Vanessa Lara Araújo

Myofascial force transmission between the latissimus dorsi and gluteus maximus muscles: An in vivo experiment

There are extensive connections between the latissimus dorsi (LD) and gluteus maximus (GMax) muscles and the thoracolumbar fascia (TLF), which suggests a possible pathway for myofascial force transmission. The present study was designed to provide empirical evidence of myofascial force transmission from LD to contralateral GMax through TFL in vivo. To accomplish this goal, we evaluated whether active or passive tensioning of the LD results in increased passive tension of the contralateral GMax, indexed by changes in the hip resting position (RP) or passive stiffness. The hip RP was defined as the angular position in which the passive joint torque equals zero, and passive hip stiffness was calculated as the change in passive torque per change in joint angle. Thirty-seven subjects underwent an assessment of their passive hip torque against medial rotation by means of an isokinetic dynamometer. These measures were carried out under three test conditions: (1) control, (2) passive LD tensioning and (3) active LD tensioning. Electromyography was used to monitor the activity of the hip muscles and the LD under all conditions. Repeated measures analyses of variance demonstrated that passive LD tensioning shifted the hip RP towards lateral rotation (p=0.009) but did not change the passive hip stiffness (p>0.05). Active LD tensioning shifted the hip RP towards lateral rotation (p<0.001) and increased the passive hip stiffness (p≤0.004). The results demonstrated that manipulation of the LD tension modified the passive hip variables, providing evidence of myofascial force transmission in vivo.

Biomechanical and Physiological Evaluation of Multi-Joint Assistance With Soft Exosuits

To understand the effects of soft exosuits on human loaded walking, we developed a reconfigurable multi-joint actuation platform that can provide synchronized forces to the ankle and hip joints. Two different assistive strategies were evaluated on eight subjects walking on a treadmill at a speed of 1.25 m/s with a 23.8 kg backpack: 1) hip extension assistance and 2) multi-joint assistance (hip extension, ankle plantarflexion and hip flexion). Results show that the exosuit introduces minimum changes to kinematics and reduces biological joint moments. A reduction trend in muscular activity was observed for both conditions. On average, the exosuit reduced the metabolic cost of walking by

A soft exosuit for patients with stroke: Feasibility study with a mobile off-board actuation unit

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Relationship between joint passive stiffness and hip lateral rotator concentric torque

and

Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during step-down task

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Efeito dos exercícios de fortalecimento e alongamento sobre a rigidez tecidual passiva

for hip extension assistance and multi-joint assistance respectively, which is equivalent to an average metabolic reduction of 4.6% and 14.6%, demonstrating that soft exosuits can effectively improve human walking efficiency during load carriage without affecting natural walking gait. Moreover, it indicates that actuating multiple joints with soft exosuits provides a significant benefit to muscular activity and metabolic cost compared to actuating single joint.

Influence of Passive Joint Stiffness on Proprioceptive Acuity in Individuals With Functional Instability of the Ankle

In this paper, we present the first application of a soft exosuit to assist walking after stroke. The exosuit combines textile garments with cable driven actuators and is lighter and more compliant as compared to traditional rigid exoskeletons. By avoiding the use of rigid elements, exosuits offer greater comfort, facilitate donning/doffing, and do not impose kinematic restrictions on the wearer - all while retaining the ability to generate significant moments at target joints during walking. The stroke-specific exosuit adapted from previous exosuit designs provides unilateral assistance to the paretic limb during walking. This paper describes stroke-specific design considerations, the design of the textile components, the development of a research-focused, mobile off-board actuation unit capable of testing the exosuit in a variety of walking conditions, a real-time gait detection and control algorithm, and proof-of-principle data validating the use of the exosuit in the chronic stroke population. Ultimately, we demonstrate reliable tracking of poststroke gait, appropriate timing of assistive forces, and improvements in key gait metrics. These preliminary results demonstrate the feasibility and promise of exosuits for poststroke gait assistance and training. Future work will involve the creation of a portable, body-worn system based on the specifications obtained from such feasibility studies that will enable community-based rehabilitation.

External rotation elastic bands at the lower limb decrease rearfoot eversion during walking: a preliminary proof of concept

BACKGROUND Adequate passive stiffness of the hip joint can prevent the occurrence of excessive transverse plane lower limb movement during functional activities. Strength training of the hip lateral rotator muscles can be used to increase the stiffness of this joint. However, the relationship between hip joint passive stiffness and muscle strength remains undocumented in the literature. OBJECTIVE To investigate the association between hip passive stiffness measured during medial rotation and hip lateral rotator concentric torque in healthy young adults. METHOD Twenty-six individuals with mean age of 24.42±2.77 years participated in the present study. To quantify hip stiffness, the passive resistance torque during medial rotation was measured using an isokinetic dynamometer. Stiffness was determined by the mean slope of the passive torque curve obtained in the first 20° of motion. Electromyography was used to ensure inactivity of the hip muscles during this procedure. The isokinetic dynamometer was also used for assessment of hip lateral rotator peak torque and work in a range of motion of 55° of rotation. RESULTS Linear regressions demonstrated correlation coefficients of r=0.70 (R²=0.50/p<0.001) and r=0.77 (R²=0.59/p<0.001) between hip passive stiffness and the measures of lateral rotator peak torque and work, respectively. CONCLUSIONS There is a moderate to good association between hip passive stiffness and lateral rotator concentric torque. This association suggests that lateral rotator strength training can increase hip stiffness.

Força muscular e índice de fadiga dos extensores e flexores do joelho de jogadores profissionais de futebol de acordo com o posicionamento em campo

Background Strengthening of the hip and trunk muscles has the potential to change lower limb kinematic patterns, such as excessive hip medial rotation and adduction during weight‐bearing tasks. This study aimed to investigate the effect of hip and trunk muscles strengthening on hip muscle performance, hip passive properties, and lower limb kinematics during step‐down task in women. Methods Thirty‐four young women who demonstrated dynamic knee valgus during step‐down were divided into two groups. The experimental group underwent three weekly sessions of strengthening exercises for eight weeks, and the control group continued their usual activities. The following evaluations were carried out: (a) isokinetic maximum concentric and eccentric work of hip lateral rotators, (b) isokinetic hip passive torque of lateral rotation and resting transverse plane position, and (c) three‐dimensional kinematics of the lower limb during step‐down. Findings The strengthening program increased concentric (P < 0.001) and eccentric (P < 0.001) work of hip lateral rotators, and changed hip resting position toward lateral rotation (P < 0.001). The intervention did not significantly change hip passive torque (P = 0.089, main effect). The program reduced hip (P = 0.002), thigh (P = 0.024) and shank (P = 0.005) adduction during step‐down task. Hip, thigh and knee kinematics in transverse plane and foot kinematics in frontal plane did not significantly modify after intervention (P ≥ 0.069, main effect). Interpretation Hip and trunk strengthening reduced lower limb adduction during step‐down. The changes in hip maximum work and resting position may have contributed to the observed kinematic effects. HighlightsHip and trunk strengthening increased maximum work of hip lateral rotators muscles.The strengthening program changed hip resting position toward lateral rotation.The intervention did not change hip passive torque during medial rotation.The strengthening program reduced lower limb adduction during step‐down task.Kinematics in transverse plane during step‐down did not change after intervention.

Prevalence of knee osteoarthritis in former athletes: a systematic review with meta-analysis

INTRODUCTION: High or low levels of passive stiffness of muscles, tendons, ligaments and fascia can be related to the occurrence of movement dysfunctions and to the development of musculoskeletal injuries. The treatment of these conditions often involves the use of techniques to modify stiffness, such as strengthening or stretching. OBJECTIVE: To conduct a critical review in order to investigate the effects of strength and stretching exercises on tissue passive stiffness. MATERIALS AND METHODS: A literature research was performed with the Medline, Scielo, Lilacs and PEDro. Experimental studies carried out in animals and humans, without data limit, were included in this research. RESULTS: Twenty studies about the effect of strength training on passive stiffness and 13 studies about the effect of stretching exercises on passive stiffness were selected. CONCLUSION: The studies suggest that strength exercises of high intensity are capable to increase the levels of tissue stiffness in animals and humans. The increase in cross-sectional area and changes in tissue composition are some of the mechanisms responsible to this enhance. Regarding the muscle strengthening in lengthen position and the eccentric strengthening in the whole range of motion with moderate load, the results are insufficient to confirm the real effects of these techniques in reducing the stiffness levels. Finally, static or contract-relax stretching programs seem to decrease tissue stiffness when performed through protocols of long duration and/or high frequency.