Effects of Functional Training and Calf Stretching on Risk of Falls in Older People: A Pilot Study.

This study aimed to determine the effects of a functional training and ankle stretching program in triceps surae torque, passive stiffness index, and in the risk for fall indicators in older adults. Twenty women (73.4 ± 7.3 years) were allocated into an intervention or control group. The 12-week intervention consisted of functional training and calf stretching exercises performed twice a week. Measurements of peak passive and active torque, passive stiffness, maximum dorsiflexion angle, and indexes of risk for falls (Timed Up and Go, functional reach test, QuickScreen-test) were collected. There were no significant differences for all variables, except the maximum dorsiflexion angle, which increased in the intervention group from 33.78 ± 8.57° to 38.89 ± 7.52°. The exercise program was not sufficient to enhance performance on functional tests and decrease the risk for falls in older adults. The significant increase in the maximum dorsiflexion indicates a positive impact of stretching exercises.

Ultrasound biomicroscopy and claudication test for in vivo follow-up of muscle repair enhancement based on platelet-rich plasma therapy in a rat model of gastrocnemius laceration.

PURPOSE: To track the regeneration process of lateral gastrocnemius due to a muscle laceration in rats, and to treatment with plateletrich plasma (PRP). METHODS: Ultrasound (40 MHz) images were used for measuring pennation angle (PA), muscle thickness (MT) and mean pixel intensity, along with claudication scores, of treated (PRPG) and non-treated (NTG) groups of rats. RESULTS: NTG showed a PA increase for the non-injured leg (p<0.05) and a tendency of MT to increase, whereas for PRPG there were no differences. There was a progressive reduction of the claudication score for the PRPG group throughout the entire period, with an immediate difference after seven days (p<0.05), whereas the NTG had a significant reduction only at day 28 (p<0.05). CONCLUSION: It was observed a compensatory hypertrophic response due to the overload condition imposed to healthy leg for NTG that did not occur in PRPG, suggesting an accelerated repair process of the injured leg due to treatment, anticipating its use.

In vivo passive mechanical properties estimation of Achilles tendon using ultrasound.

A methodology is proposed for estimating Achilles tendon tangent modulus in vivo, to account for its large deformations and non-linear behavior. True stress is found dividing the axial force by the tendon true cross-sectional area (CSA), whose shrinking caused by axial tension is estimated with Poisson׳s coefficient. The true strain is calculated as the integral of incremental deformations along the tendon length change. Triceps surae tendon CSA and ankle moment arm, with the foot at relaxed equilibrium position, are estimated from subject-personalized data. Healthy males (N=19) volunteered for the study. The test consisted of passive ankle mobilization at the dynamometer with 5°/s velocity, from 30° of plantar flexion to the limit of dorsiflexion. Ultrasound was used to track myotendinous junction (MTJ) and tendon elongation, with the probe oriented over the medial gastrocnemius. Non-linear tendon stiffness pattern was observed during the joint range of motion, reaching 200N/mm peaks for the subjects with greater amplitudes of maximum dorsiflexion. The maximum values of modulus of elasticity, calculated from usual engineering stress and strain, (188.56±99.19MPa) were smaller than those reported in the literature for active maximum voluntary contractions tests. Maximum values for tangent modulus from true stress and strain were 312.38±171.95MPa. Such differences are likely to increase in large deformations.

Ultrasound biomicroscopy and claudication test for in vivo follow-up of muscle repair enhancement based on platelet-rich plasma therapy in a rat model of gastrocnemius laceration

PURPOSE: To track the regeneration process of lateral gastrocnemius due to a muscle laceration in rats, and to treatment with plateletrich plasma (PRP). METHODS: Ultrasound (40 MHz) images were used for measuring pennation angle (PA), muscle thickness (MT) and mean pixel intensity, along with claudication scores, of treated (PRPG) and non-treated (NTG) groups of rats. RESULTS: NTG showed a PA increase for the non-injured leg (p<0.05) and a tendency of MT to increase, whereas for PRPG there were no differences. There was a progressive reduction of the claudication score for the PRPG group throughout the entire period, with an immediate difference after seven days (p<0.05), whereas the NTG had a significant reduction only at day 28 (p<0.05). CONCLUSION: It was observed a compensatory hypertrophic response due to the overload condition imposed to healthy leg for NTG that did not occur in PRPG, suggesting an accelerated repair process of the injured leg due to treatment, anticipating its use.

Reliability of measurements of rat lateral gastrocnemius architectural parameters obtained from ultrasound biomicroscopic images.

This study used ultrasound biomicroscopy (UBM) to quantify the pennation angle (PA) and muscle thickness (MT) of rat skeletal muscle and evaluated the reliability and reproducibility of the method by statistical analysis, determining the coefficient of variation (CV), intraclass correlation coefficient (ICC) and typical error of measurement. A UBM system with a center frequency of 40 MHz was used to acquire images of the right lateral gastrocnemius of ten male Wistar rats on two different days and with two ankle positions (90° or 150°). Two independent measurements of the PA and MT were randomly performed in each of three picture frames. The analysis resulted in CVs of 10.47% and 4.81% for the PA and the MT, respectively, for the ankle at 90° and 9.24% and 5.98% for the ankle at 150°. Additionally, the ICC values ranged from 0.75 to 0.92 for the PA and 0.57 to 0.99 for the MT. Statistically significant differences between the ankle positions were observed for the PA (p = 0.00013). The reliability of the PA and MT measurements for the rat right lateral gastrocnemius, determined from the ultrasound biomicroscopy images, was high (>0.90) for the methodology proposed. This finding indicates the potential of ultrasound biomicroscopy for quantitative muscle characterization and the longitudinal examination of tissue adaptation to different conditions of use, disease and rehabilitation.

Structural adaptations of rat lateral gastrocnemius muscle-tendon complex to a chronic stretching program and their quantification based on ultrasound biomicroscopy and optical microscopic images.

BACKGROUND: A chronic regimen of flexibility training can increase range of motion, with the increase mechanisms believed to be a change in the muscle material properties or in the neural components associated with this type of training. METHODS: This study followed chronic structural adaptations of lateral gastrocnemius muscle of rats submitted to stretching training (3 times a week during 8weeks), based on muscle architecture measurements including pennation angle, muscle thickness and tendon length obtained from ultrasound biomicroscopic images, in vivo. Fiber length and sarcomere number per 100µm were determined in 3 fibers of each muscle (ex vivo and in vitro, respectively), using conventional optical microscopy. FINDINGS: Stretching training resulted in a significant pennation angle reduction of the stretched leg after 12 sessions (25%, P=0.002 to 0.024). Muscle thickness and tendon length presented no significant changes. Fiber length presented a significant increase for the stretched leg (8.5%, P=0.00006), with the simultaneous increase in sarcomere length (5%, P=0.041) since the stretched muscles presented less sarcomeres per 100µm. INTERPRETATION: A stretching protocol with characteristics similar to those applied in humans was sufficient to modify muscle architecture of rats with absence of a sarcomerogenesis process. The results indicate that structural adaptations take place in skeletal muscle tissue submitted to moderate-intensity stretching training.

Confiabilidade de medidas de arquitetura muscular do tríceps sural por ultrassonografia de imagem / Reliability of triceps surae muscle architecture measurements obtained with sonographic imaging

Há, atualmente, na literatura, poucas pesquisas de confiabilidade e validação da quantificação de parâmetros de arquitetura muscular por ultrassonografia (US), relatando informações importantes como o erro típico da medida (ETM) e o coeficiente de correlação intraclasse (ICC). O objetivo do estudo foi aplicar a técnica de US para quantificar as medidas de comprimento da fibra (CF) e ângulo de penação (AP) dos músculos gastrocnêmios e determinar a confiabilidade e a reprodutibilidade dessas medidas. Duas imagens de cada gastrocnêmio de 19 indivíduos jovens e saudáveis foram adquiridas com um equipamento de ultrassom modo-B (7,5MHz), em duas visitas. CF e AP foram medidos cinco vezes nas duas imagens de cada indivíduo, totalizando vinte medidas de cada parâmetro para cada participante. A confiabilidade do total das 760 medidas foi determinada através do coeficiente de variação (CV), ICC e ETM. O CV do CF variou de 1,67 a 4,44 por cento e do AP de 3,8 a 11,62 por cento. Todos os ICC se encontram no intervalo de grande confiabilidade, com exceção do valor referente à medida interdias do AP do gastrocnêmio medial (0,67). Os dois valores mais altos de ETM (3,1º e 3,7º) correspondem aos dois valores inferiores do ICC (0,67 e 0,83), referentes às medidas repetidas interdias dos gastrocnêmios. As medidas de CF dos gastrocnêmios medial e lateral apresentaram ETM de 2,17mm e 2,25mm, respectivamente. Os resultados obtidos demonstraram que a metodologia utilizada para medição de CF e AP realizada em imagens de ultrassom apresentou alta confiabilidade.

There are few studies in the literature concerning the reliability and validity of the quantification of muscle architecture parameters using ultrasound that also report important information such as typical error of measurement (TEM) and intraclass correlation coefficient (ICC). The aim of this study was to use ultrasound imaging to quantify fiber length (FL) and pennation angle (PA) of the gastrocnemius muscle and to determine the reliability and reproducibility of these measurements. Two images of each gastrocnemius of 19 young healthy subjects were acquired using ultrasound equipment (7.5 MHz), in two visits. FL and PA were measured five times on each image, for a total of twenty measurements of each parameter. The overall reliability of the 760 measurements was determined through coefficients of variation (CV), ICC and TEM. The CV of FL ranged from 1.67 to 4.44 percent and from 3.8 to 11.62 percent for the PA. All ICC were within the high reliability range, with the exception of the between-visits PA value of the medial gastrocnemius (0.67). The two highest TEM values (3.1º and 3.7º) correspond to the two lowest ICC values (0.67 and 0.83), referring to repeated between-visit measurements of the medial and lateral gastrocnemius. FL measurements of the medial and lateral gastrocnemius had a TEM of 2.17 and 2.25 respectively. The results showed that ultrasound-based measurement of FL and PA exhibits high reliability.