Eccentric muscle contractions: risks and benefits

Eccentric contractions, characterized by the lengthening of the muscle-tendon complex, present several unique features compared with other types of contractions, which may lead to unique adaptations. Due to its specific physiological and mechanical properties, there is an increasing interest in employing eccentric muscle work for rehabilitation and clinical purposes. However, unaccustomed eccentric exercise is known to cause muscle damage and delayed pain, commonly defined as ‘‘Delayed-Onset Muscular Soreness’’ (DOMS). To date, the most useful preventive strategy to avoid these adverse effects consists of repeating sessions involving submaximal eccentric contractions which intensity is progressively increased over the training. Despite an increased number of investigations focusing on the eccentric contraction, a significant gap still remains in our understanding of the cellular and molecular mechanisms underlying the initial damage response and subsequent adaptations to eccentric exercise. Yet, unraveling the molecular basis of exercise-related muscle damage and soreness might help uncover the mechanistic basis of pathological conditions as myalgia or neuromuscular diseases. In addition, a better insight into the mechanisms governing eccentric training adaptations should provide invaluable information for designing therapeutic interventions and identifying potential therapeutic targets.La contraction musculaire excentrique se caractérise par le développement d'une tension musculaire associée à l'étirement concomitant du complexe musculo-tendineux. Ce mode de contraction présente un intérêt croissant dans de nombreux domaines tels que l’entraînement sportif, la médecine physique et la rééducation. De plus, certaines indications de l’entraînement en mode excentrique ont été posées chez des patients porteurs de maladies chroniques. Cependant, lorsqu’il est réalisé de manière intense et inhabituelle, l’exercice excentrique peut entraîner diverses altérations de l’ultrastructure musculaire qui se manifestent par une série de symptômes cliniques comme des douleurs musculaires d’apparition retardées (Delayed-Onset Muscle Soreness, DOMS) et une altération de la fonction musculaire. Malgré la littérature abondante consacrée à la description du phénomène des DOMS, aucune théorie cohérente n’est actuellement disponible pour expliquer la survenue différée des sensations douloureuses et des signes associés. De même, toujours à l’analyse de la littérature, on ne peut que constater l’absence de solution thérapeutique susceptible d’atténuer significativement l’intensité des DOMS et de leurs conséquences fonctionnelles associées à l’exception, paradoxalement, de l’exercice excentrique lui-même qui, lorsqu’il est proposé en conditions sous-maximales d’intensité progressivement croissante, semble constituer la seule prévention réellement efficace de l’apparition des DOMS. De même, si l’efficacité d’un entraînement spécifique dans la prévention des DOMS a été confirmée par de nombreux travaux, la nature de cet effet protecteur reste sujette à conjectures. Nous sommes néanmoins convaincus qu’une meilleure compréhension des réponses aiguës et/ou adaptatives à l’exercice excentrique contribuerait d’une part, à la mise au point d’interventions thérapeutiques efficaces et d’autre part, à élucider les évènements moléculaires impliqués dans des conditions pathologiques telles que les myalgies et certaines maladies neuromusculaires.Etude du déterminisme nerveux des changements de typologie des fibres musculaires après entraînement excentriqu

DOMS: treatment or prevention?

peer reviewedThe evidence of benefits from eccentric contraction provides compelling rationale for their inclusion in force training and in the reeducation of various locomotor pathologies (i.e., tendinopathies or muscular imbalance). However, intense or unusual eccentric exercise frequently leads to muscle damage associated with prolonged loss in muscle strength and range of motion, a dramatic increase in muscle proteins circulating in blood and the development of muscle soreness. These negative functional consequences, referred to as Delayed Onset Muscle Soreness (DOMS), often disturb the progress of training or reeducation programmes. In an attempt to attenuate signs and symptoms of DOMS, several approaches have been used prophylactically and/or therapeutically. This article focuses on some of the most commonly used modalities, including the nutritionnal and pharmacological strategies, clinical therapies and exercise. Despite a large number of studies, there is little evidence indicating any benefit at the perfomance level of these various approaches. Conversely, there is unequivocal evidence that a bout of eccentric exercise is followed by protection against skeletal muscle damage associated with a subsequent bout of potentially damaging exercise for several weeks to several months. To date, specific submaximal training appears the most efficient prophylactic measure and is recommended to alleviate the prejudiciable consequences associated with DOMS in the athletic or therapeutic programs. Despite the volume of data concerning this protective effect, often called the “repeated bout effect”, the underlying mechanisms of such an adaptation are not fully understood and a better knowledge of these adaptative mechanisms could provide better guidelines for prevention or treatment practice

Etude protéomique de la moelle épinière lombaire après un exercice eccentrique quadricipital

Role of nervous system in muscle typology remodeling induce by eccentric exercis