Reductions in rearfoot eversion posture due to proximal muscle strengthening are dependent on foot-ankle varus alignment.

BACKGROUND: Strengthening the hip and trunk muscles may decrease foot pronation in upright standing due to expected increases in hip passive torque and lower-limb external rotation. However, considering the increased pronation caused by a more varus foot-ankle alignment, subjects with more varus may experience smaller or no postural changes after strengthening. OBJECTIVE: To investigate the effects of hip and trunk muscle strengthening on lower-limb posture during upright standing and hip passive torque of women with more and less varus alignment. METHODS: This nonrandomized controlled experimental study included 50 young, able-bodied women. The intervention group (n = 25) performed hip and trunk muscle strengthening exercises, and the control group (n = 25) maintained their usual activities. Each group was split into two subgroups: those with more and less varus alignment. Hip, shank, and rearfoot-ankle posture and hip passive external rotation torque were evaluated. Mixed analyses of variance and preplanned contrasts were used to assess prepost changes and between-group differences (α = 0.05). RESULTS: The less-varus subgroup of the intervention group had a reduced rearfoot eversion posture (P = 0.02). No significant changes were observed in the less-varus subgroup of the control group (P = 0.31). There were no significant differences in posture between the control and intervention groups when varus was not considered (P ≥ 0.06). The intervention group had increased hip passive torque (P = 0.001) compared to the control group, independent of varus alignment. CONCLUSION: Despite the increases in hip passive torque, the rearfoot eversion posture was reduced only in women with a less-varus alignment. Having more foot-ankle varus may prevent eversion reductions.

Vertical stiffness and lower limb inter-joint coordination in older versus younger runners.

Older runners (OR) are increasing their participation in races. Aging may impact the adopted running pattern. Hence, the analysis of stiffness and the inter-joint lower limb coordination in the sagittal plane could contribute to investigating this impact. This study aimed to compare the vertical stiffness (Kvert) and the inter-joint lower limb coordination in the sagittal plane between younger runners (YR) and OR. This cross-sectional study recruited 15 YR males and 15 OR males. The pelvis and lower limb motions were assessed while running on a treadmill at self-selected (range OR: 1.94-3.75 m.s-1, YR: 2.08-4.17 m.s-1) and fixed speeds (3.33 m.s-1). Hip-ankle, knee-ankle, and hip-knee coupling angle (CA) and its variability (CAV) were extracted using the vector coding method. Mann-Whitney U tests compared Kvert between groups at each running speed. Watson's U2 tests compared the mean CA between groups in three intervals of the contact phase at each running speed. Statistical Parametric Mapping independent t-test compared the CAV curve between groups at each running speed. OR showed greater Kvert than YR at both speeds. Hip-ankle CA pattern differed between groups during the early stance at both speed conditions. OR showed in-phase, distal dominancy in hip-ankle CA, whereas YR showed anti-phase, proximal dominancy. Knee-ankle CA was distinct only at self-selected speed, in which OR showed in-phase, proximal dominancy, while YR exhibited anti-phase, proximal dominancy. CAV did not differ between groups. The findings showed that OR adopted a stiffer pattern characterized by distinct inter-joint lower limb CA, at early stance, during self-selected and fixed speeds.

An exploration of the effects of prefabricated and customized insoles on lower limb kinetics and kinematics during walking, stepping up and down tasks: A time series analysis.

BACKGROUND: Prefabricated and customized insoles are used in clinical practice to reduce foot pronation. Although data exist on the effects at key points within the stance phase, exploring the impact of different insoles using time series analysis may reveal more detail about their efficacy. RESEARCH QUESTION: What are the effects revealed by a time series analysis of arch-supported prefabricated insoles (PREFABRICATED) versus arch-supported prefabricated insoles customized with a 6º medial wedge (CUSTOMIZED) on the lower limb biomechanics during walking, stepping up and down tasks in individuals with pronated feet? METHODS: Nineteen individuals with excessive foot pronation performed walking, stepping up and down tasks using three insoles: CONTROL (flat insole), CUSTOMIZED, and PREFABRICATED. Angles and moments of ankle and knee coronal and hip transverse planes were compared between conditions using statistical parametric mapping (SPM). RESULTS: For walking, CUSTOMIZED reduced ankle eversion moment compared to CONTROL during midstance and PREFABRICATED during propulsion. CUSTOMIZED decreased KAM during midstance and propulsion compared to PREFABRICATED. Compared to CONTROL, CUSTOMIZED and PREFABRICATED reduced hip internal rotation during propulsion and loading response, respectively. CUSTOMIZED decreased eversion movement during midstance and propulsion for the stepping up task. PREFABRICATED reduced eversion movement during midstance in comparison to CONTROL. For the stepping down task, CUSTOMIZED increased eversion movement during propulsion compared to PREFABRICATED. CUSTOMIZED reduced hip internal rotation angle for stepping up task during propulsion, decreased medial rotation movement during midstance compared to CONTROL, and reduced medial rotation during midstance compared to PREFABRICATED. CUSTOMIZED increased KAM for stepping up and down tasks during propulsion. SIGNIFICANCE: These findings suggest that both CUSTOMIZED and PREFABRICATED reduce foot pronation. However, non-local effects, such as changes in KAM and hip internal rotation, were seen only in the CUSTOMIZED. Therefore, CUSTOMIZED may be preferable if the objective is to modify the knee and hip mechanics.

Is there a dose-response of medial wedge insoles on lower limb biomechanics in people with pronated feet during walking and running?

BACKGROUND: Although the effects of medial wedge insoles on lower limb biomechanics have been investigated, information about the effects of different magnitudes of medial posting is still lacking. RESEARCH QUESTION: What are the dose-response effects of medial wedge insoles with postings varying between 0 °, 3 °, 6 °, and 9 ° of inclination on the lower limb biomechanics during walking and running in individuals with pronated feet? METHODS: Sixteen participants with an FPI ≥ 6 were recruited. Four arch-supported insole conditions with varying degrees of medial heel wedge were tested (0°, 3°, 6°, and 9°). A 3D motion analysis system with force plates was used to obtain the kinetics and kinematics of walking and running at self-selected speeds. To compare the ankle, knee, and hip angles and moments among conditions, a time series analysis was performed using Statistical Parametric Mapping (SPM). RESULTS: A reduction in ankle eversion angle was observed during walking for all insoles. For running, the 6° and 9° insoles decreased the ankle eversion angle during early stance and increased this angle during the propulsive phase. A decrease in ankle eversion moment was observed in walking and running for 6° and 9° insoles. An increase in knee adduction moment occurred in walking and running for all insoles. For hip, the 6° and 9° insoles showed, during walking, a decrease in hip adduction angle and an increase in hip adduction and external rotation moments. For most variables, statistical differences were found for a greater period across the stance phase as the medial wedge increased, except for ankle eversion moment and hip external rotation moment during walking. SIGNIFICANCE: The biomechanical effects over the time series for many of the parameters increased with the addition of insole inclination, showing a dose-response effect of medial wedge insoles on the lower limb biomechanics during walking and running in adults with excessive foot pronation.

Midfoot passive stiffness affects foot and ankle kinematics and kinetics during the propulsive phase of walking.

The midfoot joint complex (MFJC) is related to the mechanics and efficiency of the walking propulsive phase and low midfoot passive stiffness may require compensatory foot and ankle joint moments to avoid excessive pronation and inefficient propulsion. This study aimed to investigate the kinematics and kinetics of the MFJC and ankle during the propulsive phase of walking in subjects with larger and smaller midfoot passive stiffness. MFJC passive stiffness of 20 healthy adult participants, and the kinematics and kinetics of the MFJC (forefoot-rearfoot) and ankle (rearfoot-shank) during the stance phase of walking were measured. The participants were divided equally into two groups according to the MFJC passive stiffness. Ranges of motion (ROM) and mean joint moments were computed for the late stance. Independent t-tests (α = 0.05) revealed that subjects with lower midfoot passive stiffness showed an increased MFJC sagittal ROM (flattened longitudinal arch) (p = 0.002), increased ankle frontal ROM (more everted positions) (p = 0.002), increased MFJC frontal ROM (more inverted positions) (p = 0.019), as well as a tendency for larger ankle sagittal ROM (p = 0.056). They also showed increased MFJC (p = 0.021) and ankle (p = 0.018) moments in the sagittal plane, increased MFJC moment in the frontal plane (p = 0.047) and a tendency for a predominant ankle moment in the frontal (p = 0.058). Foot and ankle joint moments are possible strategies to reduce pronation and improve propulsion, but not sufficient to prevent the altered kinematics related to low midfoot stiffness. Therefore, midfoot passive stiffness is critical for foot and ankle kinematics and kinetics during walking propulsive phase and is a potential target of interventions.

Reliability and sensitivity of an instrument for measuring the midfoot passive mechanical properties.

To assess the test - retest reliability and sensitivity of an instrument developed to measure the passive mechanical properties of the midfoot joint complex (MFJC), nine female and three male healthy young adults were evaluated in two different days by two experienced examiners. After proper participant positioning on the instrument, the left forefoot was passively moved from eversion (20°) to inversion (45°) at 2°/s, while the rearfoot and shank were kept immobile. From the instrument's sensing units (torque meter and potentiometer at 100 Hz), passive torque and angle data were registered. Passive stiffness was calculated as the instantaneous slope of the torque vs. angle curve. Therefore, the variables analyzed were resting angle, passive torques and stiffnesses during inversion and eversion through the intraclass correlation coefficient (ICC3,3), standard error of measurement (SEM) and minimal detectable change (MDC95). For the resting angle, ICC3,3 ranged from 0.85 to 0.91, SEM ranged from 1.54° to 1.95° and MDC95 ranged from 4.26° to 5.41°. For the torques, ICC3,3 ranged from 0.85 to 0.97, SEM ranged from 0.09Nm to 0.42Nm and MDC95 ranged from 0.26Nm to 1.16Nm. Finally, for the stiffnesses, ICC3,3 ranged from 0.79 to 0.98, SEM ranged from 0.01Nm/° to 0.04Nm/° and MDC95 ranged from 0.01Nm/° to 0.10 Nm/°. It can be concluded that most of the measurements presented good to excellent reliability with low measurement error. Hence, clinicians and researchers may benefit from the reliable and stable measures provided by the Foot Torsimeter when assessing patients and planning interventions.

Identification of gait events in children with spastic cerebral palsy: comparison between the force plate and algorithms.

OBJECTIVE: To compare the gait event identification of five algorithms recommended in the literature with those provided by force plate (gold standard) in children with unilateral or bilateral spastic cerebral palsy (SCP). METHODS: This was a cross-sectional study of the gait of three girls and four boys with a mean age of 8.6±4.7 years. Four children had unilateral SCP with an equinus gait pattern, and the remaining three children exhibited bilateral SCP with a slide/drag gait pattern. Kinematic and kinetic gait data were collected during barefoot walking at a comfortable speed. From a total of 202 steps, the detection of 202 foot-strike (FS) and 194 toe-off (TO) events by each algorithm was compared with the detection of these same events by the force plate. The error between the events detected by the algorithms and those detected by the force plate was determined in milliseconds. Repeated measures ANOVA was used to compare the errors among the algorithms. RESULTS: The algorithm reported by Ghoussayni et al. showed the best performance in all situations, except for the identification of FS events on the unaffected side in children with unilateral SCP. For these events, the algorithms reported by Desailly et al. and Zeni et al. showed the best performance. CONCLUSION: Ghoussayni et al.'s algorithm can be used to detect gait events in children with SCP when a force plate is not available.

Comparison of the rigidity and forefoot - Rearfoot kinematics from three forefoot tracking marker clusters during walking and weight-bearing foot pronation-supination.

Due to the relative motion among the foot rays, the present study aimed to compare the rigidity as well as the forefoot - rearfoot kinematics obtained from three forefoot tracking marker clusters during walking and foot pronation-supination (PROSUP). Nineteen healthy adults performed six walking trials and ten cycles of foot PROSUP movements recorded by an optoelectronic system. Rearfoot's and forefoot's coordinate system were equal for all setups, only the forefoot's tracking markers locations varied among them, which were: (1st) a typical cluster, focusing on the proximal forefoot, (2nd) a second typical cluster, focusing on the distal forefoot and outer metatarsals, and (3rd) a new cluster proposition, focusing on the distal forefoot and central metatarsals. Cluster rigidity was the normalized intra-markers residual, and forefoot - rearfoot angles were the forefoot motion relative to the rearfoot at the peak of each plane of motion. Repeated-measures ANOVA with pairwise comparisons (α=0.05) revealed that the 3rd cluster had the smallest residual (p < 0.001) in comparison with the other clusters for both walking and PROSUP. Differences between forefoot - rearfoot angles were found in the sagittal plane for walking (p < 0.001), but not for PROSUP (p > 0.686). In the frontal and transverse planes, all clusters showed different forefoot - rearfoot angles (p < 0.001) for both walking and PROSUP. The 1st cluster showed smaller ROM in the three planes during walking, and the 3rd cluster was the only that showed forefoot - rearfoot inversion during maximum pronation. Therefore, the new forefoot tracking marker cluster proposition (3rd cluster) captured different forefoot - rearfoot kinematics and can be recommended when the objective is to maximize the cluster rigidity.

Pelvic Drop Changes due to Proximal Muscle Strengthening Depend on Foot-Ankle Varus Alignment.

BACKGROUND: Strengthening of hip and trunk muscles can modify pelvis and hip movements. However, the varus alignment of the foot-ankle complex (FAC) may influence the effects of muscle strengthening, due to the relationship of FAC alignment with pelvic and hip kinematics. This study evaluated the effects of hip and trunk muscle strengthening on pelvis and hip kinematics during walking, in subgroups with larger and smaller values of FAC varus alignment. In addition, this study evaluated the effects of hip and trunk muscle strengthening on hip passive and active properties, in the same subgroups. METHODS: Fifty-three women, who were divided into intervention and control groups, participated in this nonrandomized controlled trial. Each group was split into two subgroups with larger and smaller values of FAC varus alignment. Hip and trunk muscle strengthening was performed three times a week for two months, with a load of 70% to 80% of one repetition maximum. Before and after strengthening, we evaluated (1) pelvis and hip excursions in the frontal and transverse planes during walking, (2) isokinetic hip passive external rotator torque, and (3) isokinetic concentric and eccentric peak torques of the hip external rotator muscles. Mixed analyses of variance (ANOVAs) were carried out for each dependent variable related to walking kinematics and isokinetic measurements (α = 0.05). RESULTS: The subgroup with smaller varus alignment, of the intervention group, presented a reduction in pelvic drop after strengthening (P = 0.03). The subgroup with larger varus alignment increased pelvic drop after strengthening, with a marginal significance (P = 0.06). The other kinematic excursions did not change (pelvic anterior rotation P = 0.30, hip internal rotation P = 0.54, and hip adduction P = 0.43). The intervention group showed increases in passive torque (P = 0.002), peak concentric torque (P < 0.001), and peak eccentric torque (P < 0.001), independently of FAC alignment. These results suggest that FAC varus alignment influences the effects of strengthening and should be considered when hip and trunk muscle strengthening is used to reduce pelvic drop during walking.

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

Study Design Controlled laboratory study, cross-sectional. Background Deficits in ankle proprioceptive acuity have been reported in persons with functional instability of the ankle. Passive stiffness has been proposed as a possible mechanism underlying proprioceptive acuity. Objective To compare proprioceptive acuity and passive ankle stiffness in persons with and without functional ankle instability, and to assess the influence of passive joint stiffness on proprioceptive acuity in persons with functional ankle instability. Methods A sample of 18 subjects with and 18 without complaints of functional ankle instability following lateral ankle sprain participated. An isokinetic dynamometer was used to compare motion perception threshold, passive position sense, and passive ankle stiffness between groups. To evaluate the influence of passive stiffness on proprioceptive acuity, individuals in the lateral functional ankle instability group were divided into 2 subgroups: "high" and "low" passive ankle stiffness. Results The functional ankle instability group exhibited increased motion perception threshold when compared with the corresponding limb of the control group. Between-group differences were not found for passive position sense and passive ankle stiffness. Those in the functional ankle instability group with higher passive ankle stiffness had smaller motion perception thresholds than those with lower passive ankle stiffness. Conclusion Unlike motion perception threshold, passive position sense is not affected by the presence of functional ankle instability. Passive ankle stiffness appears to influence proprioceptive acuity in persons with functional ankle instability. J Orthop Sports Phys Ther 2017;47(12):899-905. Epub 7 Oct 2017. doi:10.2519/jospt.2017.7030.

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.

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 0.21 ±0.04 and 0.67 ±0.09 W/kg 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.

Uso Terapêutico de Tecnologias Assistivas: direitos das pessoas com deficiência e habilidade física e motora [2015]

Este curso integra um conjunto de quatro qualificações sobre o tema geral "uso terapêutico de tecnologias assistivas", organizado com esta finalidade. Por meio deste módulo, o objetivo é promover a atualização sobre o uso terapêutico das tecnologias assistivas no âmbito da habilitação e da reabilitação das pessoas com deficiência, enfocando habilidade física e autonomia motora com utilização das órteses, próteses e meios auxiliares. Os temas abordados são: Contexto e pressupostos: pessoas com deficiências, direitos, políticas públicas e inclusão social; A atenção à saúde das pessoas com deficiência; Habilidade física e motora

Uso Terapêutico de Tecnologias Assistivas: direito das pessoas com deficiência e habilidade física e motora

Este curso integra um conjunto de quatro qualificações sobre o tema geral "uso terapêutico de tecnologias assistivas", organizado com esta finalidade. Por meio deste módulo, o objetivo é promover a atualização sobre o uso terapêutico das tecnologias assistivas no âmbito da habilitação e da reabilitação das pessoas com deficiência, enfocando habilidade física e autonomia motora com utilização das órteses, próteses e meios auxiliares. Os temas abordados são: Contexto e pressupostos: pessoas com deficiências, direitos, políticas públicas e inclusão social; A atenção à saúde das pessoas com deficiência; Habilidade física e motora

Curso Uso Terapêutico de Tecnologias Assistivas [2014]

O curso Uso Terapêutico de Tecnologias Assistivas (2014) integra um conjunto de quatro qualificações sobre o tema. Pretende promover atualização sobre o uso terapêutico das tecnologias assistivas no âmbito da habilitação e da reabilitação das pessoas com deficiência. Busca-se colaborar à proposta da Rede de Cuidados a Pessoa com Deficiência: a criação, ampliação e articulação de pontos de atenção à saúde para atender as pessoas com deficiência, com o objetivo de promoção do cuidado a saúde, prevenção e identificação precoce de deficiências em todas as fases da vida. Busca, ainda, atender à ampliação da oferta de órteses, próteses e meios auxiliares de locomoção e de capacidade visual e auditiva, bem como dos cuidados em habilitação e reabilitação, para promover a reinserção social das pessoas com deficiência. O curso está dividido em 5 unidades: Unidade 1. Tecnologias assistivas: direitos das pessoas com deficiência Unidade 2. Tecnologias assistivas: habilidade física e autonomia motora Unidade 3. Tecnologias assistivas: visão Unidade 4. Tecnologias assistivas: audição Unidade 5. Tecnologias assistivas: ampliação da comunicação

Força muscular e índice de fadiga dos extensores e flexores do joelho de jogadores profissionais de futebol de acordo com o posicionamento em campo / Muscular strength and fatigue index of knee extensors and flexors of professional soccer players according to their positioning in field / Fuerza muscular e índice de fatiga de los extensores y flexores de las rodillas de jugadores profesionales de fútbol, de acuerdo con el posicionamento en campo

INTRODUÇÃO: Assimetrias na capacidade de produção de força entre músculos dos membros inferiores e fadiga muscular podem favorecer a ocorrência de lesões em atletas de futebol. Considerando-se que existem diferenças individuais determinadas pelas diversas funções exercidas pelos jogadores, é possível que a presença de assimetrias de força e fadiga muscular esteja relacionada ao posicionamento em campo. OBJETIVOS: 1) Investigar diferenças na assimetria de pico de torque (PT), na assimetria de trabalho (T) e no índice de fadiga (IF) dos extensores e flexores do joelho de atletas profissionais de futebol de acordo com a posição em campo; e 2) Determinar se o IF dos flexores é superior ao dos extensores. MÉTODOS: Foram analisadas avaliações isocinéticas de 164 atletas profissionais de futebol (atacantes, zagueiros, laterais, meio-campistas e goleiros). O protocolo para avaliação da força concêntrica dos extensores e flexores do joelho consistiu em cinco repetições a 60°/s e 30 repetições a 300°/s. O teste de Kruskall-Wallis foi utilizado para verificar diferenças na assimetria de PT, assimetria de T e IF dos extensores e flexores do joelho entre jogadores de diferentes posicionamentos. O teste de Wilcoxon foi realizado para verificar se havia diferença entre o IF dos extensores e flexores. RESULTADOS: Não houve diferença entre os jogadores dos cinco posicionamentos para as assimetrias de PT e T, bem como para o IF dos extensores e flexores (p > 0,05). O IF flexor foi superior ao extensor em ambos os membros inferiores (p < 0,01). CONCLUSÃO: Variáveis isocinéticas comumente associadas a lesões não foram diferentes entre jogadores de diferentes posicionamentos. Os atletas apresentaram o IF flexor superior ao extensor, o que pode estar relacionado à maior frequência de estiramentos dos isquiossurais em comparação ao quadríceps.

INTRODUCTION: Strength asymmetry among the muscles of the lower limbs and muscle fatigue may predispose soccer players to injuries. Regarding the individual differences determined by diverse roles performed by players, it is possible that the presence of asymmetries of muscle strength and fatigue is related to playing position. OBJECTIVES: 1) To investigate differences in asymmetry of peak torque (PT), work asymmetry (W) and fatigue index (FI) of knee extensors and flexors of professional soccer players according to their positioning in field; 2) To determine if FI of knee flexors is higher than those of knee extensors. METHODS: Data from isokinetic assessment of 164 professional soccer players (forwards, fullbacks, wingers, midfielders and goalkeepers) were analyzed. The protocol of evaluation of concentric strength of knee extensors and flexors consisted of five repetitions at 60°/s and 30 repetitions at 300°/s. Kruskall-Wallis test was carried out to verify differences in PT asymmetry, W asymmetry and FI of knee extensors and flexors among players of different positions. The Wilcoxon test was performed to verify if there is difference between FI of knee extensors and flexors. RESULTS: There was no difference among playing positions for asymmetries of PT and W, as well as for FI of knee extensors and flexors (p > 0.05). The FI of knee flexors was higher than FI of knee extensors in both lower limbs (p < 0.01). CONCLUSION: Isokinetic variables, commonly associated with injuries, were not different among players of different positions. The athletes had flexor FI higher than extensor FI, which can be related to greater frequency of strain injury of hamstrings in comparison to quadriceps.

INTRODUCCIÓN: Asimetrías en la capacidad de producción de fuerza entre músculos de los miembros inferiores y la fatiga muscular pueden favorecer la ocurrencia de lesiones en atletas de fútbol. Considerándose que existen diferencias individuales, determinadas por las diversas funciones desempeñadas por los jugadores, es posible que la presencia de asimetrías de fuerza y fatiga muscular esté relacionada con el posicionamiento en campo. OBJETIVOS: 1) Investigar diferencias en la asimetría de pico de torsión (PT), en la asimetría de trabajo (T) y en el índice de fatiga (IF) de los extensores y flexores de las rodillas de atletas profesionales de fútbol, de acuerdo con la respectiva posición en campo; y 2) Determinar si el IF de los flexores es superior al de los extensores. MÉTODOS: Se analizaron evaluaciones de 164 atletas profesionales de fútbol (delanteros, zagueros, laterales, mediocampistas y arqueros). El protocolo, para evaluación de la fuerza concéntrica de los extensores y flexores de las rodillas, consistió en cinco repeticiones a 60°/s y 30 repeticiones a 300°/s. La prueba de Kruskall-Wallis fue utilizada para verificar diferencias en la asimetría de PT, asimetría de T e IF de los extensores y flexores de rodillas entre jugadores de diferentes posicionamientos. La prueba de Wilcoxon fue realizada para verificar si había diferencia entre el IF de los extensores y flexores. RESULTADOS: No hubieron diferencias entre los jugadores de las cinco posiciones cuanto a las asimetrías de PT y T, así como para el IF de los extensores y flexores (p > 0,05). El IF del flexor fue superior al del extensor en ambos miembros inferiores (p < 0,01). CONCLUSIÓN: Las variables isocinéticas, comúnmente vinculadas a lesiones, no fueron diferentes entre jugadores en diversas posiciones. Los atletas presentaron el IF de flexor superior al del extensor, lo que puede estar relacionado con más frecuencia de estiramientos de los isquiosurales en comparación con el cuádriceps.

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.

Efeito dos exercícios de fortalecimento e alongamento sobre a rigidez tecidual passiva / Effect of strength and stretching training on tissue passive stiffness

INTRODUÇÃO: Níveis excessivos ou reduzidos de rigidez passiva dos músculos, tendões, ligamentos e fáscias podem estar relacionados à ocorrência de disfunções de movimento e ao desenvolvimento de lesões musculoesqueléticas. O tratamento dessas condições comumente envolve a aplicação de técnicas voltadas para alterar a rigidez, tais como fortalecimento ou alongamento. OBJETIVO: Realizar uma revisão crítica da literatura para investigar os efeitos de exercícios de fortalecimento e alongamento sobre a rigidez tecidual passiva. MATERIAIS E MÉTODOS: Foi realizada consulta aos bancos de dados Medline, Scielo, Lilacs e PEDro. Foram incluídos estudos experimentais realizados em animais ou humanos, sem limite de data. RESULTADOS: Foram selecionados 20 estudos que investigaram o efeito do fortalecimento sobre a rigidez passiva e 13 que pesquisaram o efeito de programas de alongamento sobre a rigidez passiva. CONCLUSÃO: Os estudos sugerem que exercícios de fortalecimento de alta intensidade são capazes de aumentar os níveis de rigidez tecidual tanto em animais quanto em humanos. O aumento da área de secção transversa e modificações na composição dos tecidos são alguns dos mecanismos responsáveis por esse aumento. Em relação ao fortalecimento muscular em posição alongada e ao fortalecimento excêntrico em toda amplitude com carga moderada, os resultados são insuficientes para afirmar sobre o real efeito dessas técnicas em reduzir os níveis de rigidez. Por fim, programas de alongamento estático ou do tipo contrai-relaxa parecem reduzir a rigidez tecidual quando realizados por meio de protocolos de longa duração e/ou alta frequência.

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.

Validity and reliability of clinical tests for assessing hip passive stiffness.

Inadequate levels of hip passive joint stiffness have been associated with the occurrence of movement dysfunction, development of pathologies and reduction in performance. Clinical tests, designed to evaluate hip joint stiffness, may allow the identification of improper stiffness levels. The purpose of this study was to determine the concurrent validity as well as the intra- and inter-examiners reliabilities of clinical measures used to assess hip passive stiffness during internal rotation. Fifteen healthy participants were subjected to test-retest evaluations by two examiners. Two clinical measures were performed: 'position of first detectable resistance' and 'change in passive resistance torque'. The results of these tests were compared to the passive stiffness measured with an isokinetic dynamometer (gold standard measure). A significant correlation was found between the stiffness measured with the isokinetic dynamometer and the clinical measures of 'position of first detectable resistance' (r=-0.85 to -0.86, p<0.001) and 'change in passive resistance torque' (r=0.78 to 0.84, p≤0.001). The Intraclass Correlation Coefficients for intra- and inter-examiners reliabilities varied from 0.95 to 0.99. Thus, the results demonstrated that the clinical measures have adequate validity and reliability for obtaining information on hip passive stiffness during internal rotation.