title: Effects of eccentric exercise in rehabilitation of phasic and tonic muscles after leg immobilization in rats.
abstract: Eccentric exercise is an essential resource for skeletal muscle rehabilitation following muscle disuse however, abnormalities linked to the tissue recuperation require further research. Our aim was analyze the adaptation ability of rehabilitated muscular tissue in rats during different periods of eccentric training after 10 days of limb immobilization. Twenty-seven Wistar rats were divided into six groups: immobilized 10 days, immobilized and eccentric trained for 10 days, immobilized and eccentric trained for 21 days, and three age-matched control groups. After sacrifice, soleus and plantaris muscles were frozen, cut and stained for general histology using hematoxylin and eosin and Gomori trichrome methods and immunohistochemical methods for fiber typing (mATPase, NADH2-TR), for capillaries (CD31) and intermediate filaments (desmin, vimentin) and high resolution microscopy of resin embedded material. Immobilization resulted in more intense morphological alterations in soleus muscles such as formation of target fibers, nuclear centralization, a reduction in the number of type I fibers, diameter of type I, IIA, IIAD fibers, and capillaries. After 10 days of eccentric training, increases in the nuclear centralization and the number of lobulated fibers were observed. This period was insufficient to reestablish the capillary/fiber (C/F) ratio and distribution of fiber types as that observed in the control group. However, 21 days of rehabilitation allowed the reversal of all morphological and quantitative abnormalities. For the plantaris muscles, 10-days of training restored their basic characteristics. Despite the fact that immobilization affected soleus and plantaris muscles, 10 days of eccentric training was insufficient to restore the morphological characteristics of soleus muscles, which was not the case observed in plantaris muscle.
authors: Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, School of Medicine of Ribeirão Preto, University of São Paulo, SP, Brazil. Electronic address: anabelle_cornachione@hotmail.com.
authors: Anabelle S
authors: AS
authors: Cornachione
authors: Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, School of Medicine of Ribeirão Preto, University of São Paulo, SP, Brazil.
authors: Letícia O
authors: LO
authors: Cação-Benedini
authors: Department of Pathology, School of Medicine of Ribeirão Preto, University of São Paulo, SP, Brazil.
authors: Deise Lucia
authors: DL
authors: Chesca
authors: Department of Social Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, SP, Brazil.
authors: Edson Z
authors: EZ
authors: Martinez
authors: Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, School of Medicine of Ribeirão Preto, University of São Paulo, SP, Brazil. Electronic address: acms@fmrp.usp.br.
authors: Ana Claudia
authors: AC
authors: Mattiello-Sverzut
mesh_terms: D000818:Animals; D007103:Immobilization; D007150:Immunohistochemistry; D035002:Lower Extremity / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D009133:Muscular Atrophy / Q000503:physiopathology*; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical / Q000502:physiology
keywords: Eccentric training; Immobilization; Rats; Rehabilitation; Skeletal muscle