Prolonged bedrest and microgravity induce alterations to bone, leading to bone fragility and compromising the quality of life. In this study, we characterized the physicochemical changes, microstructure, and biomechanics of the femurs of female adult rats in response to hindlimb unloading for 21 days. Twenty 6-month-old Wistar female rats were distributed into control (CON) and hindlimb unloading (HLU) groups. Analysis the in vivo bone mineral density (BMD) by dual energy x-ray absorptiometry (DXA) from the femurs was performed at the beginning and end of the experiment; plasma levels of calcium, phosphorus, and alkaline phosphatase, tartrate-resistant acid phosphatase activity, assessed by spectrophotometry, and estradiol, measured by enzyme-linked immunosorbent assay, was performed after the experiment. We evaluated changes in the trabecular and cortical structure of the femur, after disuse, by micro-computed tomography with high resolution, for analysis of cortical porosity, Raman spectroscopy to measure the amount of physicochemical properties, and the biomechanical test to estimate the changes in biomechanical properties. Our results demonstrated that, after 21 days, HLU animals had decreased femoral BMD, deteriorated bone microarchitecture, particularly in the cortical compartment, with changes in the physicochemical properties and porosity, and reduced deformation capacity of the bone and resistance to the bone stresses. Nevertheless, this study showed the critical role of mechanical stimulation in maintaining the structure of the skeleton in female adults and that disuse, even for a few days, leads to microscopic changes in the structure of the bone matrix, which increases the risk of fracture.

The aim of the present study was to determine the modeling of muscle fibers in rats submitted to different exercise protocols. Fifty-five Wistar rats were submitted divided into four different groups: Control group (CG; N=16); endurance training group (ETG; N=13), strength training group (STG; N=13) and concurrent training group (CTG; N=13). The intensity of endurance training was determined by the critical workload. Statistical analysis involved the Kruskal-Wallis test for multiple comparisons, followed by Dunn's post test (p0.05) occurred in the STG and CTG at both four (mean:2952,95 ± 878,39 mean:2988,84 ± 822,58) and eight weeks respectively (mean:3020,26 ± 800.91; mean:3104,91 ± 817,87). The findings demonstrate similar results obtained with strength training and concurrent training, with a greater increase in muscle fiber area in both groups in comparison to the control group and group submitted to endurance training.

Right-sided heart failure has high morbidity and mortality, and may be caused by pulmonary arterial hypertension. Fractal dimension is a differentiated and innovative method used in histological evaluations that allows the characterization of irregular and complex structures and the quantification of structural tissue changes. To assess the use of fractal dimension in cardiomyocytes of rats with monocrotaline-induced pulmonary arterial hypertension, in addition to providing histological and functional analysis. Male Wistar rats were divided into 2 groups: control (C; n = 8) and monocrotaline-induced pulmonary arterial hypertension (M; n = 8). Five weeks after pulmonary arterial hypertension induction with monocrotaline, echocardiography was performed and the animals were euthanized. The heart was dissected, the ventricles weighed to assess anatomical parameters, and histological slides were prepared and stained with hematoxylin/eosin for fractal dimension analysis, performed using box-counting method. Data normality was tested (Shapiro-Wilk test), and the groups were compared with non-paired Student t test or Mann Whitney test (p < 0.05). Higher fractal dimension values were observed in group M as compared to group C (1.39 ± 0.05 vs. 1.37 ± 0.04; p < 0.05). Echocardiography showed lower pulmonary artery flow velocity, pulmonary acceleration time and ejection time values in group M, suggesting function worsening in those animals. The changes observed confirm pulmonary-arterial-hypertension-induced cardiac dysfunction, and point to fractal dimension as an effective method to evaluate cardiac morphological changes induced by ventricular dysfunction.

Background The SARS-CoV virus is a precursor to the SARS-CoV-2 virus (COVID-19) and has caused millions of deaths worldwide. Although exercise can be a non-pharmacological means for the prevention and treatment of various diseases, the effects on COVID-19 patients are not yet completely clear. Aims The aim of this study was to investigate the relationship between physical exercise and symptoms caused by COVID-19. Methods The present systematic review was sent for evaluation and received the PROSPERO registration protocol-CRD42021257475. The search for studies related to health and physical exercise was carried out in the following databases; the “National Library in Medicine MEDLINE–Ovid”, “Embase”, “Web of Science”, “SportDiscus-Ebsco”, and “Scopus”. Results Ten articles were included in the systematic review and the findings demonstrated the protective effects of physical exercise in patients with COVID-19. These effects were observed both in symptoms and in the period of hospitalization. In addition, the results show that the benefits of physical exercise seem to collaborate both in an individual manner and as an alternative to drug therapy. Finally, it was possible to verify the effect of physical exercise on variables, such as quality of life, cardiorespiratory capacity, and immunological biomarkers, and on the symptoms of the new Coronavirus. Conclusions It is possible to conclude that physical exercise can be a component for the treatment of COVID-19. In addition, it could help to reduce the symptoms and severity of COVID-19, and may be considered as an adjunct to drug therapy in patients contaminated with SARS-CoV-2.

Muscle injuries are common, and their treatment requires costs and time off. Platelet rich plasma and low level laser therapy have been shown to be affordable and easy to use. The aim of this study was to evaluate the associated effects of low level laser therapy and platelet rich plasma on the treatment of the soleus muscle injured by strain in rats. Thirty-five rats were randomly allocated into five groups: Control (C), Injury Control (IC), injury PRP (IP), injury LLLT (ILT) and injury LLLT and PRP (ILTP). The strain injury was induced in the soleus muscle and the IP group received application of platelet rich plasma immediately after the lesion, while the ILT group received low level laser therapy. After seven days, all animals were euthanized and the soleus muscle removed for further histological analysis. The association of both treatments (ILTP) resulted in better histological aspects than the low level laser therapy and platelet rich plasma alone, when compared with the injury group (IC). The collagen analysis exhibited a significant increase in the ILT group (2.99 SD=1.13) compared to the C (1.88 SD=0.41, p=0.012) and IP (2.04 SD=0.44, p=0.018). The association of low level laser therapy with platelet rich plasma produced better results on muscle injury compared to the isolated use of these therapies. Furthermore, none of the treatments could modulate the collagen deposition in relation to injury group.