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Abstract: The aim of this study was to determine the effects of a progressive loading exercise program on the bone and skeletal muscle properties of female osteopenic rats. Forty female Wistar rats (12 weeks old) were divided into four groups (n =10): sham-operated sedentary (SS); osteopenic-sedentary (OS); sham-operated training (ST) and osteopenic training (OT). Osteopenia was induced by ovariectomy (OVX). The exercise program was performed every 48h for 8 weeks and consisted of four bouts of 10 jumps. After 8 weeks, the animals were sacrificed and submitted to bone and muscle excision. The tibias were submitted to an evaluation of the physical properties and a biomechanical test. The soleus and tibialis anterior muscles were weighed and frozen for a cross-sectional area evaluation. Osteopenic sedentary animals showed a decrease in bone strength, weight and density. The OT group showed higher values for ash weights, bone mineral density and strength, as compared to the OS group. The soleus and tibialis anterior muscles of the OT group weighed more than those of the osteopenic sedentary and ST groups. Moreover the muscle weight showed a significant positive correlation to bone strength. The results of this study suggest that the exercise program had a stimulatory effect on the bone and muscle tissue of osteopenic rats, leading to the suggestion that muscle tissue hypertrophy could have a stimulatory effect on bone mass. [Copyright &y& Elsevier]

This study evaluated two different stretching protocols employed during a period of hind-limb immobilization in terms of their effects on muscle morphology. Quantitative data regarding the soleus muscle were obtained based on the clinical hypothesis that a high frequency of this exercise would improve the recovery of muscle structure. Twenty-four male Wistar rats were divided into four groups ( n = 6 each): the control group (C); the immobilized group, in which the left hind limb was immobilized in order to maintain the soleus muscle in a fully shortened position for 3 weeks (I); the ‘immobilized and stretched every 3 days’ group, in which the left hind limb was immobilized as in the immobilized group, but with the soleus muscle stretched every 3 days for 40 min (Ist3); and the ‘immobilized (as in the immobilized group) and stretched every 7 days’ group (ISt7). All soleus muscles were excised 21 days after the beginning of the experiment, and were processed for (1) haematoxylin and eosin and myosin ATPase to evaluate muscle morphology and cross-sectional area and the proportions of the different fibre types, and (2) ultrastructural analysis. The cross-sectional area was found to have decreased in all fibre types (I, II and C), mainly in ISt7, when compared with the C group and ISt3 group. The proportion of the different fibre types did not show statistical difference between groups. Light and electron microscopy examination revealed signs of cell degeneration that was more intense in the group immobilized and stretched three times a week. In conclusion, sessions of passive stretching applied to the soleus during immobilization induce muscle fibre injury, suggesting that this therapeutic tool should be applied carefully to disused muscles. [ABSTRACT FROM AUTHOR]

It has been shown that stretching exercises can improve the flexibility and independence of the elderly. However, although these exercises commonly constitute training programs, the morphological adaptations induced by stretching exercises in aged skeletal muscle are still unclear. Objective To assess the acute effects of passive mechanical static stretching on the morphology, sarcomerogenesis and modulation of important components of the extracellular matrix of the soleus muscle of aged female rats. Methods Fifteen old female rats with 26 months were divided into two groups: stretching ( n = 8, SG) and control ( n = 7, CG): The stretching protocol consisted of 4 repetitions each of 1 min with 30 s interval between sets. Stretching was performed on the left soleus muscle, 3 times a week for 1 week. After three sessions, the rats were anesthetized to remove the left soleus muscle, and then euthanized. The following analyses were carried out: muscle fiber cross-sectional area and serial sarcomere number; immunohistochemistry for the quantification of collagen I, III and TGFβ-1. Results a decrease in muscle fiber cross-sectional area of the SG was observed when compared to the CG ( p = 0.0001, Kruskal–Wallis); the percentage of type I collagen was significantly lower in the SG when compared to the CG ( p = 0.01, Kruskal–Wallis), as well as the percentage of TGFβ-1 ( p = 0.04, Kruskal–Wallis); collagen III was significantly higher in the SG than in the CG (7.06 ± 6.88% vs 4.92 ± 5.30%, p = 0.01, Kruskal–Wallis). Conclusion Although the acute stretching induced muscle hypotrophy, an antifibrotic action was detected. [ABSTRACT FROM AUTHOR]

• Gastrocnemius muscle thickness has correlation with calf circumference in older women. • Excess weight is a limitation condition when using gastrocnemius muscle thickness. • Gastrocnemius muscle thickness might be a complementary measure of calf circumference. Calf circumference (CC) is an indirect method used to evaluate muscle mass in older adults. Ultrasound has also been studied as a method for measuring muscle mass. Therefore, the aim of the present study was to correlate CC and muscle thickness of the medial gastrocnemius muscle (MGM) in healthy older women. A cross-sectional study was conducted with 74 healthy older women. The MGM thickness was evaluated using an ultrasound device (Logiq Book XP, General Electric®). The reference value for adequate CC was ≥ 31 cm. Weight and height were measured for the calculation of the body mass index (BMI), which was dichotomized as with or without excess weight based on the cutoff points recommended by the World Health Organization (1995) ; Lipschitz (1994) and the Pan-American Health Organization (2001). All participants were ≥ 64 years of age. Mean weight and height were 66.19 kg (SD: 10.48) and 1.55 m (SD: 0.06), respectively. Half of the participants had a BMI higher than 27.53 kg/m2. Moderate positive correlations were found between CC and MGM thickness (ρ = 0.432; p < 0.001), MGM thickness and weight (r = 0.422; p < 0.001) and between MGM thickness and BMI (r = 0.438; p < 0.001). However, the correlation between CC and MGM thickness was non-significant among the women with excess weight. A moderate positive correlation between MGM thickness and CC was found in healthy older women. However, this correlation was weak and non-significant among those with excess weight. [ABSTRACT FROM AUTHOR]