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Effet anabolique du blanc d’œuf VS œuf entier?

25/04/2017 | Etudes Compléments alimentaires

 

Greater Stimulation of Postexercise Muscle Protein Synthesis after Consumption of Whole Eggs versus Egg Whites in Healthy Young Men
Stephan van Vliet

The majority of protein consumed in the diet is obtained from whole food sources that contain a mixture of macro- and micronutrients. Whereas the majority of research investigated the effect of isolated protein sources on protein metabolism, our aim was to assess the muscle anabolic potential of consuming a complete protein within its naturally occurring, nutrient dense food matrix during recovery from resistance exercise in young men.

In crossover trials, 10 healthy resistance-trained men (21±1 y; 88±3 kg; bodyfat: 16±1%) received primed continuous L-[ring-2H5]phenylalanine and L-[1-13C]leucine infusions. Repeated blood and muscle biopsies were collected before and after a single bout of resistance exercise (4 sets of 10 repetitions at 80% of 10-RM for both leg press and leg extensions). Immediately after resistance exercise, participants ingested intrinsically L-[5,5,5-2H3]leucine labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat) cooked in scrambled form.

Exogenous leucine appearance rates increased (P

<0.001) after protein ingestion with peak values of 513±57 nmol leucine·kg−1·min−1 occurring at 75 min after egg white ingestion compared with 496±38 nmol leucine·kg−1·min−1 at 120 min after whole egg ingestion.

The total amount of protein derived leucine that became available in circulation over the 300 min postprandial period was similar (P=0.53) between whole egg (75±2.3%) and egg white ingestion (77±1.7%).

Whole egg ingestion supported greater post-exercise myofibrillar protein synthesis rates when compared to egg white ingestion (0.034%/h and 0.024%/h respectively; P=0.02).

We conclude that whole egg ingestion stimulates the muscle protein synthetic response more effectively than the consumption of isonitrogenous amounts of egg whites during recovery from resistance exercise in healthy young men. This effect is not attributed to divergent postprandial protein-derived amino acid availability, suggesting that some intrinsic factor within whole eggs and/or the divergent macronutrient profile may have modified the anabolic potential of this complete protein.

PTH et catabolisme

20/04/2017 | Etudes sur les hormones et Etudes Perte de poids

 

Parathyroid hormone stimulates adipose tissue browning: a pathway to muscle wasting
Thomas, Sandhya         Current Opinion in Clinical Nutrition & Metabolic Care: May 2017 - Volume 20 - Issue 3 - p 153–157

Purpose of review: Studying organ-to-organ communications (i.e. crosstalk) uncovers mechanisms regulating metabolism in several tissues. What is missing is identification of mediators of different catabolic conditions contributing to losses of adipose and muscle tissues. Identifying mediators involved in organ-to-organ crosstalk could lead to innovative therapeutic strategies because several disorders such as chronic kidney disease (CKD), cancer cachexia, and other catabolic conditions share signals of worsening metabolism and increased risk of mortality.

Recent findings: A recent breakthrough published in Cell Metabolism leads to the conclusion that parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) cause ‘browning’ of white adipose tissue plus energy production via activation of uncoupling protein-1. Browning was associated with muscle wasting in mouse models of cancer and CKD. The pathway to browning includes PTH/PTHrP activation of protein kinase A (PKA) and lost muscle mass via the ubiquitin proteasome proteolytic system (UPS).

Summary: The results suggest that crosstalk between muscle and fat contributes in a major way to tissue catabolism. The pathway initiated by PTH or PTHrP is novel and it suggests potential interrelationships that control metabolism in other catabolic conditions. Identifying how the parathyroid hormone–PKA–UPS axis relates to obesity, type 2 diabetes, and other insulin-resistant conditions remains unclear.

Angiotensine et catabolisme

20/04/2017 | Etudes sur les hormones

 

Skeletal muscle wasting: new role of nonclassical reninangiotensin system
Cabello-Verrugio           Current Opinion in Clinical Nutrition & Metabolic Care: May 2017 - Volume 20 - Issue 3 - p 158–163

Purpose of review: Skeletal muscle can be affected by many physiological and pathological conditions that contribute to the development of muscle weakness, including skeletal muscle loss, inflammatory processes, or fibrosis. Therefore, research into therapeutic treatment alternatives or alleviation of these effects on skeletal muscle is of great importance.

Recent findings: Recent studies have shown that angiotensin (1–7) [Ang-(1–7)] – a vasoactive peptide of the nonclassical axis in the renin–angiotensin system (RAS) – and its Mas receptor are expressed in skeletal muscle. Ang-(1–7), through its Mas receptor, prevents or diminishes deleterious effects induced by skeletal muscle disease or injury. Specifically, the Ang-(1–7)–Mas receptor axis modulates molecular mechanisms involved in muscle mass regulation, such as the ubiquitin proteasome pathway, the insulin-like growth factor type 1/Akt (protein kinase B) pathway, or myonuclear apoptosis, and also inflammation and fibrosis pathways.

Summary: Although further research into this topic and the possible side effects of Ang-(1–7) is necessary, these findings are promising, and suggest that the Ang-(1–7)–Mas axis can be considered a possible therapeutic target for treating patients with muscular disorders.

Effets de l’énanthate de testostérone sur les reins

21/03/2017 | Etudes sur les hormones

 

Effets de l’énanthate de testostérone sur les reins de rats mâles Wistar soumis à un entraînement en résistance
S. Karbasia         Science & Sports Available online 17 March 2017

Les Stéroïdes Anabolisants Androgéniques (AAS) sont les produits dopants les plus utilisés dans le sport et sont susceptibles d’exercer des effets secondaires sur le rein. Le but de cette étude était de déterminer les effets d’une injection d’énanthate de testostérone (TE) lors d’un entrainement en résistance (RT) de 8 semaines chez des rats Wistar mâles.

Matériels et méthodes

Vingt-huit rats Wistar mâles ont été randomisés en en 4 groupes : C : contrôle, RT : exercice en résistance + placebo, TE : énanthate de testostérone, et l’association des deux (TE + RT). Le Protocole d’entrainement en résistance consiste en la montée d’une échelle (5 fois à 3 reprises) pendant huit semaines. Le TE et le placebo (20 mg/kg de poids corporel, en IM) ont été injectés deux fois par jour. A la fin, les rats ont été euthanasiés pour réaliser l’analyse biochimique du sérum et l’examen histopathologique du tissu rénal.

Résultats

Dans le groupe RT, une augmentation significative (p

< 0,05) de la créatinine sérique a été observée en comparaison avec les groupes TE et TE + RT. Une hyperémie modérée et une congestion du tissu ont été observées dans tous les groupes de traitement.

Conclusion

Nous ne mettons pas en évidence de détérioration de la filtration glomérulaire après 8 semaines de TE (20 mg/kg) mais d’autres études sont nécessaires pour préciser l’effet rénal de ce traitement.

Rôle de la sirtuine 1 dans l’hypertrophie

02/03/2017 | Etudes sur les hormones et Etudes Musculation et Etudes Anti-âge

 

SIRT1 may play a crucial role in overload induced hypertrophy of skeletal muscle
Erika Koltai J physiol 2017

Significant skeletal muscle mass guarantees functional wellbeing and is important for high level performance in many sports. Although the molecular mechanism for skeletal muscle hypertrophy has been well-studied, it still is not completely understood. In the present study, we used a functional overload model to induce plantaris muscle hypertrophy by surgically removing the soleus, and gastrocnemius muscles in rats. Two weeks of muscle ablation resulted in a 40% increase in muscle mass, which was associated with a significant increase in SIRT1 content and activity (P

< 0.001). SIRT1-regulated Akt, eNOS, GLUT4 levels were also induced in hypertrophied muscles, and SIRT1 levels correlated with muscle mass, paired box protein 7 (Pax7), proliferating cell nuclear antigen (PCNA) and nicotinamide phosphoribosyltransferase (Nampt) levels. Alternatively, decreased FOXO1 and increased K48 polyubiquitination also suggest that SIRT1 could also be involved in the catabolic process of hypertrophy. Furthermore, increased levels of K63 and muscle RING finger 2 (MuRF2) protein could also be important enhancers of muscle mass. We report here that the levels of miR1 and miR133a decrease in hypertrophy and negatively correlate with muscle mass, SIRT1, and Nampt levels. Our results reveal a strong agreement between SIRT1 levels and activity, SIRT1 regulated pathways, and overload-induced hypertrophy.

These findings, along with the well-known regulatory

roles that SIRT1 plays in modulating both anabolic and catabolic pathways, allow us to propose the hypothesis that SIRT1 may actually play a crucial causal role in overload induced hypertrophy of skeletal muscle. This hypothesis will now require rigorous direct and functional testing.

Le mystère des aliments riche en mélatonine

31/12/2016 | Etudes sur les hormones et Etudes Compléments alimentaires et Etudes Anti-âge

 

Are the proposed benefits of melatonin-rich foods too hard to swallow?
David J. Kennaway     Critical Reviews in Food Science and Nutrition   2016 Pages 958-962

Melatonin has been proposed as a potent anti-oxidant, and its presence in many plants and foods has been suggested to be beneficial for health. Indeed, the concentrations of melatonin in blood and the melatonin metabolite 6 sulphatoxymelatonin in urine have been found to increase significantly after ingestion of melatonin-rich foods. In this review, the studies have been critically evaluated in light of the reported plant melatonin concentrations and our knowledge of pharmacokinetics of orally administered pure melatonin. In the case of studies involving measurement of plasma melatonin following ingestion of beer or fruits, the reported increase in melatonin is not consistent with the amount of melatonin ingested. Similarly, the amount of melatonin metabolite excreted following ingestion of melatonin-rich foods greatly exceeded the amount of melatonin ingested.

It is concluded that studies reporting the appearance of melatonin in blood and its metabolites in urine following ingestion of melatonin-rich foods are flawed. While there may be health benefits for certain foods, it is difficult to accept that these are due to their low melatonin content.

 

Une blessure peut avoir des conséquences psychologiques graves

08/12/2016 | Echauffement et blessures

 

Are severe musculoskeletal injuries associated with symptoms of common mental disorders among male European professional footballers?
Knee Surgery, Sports Traumatology, Arthroscopy December 2016, Volume 24, Issue 12, pp 3934–3942   Vincent Gouttebarge

Purpose

To explore the associations of severe musculoskeletal injuries (joint and muscles) and surgeries with symptoms of common mental disorders (distress, anxiety/depression, sleeping disturbance, adverse alcohol behaviour , smoking, adverse nutrition behaviour) among male European professional footballers.

Methods

Cross-sectional analyses were conducted on electronic questionnaires completed by professional footballers recruited from the national players’ unions of Finland, France, Norway, Spain or Sweden. The number of severe (time loss of more than 28 days) musculoskeletal injuries (total, joint, muscle) and surgeries during a professional football career was examined through four questions, while symptoms of common mental disorders were evaluated through validated scales.

Results

A total of 540 professional footballers (mean age of 27 years; 54 % playing in the highest leagues) participated in the study. Sixty-eight per cent of the participants had already incurred one or more severe joint injuries and 60 % one or more severe muscle injuries. Prevalence of symptoms of common mental disorders ranged from 3 % for smoking to 37 % for anxiety/depression and 58 % for adverse nutrition behaviour. The number of severe musculoskeletal injuries during a football career was positively correlated with distress, anxiety and sleeping disturbance, while the number of surgeries was correlated with adverse alcohol behaviour and smoking. Professional footballers who had sustained one or more severe musculoskeletal injuries during their career were two to nearly four times more likely to report symptoms of common mental disorders than professional footballers who had not suffered from severe musculoskeletal injuries.

Conclusion

It can be concluded that the number of severe musculoskeletal injuries and surgeries during a career is positively correlated and associated with symptoms of common mental disorders among male European professional footballers. This study emphasises the importance of applying a multidisciplinary approach to the clinical care and support of professional footballers, especially when a player faces lengthy periods without training and competition as a consequence of recurrent severe joint or muscle injuries.

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