Eccentric exercise alters muscle sensory motor control through the release of inflammatory mediators

• Published in: Brain research 2004-10, Vol.1023 (2), p.222-230
• Main Authors: Marqueste, Tanguy, Decherchi, Patrick, Messan, Folly, Kipson, Nathalie, Grélot, Laurent, Jammes, Yves
• Format: Article
• Language: English
• Subjects: Animals; Anti-Inflammatory Agents; Anti-Inflammatory Agents - pharmacology; Arachidonic Acid; Arachidonic Acid - pharmacology; Betamethasone; Betamethasone - pharmacology; Biological and medical sciences; DOMS; Dose-Response Relationship, Drug; Downhill exercise; Electric Stimulation; Electric Stimulation - methods; Evoked Potentials, Motor; Evoked Potentials, Motor - drug effects; Evoked Potentials, Motor - physiology; Evoked Potentials, Motor - radiation effects; Female; Fundamental and applied biological sciences. Psychology; Group IV afferent; In Vitro Techniques; Inflammation Mediators; Inflammation Mediators - metabolism; Lactic Acid; Lactic Acid - pharmacology; Lengthening; Life Sciences; Muscle Contraction; Muscle Contraction - drug effects; Muscle Contraction - physiology; Muscle Fibers; Muscle Fibers, Skeletal - drug effects; Muscle Fibers, Skeletal - physiology; Muscle Fibers, Skeletal - radiation effects; Neurons and Cognition; Physical Conditioning, Animal; Pliometric; Potassium Chloride; Potassium Chloride - pharmacology; Rat; Rats; Rats, Sprague-Dawley; Striated muscle. Tendons; Time Factors; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 0006-8993; 1872-6240; 0006-8993
• DOI: 10.1016/j.brainres.2004.07.027

Following downhill exercise, muscle damage and local inflammatory reactions, induced by lengthening contractions, are observed and voluntary muscle activation decreases. The hypothesis that feedback carried by the group IV muscle afferents could be involved has often been raised but never measured in vivo in these conditions. In this experiment, we tested the response of the group IV muscle afferents from the lower limb to injections of KCl and lactic acid in non-exercising rats and at 1, 2, and 8 days after one running session (−13°, 16 m/min). At days 1 and 2, the baseline discharge of the group IV afferents increased, but further activation by test agents was absent. After 8 days, the afferent response was equivalent to the control response. Pretreatment with betamethasone before exercise abolished the effects of downhill exercise. In non-exercising rats, arachidonic acid evoked group IV afferent discharge and suppressed their further response to another stimulus. These results demonstrate that exhaustive downhill running highly activates, for at least 2 days, the sensory feedback carried by group IV afferents through the local release of inflammatory mediators. Such an altered sensori-motor control, accompanying the post-eccentric inflammatory syndrome, could play a key role in deterioration of muscle performance and of its voluntary activation.