Propriedades mecânicas do músculo de ratos adultos e idosos, exercitado pós-imobilização

Abstract

ObjectivesTo describe the effects of immobilization, free remobilization and remobilization by physical exercise about mechanical properties of skeletal muscle of rats of two age groups.Methods56 Wistar rats divided into two groups according to age, an adult group (five months) and an older group (15 months). These groups were subdivided in: control, immobilized, free remobilized and remobilized by physical exercise. The pelvic limb of rats was immobilized for seven days. The exercise protocol consisted of five swimming sessions, once per day and 25 minutes per session. The gastrocnemius muscle was subjected to tensile tests, and evaluated the properties: load at the maximum limit, stretching at the maximum limit and stiffness.ResultsThe immobilization reduced the values of load at the maximum limit and the remobilization protocols were not sufficient to restore control levels in adult group and older rats. The stretching at the maximum limit differs only in the older group.ConclusionsThe immobilization reduces the muscle's ability to bear loads and exercise protocol tends to restore the default at control values in adult and older rats. The age factor only interfered in the stretching at the maximum limit, inducing a reduction of this property in the post-immobilization. Level of Evidence II, Investigating the Results of Treatment.

Supplement with Cystoseira canariensis promotes an increase of resistance to the maximum load in the grastrocnemius muscle of female rats

“…This result is a positive indication of the action of Cystoseira canariensis on the muscle, once higher values were also observed for the maximum load in these muscles, making them more resistant to lesion and/or rupture. This resistance has been observed by other authors by other authors, and it indicates that the traction trial is a form of analysis to preserve the physiological aspects of the muscle 24,33,34 . The fact that the gastrocnemius muscle of animals who received Cystoseira canariensis presented better results for the studied mechanical properties indicates a possible change in the structure of this muscle among female rats, which could not be confirmed due to the lack of histological analysis -a limitation of this study.…”

“…For each load increase applied to the muscle, there was a resulting stretching value, which enabled the construction of graphics showing load versus stretching, by using the software Microsoft Excel Xp Professional ® . Afterwards, the following mechanical properties were analyzed: load at maximum limit; stretching at maximum limit; and rigidity [21][22][23][24] .…”

The development of a mechanical device to stretch skeletal muscle of young and old rats

“…These authors reported that the soleus of aged rats demonstrated a decline in passive muscle resistive force compared with the soleus of young rats 33. Kodama et al 15 also observed a decrease in the passive resistive force of the gastrocnemius muscle of aged rats (15 months) submitted to traction tests compared with the gastrocnemius muscle of young rats. These results corroborate the findings presented in the current paper.…”

“…The device was tested to mechanically stretch the soleus muscle of young and aged rats. Thus, twelve female Wistar rats ( Rattus norvegicus albinus ) were used and divided into two groups: a young group (YG, n=6) of 3-month-old animals and an aged group (AG, n=6) of 15-month-old animals 15-17. The project followed the international ethics standard for animal experiments 18 and was approved by the Ethics Committee on Animal Use of the Pontifical Catholic University of Paraná (PUCPR) (PROTOCOL n° 732/2012).…”

Collagen I and III Ratios and Tenacity of Rats’ Muscle Injured and Treated with Platelet-Rich Plasma

“…The test was conducted at a speed of 10 mm/ minute and the load applied was registered by the software until the moment of muscle break, the break was considered when there was a 70 % load drop in 10 mm of stretching. The steps followed for the mechanical test were adapted from the study of Kodama et al (2012).…”