by Lee Wai Chi, Edwin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 115-125). / Acknowledgments --- p.I / List of figures --- p.II / List of tables --- p.III / List of graphs --- p.III / Abstract --- p.VIII / Chapter I.CHAPTER ONE --- Introduction --- p.1 / Chapter 1.1 --- Electromagnetic / Magnetic field in biological interventions --- p.1 / Chapter 1.2 --- Objective of the study --- p.4 / Chapter 1.3 --- Hypothesis of the study --- p.5 / Chapter II.CHAPTER TWO --- Literature Review --- p.6 / Chapter 2.1 --- Inflammation / Chapter 2.1.1 --- Models of studying tendon injuries --- p.6 / Chapter 2.1.2 --- Methods of measuring inflammation --- p.7 / Chapter 2.1.3 --- Treatments of soft tissue inflammation --- p.9 / Chapter 2.2 --- Aspects of electromagnetic and magnetic fields / Chapter 2.2.1 --- Applications of electromagnetic / magnetic fields in soft tissue inflammation --- p.12 / Chapter 2.2.2 --- Physiological effects of electromagnetic/magnetic fields / Chapter 2.2.2.1 --- Experiments on inflammation --- p.16 / Chapter 2.2.2.2 --- Experiments on soft tissue / tendon injuries --- p.16 / Chapter 2.2.2.3 --- Experiments on blood circulation --- p.18 / Chapter 2.2.3 --- Experiments with different parameter settings of PEMF / PMF in soft tissue inflammation --- p.19 / Chapter 2.2.4 --- Proposed mechanisms of electromagnetic/magnetic fields --- p.22 / Chapter III.CHAPTER THREE --- Methods and Materials --- p.23 / Chapter 3.1 --- Animal models --- p.23 / Chapter 3.2 --- Apparatus --- p.24 / Chapter 3.3 --- Treatment Regimen --- p.27 / Chapter 3.4 --- Assessments --- p.29 / Chapter IV.CHAPTER FOUR --- Histological Assessment --- p.30 / Chapter 4.1 --- Introduction --- p.30 / Chapter 4.2 --- Methods --- p.31 / Chapter 4.3 --- Results --- p.31 / Chapter 4.4 --- Discussions --- p.45 / Chapter V.CHAPTER FIVE --- Morphometrical analysis on tissue sections with immunochemical staining --- p.51 / Chapter 5.1 --- Introduction / Chapter 5.1.1 --- Different approaches in identification of macrophages --- p.51 / Chapter 5.1.2 --- Avidin-biotin enzyme complex assay --- p.52 / Chapter 5.2 --- Methods --- p.54 / Chapter 5.2.1 --- ABC method --- p.54 / Chapter 5.2.2 --- Morphometric analysis of tissue sections --- p.55 / Chapter 5.2.3 --- Statistical method --- p.56 / Chapter 5.3 --- Results / Chapter 5.3.1 --- Immunochemical results --- p.56 / Chapter 5.3.2 --- Morphometric results --- p.60 / Chapter 5.4 --- Discussions --- p.64 / Chapter VI.CHAPTER SIX --- Biochemical Assessments --- p.67 / Chapter 6.1 --- Water content / Chapter 6.1.1 --- Introduction --- p.67 / Chapter 6.1.2 --- Methods --- p.68 / Chapter 6.1.2.1 --- Water content measurement --- p.68 / Chapter 6.1.2.2 --- Statistical method --- p.69 / Chapter 6.1.3 --- Results --- p.72 / Chapter 6.1.4 --- Discussions --- p.77 / Chapter 6.2 --- Total collagen content / Chapter 6.2.1 --- Introduction --- p.81 / Chapter 6.2.1.1 --- Hydroxyproline as an indicator for collagen content assay --- p.81 / Chapter 6.2.2 --- Methods / Chapter 6.2.2.1 --- Hydrolysis method --- p.82 / Chapter 6.2.2.2 --- Standard-curve preparation --- p.83 / Chapter 6.2.2.3 --- Statstical method --- p.84 / Chapter 6.2.3 --- Results --- p.84 / Chapter 6.2.4 --- Discussions --- p.89 / Chapter VII.CHAPTER SEVEN --- Discussion --- p.92 / Chapter VIII.CHAPTER EIGHT --- Summary and Conclusions --- p.103 / Appendix A : Histological reagents preparations --- p.106 / Appendix B : Staining procedures for standard H & E --- p.107 / Appendix C : Immunochemical staining reagents preparations --- p.108 / Appendix D : Staining procedure for StreptABComplex / HRP --- p.110 / AppendixE : Biochemical reagents and preparations --- p.111 / Appendix F : Hydrolysis method for the tendon --- p.112 / Appendix G : Standard-curve of hydroxyproline --- p.113 / Appendix H : Determination of optimal hours for collagen hydrolysis --- p.114 / REFERENCES --- p.115

Honors Project--Smith College, Northampton, Mass., 2010. / Includes bibliographical references (p. 43-46)

Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 4 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 6 uppsatser.

Midportion Achilles tendinopathy (tendinosis) is a troublesome painful condition, often characterised by pain, local swelling, tenderness and functional disability. Despite extensive research, the pathogenesis is poorly understood and treatment remains challenging. Features related to the peritendinous connective tissue can be of importance. Recently it has been suggested that the plantaris tendon might be involved in this condition. Furthermore, it has been hypothesised that tendon pain and the tendinosis-related tissue changes in tendinopathy might be mediated by signalling substances such as glutamate and acetylcholine. A clinical observation, not scientifically evaluated, has been that unilateral treatment for bilateral Achilles tendinosis can lead to an effect on the contralateral side.      The aim of this work was to examine the morphology and innervation patterns in the plantaris tendon and the peritendinous connective tissue in between the Achillles and plantaris tendons in midportion Achilles tendinopathy, and to evaluate if plantaris tendon removal has an effect on Achilles tendon structure. Another aim was to determine if unilateral treatment for Achilles tendinopathy targeting the peritendinous connective tissue can result in bilateral recovery. Furthermore the presence of non-neuronal cholinergic and glutamate systems was examined.      Sections of plantaris tendons with adjacent peritendinous connective tissue from patients with midportion Achilles tendinopathy were stained for morphology (H&E), and innervation patterns were evaluated using antibodies against general nerve marker (PGP9.5), sensory (CGRP) and sympathetic (TH) nerve fibres and Schwann cells (S-100β). Furthermore immunostainings against non-neuronal aceylcholine (ChAT) and glutamate signalling components (glutamate, VGluT2, NMDAR1) were performed. Plantaris tendon cells were cultured and also stained for glutamate signalling components, and were stimulated with glutamate and glutamate receptor agonist NMDA. Furthermore, Ultrasound Tissue Characterisation (UTC) was used to monitor the integrity of the Achilles tendon collagen structure after plantaris tendon removal.      Plantaris tendons exhibited tendinosis-like tissue patterns such as hypercellularity, collagen disorganisation and large numbers of blood vessels. The peritendinous connective tissue between the plantaris and Achilles tendons contained large numbers of fibroblasts and blood vessels and to some extent macrophages and mast cells. A marked innervation was found in the peritendinous connective tissue and there were also nerve fibres in the loose connective tissue spaces within the tendon tissue proper. Most nerve fibres were identified as sensory fibres. Some nerve fascicles in the peritendinous connective tissue showed absence of axons but homogenous reactions for Schwann cell marker. Tenocytes and cells in the peritendinous connective tissue expressed ChAT, glutamate, VGluT2 and NMDAR1. Tendon cells in vitro expressed VGluT2, NMDAR1 and glutamate. UTC showed significant improvement of Achilles tendon integrity 6 months after surgical plantaris tendon removal and scraping procedure. Eleven out of thirteen patients reported of a bilateral recovery after unilateral surgical treatment.      The results of this work show that plantaris tendons exhibit tendinosis-like tissue changes, internal innervation and features that suggest occurrence of glutamate and acetylcholine production and signalling. Plantaris removal improves Achilles tendon structure suggesting possible compressive/shearing interference between the Achilles and plantaris tendons in tendinopathy. The peritendinous connective tissue shows marked innervation, which thus might transmit pain when being compressed. The partial absence of axons indicates a possible nerve degeneration. On the whole, the study gives new evidence favouring that the plantaris tendon and the peritendinous connective tissue might be of importance for pain and the tendinopathy process in midportion Achilles tendinopathy.

Introdução: os estudos sobre flexibilidade vêm tentando compreender quais propriedades explicam o aumento da amplitude de movimento (ADM), além do aumento de extensibilidade muscular. Propriedades mecânicas passivas de outros tipos de tecido, como o tendão, vêm sendo avaliadas, para entender a sua interferência no aumento da ADM. Desenho do estudo: o estudo foi do tipo ensaio clínico randomizado. Objetivos: analisar, minuto a minuto, o deslocamento da junção miotendínea (JMT) do músculo gastrocnêmio medial com o tendão do calcâneo e o torque passivo durante uma sessão de 10 minutos de alongamento estático passivo de flexores plantares, e analisar a mudança destas e de outras propriedades passivas mecânicas da unidade músculo-tendínea (UMT) do tríceps sural antes e após essa intervenção, verificando se estas mudanças perduram após 15, 30, 45 e 60 minutos após o protocolo de alongamento. Métodos: 30 participantes saudáveis foram divididos em grupo controle, o qual permaneceu em repouso, e experimental, o qual realizou uma sessão de 10 minutos de alongamento estático passivo no dinamômetro isocinético. Os participantes realizaram os testes de ADM, torque passivo, deslocamento da JMT e histerese antes e após a intervenção (0, 15, 30, 45 e 60 minutos). A partir dessas variáveis, foram calculadas as medidas de rigidez tendínea, muscular e da UMT. Resultados: Cinco participantes não permaneceram relaxados durante os testes e foram excluídos após análise dos dados eletromiográficos. 25 participantes foram incluídos na análise. Os resultados foram divididos em dois estudos diferentes. No primeiro estudo, apenas os 12 participantes do grupo experimental foram incluídos e, ao longo da intervenção, foi encontrada uma redução significativa do torque passivo, com a principal diferença ocorrendo nos minutos cinco e sete. No segundo estudo, foram comparados os indivíduos do grupo controle (n=13) e do grupo experimental (n=12), com um período de follow up de 60 minutos após a intervenção. A ADM aumentou e permaneceu aumentada até uma hora após a intervenção em ambos os grupos. As variáveis de deslocamento da JMT, rigidez muscular e histerese aumentaram em alguns momentos ao longo do tempo, sem diferença entre os grupos. A rigidez tendínea não apresentou diferença nem para grupo e nem para tempo. As variáveis de torque passivo e rigidez da UMT apresentaram uma interação significativa entre grupo e tempo, com uma redução das duas ao longo do tempo no grupo experimental. Conclusões: há uma redução de torque passivo ao longo de uma sessão de alongamento estático de 10 minutos dos flexores plantares de tornozelo, e fazer parte do grupo experimental influenciou no comportamento do torque passivo e da rigidez da UMT, levando a uma maior redução das mesmas para o grupo que realizou o alongamento. A ADM aumentou e permaneceu aumentada até uma hora após a intervenção. / Background: studies on flexibility have attempted to understand which properties explain increased range of motion (ROM), in addition to increased muscle extensibility. Mechanical and passive properties of other types of tissue, such tendon tissue, have been evaluated in order to understand their interference in increased ROM. Study Design: randomized clinical trial. Objectives: to analyze, minute by minute, myotendinous junction (MTJ) displacement of the medial gastrocnemius muscle with Achilles tendon and passive torque during a 10-minute passive static stretching of the ankle plantar flexors. To analyze, also, the time course change of these and other muscle-tendon unit (MTU) mechanical properties of the triceps surae before and after the intervention, verifying if the changes persist after 15, 30, 45 and 60 minutes after the stretching protocol. Methods: 30 healthy participants were divided into a control group, which remained at rest, and an experimental group, which performed a 10-minute passive static stretching on the isokinetic dynamometer. Participants performed tests of ROM, passive torque, MTJ displacement and hysteresis before and after the intervention (0, 15, 30, 45 and 60 minutes). From these variables, the measures of tendinous, muscular and MTU stiffness were calculated. Results: Five participants did not remain relaxed during the test and were excluded after electromyographic data analysis. 25 participants were included in the analysis. Results were divided into two different studies. In the first one, only 12 participants of experimental group were included and during the intervention, a significant reduction of the passive torque was found, with the main difference occurring in minutes five and seven. In the second study, individuals from control group (n=13) and experimental group (n=12) were compared, with a 60 minute follow-up period after the intervention. ADM increased and remained increased up to one hour after the intervention. The variables of MTJ displacement, muscular stiffness and hysteresis increased at some moments over time, with no difference between the groups. The tendinous stiffness showed no difference neither for group nor for time. The variables of passive torque and MTU stiffness showed a significant interaction between group and time, with a reduction of the two over time in the experimental group. Conclusions: passive torque decreased throughout a 10-minute passive static stretching of the ankle plantar flexors, and being part of the experimental group influenced the behavior of the passive torque and the MTU stiffness, leading to a greater reduction of the same for the group who performed the stretching.

The purpose of this study was to determine the functional changes due to the Graston Therapeutic Technique (GTT) in an animal model. This study attempted to verify the biomechanical changes associated with the Graston Therapeutic Technique (GTT) in order to possibly apply it to humans as a major physical therapy modality. Eighteen adult, male Sprague-Dawley rats were assigned randomly to three groups. The groups were classified as follows: (a) no injured plus GTT treatment, (b) injured minus GTT treatment, (c) injured plus GTT treatment. The GTT therapy began after one week following injury to allow for optimum inflammation and scar formation. The animals receiving GTT had six treatments over the course of two weeks. Running tests were performed on a treadmill at a velocity of 22 cm/s prior to induction of injury, one week following injury, two weeks following injury, and three weeksfollowing injury in the experimental groups. Variables analyzed were knee and ankle range of motion (ROM), stride length (SL), and stride frequency (SF). Significance of effect between experimental groups were determined by repeated measures one-way ANOVA, Scheffe's post hoc test, and Newman-Keuls post hoc test. The stride length and stride frequency results of the present study appeared to indicate that the Graston Therapeutic Technique (GTT) had an effect on changes in the stride length and stride frequency after injury. Statistical analysis between observations for the GTT plus groups indicated a significant difference in the swing phase of knee ROM. The results of this study also indicated that the Graston Therapeutic Technique may have had an influence on knee joint range of motion. / School of Physical Education

Introdução: os estudos sobre flexibilidade vêm tentando compreender quais propriedades explicam o aumento da amplitude de movimento (ADM), além do aumento de extensibilidade muscular. Propriedades mecânicas passivas de outros tipos de tecido, como o tendão, vêm sendo avaliadas, para entender a sua interferência no aumento da ADM. Desenho do estudo: o estudo foi do tipo ensaio clínico randomizado. Objetivos: analisar, minuto a minuto, o deslocamento da junção miotendínea (JMT) do músculo gastrocnêmio medial com o tendão do calcâneo e o torque passivo durante uma sessão de 10 minutos de alongamento estático passivo de flexores plantares, e analisar a mudança destas e de outras propriedades passivas mecânicas da unidade músculo-tendínea (UMT) do tríceps sural antes e após essa intervenção, verificando se estas mudanças perduram após 15, 30, 45 e 60 minutos após o protocolo de alongamento. Métodos: 30 participantes saudáveis foram divididos em grupo controle, o qual permaneceu em repouso, e experimental, o qual realizou uma sessão de 10 minutos de alongamento estático passivo no dinamômetro isocinético. Os participantes realizaram os testes de ADM, torque passivo, deslocamento da JMT e histerese antes e após a intervenção (0, 15, 30, 45 e 60 minutos). A partir dessas variáveis, foram calculadas as medidas de rigidez tendínea, muscular e da UMT. Resultados: Cinco participantes não permaneceram relaxados durante os testes e foram excluídos após análise dos dados eletromiográficos. 25 participantes foram incluídos na análise. Os resultados foram divididos em dois estudos diferentes. No primeiro estudo, apenas os 12 participantes do grupo experimental foram incluídos e, ao longo da intervenção, foi encontrada uma redução significativa do torque passivo, com a principal diferença ocorrendo nos minutos cinco e sete. No segundo estudo, foram comparados os indivíduos do grupo controle (n=13) e do grupo experimental (n=12), com um período de follow up de 60 minutos após a intervenção. A ADM aumentou e permaneceu aumentada até uma hora após a intervenção em ambos os grupos. As variáveis de deslocamento da JMT, rigidez muscular e histerese aumentaram em alguns momentos ao longo do tempo, sem diferença entre os grupos. A rigidez tendínea não apresentou diferença nem para grupo e nem para tempo. As variáveis de torque passivo e rigidez da UMT apresentaram uma interação significativa entre grupo e tempo, com uma redução das duas ao longo do tempo no grupo experimental. Conclusões: há uma redução de torque passivo ao longo de uma sessão de alongamento estático de 10 minutos dos flexores plantares de tornozelo, e fazer parte do grupo experimental influenciou no comportamento do torque passivo e da rigidez da UMT, levando a uma maior redução das mesmas para o grupo que realizou o alongamento. A ADM aumentou e permaneceu aumentada até uma hora após a intervenção. / Background: studies on flexibility have attempted to understand which properties explain increased range of motion (ROM), in addition to increased muscle extensibility. Mechanical and passive properties of other types of tissue, such tendon tissue, have been evaluated in order to understand their interference in increased ROM. Study Design: randomized clinical trial. Objectives: to analyze, minute by minute, myotendinous junction (MTJ) displacement of the medial gastrocnemius muscle with Achilles tendon and passive torque during a 10-minute passive static stretching of the ankle plantar flexors. To analyze, also, the time course change of these and other muscle-tendon unit (MTU) mechanical properties of the triceps surae before and after the intervention, verifying if the changes persist after 15, 30, 45 and 60 minutes after the stretching protocol. Methods: 30 healthy participants were divided into a control group, which remained at rest, and an experimental group, which performed a 10-minute passive static stretching on the isokinetic dynamometer. Participants performed tests of ROM, passive torque, MTJ displacement and hysteresis before and after the intervention (0, 15, 30, 45 and 60 minutes). From these variables, the measures of tendinous, muscular and MTU stiffness were calculated. Results: Five participants did not remain relaxed during the test and were excluded after electromyographic data analysis. 25 participants were included in the analysis. Results were divided into two different studies. In the first one, only 12 participants of experimental group were included and during the intervention, a significant reduction of the passive torque was found, with the main difference occurring in minutes five and seven. In the second study, individuals from control group (n=13) and experimental group (n=12) were compared, with a 60 minute follow-up period after the intervention. ADM increased and remained increased up to one hour after the intervention. The variables of MTJ displacement, muscular stiffness and hysteresis increased at some moments over time, with no difference between the groups. The tendinous stiffness showed no difference neither for group nor for time. The variables of passive torque and MTU stiffness showed a significant interaction between group and time, with a reduction of the two over time in the experimental group. Conclusions: passive torque decreased throughout a 10-minute passive static stretching of the ankle plantar flexors, and being part of the experimental group influenced the behavior of the passive torque and the MTU stiffness, leading to a greater reduction of the same for the group who performed the stretching.

Introdução. Rupturas agudas do tendão de Aquiles afetam as propriedades mecânicas tendíneas. Estudos vêm preconizando o uso de mobilização precoce (tratamento acelerado) para evitar grandes prejuízos tendíneos. Entretanto, estudos que avaliem as propriedades mecânicas do tendão de Aquiles de humanos após ruptura total, submetidos à mobilização precoce, não foram encontrados na literatura específica da área. Objetivo: comparar as propriedades mecânicas e morfológicas do tendão de Aquiles entre pacientes submetidos a tratamento conservador e pacientes submetidos a tratamento acelerado (mobilização precoce) após a sutura do tendão de Aquiles. Materiais e Métodos: A amostra foi dividida intencionalmente em três grupos: controle (CTR; n=9), grupo conservador (CON; n=9; Pós-Cirúrgico: 28,3±3,6 meses) e grupo acelerado (ACE; n=9; Pós-Cirúrgico: 29,8±4,8 meses). Um dinamômetro isocinético foi utilizado para avaliação do torque dos grupos musculares flexores plantares e flexores dorsais do tornozelo. Foram obtidos os valores de área de secção transversa (AST) e comprimento do tendão (CT) de Aquiles. Para a avaliação da relação stress-strain os sujeitos realizaram duas contrações voluntárias máximas em rampa para flexão plantar no ângulo de 0º com duração de 10 segundos cada. Durante as duas contrações voluntárias máximas o deslocamento da JMT do músculo gastrocnêmio medial com o tendão de Aquiles foi verificado por meio de ultrassonografia utilizando uma sonda com arranjo linear. Simultaneamente a este procedimento, foi adquirido o sinal eletromiográfico do músculo tibial anterior, utilizado para a correção da força do tendão de Aquiles. As imagens necessárias para o cálculo do strain, bem como os sinais EMG e de torque foram sincronizados. Os valores máximos de stress, strain, força, deformação, módulo de Young, CT e AST foram comparados. Resultados: Não foram encontradas diferenças significativas nas propriedades mecânicas e morfológicas entre membros do grupo CTR. Não houve diferença significativa entre os membros saudáveis dos grupos CON e ACE e os do grupo CTR. Dessa forma, os membros saudáveis dos grupos CON e ACE foram utilizados como controle do membro lesão em ambos os grupos. Tanto no grupo CON, quanto no grupo ACE, o stress, a força e o módulo de Young apresentaram menores valores no membro lesionado, enquanto que o strain obtido em 10MPa e a AST foram maiores neste membro comparado ao contralateral saudável. Não houve diferença significativa no CT entre os membros, independente do grupo. Não foram encontradas diferenças significativas nas propriedades mecânicas, bem como na morfologia do tendão de Aquiles na comparação entre os membros lesionados dos grupos CON e ACE. Discussão: Esta maior complacência tendínea encontrada nos tendões lesados, independente do grupo, pode estar associada tanto as adaptações decorrentes da lesão que não recuperaram a níveis de normalidade, bem como a mudança nos hábitos de vida após a lesão. Além disso, o protocolo acelerado de reabilitação não foi capaz de reduzir as perdas advindas da ruptura tendínea. Tal resultado pode estar associado à especificidade do protocolo utilizado, que foi desenhado para ganho de flexibilidade no tornozelo e não para força muscular. Conclusão: Em um período mínimo de 21 meses de pós-operatório o tendão de Aquiles ainda apresenta efeitos deletérios da ruptura total nas propriedades estruturais e mecânicas do tendão. O protocolo de reabilitação utilizado não foi eficaz para a redução de tais efeitos. / Introduction. Acute Achilles tendon rupture affects the mechanical properties of the tendon. Despite the tendinous adaptations generated by decreased use, few studies have used early weight bearing (accelerated treatment) to avoid the large losses in the musculoskeletal tissues. In addition, studies that evaluated the mechanical properties of human Achilles tendon after acute rupture, subjected to early weight bearing were not found. Purpose: to compare the mechanical and morphological properties of the Achilles tendon between patients undergoing conservative and accelerated treatment, after Achilles tendon suture. Materials and Methods: subjects were intentionally allocated into three groups: control (CTR; n=9), conservative treatment (CON; n=9; Postsurgical time: 28.3±3.6 months) and accelerated treatment (ACC; n=9; Postsurgical time: 29.8±4.8 months). An isokinetic dynamometer was used to evaluate the torque production of ankle dorsi- and plantar-flexor muscles. The values of Achilles tendon cross sectional area (CSA) and length were obtained. To evaluate the stress-strain relation, patients were asked to produce two isometric maximal voluntary contractions during a ramp protocol (angle: neutral position; duration: 10 seconds) of the plantar flexor muscles. During the maximal contractions the displacement of the myotendinous junction of the gastrocnemius medialis muscle was evaluated by ultrasound with a linear array probe. Simultaneously, the electromyography (EMG) signal of the tibialis anterior was recorded, and used to correct the Achilles tendon force. The ultrasound images, EMG signals and torque were synchronized. The maximal values of stress, strain, force, displacement, Young’s modulus, tendon length and CSA were compared. Results: there were no significant differences in the morphological and mechanical properties between limbs in the CTR group. Moreover, there were no significant differences in the morphological and mechanical properties between healthy limbs amongst groups. Thus, the healthy limbs of the CON and ACC groups were used as control of the injured limb. In CON and ACC groups the stress, force and Young’s modulus had lower values in the injured limb compared to the contralateral healthy limb, while the strain obtained at 10MPa and the CSA were higher in the injured limb. There were no significant differences in the tendon length between groups and limbs. Moreover, there were no significant differences in the morphological and mechanical properties between injured limbs (CON and ACC). Discussion: The highest tendinous compliance found on the injured tendons, independent of the group might be associated to both the adaptations due to injury that did not return to normal healthy levels and to possible changes in the daily life activities after injury. In addition, the accelerated treatment was unable to reduce the losses due to tendon rupture. These results might be associated to the specificity of the rehabilitation protocol used that was designed for the gain of flexibility and not for strength gains. Conclusion: Twenty-one months post-surgery were unable to recover the deleterious effects of acute Achilles tendon rupture on the structural and mechanical tendon properties. The accelerated rehabilitation protocol was ineffective to reduce these deleterious effects.

Introdução: os estudos sobre flexibilidade vêm tentando compreender quais propriedades explicam o aumento da amplitude de movimento (ADM), além do aumento de extensibilidade muscular. Propriedades mecânicas passivas de outros tipos de tecido, como o tendão, vêm sendo avaliadas, para entender a sua interferência no aumento da ADM. Desenho do estudo: o estudo foi do tipo ensaio clínico randomizado. Objetivos: analisar, minuto a minuto, o deslocamento da junção miotendínea (JMT) do músculo gastrocnêmio medial com o tendão do calcâneo e o torque passivo durante uma sessão de 10 minutos de alongamento estático passivo de flexores plantares, e analisar a mudança destas e de outras propriedades passivas mecânicas da unidade músculo-tendínea (UMT) do tríceps sural antes e após essa intervenção, verificando se estas mudanças perduram após 15, 30, 45 e 60 minutos após o protocolo de alongamento. Métodos: 30 participantes saudáveis foram divididos em grupo controle, o qual permaneceu em repouso, e experimental, o qual realizou uma sessão de 10 minutos de alongamento estático passivo no dinamômetro isocinético. Os participantes realizaram os testes de ADM, torque passivo, deslocamento da JMT e histerese antes e após a intervenção (0, 15, 30, 45 e 60 minutos). A partir dessas variáveis, foram calculadas as medidas de rigidez tendínea, muscular e da UMT. Resultados: Cinco participantes não permaneceram relaxados durante os testes e foram excluídos após análise dos dados eletromiográficos. 25 participantes foram incluídos na análise. Os resultados foram divididos em dois estudos diferentes. No primeiro estudo, apenas os 12 participantes do grupo experimental foram incluídos e, ao longo da intervenção, foi encontrada uma redução significativa do torque passivo, com a principal diferença ocorrendo nos minutos cinco e sete. No segundo estudo, foram comparados os indivíduos do grupo controle (n=13) e do grupo experimental (n=12), com um período de follow up de 60 minutos após a intervenção. A ADM aumentou e permaneceu aumentada até uma hora após a intervenção em ambos os grupos. As variáveis de deslocamento da JMT, rigidez muscular e histerese aumentaram em alguns momentos ao longo do tempo, sem diferença entre os grupos. A rigidez tendínea não apresentou diferença nem para grupo e nem para tempo. As variáveis de torque passivo e rigidez da UMT apresentaram uma interação significativa entre grupo e tempo, com uma redução das duas ao longo do tempo no grupo experimental. Conclusões: há uma redução de torque passivo ao longo de uma sessão de alongamento estático de 10 minutos dos flexores plantares de tornozelo, e fazer parte do grupo experimental influenciou no comportamento do torque passivo e da rigidez da UMT, levando a uma maior redução das mesmas para o grupo que realizou o alongamento. A ADM aumentou e permaneceu aumentada até uma hora após a intervenção. / Background: studies on flexibility have attempted to understand which properties explain increased range of motion (ROM), in addition to increased muscle extensibility. Mechanical and passive properties of other types of tissue, such tendon tissue, have been evaluated in order to understand their interference in increased ROM. Study Design: randomized clinical trial. Objectives: to analyze, minute by minute, myotendinous junction (MTJ) displacement of the medial gastrocnemius muscle with Achilles tendon and passive torque during a 10-minute passive static stretching of the ankle plantar flexors. To analyze, also, the time course change of these and other muscle-tendon unit (MTU) mechanical properties of the triceps surae before and after the intervention, verifying if the changes persist after 15, 30, 45 and 60 minutes after the stretching protocol. Methods: 30 healthy participants were divided into a control group, which remained at rest, and an experimental group, which performed a 10-minute passive static stretching on the isokinetic dynamometer. Participants performed tests of ROM, passive torque, MTJ displacement and hysteresis before and after the intervention (0, 15, 30, 45 and 60 minutes). From these variables, the measures of tendinous, muscular and MTU stiffness were calculated. Results: Five participants did not remain relaxed during the test and were excluded after electromyographic data analysis. 25 participants were included in the analysis. Results were divided into two different studies. In the first one, only 12 participants of experimental group were included and during the intervention, a significant reduction of the passive torque was found, with the main difference occurring in minutes five and seven. In the second study, individuals from control group (n=13) and experimental group (n=12) were compared, with a 60 minute follow-up period after the intervention. ADM increased and remained increased up to one hour after the intervention. The variables of MTJ displacement, muscular stiffness and hysteresis increased at some moments over time, with no difference between the groups. The tendinous stiffness showed no difference neither for group nor for time. The variables of passive torque and MTU stiffness showed a significant interaction between group and time, with a reduction of the two over time in the experimental group. Conclusions: passive torque decreased throughout a 10-minute passive static stretching of the ankle plantar flexors, and being part of the experimental group influenced the behavior of the passive torque and the MTU stiffness, leading to a greater reduction of the same for the group who performed the stretching.