Paula Silva

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.

Caracterização da performance muscular em atletas profissionais de futebol

INTRODUCTION AND OBJECTIVE: The association of muscular performance with risk of injury and functional performance in different sports has been reported in numerous studies in the literature. However, there is a paucity of data that characterizes the muscular performance in Brazilian professional soccer athletes. Therefore, the objective of this study was to make a descriptive analysis of parameters related to the muscular performance of this population. METHODS: The sample of this study was composed of 117 athletes belonging to professional soccer clubs in Minas Gerais State. In order to evaluate the muscular performance of the athletes, an isokinetic dynamometer was used and the tests involved maximum voluntary contractions of the selected muscles. Hip abductors and adductors were assessed at the speeds of 30o/s, 60o/s and 120o/s; knee flexors and extensors at 60o/s, 180o/s and 300o/s; and ankle dorsiflexors, plantarflexors, invertors and evertors at 30o/s, 60o/s and 180o/s. Descriptive statistics were used to present the normative data and paired t-tests were used to identify significant differences between legs considering the parameters evaluated in this study. RESULTS: This study generated normative data to characterize the profile of Brazilian professional soccer players relative to their capacity of producing torque, muscle work and power. Significant differences were observed between legs considering some of the studys variables. CONCLUSION: The established normative data can be used as reference values in the prevention, training and rehabilitation of the athletes. In addition, these data may be used as reference for future studies with the objective of testing the association between muscular performance and incidence of injury in soccer practice.

Proprioception in Individuals with ACL-Deficient Knee and Good Muscular and Functional Performance

The objective of this study was to verify whether proprioception is affected in individuals with ACL-deficient knees and good functional and muscular performances. Eleven subjects with ACL injury and 11 controls participated in the study. Functional performance was assessed using the Cincinnati Knee Rating System (CKRS), hop index, and figure-eight ratio. An isokinetic test was done to evaluate muscular performance. Proprioception was evaluated through position sense and threshold tests. Analyses of variance were used for data analysis. The injured subjects scored significantly lower in the CKRS (p = 0.001). No statistically significant differences were found in the hop index, in the figure-eight ratio, or in peak torque. There were no statistically significant differences in proprioception between groups and between legs. These results indicated that the individuals evaluated in this study with ACL injury and good functional and muscular performance did not have proprioceptive deficits, suggesting that the ligament mechanoreceptors, in some cases, might not contribute relevantly to proprioception. This work was partially supported through grants conferred to the first author by Brazilian government agencies CNPq and FAPEMIG and by the Universidade Federal de Minas Gerais (PRPq). We would also like to thank CNPq and PRPq agencies for the scholarships conferred to the second and third authors.

Clinical measures of hip and foot–ankle mechanics as predictors of rearfoot motion and posture

Health professionals are frequently interested in predicting rearfoot pronation during weight-bearing activities. Previous inconsistent results regarding the ability of clinical measures to predict rearfoot kinematics may have been influenced by the neglect of possible combined effects of alignment and mobility at the foot-ankle complex and by the disregard of possible influences of hip mobility on foot kinematics. The present study tested whether using a measure that combines frontal-plane bone alignment and mobility at the foot-ankle complex and a measure of hip internal rotation mobility predicts rearfoot kinematics, in walking and upright stance. Twenty-three healthy subjects underwent assessment of forefoot-shank angle (which combines varus bone alignments at the foot-ankle complex with inversion mobility at the midfoot joints), with a goniometer, and hip internal rotation mobility, with an inclinometer. Frontal-plane kinematics of the rearfoot was assessed with a three-dimensional system, during treadmill walking and upright stance. Multivariate linear regressions tested the predictive strength of these measures to inform about rearfoot kinematics. The measures significantly predicted (pxa0≤xa00.041) mean eversion-inversion position, during walking (r(2)xa0=xa00.40) and standing (r(2)xa0=xa00.31), and eversion peak in walking (r(2)xa0=xa00.27). Greater values of varus alignment at the foot-ankle complex combined with inversion mobility at the midfoot joints and greater hip internal rotation mobility are related to greater weight-bearing rearfoot eversion. Each measure (forefoot-shank angle and hip internal rotation mobility) alone and their combination partially predicted rearfoot kinematics. These measures may help detecting foot-ankle and hip mechanical variables possibly involved in an observed rearfoot motion or posture.

Impact of leg length and body mass on the stride length and gait speed of infants with normal motor development: A longitudinal study

BACKGROUNDnGait acquisition is supported by changes in the neuromusculoskeletal system of the child. Changes in the dimensions of the body structures resulting from the growth of the child partly explain gait improvement in the first year of life.nnnOBJECTIVESnTo evaluate whether changes in body mass and leg length modulate the effect of independent gait practice (experience) on gait speed and stride length.nnnMETHODnThirty-two infants with normal development were monitored monthly from the acquisition of independent gait until six months post-acquisition. Longitudinal evaluations included measurements of the body mass and leg length of each child. Temporospatial variables of gait (speed and stride length) were documented using the Qualisys Pro-reflex(r) system. The data were analyzed using multilevel regression models, with a significance level of α=0.05.nnnRESULTSnAn effect of the practice time on speed (p<0.0001) and stride length (p<0.0001) was observed. The change in leg length had a marginal effect on the rate of gait speed change: children whose leg growth was faster showed a higher rate of speed change (p=0.07). No other effects of anthropometric parameters were observed.nnnCONCLUSIONSnThe results suggest that the practice time promotes the improvement of the gait pattern of infants in the first year of life. However, the effects of the leg length and body weight of infants on the benefit of practice time remain undefined.

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.

Assessment of gait in toddlers with normal motor development and in hemiplegic children with mild motor impairment: a validity study

BACKGROUND: The optimization of gait performance is an important goal in the rehabilitation of children with cerebral palsy (CP) who present a prognosis associated with locomotion. Gait analysis using videos captured by digital cameras requires validation. OBJECTIVE: To evaluate the validity of a method that involves the analysis of videos captured using a digital camera for quantifying the temporal parameters of gait in toddlers with normal motor development and children with CP. METHOD: Eleven toddlers with normal motor development and eight children with spastic hemiplegia who were able to walk without assistive devices were asked to walk through a space contained in the visual field of two instruments: a digital camera and a three-dimensional motion analysis system, Qualisys Pro-Reflex. The duration of the stance and swing phases of gait and of the entire gait cycle were calculated by analyzing videos captured by a digital camera and compared to those obtained by Qualisys Pro-Reflex, which is considered a highly accurate system. RESULTS: The Intraclass Correlation Coefficient (ICC) demonstrated excellent agreement (ICC>0.90) between the two procedures for all measurements, except for the swing phase of the normal toddlers (ICC=0.35). The standard error of measurement was less than 0.02 seconds for all measures. CONCLUSIONS: The results reveal similarities between the two instruments, suggesting that digital cameras can be valid instruments for quantifying two temporal parameters of gait. This congruence is of clinical and scientific relevance and validates the use of digital cameras as a resource for helping the assessment and documentation of the therapeutic effects of interventions targeted at the gait of children with CP.

Relationship between joint passive stiffness and hip lateral rotator concentric torque

BACKGROUNDnAdequate 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.nnnOBJECTIVEnTo investigate the association between hip passive stiffness measured during medial rotation and hip lateral rotator concentric torque in healthy young adults.nnnMETHODnTwenty-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.nnnRESULTSnLinear 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.nnnCONCLUSIONSnThere 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.

Power at hip, knee and ankle joints are compromised in women with mild and moderate knee osteoarthritis.

BACKGROUNDnAnalyses of the biomechanical characteristics of gait of women with mild and moderate knee osteoarthritis may identify parameters that could be targeted by physical therapy interventions. Therefore, the purpose of the present study was to compare the joint power profiles during gait between a group of elderly women with mild and moderate levels of knee osteoarthritis and a group of age-matched asymptomatic women.nnnMETHODSnThirty-nine women diagnosed with osteoarthritis at the medial compartment of the knee and 39 healthy women with no diagnosis of knee osteoarthritis participated in the study. Joint power profiles of the hip, knee and ankle joints in the sagittal plane during gait were performed using video and force data obtained using Qualisys ProReflex System synchronized with two force plates. Principal component analysis was applied to extract features from the joint power waveforms characterizing their main modes of temporal variation. The extracted features were compared between groups.nnnFINDINGSnWomen with knee osteoarthritis absorbed and generated less energy at the hip and ankle joints, and absorbed less energy at the knee when compared to the asymptomatic group.nnnINTERPRETATIONnThe observed power pattern in women with knee osteoarthritis may be related to their reduced gait speed, a suboptimal strategy possibly used to reduce reaction forces at the knee. Clinical studies should investigate whether interventions designed to improve muscular resources, as a means to control the flow of forces at the knee, would optimize power patterns and gait performance in women with knee osteoarthritis.

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.