The effects of acute alcohol consumption on recovery from a simulated rugby match
Journal of Sports Sciences Volume 30, Issue 3, 2012

In this study, we investigated the effects of acute post-exercise alcohol consumption on measures of physical performance, creatine kinase, and immunoendocrine function in the 48 h following a rugby game simulation. Ten male senior rugby union players completed a rugby game simulation after which they consumed either 1 g of alcohol per kilogram of body mass or a non-alcoholic control beverage. Agility, 15 m sprint, countermovement jump, and srummaging performance were assessed pre-simulation and 24 and 48 h post-simulation. White blood cell count, testosterone, cortisol, and creatine kinase were measured before the simulation and 30 min, 12, 24, 36, and 48 h after the simulation. One week after the first trial, participants completed the second simulation after which the other beverage was consumed. The acute consumption of alcohol after a rugby game simulation negatively affected countermovement jump performance in the days following the simulation (P = 0.028). No differences between treatments were observed for the other criterion measures made in this study. In conclusion, after 80 min of a simulated rugby game, the consumption of 1 g of alcohol per kg body mass negatively impacts lower body vertical power output. However, performance of tasks requiring repeated maximal muscular effort is not affected.

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Aim:
Sprint exercise is characterized by repeated sessions of brief intermittent exercise at a high relative workload. However, little is known about the effect on mTOR pathway, an important link in regulation of muscle protein synthesis. An earlier training study showed a greater increase in muscle fibre cross sectional area in females than males. Therefore, we tested the hypothesis that activation of mTOR signalling is more pronounced in females than in males. Healthy males (n=9) and females (n=8) performed three bouts of 30-s sprint exercise with 20 min rest between.
Methods:
Multiple blood samples were collected over time and muscle biopsy specimens were obtained at rest and 140 min after the last sprint.
Results:
Serum insulin increased by sprint exercise and more so in females than in males (gender (g) x time (t):P=0.04. In skeletal muscle, phosphorylation of Akt increased by 50% (t, P=0.001) and mTOR by 120% (t, P=0.002) independent of gender. The elevation in p70S6k phosphorylation was larger in females (g x t, P=0.03) and averaged 230% (P=0.006) as compared to 60% in males (P=0.04). Phosphorylation rpS6 increased by 660% over time independent of gender (t, P=0.003). Increase in phosphorylation of p70S6k was directly related to increase in serum insulin (r=0.68, P=0.004).
Conclusion:
It is concluded that repeated 30-s all out bouts of sprint exercise separated by 20 min of rest, increases Akt/mTOR signalling in skeletal muscle. Secondly, signalling downstream of mTOR was stronger in females than in males after sprint exercise indicated by increased phosphorylation of p70S6k.

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Science & Sports 2012

Objectif
Cette étude se propose de comparer les effets de l’intensité de l’exercice sur les réponses de variabilité de la fréquence cardiaque (VFC) postexercice.

Méthode
Dix hommes sains familiarisés avec les exercices de musculation de type résistance, ont volontairement réalisé une séance de musculation de dix ateliers, un test progressif intermittent (30-15IFT) et un exercice continu à une intensité sous-maximale correspondant à 45 % de la vitesse finale atteinte au cours du 30-15IFT (45 %VIFT). La réponse du système nerveux autonome (SNA) a été déterminée à partir de l’analyse de la VFC et des indices de réactivation parasympathique mesurés au cours des dix premières minutes de récupération à la suite de chaque exercice.

Résultats
Les indices du domaine temporel de la VFC sont moins élevés à la suite du 30-15IFT et de la séance de musculation qu’à la suite de l’exercice sous-maximal (déviation standard des intervalles R-R (SDNN) : 32,0 ± 15,4, 11,0 ± 3,7, 45,5 ± 15,3, P < 0,05 ; racine carrée des différences au carré des intervalles R-R successifs (RMSSD) : 17,0 ± 8,3, 5,6 ± 2,7, 30,0 ± 11,0, P < 0,05, respectivement). L’analyse spectrale observe une réponse identique à celle des indices du domaine temporel (bande de basses fréquences (LF) : 5,5 ± 1,0, 3,1 ± 0,9, 6,1 ± 0,9, P < 0,05 ; bande de hautes fréquences (HF) : 4,0 ± 1,0, 1,0 ± 0,7, 4,5 ± 0,9, P < 0,05 ; et (LF + HF) : 5,7 ± 1,1, 3,2 ± 0,8, 6,3 ± 0,9, P < 0,05, respectivement). Si l’indice de réactivation parasympathique (T30) n’est pas significativement différent à la suite du 30-15IFT et de la séance de musculation (P > 0,05), T30 est significativement plus important après l’exercice d’intensité sous-maximale (P < 0,05).

Conclusion
Nos résultats montrent une réponse plus lente du SNA à la suite d’une séance de musculation par rapport à un exercice d’aérobie.

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Après, tu passes à la muscu, et tu te fais mal partout

Expression of extracellular matrix components and related growth factors in human tendon and muscle after acute exercise
K. M. Heinemeier, S. S. Bjerrum, P. Schjerling, M. Kjaer
Scandinavian Journal of Medicine & Science in Sports Early View

Acute kicking exercise induces collagen synthesis in both tendon and muscle in humans, but it is not known if this relates to increased collagen transcription and if other matrix genes are regulated. Young men performed 1 h of one-leg kicking at 67% of max workload. Biopsies were taken from the patellar tendon and vastus lateralis muscle of each leg at 2 (n = 10), 6 (n = 11), or 26 h (n = 10) after exercise. Levels of messenger ribonucleic acid mRNA for collagens, noncollagenous matrix proteins, and growth factors were measured with real-time reverse transcription polymerase chain reaction. In tendon, gene expression was unchanged except for a decrease in insulin-like growth factor-IEa (IGF-IEa; P < 0.05). In muscle, collagen expression was not significantly altered, while levels of connective tissue growth factor (CTGF), IGF-IEa, transforming growth factor-β1, -2 (TGF-β), and the TGF-β receptor II mRNA were increased (P < 0.05). Matrix components tenascin-C, fibronectin, and decorin were also induced in loaded muscle (P < 0.05), while fibromodulin was unaffected. In conclusion, the relatively robust changes in matrix components and related growth factors in muscle indicate a stimulation of extracellular matrix even with moderate exercise. However, in tendon tissue, this exercise model does not appear to induce any anabolic response on the transcriptional level.

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Exploration détaillée des composantes de la glycorégulation chez des sportifs sujets aux hypoglycémies d’effort. Intérêt de l’oral minimal model
J.-F. Brun   Science & Sports Volume 26, Issue 5, November 2011, Pages 286-291

Les hypoglycémies à l’exercice (HE) sont une situation très fréquente mais peu étudiée. Elles surviennent chez des sujets présentant des valeurs élevées d’insulino-sensibilité (SI) et d’efficience glucidique (SG). SI et SG peuvent être calculées à partir de repas-tests par une modélisation mathématique qui permet aussi une étude approfondie des composantes de la sécrétion d’insuline.

Méthodes et résultats
Nous avons étudié les résultats fournis par cette méthode chez 19 sportifs se plaignant d’HE comparés à 58 sportifs appariés ne présentant pas ce problème. On observe des valeurs plus élevées de SI (p < 0,05) et SG (p

Conclusion
Ainsi, ces sujets ont une assimilation glucidique massive, leur sécrétion d’insuline se réduisant de façon compensatoire mais cette réduction a des limites et peut s’avérer insuffisante, notamment en ce qui concerne la sensibilité β-pancréatique au glucose.

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Muscle fatigue induced by two different resistances: Elastic tubing versus weight machines
Journal of Electromyography and Kinesiology Volume 21, Issue 6, December 2011, Pages 954-959   G. Melchiorri

Elastic tubes are devices relatively inexpensive, easy to use, portable and safe, which are claimed to provide advantages with respect to training with free weights or weight machine. The aim of this work was to assess neuromuscular modification induced by the use of two different muscle contraction modalities (elastic versus weight resistances) until exhaustion. Fourteen healthy physically active male students (age: 28 ± 6 years; body mass 72.1 ± 11.0 kg; height: 173.5 ± 6.9 cm) were recruited. They were requested to reach exhaustion with dynamic contraction at 70% of their own One Repetition Maximal (1RM) using, in two different days and in random order, Thera Band® tubes or traditional weight plates on an arm machine designed and built for those tasks. Before and after such contractions a standardized fatiguing isometric test (3 Maximal Voluntary Contractions, MVC plus 60 s at 60% MVC) was requested to assess differences induced by the exhaustion sessions. During fatiguing tests surface EMG signals were recorded from biceps brachii muscle with linear arrays of eight electrodes (silver bars 10 mm apart, 5 mm long, and 1 mm diameter) in single differential configuration. Initial values and rates of change of Average Rectified Value (ARV), MeaN power Frequency (MNF) and muscle fiber Conduction Velocity (CV) were calculated to compare the effects of the two contraction modalities. No differences were found between “elastic session” and “weight session” PRE MVCs (31.9 ± 8.8 and 29.9 ± 8.3 nm, respectively) and endurance times (28 ± 6 and 26 ± 7 s, respectively). The same was observed for POST values. During the post-contraction isometric fatigue test, the only parameters influenced by the contraction modality were the initial CV and the rate of change in CV which were 12% and 37% greater (p

These findings confirm others for which contractions done with the use of elastic band seem to require greater muscle activation; moreover, they highlight a sort of “muscle conditioning” after that specific contraction modality which requires the use of faster motor units. It is thus possible to consider the practical use of such elastic devices to increase the neuromuscular activation, for instance in specific rehabilitation settings where slow movements with minimal risk of injury are requested (post surgery rehabilitation, physical activity with elderly people or children).

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