Effects of eccentrically and concentrically biased training on mouse muscle phenotype

in Medicine & Science in Sports & Exercise (2013)

Introduction: The molecular adaptations specifically induced by different muscle contraction types have only been partially elucidated. We previously demonstrated that eccentric contractions in human ... [more ▼]

Introduction: The molecular adaptations specifically induced by different muscle contraction types have only been partially elucidated. We previously demonstrated that eccentric contractions in human quadriceps elicited proteome modifications that suggest a muscle fiber typology adaptation. We address this question in a more systematic way by examining here the effects of different running modes on the mouse muscle proteome and the muscle fiber typology. Methods: Male adult mice (C57BL6) were randomly divided into downhill running (DHR, quadricipital eccentrically biased contractions), uphill running (UHR, quadricipital concentrically biased contractions) and untrained control (CONT) groups. Running groups performed five training sessions on an inclined treadmill for 75 to 135 min/day and the quadriceps muscles were dissected 96hours after the last session. Muscle protein extracts of DHR and UHR groups (n=4/group) were subjected to a 2D-DIGE analysis coupled with mass spectrometry. The assessment of fiber type, size and number was performed on the rectus femoris of the three groups (n=6/group) using myosin heavy chain (MHC) immunohistochemistry. Results: In the proteomic analysis, eight spots identified as the fast MHC isoforms exhibited a lower abundance in DHR compared to UHR (p<0.05, t-test). In contrast, ATP synthase subunit α and tubulin β were more expressed in DHR (p<0.05). A significant higher proportion of type I and IIa fibers was found for DHR compared to UHR or CONT groups (p<0.05, one-way ANOVA). Conclusions: Our data suggest that the eccentrically biased contractions in mice induced specific adaptations in protein expression and muscle fiber composition which may reflect a more oxidative muscle phenotype. The differences in stress placed on the muscle between both trainings may be responsible for some unique adaptations resulting from the eccentrically biased training. [less ▲]

Return-To-Play criteria after hamstring injury: actual medicine practice in professional soccer

Poster (2013, April 25)

Exuberant inflammatory reaction after an infiltration of platelet-rich plasma (PRP)

in Abstract Book of the 3rd Congress of the ECOSEP (2013, April)

Background: PRP, obtained from centrifuged autologous blood, contains a large quantity of growth factors, which may enhance the tissue healing processes. Local infiltration of PRP represents a relatively ... [more ▼]

Background: PRP, obtained from centrifuged autologous blood, contains a large quantity of growth factors, which may enhance the tissue healing processes. Local infiltration of PRP represents a relatively new treatment for tendinopathies. To date, no side effects have been reported after infiltration of PRP to treat tendinopathy. Case report: A 35-year-old patient had a right upper patellar tendinopathy which was resistant to all conservative treatments for more than 6 months. The patient was a type 1 diabetic (well controlled). He had an intratendinous infiltration of 6 mL of PRP (8.105 platelets/mm3, almost no red or white blood cells) after disinfection but without local anaesthetic. Immediately following the infiltration, local cryotherapy was performed for 15 minutes. NSAIDs were avoided, but class-1 or -2 pain-killers were authorised if necessary. A standardised sub-maximal eccentric rehabilitation should have been started 1 week after. However, the patient experienced local swelling with erythema, increased heating and pain which appeared just underneath the patella, but without biological inflammatory syndrome. A great Doppler signal in a thicker patellar tendon was observed by US, but there was no sign of local infectious disease demonstrated by either CT or MRI. However, the local inflammation did not decrease after a progressive 3-week treatment of local cryotherapy, local and oral NSAIDs and colchicine 1 mg. Thus, an insidious infection was suspected, even though there was neither evidence of biological inflammatory syndrome nor sign of infectious lesion on imagery examination. An antibiotic therapy (rifampicine 600 mg + minocycline 100 mg) was initiated for 3 months. Finally, a 3-phase bone scintigraphy suggested the presence of a complex regional pain syndrome type 1 treated by a classical physical therapy and concomitant class-2 pain killers. The evolution was favourable after 6 months of symptomatic treatment, and the pain decreased to a level similar to that before the infiltration of PRP. Discussion/Conclusions: This case report draws attention to potential side effects that are linked to this new therapy by infiltration of platelet rich plasma in case of tendinopathy, in particular when used in patients with type 1 diabetes. Thus, the balance between benefits and risks must be carefully evaluated before using this treatment in patients with type 1 diabetes. Reference: Platelet-rich plasma application in the management of chronic tendinopathies. Acta Orthop Belg 2013; 79: 10-15. [less ▲]

Prévention des courbatures musculaires en pratique sportive

in Prévention des lésions musculo-squelettiques chez le sportif (2013)

L’exercice excentrique, lorsqu’il est réalisé de manière intense et/ou inhabituelle, est réputé être à l’origine de diverses sensations de courbatures d’apparition retardée. Ces douleurs musculaires ... [more ▼]

L’exercice excentrique, lorsqu’il est réalisé de manière intense et/ou inhabituelle, est réputé être à l’origine de diverses sensations de courbatures d’apparition retardée. Ces douleurs musculaires, appelées DOMS pour Delayed-Onset Muscle Soreness, s’accompagnent de déficits structuro-fonctionnels pouvant persister pendant plusieurs jours. Bien qu’il disparaisse spontanément après quelques jours de récupération, le phénomène des DOMS reste problématique chez le sportif en raison des conséquences néfastes associées : perturbation de l’entraînement sportif, diminution de la performance athlétique et majoration du risque de lésions véritables en cas de poursuite d’activités sportives. Il apparaît donc essentiel, pour un sportif soumis à un entraînement excentrique, d’échapper aux DOMS. La mise au point d’approches susceptibles de réduire les conséquences néfastes des DOMS a constitué un objectif prioritaire de nombreuses études. Ainsi, les premiers essais ont été basés sur des stratégies nutritionnelles ou pharmacologiques ainsi que sur des procédés cliniques. Bien que certains procédés tels que le massage ou les apports nutritionnels puissent influencer de manière positive l’un ou l’autre symptôme, ceux-ci ne semblent pas capables d’agir sur le phénomène des DOMS dans sa globalité. Actuellement, la seule démarche préventive réellement efficace reste la réalisation d’un entraînement excentrique à intensité sous-maximale progressivement intensifiées. [less ▲]

Application pratique du concept de charge de travail au sein d'un club de football professionnel

in Prévention des troubles musculo-squelettiques chez le sportif (2013)

Approche préventive de la lésion d'épaule chez le sportif

in Prévention des troubles musculo-squelettiques chez le sportif (2013)

Aspects spécifiques des démarches préventives chez le jeune sportif

in Prévention des troubles musculo-squelettiques chez le sportif (2013)

L'apport de l'analyse biomécanique 3-D dans les stratégies préventives à partir de 2 exemples

in Julia, M; Croisier, Jean-Louis; Perrey, S (Eds.) et al Prévention des troubles musculo-squelettiques chez le sportif (2013)

De nouveaux outils de mesure permettent de quantifier la cinématique et la dynamique articulaire fonctionnelle des athlètes (systèmes optoélectroniques 3D, plateforme de forces, électromyographie, …). Ces ... [more ▼]

De nouveaux outils de mesure permettent de quantifier la cinématique et la dynamique articulaire fonctionnelle des athlètes (systèmes optoélectroniques 3D, plateforme de forces, électromyographie, …). Ces données sont importantes dans le sens où elles donnent à l’équipe médicale et sportive des informations objectives sur le geste du sportif dans sa pratique réelle. Elles favorisent la compréhension et l’amélioration de la performance ainsi que la prévention lésionnelle et la détection de situations à risque. Dans le cadre d’un suivi longitudinal des sportifs, ces mesures sont intéressantes pour mettre en place des critères objectifs et spécifiques à l’athlète de retour sur le terrain après une blessure. Ce document a pour objectif de présenter les principaux outils disponibles dans les laboratoires de biomécanique et d’illustrer leurs utilisations à travers 2 exemples : l’influence de la raideur de l’épaule sur la mobilité de l’épaule et l’analyse cinématique du service au tennis. [less ▲]

Eccentric training improves tendon biomechanical properties: a rat model

in Journal of Orthopaedic Research (2013), 31(1), 119-124

Introduction: The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favourable, the biomechanical changes to the tissue are not yet clear. Even if the ... [more ▼]

Introduction: The treatment of choice for tendinopathies is eccentric reeducation. Although the clinical results appear favourable, the biomechanical changes to the tissue are not yet clear. Even if the mechanotransduction theory is commonly accepted, the physiology of tendons is not clearly understood. We aimed to better define the biomechanical and histological changes that affect healthy tendon after eccentric and concentric training. Materiel and Methods: This study compared the effects of 2 methods of training (eccentric (E) training and concentric (C) training) with untrained (U) rats. The animals were trained over a period of 5 weeks. The tricipital, patellar and Achilles tendons were removed, measured and a tensile test until failure was performed. A histological analysis (hematoxylin and eosin and Masson's trichrome stains) was also realized. Results: There was a significant increase in the rupture force of the patellar and tricipital tendons between the U and E groups. The tricipital tendons in the control group presented a significantly smaller cross-sectional area than the E- and C-trained groups, but none was constated between E and C groups. No significant difference was observed for the mechanical stress between the three groups for all three tendons. Histological studies demonstrated the development of a greater number of blood vessels and a larger quantity of collagen in the E group. Discussion and conclusion: The mechanical properties of tendons in rats improve after specific training, especially following eccentric training. Our results partly explained how mechanical loading, especially in eccentric mode, could improve the healing of tendon. [less ▲]

Prévention des troubles musculo-squelettiques chez le sportif

Book published by Sauramps Medical (2013)