scholarly journals Contemporary Nutrition Interventions to Optimize Performance in Middle-Distance Runners

2019 ◽  
Vol 29 (2) ◽  
pp. 106-116 ◽  
Author(s):  
Trent Stellingwerff ◽  
Ingvill Måkestad Bovim ◽  
Jamie Whitfield
Keyword(s):  
Muscle Glycogen ◽  
Point Of View ◽  
Glycolytic Flux ◽  
Fiber Morphology ◽  
Distance Runners ◽  
Nutrition Interventions ◽  
Nutritional Interventions ◽  
Intervention Point ◽  
Elite Level ◽  
Global Travel

Middle-distance runners utilize the full continuum of energy systems throughout training, and given the infinite competition tactical scenarios, this event group is highly complex from a performance intervention point of view. However, this complexity results in numerous potential periodized nutrition interventions to optimize middle-distance training adaptation and competition performance. Middle-distance race intensity is extreme, with 800- to 5,000-m races being at ∼95% to 130% of VO2max. Accordingly, elite middle-distance runners have primarily Type IIa/IIx fiber morphology and rely almost exclusively on carbohydrate (primarily muscle glycogen) metabolic pathways for producing adenosine triphosphate. Consequently, the principle nutritional interventions that should be emphasized are those that optimize muscle glycogen contents to support high glycolytic flux (resulting in very high lactate values, of >20 mmol/L in some athletes) with appropriate buffering capabilities, while optimizing power to weight ratios, all in a macro- and microperiodized manner. From youth to elite level, middle-distance athletes have arduous racing schedules (10–25 races/year), coupled with excessive global travel, which can take a physical and emotional toll. Accordingly, proactive and integrated nutrition planning can have a profound recovery effect over a long race season, as well as optimizing recovery during rounds of championship racing. Finally, with evidence-based implementation and an appropriate risk/reward assessment, several ergogenic aids may have an adaptive and/or performance-enhancing effect in the middle-distance athlete. Given that elite middle-distance athletes undertake ∼400 to 800 training sessions with 10–25 races/year, there are countless opportunities to implement various periodized acute and chronic nutrition-based interventions to optimize performance.

scholarly journals Reposición del Glucógeno Muscular en la Recuperación del Deportista

2019 ◽  
Vol 8 (1) ◽  
pp. 57-66 ◽  
Author(s):  
F. Mata-Ordoñez ◽  
M. Grimaldi-Puyana ◽  
A. J. Sánchez-Oliver
Keyword(s):  
Muscle Glycogen ◽  
Athletic Performance ◽  
Recovery Phase ◽  
Post Exercise ◽  
Nutritional Interventions ◽  
Carbohydrate Consumption ◽  
Cellular Processes ◽  
Intense Training ◽  
Post Exercise Recovery ◽  
Glycogen Stores

Las estrategias nutricionales durante la fase de recuperación del deportista son fundamentales. Uno de los principales objetivos de la recuperación es la reposición del glucógeno muscular. Este aspecto se hace más importante cuando los deportistas se enfrentan a entrenamientos intensos o eventos competitivos con cortos periodos de recuperación. Además, la manipulación deliberada de su disponibilidad puede mejorar las adaptaciones moleculares al entrenamiento. La presente revisión tiene por objetivo informar sobre los aspectos fisiológicos básicos de esta situación, así como conocer el momento del consumo, la cantidad, el tipo y la interacción de diferentes nutrientes con los hidratos de carbono, para poder maximizar o jugar con la reposición del mismo en función de las necesidades y/o las estrategias planteadas. El glucógeno ya no debe ser visto como un simple almacén de energía sino como una molécula que puede desencadenar numerosos procesos celulares importantes para el deportista. Nutritional interventions play a fundamental role during the post-exercise recovery phase. One of the main goals of recovery is restoring muscle glycogen stores. This becomes more important when athletes are subjected to intense training or competition with short recovery periods be-tween bouts. Furthermore, manipulating muscle glycogen availability can improve molecular adaptations to training. The objective of this review is thus to present the basic physiological aspects of this phenomenon, and to discuss carbohydrate consumption, timing, type, and amount, as well as its interaction with different nutrients, in order to maximize or play with the restoration of muscle glycogen depending on the needs and/or the strategies proposed. Glyco-gen should no longer be seen as a simple form of energy storage, but as a molecule that can trigger numerous cellular processes important for athletic performance.

scholarly journals Regenerated Cellulose/Graphene Composite Fibers with Electroconductive Properties

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Kulpinski Piotr ◽  
Jeremiasz K. Jeszka ◽  
Malolepszy Artur ◽  
Stobinski Leszek
Keyword(s):  
Graphene Oxide ◽  
Water Solution ◽  
Cellulose Fibers ◽  
Fiber Spinning ◽  
Point Of View ◽  
Regenerated Cellulose ◽  
Fiber Morphology ◽  
Reduced Graphene ◽  
The Difference ◽  
Electronic Elements

AbstractConductive cellulose fibers may find application in producing antistatic materials and fibrous electronic elements for smart textiles (textronics). In this paper, we present a method of fabrication of cellulose fibers modified with the reduced graphene oxide (rGO) and graphene oxide (GO). The fibers were obtained by using N-methylmorpholine-N-oxide (NMMO) as a direct solvent, adding dispersion of GO during the cellulose dissolution process. In the next step, the GO enclosed in the fibers was reduced for ca. half an hour at 90°C with the excess of water solution of hydrazine to obtain fibers containing rGO. The viscosity of the spinning solution increased when GO was added; however, the difference is important at low shearing rates but decreases at high shearing rates, similar to that used in the process of fiber spinning. Cellulose fibers containing 3, 4, 6, and 10% w/w of rGO were obtained. Fiber morphology was studied using electron microscopy. The results of the electrical properties’ measurements showed that the conductivity of modified fibers strongly depends on the concentration of rGO. At 10% rGO conductivity was 9 x 10−3 S/cm. The mechanical properties of the obtained fibers were slightly changed by the presence of GO and rGO. Tenacity and elongation at break decreased with the increase in the content of GO and rGO in the fibers but remain at an acceptable level from the textiles processing point of view.

scholarly journals EDUCAÇÃO, PEDAGOGIA E JUSTIÇA SOCIAL NO ENSINO SUPERIOR EM AMBIENTE PRISIONAL

2021 ◽  
Vol 1 ◽  
pp. 89
Author(s):  
José António Moreira ◽  
Sara Dias-Trindade
Keyword(s):  
Educational Communication ◽  
Point Of View ◽  
Self Concept ◽  
Education For All ◽  
Education Students ◽  
Positive Effects ◽  
Intervention Point ◽  
Motivation Orientation ◽  
Networked Society ◽  
Modelo Pedagógico

RESUMOO mundo em permanente transformação, veloz, universal e em rede, e o advento da Internet propiciaram o surgimento de uma sociedade em rede marcada por mudanças acentuadas na economia, impulsionando o nascimento de novos paradigmas, modelos, processos de comunicação educacional e novos cenários de aprendizagem. É, precisamente, um desses novos cenários que pretendemos analisar, descrevendo o seu impacto no autoconceito académico de vinte estudantes reclusos da Universidade Aberta, Portugal, a partir da análise qualitativa das suas perceções e narrativas e tendo como referencial o Modelo Pedagógico desenvolvido por Moreira (2017) para o desenho de e-atividades de aprendizagem centradas na “desconstrução” de imagens em movimento. Os resultados mostram que o design do ambiente, ancorado neste modelo e na utilização de tecnologias audiovisuais, pode ter efeitos muito positivos no autoconceito académico dos estudantes do ensino superior, a nível das diferentes dimensões consideradas: Motivação, Orientação para a Tarefa, Confiança nas suas Capacidades e Relação com os Colegas. São discutidas as implicações dos resultados encontrados, tanto do ponto de vista de intervenção prática, quanto em termos de investigações futuras.Palavras-chave: Pedagogia. Ambiente Educativo. Cinema. Educação para Todos. Justiça Social. ABSTRACTBoth the world in permanent change, fast, universal and networked and the Internet have propitiated the emergence of a networked society marked by changes in the economy, setting the birth of new paradigms, models, processes of educational communication and new pedagogical scenarios. It is precisely one of these new pedagogical scenarios, that we intend to analyze, describing its impact on the academic self-concept of twenty prisoners/students from the Open University, Portugal, based on the qualitative analysis of their own perceptions and narratives having as reference the Pedagogical Model developed by Moreira (2017). The results show that the design of the environment, anchored in this model and the use of audiovisual technologies can have very positive effects on the academic self-concept of higher education students in the various dimensions taken into consideration: Motivation, Orientation for the task, Trust in their own capacities and Relationship with colleagues. The implications of the results are discussed not only from a practical intervention point of view but also in terms of future research.Keywords: Pedagogy. Educational Environment. Cinema. Education for All. Social Justice.

scholarly journals Effect of acute activation of 5′-AMP-activated protein kinase on glycogen regulation in isolated rat skeletal muscle

2007 ◽  
Vol 102 (3) ◽  
pp. 1007-1013 ◽  
Author(s):  
Licht Miyamoto ◽  
Taro Toyoda ◽  
Tatsuya Hayashi ◽  
Shin Yonemitsu ◽  
Masako Nakano ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Glycogen ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycolytic Flux ◽  
Ampk Activation ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase ◽  
Isolated Rat

5′-AMP-activated protein kinase (AMPK) has been implicated in glycogen metabolism in skeletal muscle. However, the physiological relevance of increased AMPK activity during exercise has not been fully clarified. This study was performed to determine the direct effects of acute AMPK activation on muscle glycogen regulation. For this purpose, we used an isolated rat muscle preparation and pharmacologically activated AMPK with 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR). Tetanic contraction in vitro markedly activated the α1- and α2-isoforms of AMPK, with a corresponding increase in the rate of 3- O-methylglucose uptake. Incubation with AICAR elicited similar enhancement of AMPK activity and 3- O-methylglucose uptake in rat epitrochlearis muscle. In contrast, whereas contraction stimulated glycogen synthase (GS), AICAR treatment decreased GS activity. Insulin-stimulated GS activity also decreased after AICAR treatment. Whereas contraction activated glycogen phosphorylase (GP), AICAR did not alter GP activity. The muscle glycogen content decreased in response to contraction but was unchanged by AICAR. Lactate release was markedly increased when muscles were stimulated with AICAR in buffer containing glucose, indicating that the glucose taken up into the muscle was catabolized via glycolysis. Our results suggest that AMPK does not mediate contraction-stimulated glycogen synthesis or glycogenolysis in skeletal muscle and also that acute AMPK activation leads to an increased glycolytic flux by antagonizing contraction-stimulated glycogen synthesis.

Elite Female Distance Runners and Advice During Pregnancy: Sources, Content, and Trust

2016 ◽  
Vol 24 (2) ◽  
pp. 170-176 ◽  
Author(s):  
Francine Darroch ◽  
Audrey R. Giles ◽  
Roisin McGettigan-Dumas
Keyword(s):  
Physical Activity ◽  
Well Being ◽  
Medical Professionals ◽  
Informational Needs ◽  
Sources Of Information ◽  
Distance Runners ◽  
Physical Activity Guidelines ◽  
Healthy Pregnancy ◽  
Elite Level ◽  
The Usa

More elite female distance runners are opting to have children during their athletic careers. Despite this, there is a dearth of information regarding pregnancy and physical activity for elite level athletes. Further, current pregnancy physical activity guidelines are not relevant for this population`s needs. Two research questions frame this study: are elite female distance runners’ pregnancy informational needs being met?; where do they seek and find trustworthy advice on physical activity during pregnancy? Open-ended, semistructured interviews were conducted with 14 women who experienced at least one pregnancy within the past five years, had achieved a minimum of the USA Track and Field 2012 Olympic Team marathon trials ‘B’ entry standard or equivalent performances for distance running events 1,500m or longer. The participants had between one—three children, hail from five countries and participated in 14 Olympic Games and 72 World Championships. Utilizing poststructuralist feminist theory and thematic analysis, our findings revealed that the participants received advice from three main sources, both in person and online: medical professionals, coaches, and other elite female distance runners. However, we found that they also received unsolicited advice and comments from community members where they lived. The participants identified fellow elite female distance runners as the most reliable and trustworthy sources of information, followed by medical professionals, then coaches. Ultimately, the women revealed a lack of formal sources they could turn to for trustworthy advice about how to have a safe and healthy pregnancy while continuing to train at a high intensity. These results illuminate the need to meet female elite athletes’ informational needs in terms of well-being during pregnancy.

Carbohydrate balance in competitive runners during successive days of intense training

1988 ◽  
Vol 65 (6) ◽  
pp. 2601-2606 ◽  
Author(s):  
J. P. Kirwan ◽  
D. L. Costill ◽  
J. B. Mitchell ◽  
J. A. Houmard ◽  
M. G. Flynn ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Perceived Exertion ◽  
Glycogen Content ◽  
Running Economy ◽  
Type I ◽  
Type Ii ◽  
Distance Runners ◽  
Intense Training ◽  
Type I Fibers ◽  
Glycogen Stores

This study was designed to investigate the effect of intense training on muscle glycogen stores under conditions of controlled carbohydrate (CHO) intake. On two separate occasions, 10 highly trained distance runners increased their training load for 5 days (20 km/day, approximately 80% maximal O2 consumption) while eating a diet whose carbohydrate composition either equaled (EQ-CHO) or contained approximately 50% of the runner's estimated daily expenditure (LO-CHO). Total muscle glycogen levels were lower after the LO-CHO regimen. Photometric analysis of the glycogen content in individual fibers revealed that 27% type I and 17% type II fibers had optical densities less than 0.2 U after the LO-CHO regimen, whereas 7% type I and 0% type II were similarly depleted after the EQ-CHO diet. A linear relationship was observed between the histochemical and direct chemical analysis of muscle glycogen content. Treadmill O2 uptake measured at 185 and 238 m/min was higher during the LO-CHO than the EQ-CHO regimen. Ratings of perceived exertion were higher during the 238-m/min run for the LO-CHO regimen. After 3 days of rest, running economy and perception of effort returned to pretraining levels and muscle glycogen stores were approximately 85% of the pretraining values. Thus when CHO intake was only approximately 50% of the energy requirements there was a marked depletion of muscle glycogen stores, particularly in type I fibers, and a concomitant decrease in running economy and increased perception of fatigue.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutrition Interventions to Manage Sarcopenia: An Appraisal of the Existing Evidence

2018 ◽  
pp. 1-19
Keyword(s):  
Older Adults ◽  
Clinical Trials ◽  
Amino Acid ◽  
Protein Intake ◽  
Scientific Evidence ◽  
Amino Acid Supplementation ◽  
Common Condition ◽  
Nutrition Interventions ◽  
Serious Adverse Events ◽  
Nutritional Interventions

Sarcopenia is a common condition that can lead to serious adverse events in older adults. However, sarcopenia can be prevented and treated and nutrition plays a major role in its management. This article aims to appraise the scientific evidence on nutritional interventions to prevent and treat sarcopenia in older adults, highlighting the effect of an adequate caloric and protein intake, protein and amino-acid supplementation, micronutrients, and phospholipids. Unfortunately, clinical trials assessing the effect of these interventions on sarcopenia or muscle parameters are scarce, and the majority were not conducted in sarcopenic individuals.

Muscle glycogen inharmoniously regulates glycogen synthase activity, glucose uptake, and proximal insulin signaling

2006 ◽  
Vol 290 (1) ◽  
pp. E154-E162 ◽  
Author(s):  
Jørgen Jensen ◽  
Einar Jebens ◽  
Erlend O. Brennesvik ◽  
Jérôme Ruzzin ◽  
Maria A. Soos ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Glucose Uptake ◽  
Insulin Signaling ◽  
Muscle Glycogen ◽  
Glycogen Synthase ◽  
Blood Glucose Concentration ◽  
Glycogen Synthesis ◽  
Normal Diet ◽  
Glycolytic Flux ◽  
Glut4 Expression

Insulin-stimulated glucose uptake and incorporation of glucose into skeletal muscle glycogen contribute to physiological regulation of blood glucose concentration. In the present study, glucose handling and insulin signaling in isolated rat muscles with low glycogen (LG, 24-h fasting) and high glycogen (HG, refed for 24 h) content were compared with muscles with normal glycogen (NG, rats kept on their normal diet). In LG, basal and insulin-stimulated glycogen synthesis and glycogen synthase activation were higher and glycogen synthase phosphorylation (Ser645, Ser649, Ser653, Ser657) lower than in NG. GLUT4 expression, insulin-stimulated glucose uptake, and PKB phosphorylation were higher in LG than in NG, whereas insulin receptor tyrosyl phosphorylation, insulin receptor substrate-1-associated phosphatidylinositol 3-kinase activity, and GSK-3 phosphorylation were unchanged. Muscles with HG showed lower insulin-stimulated glycogen synthesis and glycogen synthase activation than NG despite similar dephosphorylation. Insulin signaling, glucose uptake, and GLUT4 expression were similar in HG and NG. This discordant regulation of glucose uptake and glycogen synthesis in HG resulted in higher insulin-stimulated glucose 6-phosphate concentration, higher glycolytic flux, and intracellular accumulation of nonphosphorylated 2-deoxyglucose. In conclusion, elevated glycogen synthase activation, glucose uptake, and GLUT4 expression enhance glycogen resynthesis in muscles with low glycogen. High glycogen concentration per se does not impair proximal insulin signaling or glucose uptake. “Insulin resistance” is observed at the level of glycogen synthase, and the reduced glycogen synthesis leads to increased levels of glucose 6-phosphate, glycolytic flux, and accumulation of nonphosphorylated 2-deoxyglucose.

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