Thales R. Souza

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.

Late Rearfoot Eversion and Lower-limb Internal Rotation Caused by Changes in the Interaction between Forefoot and Support Surface

BACKGROUND The influence of distal mechanical factors that change the interaction between the forefoot and the support surface on lower-limb kinematics is not well established. This study investigated the effects of the use of lateral wedges under the forefoot on the kinematics of the lower extremity during the stance phase of walking. METHODS Sixteen healthy young adults participated in this repeated-measures study. They walked wearing flat sandals and laterally wedged sandals, which were medially inclined only in the forefoot. One wedged sandal had a forefoot lateral wedge of 5 degrees and the other wedged sandal had a forefoot lateral wedge of 10 degrees. Kinematic variables of the lower extremity, theoretically considered clinically relevant for injury development, were measured with a three-dimensional motion analysis system. The variables were evaluated for three subphases of stance: loading response, midstance, and late stance. RESULTS The 5 degrees laterally wedged sandal increased rearfoot eversion during midstance and the 10 degrees laterally wedged sandal increased rearfoot eversion during mid- and late stances, in comparison to the use of flat sandals. The 10 degrees laterally wedged sandal produced greater internal rotation of the shank relative to the pelvis and of the hip joint, during the midstance, also compared to the use of flat sandals. CONCLUSIONS Lateral wedges under the forefoot increase rearfoot eversion during mid-and late stances and may cause proximal kinematic changes throughout the lower-extremity kinetic chain. Distal mechanical factors should be clinically addressed when a patient presents late excessive rearfoot eversion during walking.

Prestress revealed by passive co-tension at the ankle joint.

This study was designed to test the assumption that elastic tissues of the ankle are prestressed, by investigating the presence of simultaneous opposite passive elastic moments and thus, passive co-tension, at the ankle joint. A prestressed two-spring model used to generate qualitative predictions of the effects of stretching the posterior elastic structures of the ankle on the net passive moment of this joint was used. Twenty-seven healthy individuals were subjected to passive evaluation of the net elastic moment of the ankle in the sagittal plane, with the knee positioned at 90 degrees, 60 degrees, 30 degrees and 0 degrees of flexion, in order to change the length of the posterior biarticular elastic structures. The placement of the knee in the more extended positions caused changes in the net passive moment as predicted by the prestressed model. The ankle position in which the net passive moment was equal to zero was shifted to more plantar flexed positions (p<0.001) and there was a global increase in ankle stiffness since both passive dorsiflexion stiffness (p< or =0.037) and passive plantar flexion stiffness (p< or =0.029) increased. The normalized terminal plantar flexion stiffness also increased (p< or =0.047), suggesting that biarticular posterior elastic structures are pre-strained and still under tension when the ankle is maximally plantar flexed and the knee is positioned at 60 degrees of flexion. Resting positions were indicative of equilibrium between opposite passive elastic moments. The results revealed that there is passive co-tension at the ankle, demonstrating the existence of prestress in elastic structures of this joint.

Muscular performance characterization in athletes: a new perspective on isokinetic variables

Background: Isokinetic dynamometry allows the measurement of several variables related to muscular performance, many of which are seldom used, while others are redundantly applied to the characterization of muscle function. Objectives: The present study aimed to establish the particular features of muscle function that are captured by the variables currently included in isokinetic assessment and to determine which variables best represent these features in order to achieve a more objective interpretation of muscular performance. Method: This study included 235 male athletes. They performed isokinetic tests of concentric knee flexion and extension of the dominant leg at a velocity of 60º/s. An exploratory factor analysis was performed. Results: The findings demonstrated that isokinetic variables can characterize more than muscle torque production and pointed to the presence of 5 factors that enabled the characterization of muscular performance according to 5 different domains or constructs. Conclusions: The constructs can be described by torque generation capacity; variation of the torque generation capacity along repetitions; movement deceleration capacity; mechanical/physiological factors of torque generation; and acceleration capacity (torque development). Fewer than eight out of sixteen variables are enough to characterize these five constructs. Our results suggest that these variables and these 5 domains may lead to a more systematic and optimized interpretation of isokinetic assessments.

Between-Day Reliability of a Cluster-Based Method for Multisegment Kinematic Analysis of the Foot-Ankle Complex

BACKGROUND Detailed description of foot pronation-supination requires multisegment evaluation of the kinematics of the foot-ankle complex. There are noninvasive methods with independent (single) tracking markers attached directly to the skin. However, these methods are inconsistent with the usual rigid segments assumption. In contrast, using clustered markers is compatible with this assumption and is necessary for analyses that need tracking markers to be distant from the foot (eg, shod walking). This study investigated the between-day reliability of a cluster-based method for multisegment analysis of foot-ankle angles related to pronation-supination. METHODS Ten healthy adults participated in the study. An anatomically based, three-dimensional model comprising the shank, calcaneus, and forefoot was created. Rigid clusters of tracking markers were used to determine the relative positions and motions of the segments. Mean positions were measured with the subtalar joint in neutral position during standing. Furthermore, mean angles, peaks, and timings of peaks were measured during the stance phase of walking. All of the variables were measured twice, with a 1-week interval. To evaluate reliability, intraclass correlation coefficients were calculated for discrete variables and coefficients of multiple correlation for entire gait curves. RESULTS Intraclass correlation coefficients varied from 0.8 to 0.93 for the angles obtained when the subtalar joint was in neutral and from 0.76 to 0.9 for walking variables. Coefficients of multiple correlation varied from 0.93 to 0.97 for walking curves. CONCLUSIONS The method described has good to high reliability and provides a systematic method for multisegment kinematic evaluation of foot-ankle pronation-supination.

A Quick and Reliable Procedure for Assessing Foot Alignment in Athletes

BACKGROUND Quick procedures with proper psychometric properties that can capture the combined alignment of the foot-ankle complex in a position that may be more representative of the status of the lower limb during ground contact are essential for assessing a large group of athletes. METHODS The assessed lower limb was positioned with the calcaneus surface facing upward in a way that all of the marks could be seen at the center of the camera display. After guaranteeing maintenance of the foot at 90° of dorsiflexion actively sustained by the athlete, the examiner took the picture of the foot-ankle alignment. RESULTS Intraclass correlation coefficients ranging from 0.82 to 0.93 demonstrated excellent intratester and intertester reliability for the proposed measurements of forefoot, rearfoot, and shank-forefoot alignments. The intraclass correlation coefficient between the shank-forefoot measures and the sum of the rearfoot and forefoot measures was 0.98, suggesting that the shank-forefoot alignment measures can represent the combined rearfoot and forefoot alignments. CONCLUSIONS This study describes a reliable and practical measurement procedure for rearfoot, forefoot, and shank-forefoot alignments that can be applied to clinical and research situations as a screening procedure for risk factors for lower-limb injuries in athletes.

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

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.

External devices (including orthotics) to control excessive foot pronation.

▶ Cheung RT, Chung RC, Ng GY. Efficacies of different external controls for excessive foot pronation: a meta-analysis. Br J Sports Med 2011;45:743–51.[OpenUrl][1][Abstract/FREE Full Text][2] Foot pronation during the early stance phase of gait allows the foot to accommodate to the irregularities of the ground surface and to attenuate ground reaction forces. Pronation involves multiple joint movements at the rearfoot and midfoot, and may influence more proximal segments leading to internal rotation of the lower limb and hip.1 Excessive foot pronation may promote non-physiological stresses on bone and musculo-tendinous structures of the lower limb and subsequent injury.2 Several overuse injuries have been attributed to excessive foot pronation. Injuries might occur at the foot level, such as plantar fasciitis, as well as at … [1]: {openurl}?query=rft.jtitle%253DBr%2BJ%2BSports%2BMed%26rft_id%253Dinfo%253Adoi%252F10.1136%252Fbjsm.2010.079780%26rft_id%253Dinfo%253Apmid%252F21504966%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [2]: /lookup/ijlink?linkType=ABST&journalCode=bjsports&resid=45/9/743&atom=%2Fbjsports%2F46%2F2%2F110.atom

Dynamic touch is affected in children with cerebral palsy

Children with developmental disorders such as cerebral palsy have limited opportunities for effortful interactions with objects and tools. The goal of the study was to investigate whether children with cerebral palsy have deficits in their ability to perceive object length by dynamic touch when compared to typically developing children. Fourteen children with typical development and 12 children with cerebral palsy were asked to report the length of hand-held rods after wielding them out of sight. Multilevel regression models indicated that I1 (maximum principal moment of inertia) was a significant predictor of perceived length - LP (p<.0001). The effect of I1 on LP was significantly different among children (p=.001) and the presence of cerebral palsy (group factor) partially explained such variance (p=.002). In addition, accuracy and reliability of the length judgments made by children with cerebral palsy were significantly lower than the typically developing children (p<.05). Theoretical and clinical implications of these results were identified and discussed.

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

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.