Kinematics and muscle forces in women with patellofemoral pain during the propulsion phase of the single leg triple hop test.

BACKGROUND: Approximately 25% of orthopedic knee conditions are related to patellofemoral pain (PFP), with young women being the most affected. It is thought that this condition is associated with modifications in the kinematics and muscle control patterns of the lower limb during weight-bearing support activities, which increases femur movement under the patella. OBJECTIVES: To compare kinematics and muscle induced acceleration patterns between PFP subjects and healthy controls during the preparation phase of the single leg triple hop test. STUDY DESIGN: Biomechanical analysis was performed using OpenSim. Ten physically active women (23.2 ±â€¯4 years, 59.3 ±â€¯5.8 kg, and 1.63 ±â€¯0.06 m) with no history of lower limb injury (CG) and 11 volunteers (23.5 ±â€¯2 years, 55.4 ±â€¯4.9 kg, and 1.66 ±â€¯0.04 m) with PFP (PFPG) were recruited. The participants performed a series of single leg triple hop tests while the ground reaction forces and kinematic data were recorded. RESULTS: Vector field statistical analysis indicated increased lumbar extension, anterior pelvic tilt, contralateral pelvic drop, and lower induced accelerations from the core and hip muscles in PFPG. CONCLUSION: PFP volunteers presented with alterations in lumbar muscle control associated with a possible compensatory pelvic strategy to minimize knee extensor moment.

Predicting muscle forces during the propulsion phase of single leg triple hop test.

Functional biomechanical tests allow the assessment of musculoskeletal system impairments in a simple way. Muscle force synergies associated with movement can provide additional information for diagnosis. However, such forces cannot be directly measured noninvasively. This study aims to estimate muscle activations and forces exerted during the preparation phase of the single leg triple hop test. Two different approaches were tested: static optimization (SO) and computed muscle control (CMC). As an indirect validation, model-estimated muscle activations were compared with surface electromyography (EMG) of selected hip and thigh muscles. Ten physically healthy active women performed a series of jumps, and ground reaction forces, kinematics and EMG data were recorded. An existing OpenSim model with 92 musculotendon actuators was used to estimate muscle forces. Reflective markers data were processed using the OpenSim Inverse Kinematics tool. Residual Reduction Algorithm (RRA) was applied recursively before running the SO and CMC. For both, the same adjusted kinematics were used as inputs. Both approaches presented similar residuals amplitudes. SO showed a closer agreement between the estimated activations and the EMGs of some muscles. Due to inherent EMG methodological limitations, the superiority of SO in relation to CMC can be only hypothesized. It should be confirmed by conducting further studies comparing joint contact forces. The workflow presented in this study can be used to estimate muscle forces during the preparation phase of the single leg triple hop test and allows investigating muscle activation and coordination.

Comparação de dois protocolos de alongamento para amplitude de movimento e força dinâmica / Comparison of two stretching protocols for range of motion and dynamic strength / Comparación de dos protocolos de estiramiento para amplitud de movimiento y fuerza dinámica

RESUMO Introdução: Apesar de existirem evidências sobre o efeito agudo do alongamento estático sobre a força dinâmica, pouco se sabe se o volume total do protocolo é mais importante do que o tempo individual dedicado a cada série. Objetivo: Verificar o efeito de duas rotinas distintas de alongamento estático com mesmo volume total, sobre a amplitude de movimento (ADM) passiva, a ativação muscular (EMGRMS e EMGFM) e o desempenho da força de resistência (10-RM). Métodos: Catorze indivíduos do sexo masculino foram submetidos a três procedimentos diferentes, de forma randomizada: a) condição controle (CC), b) alongamento estático fracionado (AL-30 s) e c) alongamento estático contínuo (AL-2 min.). Para medir a ADM usou-se o método de fotogrametria digital, e o desempenho da força e a ativação mioelétrica foram aferidos pelos testes de 10-RM no exercício leg press unilateral e pelo registro do sinal eletromiográfico do músculo vasto lateral (VL), respectivamente. Resultados: Houve diferença significativa na ADM nas comparações de AL-2 minutos vs. CC (P = 0,006) e AL-30 s vs. CC (P = 0,01). As duas condições de alongamento promoveram aumentos agudos significativos na ADM nas comparações anterior e imediatamente após (P = 0,0001; 144,2 ± 10,2 vs. 152,2 ± 10,5 para AL-30 s e 147,4 ± 11,9 vs. 155,1 ± 9,9 para AL-2 min.), porém, sem diferença entre os procedimentos. Não houve diferença significativa para nenhuma das outras variáveis testadas. Conclusão: Rotinas contínuas e fracionadas de alongamento estático com menor volume podem ser utilizadas para aumentar de forma aguda os níveis de ADM sem provocar prejuízo nos níveis de força ou de ativação muscular. Nível de Evidência II; ECRC de menor qualidade.

ABSTRACT Introduction: Although there is evidence of the acute effect of static stretching on dynamic force, it is not known whether the total volume of the protocol is more important than the individual time spent in each series. Objective: To evaluate the effect of two different static stretching routines with the same total volume on passive range of motion (ROM), muscle activation (EMGRMS and EMGFM) and the performance resistance force (10-RM). Methods: Fourteen male subjects underwent three different randomized procedures: a) control condition (CC); b) fractionated static stretching (SS-30 s), and c) continuous static stretching (SS-2 min.). To measure the ROM, the digital photogrammetry method was used, and the force performance and myoelectric activation were measured by the 10-RM test in the unilateral leg press exercise and by the electromyographic signal of the vastus lateralis (VL), respectively. Results: There was significant difference in the ROM in the comparison between SS-2 min. vs. CC (P=0.006) and SS-30 s vs. CC (P=0.01). Both stretching conditions promoted significant acute increases in ROM in the comparisons prior to and immediately after (P=0.0001, 144.2±10.2 vs. 152.2±10.5 for SS-30 s and 147.4±11.9 vs. 155.1±9.9 for SS-2 min.), but with no difference between procedures. There was no significant difference for any other variables tested. Conclusion: Continuous and fractionated static stretching routines with less volume can be used to acutely increase the ROM levels without causing damage to muscle strength or activation levels. Level of Evidence II; II; Lesser quality RCT.

RESUMEN Introducción: A pesar de que existen evidencias sobre el efecto agudo del estiramiento estático sobre la fuerza dinámica, poco se sabe si el volumen total del protocolo es más importante que el tiempo individual dedicado a cada serie. Objetivo: Verificar el efecto de dos rutinas distintas de estiramiento estático, con el mismo volumen total, sobre la amplitud de movimiento (ADM) pasiva, la activación muscular (EMGRMS y EMGFM) y el desempeño de la fuerza de resistencia (10-RM). Métodos: Catorce sujetos del sexo masculino se sometieron a tres procedimientos diferentes, de forma aleatorizada; a) condición de control (CC); b) estiramiento estático fraccionado (ES-30 s) y c) estiramiento estático continuo (ES-2 min.). Para medir la ADM se utilizó el método de fotogrametría digital, y el desempeño de la fuerza y la activación mioeléctrica fueron evaluados por las pruebas de 10-RM en el ejercicio de prensa de piernas unilateral y por registro de la señal electromiográfica del músculo vasto lateral (VL), respectivamente. Resultados: Se encontró una diferencia significativa en ADM en las comparaciones de ES-2 minutos vs. CC (P = 0,006) y ES-30 s vs. CC (P = 0,01). Las dos condiciones de estiramiento promovieron aumentos agudos significativos en la ADM en las comparaciones antes e inmediatamente después (P = 0,0001, 144,2 ± 10,2 vs. 152,2 ± 10,5 para ES-30 s y 147,4 ± 11,9 vs. 155,1 ± 9,9 para ES-2 min.), sin embargo, sin diferencia entre los procedimientos. No hubo diferencia significativa para ninguna de las otras variables probadas. Conclusión: Las rutinas continuas y fraccionadas de estiramiento estático con menor volumen pueden ser utilizadas para aumentar de forma aguda los niveles de ADM sin provocar daño en los niveles de fuerza o de activación muscular. Nivel de Evidencia II; ECRC de menor calidad.