A simple experimental protocol applying a quantitative ultrasound (QUS) pulse-echo technique was used to measure the acoustic parameters of healthy femoral diaphyses of Wistar rats in vivo. Five quantitative parameters [apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), time slope of apparent backscatter (TSAB), integrated reflection coefficient (IRC), and frequency slope of integrated reflection (FSIR)] were calculated using the echoes from cortical and trabecular bone in the femurs of 14 Wistar rats. Signal acquisition was performed three times in each rat, with the ultrasound signal acquired along the femur's central region from three positions 1 mm apart from each other. The parameters estimated for the three positions were averaged to represent the femur diaphysis. The results showed that AIB, FSAB, TSAB, and IRC values were statistically similar, but the FSIR values from Experiments 1 and 3 were different. Furthermore, Pearson's correlation coefficient showed, in general, strong correlations among the parameters. The proposed protocol and calculated parameters demonstrated the potential to characterize the femur diaphysis of rats in vivo. The results are relevant because rats have a bone structure very similar to humans, and thus are an important step toward preclinical trials and subsequent application of QUS in humans.

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Bone mineral density is an important parameter for the diagnosis of bone diseases, as well as for predicting fractures and treatment monitoring. Thus, the aim of the present study was to evaluate the potential of Quantitative Ultrasound (QUS) to monitor bone changes after calcium, phosphorus, and magnesium loss in rat femurs in vitro during a demineralization process. Four quantitative ultrasound parameters were estimated from bone surface echoes in eight femur diaphysis of rats. The echo signals were acquired during a decalcification process by Ethylenediaminetetraacetic Acid (EDTA). The results were compared to Quantitative Computed Tomography (QCT) and inductively coupled plasma optical emission spectrometry measurements for validation. Integrated Reflection Coefficient (IRC) reflection parameters and Frequency Slope of Reflection Transfer Function (FSRTF) during demineralization tended to decrease, while the backscattering parameter Apparent Integrated Backscatter (AIB) increased and Frequency Slope of Apparent Backscatter (FSAB) showed an oscillatory behavior with no defined trend. Results indicate a clear relation between demineralization and the corresponding decrease in the reflection parameters and increase in the scattering parameters. The trend analysis of the fall curve of the chemical elements showed a better relationship between IRC and QCT. It was possible to monitor bone changes after ions losses, through the QUS. Thus, it is an indication that the proposed protocol has potential to characterize bone tissue in animal models, providing consistent results towards standardization of bone characterization studies by QUS endorsing its use in humans.

The evaluation of the stretching effects through mean values of the entire sample can hide different adaptations between groups with distinct characteristics of joint flexibility. This study aimed to employ artificial neural networks to classify subjects according to their flexibility level and to investigate the effects of a 10-week stretching training. The stretching group (SG, n= 9) performed stretching exercises for triceps surae muscles 4-5 times a week over 10 weeks. Maximum dorsiflexion angle (MDA) and peak passive torque (PPT) data at pre-intervention were used in a k-means (k= 3) algorithm to group participants as flexible, intermediate or stiff. A feed-forward artificial neural network (multilayer perceptron) was trained using the pre-intervention dataset with the k-means labeled groups and classified the post-intervention data generated after the stretching protocol. MDA of SG increased significantly (p= 0.015) from 24.72±7.70 to 29.81±6.95°whereas PPT showed no significant differences. Following intervention, two subjects from the SG shifted from the intermediate to the flexible group, whereas one stiff subject changed to the intermediate group. The control group presented a random pattern of group change. This approach can aid future analysis of different adaptations to stretching programs.

The aim of this work was to characterize the periodicity of a commercial available trabecular bone phantom with ultrasound (US) backscattered signals. Three US frequencies were applied (1.0, 2.25 and 5.0 MHz), and spectral analysis methods were used to estimate the mean scatterer spacing (MSS) of 100 signals/sample from five different samples. The results showed that it is possible to estimate the medium periodicity (trabecular spacings varying from 1.5 to 2.5 mm), and at higher frequencies the average MSS decreased, which is expected because of a higher spatial resolution (identification of the trabecular thickness periodicity). MSS values are in agreement with intertrabecular distances declared by the product supplier.

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Purpose: The study aimed to identify the variables that differentiate judo athletes at national and regional levels. Multivariable analysis was applied to biomechanical, anthropometric, and Special Judo Fitness Test (SJFT) data. Method: Forty-two male judo athletes from 2 competitive groups (14 national and 28 state levels) performed the following measurements and tests: (1) skinfold thickness, (2) circumference, (3) bone width, (4) longitudinal length, (5) stabilometric tests, (6) dynamometric tests, and (7) SJFT. The variables with significant differences in the Wilcoxon rank-sum test were used in stepwise logistic regression to select those that better separate the groups. The authors considered models with a maximum of 3 variables to avoid overfitting. They used 7-fold cross validation to calculate optimism-corrected measures of model performance. Results: The 3 variables that best differentiated the groups were the epicondylar humerus width, the total number of throws on the SJFT, and the stabilometric mean velocity of the center of pressure in the mediolateral direction. The area under the receiver-operating-characteristic curve for the model (based on 7-fold cross validation) was 0.95. Conclusion: This study suggests that a reduced set of anthropometric, biomechanical, and SJFT variables can differentiate judo athlete’s levels.