement et méthodes Au total, une trentaine de jeunes joueuses de futsal (âgées de 19,83±1,13 ans) ont participé à l’étude, conçue comme une étude randomisée et en double insu, sur base volontaire. Les participants ont été assignés au hasard soit au groupe créatine (n=15) ou au groupe Placebo (n=15). Sur 7jours, le groupe créatine a reçu 0,25g/kg/jour de monohydrate de créatine pure micronisée (Creapure, Hardline Nutrition, Kavi Gida Istanbul, Turquie) et le groupe placebo n’a pas pris de suppléments hormis la maltodextrine (Fantomalt, Nutricia, Royaume-Uni). Avant et après 7jours de chargement de supplémentation en créatine, le poids corporel, la force des jambes, la vélocité et l’agilité des participants ont été déterminés. Les données obtenues ont été analysées avec le modèle statistique ANCOVA. Résultats La supplémentation en créatine a significativement amélioré les performances en vitesse de 10m, 20m et 30m (p<0,05), la force des jambes (p<0,05) et l’agilité (p<0,05) chez les joueuses de futsal. Cependant, en fonction de la charge en créatine, aucun changement significatif du poids corporel n’a été observé (p<0,05). Les données obtenues indiquent qu’une supplémentation en créatine à faible dose de 7jours peut être une approche efficace pour améliorer la capacité d’exercice chez les joueuses féminines de futsal sans augmentation associée du poids corporel