Hip external rotation isometric torque for soccer, basketball, and volleyball athletes: normative data and asymmetry index.

BACKGROUND: Deficits in strength of the hip external rotators (ER) affect trunk, hip, and knee movement patterns, potentially contributing to injury in athletes. OBJECTIVES: To provide normative data on isometric torque for hip ER in athletes of three distinct sports and to determine if isometric torque for the hip ER and torque asymmetry between legs differ among sports and between sexes. METHODS: Basketball, soccer, and volleyball athletes (n=451) were evaluated. Hip ER torque was quantified bilaterally with athletes in prone and 90° of knee flexion using a hand-held dynamometer. RESULTS: Data are expressed as mean and 95% confidence interval. Hip ER torque values in Nm/kg for the dominant and non-dominant limbs were, respectively, 0.46 (0.44, 0.48) and 0.42 (0.40, 0.44) for male soccer athletes; 0.35 (0.32, 0.37) and 0.27 (0.25, 0.29) for male basketball athletes; and 0.37 (0.34, 0.39) and 0.35 (0.32, 0.37) for male volleyball athletes. Hip ER torque in Nm/kg for the female volleyball athletes was 0.29 (0.26, 0.33) for the dominant and 0.29 (0.25, 0.32) for the non-dominant limb. The Limb Symmetry Index for male soccer, basketball, and volleyball players was, respectively, 94% (91, 97), 81% (75, 87), and 95% (91, 99). For female volleyball players the Limb Asymmetry Index was 102% (95, 108). Male volleyball athletes showed higher torque values than female volleyball athletes. CONCLUSIONS: This study reported normative values for hip ER isometric torque of youth athletes. Clinicians can use the reported data as reference to identify torque deficits in athletes of the three reported sports.

Foot pronation affects pelvic motion during the loading response phase of gait.

BACKGROUND: Increased foot pronation during walking has been associated with low back pain. This association may be due to the impact of increased pronation on pelvic motion. OBJECTIVE: To investigate the effects of increased bilateral foot pronation on pelvic kinematic in frontal and transverse planes during the loading response phase of gait. METHODS: Pelvic, hip, and foot angular positions of 20 participants were collected while they walked at fast speed wearing flat and medially inclined insoles inserted in the shoes. Pelvic motion in frontal and transverse planes was analyzed during the loading response phase. Foot eversion-inversion was analyzed during the complete stance phase to verify the insoles effectiveness in inducing increased pronation and to exclude excessive pronators. RESULTS: Inclined insoles were effective in inducing increased foot pronation. Pelvic and hip motion were altered in the increased pronation condition compared to the control condition. In the frontal plane, mean pelvic position was more inclined to the contralateral side (mean difference [MD]: 0.54°; 95%CI: 0.23, 0.86) and its range of motion (ROM) was reduced (MD: 0.50°; 95%CI: 0.20, 0.79). In the transverse plane, mean pelvic position was less rotated toward the contralateral leg (MD: 1.03°; 95%CI: 0.65, 1.60) without changes in ROM (MD: 0.04°; 95%CI: -0.17, 0.25). The hip was more internally rotated (MD: 1.37°; 95%CI: 0.76, 1.98) without changes in ROM (MD: 0.10°; 95%CI: -1.02, 1.23). CONCLUSION: Increased bilateral foot pronation changes pelvic motion during walking and should be assessed, as a contributing factor to possible pelvic and lower back disorders.

Mechanisms contributing to gait speed and metabolic cost in children with unilateral cerebral palsy.

BACKGROUND: Gait speed and metabolic cost are indicators of functional capacity in children with cerebral palsy. Uncovering their mechanisms helps guide therapeutic actions. OBJECTIVES: To investigate the contributions of energy-generating and energy-conserving mechanisms to gait speed and metabolic cost of children with unilateral cerebral palsy. METHODS: Data on eccentric and concentric muscle work, co-contraction, elastic torque and vertical stiffness of the affected-limb, forcing torque of the non-affected limb, gait speed and metabolic cost were collected from 14 children with unilateral cerebral palsy, aged 6-12 years. Analyses included two groups of multiple regression models. The first group of models tested the association between each dependent variable (i.e., speed and metabolic cost) and the independent variables that met the input criteria. The second group verified the contribution of the non-selected biomechanical variables on the predictors of the first model. RESULTS: Gait speed (R2=0.80) was predicted by elastic torque (ß=0.62; 95%CI: 0.60, 0.63), vertical stiffness (ß=-0.477; 95%CI: -0.479, -0.474) and knee co-contraction (ß=0.27; 95%CI: -1.96, 2.49). The production of eccentric work by the affected limb proved relevant in adjusting the vertical stiffness (R2=0.42; ß=-0.64; 95%CI: 0.86, -0.42); elastic torque of the affected-leg was associated with impulsive torque of the non-affected leg (R2=0.31; ß=0.55; 95%CI: 0.46, 0.64). Metabolic cost of gait (R2=0.48) was partially predicted by knee co-contraction (ß=0.69; 95%CI: 0.685, 0.694). CONCLUSIONS: The chain of associations revealed by the two steps models helped uncover the mechanisms involved in the locomotion of children with unilateral cerebral palsy. Intervention that changes specific energy conserving and generating mechanisms may improve gait of these children.

Towards an ecologically grounded functional practice in rehabilitation.

According to the International Classification of Functioning, Disability and Health, effective rehabilitation requires interventions that go beyond minimizing pathological conditions and associated symptoms. The scope of practice must include promoting an individual's activity within relevant contexts. We argue that best practice requires decisions that are not only evidence-based but also theory-based. Perception and action theories are essential for interpreting evidence and clinical phenomena as well as for developing new interventions. It is our contention that rehabilitation goals can best be achieved if inspired by the ecological approach to perception and action, an approach that focuses on the dynamics of interacting constraints of performer, task and environment. This contrasts with organism-limited motor control theories that have important influence in clinical practice. Parallels between such theories and the medical model of care highlight their fundamental inconsistency with the current understanding of functioning. We contend that incorporating ecological principles into rehabilitation research and practice can help advance our understanding of the complexity of action and provide better grounding for the development of effective functional practice. Implications and initial suggestions for an ecologically grounded functional practice are outlined.

Upper limb performance and the structuring of joint movement in teenagers with cerebral palsy: the reciprocal role of task demands and action capabilities.

Individuals with unilateral cerebral palsy (CP) demonstrate reduced performance in upper limb tasks compared to typically developing (TD) peers. We examined whether task conditions modify differences between teenagers with and without CP during a reciprocal aiming task. Twenty teenagers (nine CP and 11 TD) moved a pointer between two targets as fast as possible without missing a target. Task conditions were manipulated by changing the targets' size, by modifying the inertial properties of the pointer and by varying the upper limb used to perform the task (preferred/non-affected and non-preferred/affected upper limbs). While compared to TD peers, CP teenagers exhibited lower performance (longer movement times). Such differences were attenuated when the task was performed with the preferred upper limb and when accuracy requirements were less stringent. CP teenagers were not differentially affected by the pointer inertia manipulation. Task conditions not only affected performance but also joint kinematics. CP teenagers revealed less movement at the elbow and more movement at the shoulder when performing the task with their less skilled upper limb. However, both CP and TD teenagers demonstrated a larger contribution of trunk movement when facing more challenging task conditions. The overall pattern of results indicated that the joint kinematics employed by individuals with unilateral CP constituted adaptive responses to task requirements. Thus, the explanation of the effects of unilateral CP on upper limb behavior needs to go beyond a context-indifferent manifestation of the brain injury to include the interaction between task demands and action capabilities.

Active control stabilization of pelvic position in the transverse plane: an evaluation of soccer players' performance.

OBJECTIVES: To describe the capability of soccer players to stabilize pelvic position actively in the transverse plane; and, to evaluate the influence of lower limb dominance, length of exposure to soccer practice, and field position on pelvic stabilization capability. DESIGN: Cross-sectional. PARTICIPANTS: Sixty-eight soccer players from under-15 (U-15) and professional categories. MAIN OUTCOME MEASURES: Magnitude and asymmetry of pelvic tilt in the transverse plane, evaluated using the bridge test with unilateral knee extension. RESULTS: The magnitude of pelvic tilt did not differ between dominant and non-dominant sides, suggesting absence of relative asymmetry. However, there was difference between the sides of greater and lesser magnitude of pelvic tilt, indicating presence of absolute asymmetry. Players with shorter length of exposure to soccer practice (U-15 group) had greater pelvic tilt than players with longer length of exposure (professional group). There was no association of field position with the magnitude and asymmetry of pelvic tilt. CONCLUSION: Soccer players showed asymmetry in pelvic stabilization capability that was unrelated to lower limb dominance or field position. Athletes with longer length of exposure to soccer practice present better capability to stabilize the pelvis in the transverse plane than those with shorter length of exposure to soccer practice.

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.

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

BACKGROUND: Analyses 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. METHODS: Thirty-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. FINDINGS: Women 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. INTERPRETATION: The 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.

Eletromiografia: interpretação e aplicações nas ciências da reabilitação / Electromyography: interpretation and applications in the rehabilitation sciences

A eletromiografia (EMG) é uma técnica que permite o registro dos sinais elétricos gerados pelas células musculares, possibilitando a análise da atividade muscular durante o movimento. A compreensão de conceitos relativos a EMG é essencial para se assegurar a validade e confiabilidade desse instrumento de mensuração em pesquisas da área de reabilitação e na prática clínica de fisioterapeutas. Dessa forma, foi objetivo deste estudo discutir aspectos relevantes relacionados à coleta, processamento e análise de dados eletromiográficos de forma a facilitar a compreensão da instrumentação, aplicações e limitações da técnica. De acordo com a revisão realizada, diversos fatores que influenciam a qualidade dos dados coletados devem ser considerados, não apenas na utilização da técnica, mas também na interpretação e avaliação crítica de estudos que utilizam a EMG. Quando todos estes fatores são considerados, a EMG se torna uma ferramenta adequada para investigação da função muscular, tanto na pesquisa quanto na prática clínica de fisioterapeutas.

Electromyography (EMG) is a procedure used to register the electrical activity generated by muscle cells, allowing the analysis of muscle activity during movement. The comprehension of concepts relative to EMG is essential to assure the validity and reliability of this instrument in rehabilitation research and clinical practice of physiotherapists. Therefore, the objective of this study was to discuss relevant aspects related to the acquisition, processing and analysis of electromyographic data in order to assist the comprehension of the instrumentation, applications and limitations of the technique. According to the literature review, several factors that can influence the quality of the data collected should be considered not only for the utilization of the technique but also for the interpretation and critical appraisal of studies that use EMG. Provided that all this factors are considered, EMG is an adequate instrument for the investigation of muscle function either in research or in clinical practice of physical therapists.