No abstract

SUMMARY:The aim of this study was to analyze changes in the skeletal muscle tissue of rats after muscle stretch injury using fractal analysis. Nineteen rats were divided into three groups, Control (n= 5) (C), Lesion two days (n= 7) (L2), and Lesion seven days (n= 7) (L7). Histological slides of the gastrocnemius muscle of the animals were prepared and stained with Hematoxylin and eosin for analysis of the inflammatory process, and picrosirius for the demonstration of collagen. The stained slides were subsequently analyzed using Fractal Dimension (FD). The results showed high FD values of the inflammatory process in the experimental groups L2 and L7 in relation to C (p= 0.000). The analysis of collagen in the picrosirius stained slides showed high FD in the L2 group compared to the L7 (p= 0.0001), with no statistically significant difference among other groups. In summary, the present study demonstrated that fractal analysis was able to identify changes in the inflammatory process in injured skeletal muscle tissue.

Objectives: To evaluate alterations from different therapies in muscular injury using the Fractal Dimension (FD) method. Methods: 35 animals were allocated in Control Group (C), Injury Control Group (IC), Injury Low Level Laser Therapy Group (ILT), Injury Platelet Rich Plasma Group (IP), and Injury LLLT and PRP Group (ILP). The animals suffered a stretch injury in gastrocnemius muscle and after that IP and ILP groups received PRP application. The ILT and ILP groups received daily LLLT applications for seven days. After seven days the animals were euthanized and the gastrocnemius muscle removed and frozen. The muscles were stained with Hematoxylin and Eosin (HE) and Picrosirius Red, for observation of the morphology of the injury and semi-quantitative and quantitative analysis through the Fractal Dimension (FD) method. Results: In the qualitative and semi-quantitative analysis, in relation to IC group, the ILT presented a reduction in rounded fibers and the IP in angular fibers. The ILP group demonstrated a reduction in both polymorphic fibers and inflammatory infiltrate. The FD of the muscles stained with HE was higher in the groups that suffered the injury when compared to the C group (p < 0.05); the FD of the collagen demonstrated no statistical difference between the groups. Conclusion: Both treatments were able to accelerate injury repair, and the association of both presented better results than the isolated applications. However, the FD method showed no sensitivity to differentiate the treatments, either in the histological aspects or the injury in collagen.

Treatment of muscle injuries usually results in the interruption of sports practice; thus, studies aimed at accelerating the return to activity, with proper tissue repair, are important. Therefore, this study aimed to evaluate the effects of photobiomodulation (PBM), associated or not with platelet-rich plasma (PRP), on the treatment of muscle injury. Thirty-five animals were used and divided into five groups (n = 7): control (C), control lesion (CL), lesion treated with low-level laser therapy (LLLT) (LLt), lesion treated with PRP (LP), and lesion treated with both techniques, LLLT and PRP (LLtP). Muscle injury was induced by stretching the gastrocnemius muscle, and the animals in the LLtP and LP groups received the application of PRP immediately following the injury. The LLLT was applied daily for 7 days. The animals were euthanized 7 days after the injury. Analysis of the NADH/NAD ratio and collagen was performed by Raman spectroscopy; in addition to which, histological analysis of the gastrocnemius muscle was performed. The LLtP group demonstrated a reduction in the area of injury, regenerating cells and a healthy appearance of muscle fibers. The Raman analyses showed a reduction in the NADH/NAD ratio in the CL group, demonstrating oxidative stress, and the collagen presented a reduction in the CL and LLt groups, when compared with the C group. It is concluded that either PBM or PRP, and the association of both, was able to reduce the oxidative stress promoted by injury and modulate collagen production at the site of the injury. Furthermore, although both treatments individually were effective for repairing the damage caused by muscle injury, the association of both demonstrated a better histological aspect.

HighlightsLLLT and PRP can be used to enhance muscle regeneration.The association of LLLT with PRP produces better treatment than their use in isolation.LLLT could modulate the production of collagen during muscle injury.

The objective of this study was to investigate the alterations in morphology and aerobic resistance of rats subjected to different physical training protocols. The study consisted of 55 rats of the "Wistar" breed, 100 days of age, over a period of 8 weeks. The animals were randomly distributed between four groups: control (CTLE); neuromuscular anaerobic (TAN); aerobic (TAE) and concurrent training (TCc). After four weeks, some of the animals were euthanized. The body mass index (BMI), Lee index (Lee), epididymal adipose tissue (TecAdp), body weight, and feed efficiency ratio (CoefAlim) were measured. The Anaerobic Threshold was determined by critical workload (7 %, 9 % and 11 % of body weight). TAE and TCc training caused alterations in Lee and BMI, at four and eight weeks respectively (LeeTAE=X:2.86±0.08; X:2.89±0.07 and LeeTCc=X:2.85±0.05; X:3.00±0.09). For the TecAdp, all groups presented a decrease, with the TCc value down after eight weeks (X:1.77±0.32). Finally, TAN training improved the CoefAlim (X:31.57±3.70) after the eight week period and the TCc presented the highest value for Lan (X:7.10±0.80).

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.

SUMMARY:The aim of the present study was to observe the changes in the muscle tissue of rats after application of growth hormone (GH) and performing a strength training protocol (ST). In total, 40 male Wistar rats, 60 days old, were used, divided into four groups: control (C), control and application of GH (GHC), strength training (T), and strength training with the application of GH (GHT). The physical training protocol (PT) was composed of four series of 10 jumps in water, 3x/week, with an overload of 50 % of body weight for four weeks. GH was administered intraperitoneally at a dose of 0.2 IU/Kg to the GHC and GHT groups and saline (0.9 % sodium chloride) to the C and T groups. After four weeks of PT, the animals were euthanized and samples taken from the Soleus muscle. Histological sections were produced with a thickness of 5 mm and stained with hematoxylin-eosin (HE) and nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR). The markings for determining the measurement of the smallest diameter of muscle fibers (MF) were carried out using the software (AuxioVisionRel 4.8-Carl Zeiss ® and NIS-Elements D3.0-SP7-Nikon ® ). After obtaining the data, the Shapiro-Wilk test for normality was performed and then the nonparametric Kruskal-Wallis with Dunn post-test were used for analysis of MF and the Student t test for the analysis of intragroup body weights. All procedures adopted a 5 % significance value (p <0.05) and were performed using the software SPSS 22.0 for Windows ® . It was observed that both the GH and PT were able to generate increased diameter of MF (C:31.81±6.35; GHC:36.88±6.38; T:38.38± 6.94; GHT:36.89±7.16). Moreover, when analyzing the type, a significant increase was found only in the fast twitch MF (C:33.78±7.78; GHC:37.80±6.03; T:38.53±6.94; GHT:37.98±7.65) when compared to the slow twitch (C:25.93±6.66; GHC:26.95±8.03; T:26.24±6.90; GHT:27.20±5.77).