EFFECTS OF THE ASSOCIATION OF RESISTIVE EXERCISE AND STRETCHING ON THE RAT MUSCLE FIBER MORPHOLOGY

Karoline Secchi
Physical Therapy, Tuiuti University of Paran

Clodoaldo Morais
Physical Therapy, Tuiuti University of Paran?

Pamella Cimatti
Occupational Therapy, Tuiuti University of Paran?

Eunice Tokars
Physical Therapy, Tuiuti University of Paran?

Anna Raquel Gomes
Physical Therapy, Federal University of Paran

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     Last modified: February 24, 2007

Abstract
Objective: Evaluate the effect of the association of progressive loading exercise and stretching in the rat soleus muscle morphology. Material and Methods: It was used 23 male Wistar rats (38050g) divided into 4 groups: Control Group (CG) (n=3) intact control group; Stretch Group (SG) (n=6) the left ankle was held in full dorsal flexion by a piece of tape, for 40min, to stretch the left soleus muscle, twice a week for 8 weeks; Progressive Loading Exercise Group (PLEG) (n=6) the animals were trained in a progressive loading exercise carried out by fixing an additional load on the animal?s body. The protocol consisted by 4 bouts of 10 jumps, resting 60s between each bout, in a container filled with warm water, 3 times/week, for 8 weeks; Progressive Loading Exercise and Stretching group (PLESG) (n=6) the animals were submitted to both protocols PLE and Stretching. After 8 weeks all the animals were weighed and euthanasied to soleus muscle excision. It was evaluated the following variables: body and muscle weights, muscle length, serial sarcomere number, sarcomere length and cross-sectional area (CSA). It was observed an increase in the final body weight in the group PLESG when compared to the initial ones (37016g vs 32224g, p=0,007, paired t test). The muscle weight of the PLEG was superior (0,240,03g) than CG (0,180,02g, p=0,003, ANOVA), SG (0,190,01g, p=0,01, ANOVA) and PLESG (0,160,01g, p=0,0003, ANOVA). The left soleus length in the PLESG was inferior (16,21,47mm) when compared to CG (191,41mm, p=0,04, ANOVA), SG (19,91,2mm, p=0,005, ANOVA) and PLEG (21,82,4mm, p=0,0003, ANOVA). The group submitted to PLE showed an increase in the soleus length in comparison to the CG (21,82,4mm vs 191,41mm, p=0,05, ANOVA). The PLESG presented a decrease in the serial sarcomere number when compared to SG (p=0,002, ANOVA) and PLEG (p=0,001, ANOVA). It was observed an increase in the CSA of the SG (1896342?m2) when compared to the CG (1869163?m2, p=0,04, ANOVA). The sarcomere length did not change. Conclusions: The association of loading exercise and stretching did not prevent the gain of body weight. However, this combination decreased the muscle length and the serial sarcomere number that suggest lesion induced by the daily overloaded. The stretching protocol applied isolated was efficient to induce muscle hypertrophy.
Financial Support: Tuiuti University of Paran? and Evang?lica Faculty of Paran?.