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1.
Gait Posture ; 75: 149-154, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31683185

RESUMO

BACKGROUND: Gastrocnemius medialis (GM) and lateralis (GL) act at the ankle complex in the sagittal and frontal planes and there is evidence that their actions can be somewhat uncoupled from each other. Some independence of GM and GL from each other could be advantageous, e.g. to stabilise the ankle complex in unstable walking conditions. Given the compartmentalised structure of the Achilles tendon, the sub-tendons of GM and GL may exhibit different elongation during plantarflexion contractions, particularly with the foot in different frontal plane positions. RESEARCH QUESTIONS: METHODS: Sub-tendon elongation was determined from 18 participants during ramped isometric plantarflexion contractions to 70% of their maximum voluntary contraction (MVC) level with the foot in neutral, inversion and eversion. One-dimensional statistical parametric mapping was applied to determine elongation differences. RESULTS: Elongation within a sub-tendon did not differ in the three foot positions. Elongation was similar between both sub-tendons at very low contraction levels, but GM sub-tendon elongation exceeded GL sub-tendon displacement significantly from 30% MVC. The elongation differences between the sub-tendons were not affected by foot position. SIGNIFICANCE: Greater GM sub-tendon elongation is likely caused by the greater force production capability of GM but may also indicate that the sub-tendons of GM and GL have different mechanical properties, which is currently unknown. Elongation differences were contraction level dependent suggesting that contributions of GM and GL to plantarflexion torque may also be contraction level dependent.


Assuntos
Articulação do Tornozelo/fisiologia , Pé/fisiologia , Músculo Esquelético/fisiologia , Tendões/fisiologia , Tendão do Calcâneo/fisiologia , Adulto , Feminino , Humanos , Contração Isométrica/fisiologia , Masculino , Pessoa de Meia-Idade , Torque
2.
J Sports Med Phys Fitness ; 59(10): 1684-1690, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31694362

RESUMO

BACKGROUND: Athletes in jumping and running sports have a high incidence of Achilles tendon (AT) injuries. We compared AT loading during jumping and landing phases in anteroposterior (AP) and mediolateral (ML) directions. METHODS: Sixteen males (age: 21.6±1.8 years, height: 178.4±6.4 cm, weight: 76.4±11.2 kg) performed single leg AP and ML jump-landings during both propulsive (jump) and braking (land) phases. Inverse dynamics and static optimization were used to determine muscle forces. AT cross sectional area was measured with ultrasound. AT force was divided by cross sectional area to determine stress while strain was determined from previous data. Two-way repeated measures analysis of variance (α=0.05) compared several variables (vertical ground reaction force (VGRF), ankle and knee angle, ankle joint muscle moment arm, external ankle moment arm, AT tendon force, stress, and strain) between movements (jump-landings) and directions (AP/ML). RESULTS: AT loading was higher during jump than land in the ML compared to AP direction. VGRF was higher during land versus jump with no direction effect (AP/ML). An interaction showed a higher VGRF during the AP land and ML jump. The ankle joint moment arm was lower in jump and AP direction at peak tendon stress. External ankle moment arm at peak tendon stress was higher in jump and ML direction with an interaction. A larger external ankle moment arm occurred in ML but the change was less in the jump. CONCLUSIONS: Higher tendon loading occurred during the jump and ML direction. This may provide insight into both injuries and rehabilitation efforts.


Assuntos
Tendão do Calcâneo/química , Tendão do Calcâneo/fisiologia , Adulto , Traumatismos do Tornozelo , Articulação do Tornozelo/fisiologia , Atletas , Fenômenos Biomecânicos/fisiologia , Humanos , Articulação do Joelho/fisiologia , Masculino , Movimento , Corrida , Adulto Jovem
3.
J Sports Sci ; 37(23): 2735-2743, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31506014

RESUMO

The capacity of foot-strike running patterns to influence the functional properties of the Achilles tendon is controversial. This study used transmission-mode ultrasound to investigate the influence of habitual running foot-strike pattern on Achilles tendon properties during barefoot walking and running. Fifteen runners with rearfoot (RFS) and 10 with a forefoot (FFS) foot-strike running pattern had ultrasound transmission velocity measured in the right Achilles tendon during barefoot walking (≈1.1 ms-1) and running (≈2.0 ms-1). Temporospatial gait parameters, ankle kinematics and vertical ground reaction force were simultaneously recorded. Statistical comparisons between foot-strike patterns were made using repeated measure ANOVAs. FFS was characterised by a significantly shorter stance duration (-4%), greater ankle dorsiflexion (+2°), and higher peak vertical ground reaction force (+20% bodyweight) than RFS running (P < .05). Both groups adopted a RFS pattern during walking, with only the relative timing of peak dorsiflexion (3%), ground reaction force (1-2%) and peak vertical force loading rates (22-23%) differing between groups (P < .05). Peak ultrasound transmission velocity in the Achilles tendon was significantly higher in FFS during walking (≈100 ms-1) and running (≈130 ms-1) than RFS (P < .05). Functional Achilles tendon properties differ with habitual footfall patterns in recreational runners.


Assuntos
Tendão do Calcâneo/fisiologia , Pé/fisiologia , Marcha/fisiologia , Corrida/fisiologia , Tendão do Calcâneo/diagnóstico por imagem , Adulto , Tornozelo/fisiologia , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Ultrassonografia , Adulto Jovem
4.
Elife ; 82019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31535975

RESUMO

Changes in cell proliferation define transitions from tissue growth to physiological homeostasis. In tendons, a highly organized extracellular matrix undergoes significant postnatal expansion to drive growth, but once formed, it appears to undergo little turnover. However, tendon cell activity during growth and homeostatic maintenance is less well defined. Using complementary methods of genetic H2B-GFP pulse-chase labeling and BrdU incorporation in mice, we show significant postnatal tendon cell proliferation, correlating with longitudinal Achilles tendon growth. Around day 21, there is a transition in cell turnover with a significant decline in proliferation. After this time, we find low amounts of homeostatic tendon cell proliferation from 3 to 20 months. These results demonstrate that tendons harbor significant postnatal mitotic activity, and limited, but detectable activity in adult and aged stages. It also points towards the possibility that the adult tendon harbors resident tendon progenitor populations, which would have important therapeutic implications.


Assuntos
Tendão do Calcâneo/crescimento & desenvolvimento , Ciclo Celular/genética , Proliferação de Células/fisiologia , Homeostase/genética , Tendão do Calcâneo/fisiologia , Animais , Matriz Extracelular/genética , Matriz Extracelular/fisiologia , Camundongos , Células-Tronco/metabolismo
5.
Foot Ankle Clin ; 24(3): 371-385, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31370991

RESUMO

The pathologic conditions of the Achilles tendon are best understood in the context of its unique anatomy and functional demands. Some of these unique considerations include its high physiologic load demands, microscopic tissue composition, muscular origin spanning the knee joint, intimate insertional relationship with the plantar fascia, sensory innervation, and vascular supply with watershed areas. Risks of both acute rupture and chronic tendinopathy are affected by the tendon's anatomy and its functional demands. The tendon's functional anatomy changes with advancing age, notably in its collagen composition and vascular supply.


Assuntos
Tendão do Calcâneo/anatomia & histologia , Tendão do Calcâneo/fisiologia , Tendinopatia/fisiopatologia , Traumatismos dos Tendões/fisiopatologia , Tendão do Calcâneo/lesões , Humanos , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/fisiologia , Ruptura
6.
Hand Surg Rehabil ; 38(5): 323-327, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31386923

RESUMO

The aim of this study was to evaluate the effect of vascularized and non-vascularized fascial flaps on tendon healing, specifically the maximum strain, maximum stress, elasticity and resistance of the repaired tendon. Rats were randomly divided into 3 groups: Group 1 - primary repair; Group 2 - vascularized pedicled fascial graft; Group 3 - non-vascularized free fascial graft. The rats were euthanized after 2 weeks and 40mm-long samples were taken from the Achilles tendon and gastrocnemius muscle. To evaluate the mechanical properties of the tendons, maximum load, maximum deformation, energy stored until yield point and stiffness on the load-deformation curve were measured. Based on this mechanical testing, the best group in terms of tissue strength and quality was the primary repair group. When the samples were examined individually, the two samples with the highest breaking force after the control group were in the pedicled graft group. The worst results overall were in the free graft group. We believe that if the blood flow is preserved for the fascial flap in the pedicled graft group, the tendon's breaking force would be higher.


Assuntos
Tendão do Calcâneo/fisiologia , Tendão do Calcâneo/cirurgia , Tecido Adiposo/transplante , Fáscia/transplante , Retalhos Cirúrgicos , Resistência à Tração/fisiologia , Tendão do Calcâneo/lesões , Animais , Modelos Animais , Ratos Wistar , Retalhos Cirúrgicos/irrigação sanguínea , Traumatismos dos Tendões/cirurgia
7.
J Sports Sci Med ; 18(3): 454-461, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31427867

RESUMO

Higher stiffness of the Achilles tendon (AT) and gastrocnemius have been found to be risk factors associated with Achilles tendinitis. Static stretching (SS) is one intervention that has been investigated to improve the flexibility and therefore reduce injury risk. Previous studies have investigated the acute effect of SS on one region for AT and gastrocnemius morphology and stiffness; however, there is a lack of knowledge about the effect of SS on other regions of the AT and gastrocnemius (e.g., proximal vs. distal, within gastrocnemius). The aims of the present study were: (1) to investigate the acute effects of SS on the shear modulus of the medial gastrocnemius muscles (MG) and lateral gastrocnemius muscles (LG) and AT for different regions; (2) to examine the differences in range of motion (ROM) before and after SS; and (3) to investigate the change of thickness of AT and fascicle length of MG and LG before and after SS. The stiffness of AT and the gastrocnemius, fascicle length of the muscles, thickness of the AT, and maximal ankle joint dorsiflexion angle were measured in thirty healthy subjects (15 males, 15 females) before(pre) and immediately after (post) 5-minute SS. Stretching effects are not homogeneous among different regions. After SS administration, the proximal, middle, and distal regions of MG stiffness decreased by 34.12%, 22.45%, and 25.27%, respectively (p = 0.000), and LG stiffness decreased by 37.71%, 30.47%, and 22.13%, respectively (p = 0.000), whereas AT stiffness increased by 25.73%, 17.01%, and 19.53%, respectively (p= 0.000). ROM of ankle joint increased by 8.02% (p=0.00). Nevertheless, there were no changes in the thickness of AT and fascicle length of the gastrocnemius. These results suggest that non-uniform behaviour is consistently present within the gastrocnemius and AT, and the gastrocnemius heterogeneity is reduced after SS. The stretching maneuver could be effective to increase the flexibility.


Assuntos
Tendão do Calcâneo/fisiologia , Exercícios de Alongamento Muscular/métodos , Músculo Esquelético/fisiologia , Tendão do Calcâneo/anatomia & histologia , Tendão do Calcâneo/diagnóstico por imagem , Articulação do Tornozelo/fisiologia , Módulo de Elasticidade/fisiologia , Técnicas de Imagem por Elasticidade , Feminino , Humanos , Masculino , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/diagnóstico por imagem , Amplitude de Movimento Articular/fisiologia , Adulto Jovem
8.
Hum Mov Sci ; 67: 102494, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31326740

RESUMO

Achilles tendinopathy is the most frequent foot overuse injury in ballet dancers and knowledge of clinically modifiable factors related to tendon structure in a population at risk, such as ballet dancers, would be important for the development of preventive programs. Therefore, the present study aimed to assess relationships of gastrocnemius muscle architecture and ankle plantar flexors function with Achilles tendon morphology in ballet dancers. Fifty-four measures from 27 ballet dancers were collected. Tendon morphology (thickness, echogenicity, hypoechoic areas and neovascularisation) and muscle architecture (thickness, pennation angle and fascicle length) were evaluated using ultrasonography; ankle plantar flexors torque was evaluated using hand-held dynamometry, flexibility was evaluated in maximal weight-bearing ankle dorsiflexion position using inclinometer, and endurance was evaluated using the heel rise test. Ankle plantar flexors torque and medial gastrocnemius muscle architecture (thickness, pennation angle and fascicle length) are associated with Achilles tendon thickness in ballet dancers (r2 = 0.24, p = 0.008). Ankle plantar flexors torque and medial gastrocnemius muscle fascicle length are also associated with the echogenicity of the Achilles tendon (r2 = 0.13, p = 0.03). These findings call attention to the potential importance of ankle plantar flexors muscle force in healthy ballet dancers for the prevention of alterations in Achilles tendon structure.


Assuntos
Tendão do Calcâneo/anatomia & histologia , Dança/fisiologia , Músculo Esquelético/anatomia & histologia , Tendão do Calcâneo/diagnóstico por imagem , Tendão do Calcâneo/fisiologia , Adolescente , Adulto , Articulação do Tornozelo/diagnóstico por imagem , Articulação do Tornozelo/fisiologia , Feminino , Humanos , Masculino , Força Muscular/fisiologia , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologia , Amplitude de Movimento Articular/fisiologia , Torque , Ultrassonografia , Suporte de Carga/fisiologia , Adulto Jovem
9.
J Sports Sci Med ; 18(2): 327-336, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31191103

RESUMO

The purpose of this study was to examine the acute effects of short-term Achilles tendon vibration on plantar flexor torque, twitch contractile properties as well as muscle and cortical activity in young athletes. Eleven female elite soccer players aged 15.6 ± 0.5 years participated in this study. Three different conditions were applied in randomized order: Achilles tendon vibration (80 Hz) for 30 and 300 s, and a passive control condition (300 s). Tests at baseline and following conditions included the assessment of peak plantar flexor torque during maximum voluntary contraction, electrically evoked muscle twitches (e.g., potentiated twitch peak torque [PT]), and electromyographic (EMG) activity of the plantar flexors. Additionally, electroencephalographic (EEG) activity of the primary motor and somatosensory cortex were assessed during a submaximal dynamic concentric-eccentric plantar flexion exercise using an elastic rubber band. Large-sized main effects of condition were found for EEG absolute alpha-1 and beta-1 band power (p ≤ 0.011; 1.5 ≤ d ≤2.6). Post-hoc tests indicated that alpha-1 power was significantly lower at 30 and 300 s (p = 0.009; d = 0.8) and beta-1 power significantly lower at 300 s (p < 0.001; d = 0.2) compared to control condition. No significant effect of condition was found for peak plantar flexor torque, electrical evoked muscle twitches, and EMG activity. In conclusion, short-term local Achilles tendon vibration induced lower brain activity (i.e., alpha-1 and beta-1 band power) but did not affect lower limb peak torque, twitch contractile properties, and muscle activity. Lower brain activity following short-term local Achilles tendon vibration may indicate improved cortical function during a submaximal dynamic exercise in female young soccer players.


Assuntos
Tendão do Calcâneo/fisiologia , Córtex Motor/fisiologia , Contração Muscular , Músculo Esquelético/fisiologia , Córtex Somatossensorial/fisiologia , Torque , Vibração , Adolescente , Atletas , Estudos Cross-Over , Eletroencefalografia , Eletromiografia , Feminino , Humanos , Dinamômetro de Força Muscular , Futebol
10.
Ultrasound Med Biol ; 45(7): 1574-1585, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31076233

RESUMO

The purposes of this study were to (i) evaluate the intra-rater reliability of estimating Achilles tendon mechanical properties with continuous shear wave elastography (cSWE), (ii) propose an equivalent shear modulus comparable to Supersonic Shear Imaging, (iii) demonstrate construct validity of cSWE and (iv) explore relationships between tensile and shear properties. Achilles tendon mechanical properties were estimated with cSWE at four time points throughout a 4-h period and at a 2-wk follow up. Additionally, properties were estimated with cSWE across four different ankle positions. In these four positions, B-mode ultrasound imaging and dynamometry were used to quantify Young's modulus. Intra-rater reliability was fair-to-excellent for Achilles tendon mechanical properties estimated with cSWE. Construct validity was demonstrated with increased ankle dorsiflexion leading to increased mechanical properties. Linear relationships were found between tensile and shear mechanical properties. Findings demonstrate that cSWE has sufficient intra-rater reliability and validity for estimating Achilles tendon mechanical properties.


Assuntos
Tendão do Calcâneo/anatomia & histologia , Tendão do Calcâneo/fisiologia , Técnicas de Imagem por Elasticidade/métodos , Adulto , Módulo de Elasticidade , Feminino , Humanos , Masculino , Reprodutibilidade dos Testes , Adulto Jovem
11.
J Foot Ankle Res ; 12: 30, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31139262

RESUMO

Background: Mechanical and morphological properties of the Achilles tendon are altered in disease and in response to changes in mechanical loading. In the last few years different ultrasound based technologies have been used to detect tendon mechanical properties changes mainly in resting condition. Therefore the aim of this study was to evaluate if strain sonoelastography can identify changes in Achilles tendon elasticity during isometric contractions of increasing intensity. Methods: This cross-sectional study enrolled 37 healthy volunteers (19 women) with mean (±SD) age of 27.1 (±7.0) years between January and June 2017. Strain sonoelastography images of the Achilles tendon were acquired during an isometric ramp force (0 kg, 0.5 kg, 1 kg, 2 kg, 5 kg and, 10 kg). An external reference material was used to provide a comparison between the examined tissue and a material of constant elasticity. Friedman test with post hoc pairwise comparison were used to determine the correlation between the difference contraction levels. Results: The median and interquartile range (IQR) values for the strain ratio were 1.61 (1.5-2.9) in a relaxed state and 1.30 (1.07-2.02), 1.00 (0.76-1.66), 0.81 (0.70-1.19), 0.47 (0.39-0.73) and 0.33 (0.28-0.40) for 0.5 kg, 1 kg, 2 kg, 5 kg and 10 kg, respectively revealing increased tendon hardness with increasing contraction intensities. Friedman test revealed significant differences (p < 0.05) in the strain ratio between all contractions except between 0.5 kg - 1 kg (p = 0.41); 1 kg - 2 kg (p = 0.12) and 5 kg - 10 kg (p = 0.12). Conclusion: Strain sonoelastography can detect changes in Achilles tendon elasticity between different contraction intensities. The results provide an original force-elasticity curve for the Achilles tendon in a healthy, asymptomatic population. Trial registration: The study was approved by the Ethics Committee of Canton Ticino.


Assuntos
Tendão do Calcâneo/diagnóstico por imagem , Técnicas de Imagem por Elasticidade/métodos , Contração Isométrica/fisiologia , Tendão do Calcâneo/fisiologia , Adulto , Articulação do Tornozelo/fisiologia , Fenômenos Biomecânicos , Estudos Transversais , Elasticidade , Feminino , Voluntários Saudáveis , Humanos , Masculino , Dinamômetro de Força Muscular , Estudos Prospectivos , Amplitude de Movimento Articular/fisiologia , Adulto Jovem
12.
J Sports Sci ; 37(17): 1972-1980, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31032698

RESUMO

This study aimed to investigate the influence of foot strike patterns on the behaviour of the triceps surae muscle-tendon unit, including the Achilles tendon whose length nearly corresponds to force of the triceps surae, and the medial gastrocnemius muscle (MG) during running. Seven male volunteers ran with forefoot and rearfoot strikes at 10, 14 and 18 km h-1 on a treadmill. The MG fascicle length was measured using ultrasonography. The in vivo length of the curved Achilles tendon was quantified by combining ultrasonography with optical motion capture of reflective markers on the right lower limb and an ultrasound probe. The forefoot strike resulted in a significantly shorter MG fascicle length at the initial contact, at Achilles tendon peak elongation, and at toe-off, than the rearfoot strike. The Achilles tendon length at initial contact was greater during the forefoot strike than during the rearfoot strike at 18 km h-1, while its peak elongation was not significantly different during forefoot and rearfoot running. These results indicate that the MG, with a shorter length during forefoot running, manages to address demands for a similar peak force of the triceps surae than during rearfoot running.


Assuntos
Pé/fisiologia , Marcha , Músculo Esquelético/fisiologia , Corrida/fisiologia , Tendão do Calcâneo/fisiologia , Fenômenos Biomecânicos , Humanos , Masculino , Ultrassonografia , Adulto Jovem
13.
PLoS One ; 14(4): e0215595, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31002728

RESUMO

Biomechanical research on tendon tissue evaluating new treatment strategies to frequently occurring clinical problems regarding tendon degeneration or trauma is of expanding scientific interest. In this context, storing tendon tissue deep-frozen is common practice to collect tissue and analyze it under equal conditions. The commonly used freezing medium, phosphate buffered saline, is known to damage cells and extracellular matrix in frozen state. Dimethyl sulfoxide, however, which is used for deep-frozen storage of cells in cell culture preserves cell vitality and reduces damage to the extracellular matrix during freezing. In our study, Achilles tendons of 26 male C57/Bl6 mice were randomized in five groups. Tendons were deep frozen in dimethyl sulfoxide or saline undergoing one or four freeze-thaw-cycles and compared to an unfrozen control group analyzing biomechanical properties, cell viability and collagenous structure. In electron microscopy, collagen fibrils of tendons frozen in saline appeared more irregular in shape, while dimethyl sulfoxide preserved the collagenous structure during freezing. In addition, treatment with dimethyl sulfoxide preserved cell viability visualized with an MTT-Assay, while tendons frozen in saline showed no remaining metabolic activity, indicating total destruction of cells during freezing. The biomechanical results revealed no differences between tendons frozen once in saline or dimethyl sulfoxide. However, tendons frozen four times in saline showed a significantly higher Young's modulus over all strain rates compared to unfrozen tendons. In conclusion, dimethyl sulfoxide preserves the vitality of tendon resident cells and protects the collagenous superstructure during the freezing process resulting in maintained biomechanical properties of the tendon.


Assuntos
Tendão do Calcâneo/efeitos dos fármacos , Criopreservação/métodos , Dimetil Sulfóxido/farmacologia , Módulo de Elasticidade/efeitos dos fármacos , Tendão do Calcâneo/citologia , Tendão do Calcâneo/fisiologia , Animais , Fenômenos Biomecânicos/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Crioprotetores/farmacologia , Módulo de Elasticidade/fisiologia , Masculino , Camundongos Endogâmicos C57BL
14.
J Sci Med Sport ; 22(8): 882-886, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31000456

RESUMO

OBJECTIVES: Although expected, tendon adaptations in adolescent elite athletes have been underreported. Morphologically, adaptations may occur by an increase in collagen fiber density and/or organization. These characteristics can be captured using spatial frequency parameters extracted from ultrasound images. This study aims to compare Achilles tendon (AT) morphology among sports-specific cohorts of elite adolescent athletes and to compare these findings to recreationally active controls by use of spatial frequency analysis. DESIGN: Cross-sectional observational study. METHOD: In total, 334 healthy adolescent athletes from four sport categories (ball, combat, endurance, explosive strength) and 35 healthy controls were included. Longitudinal ultrasound scans were performed at the AT insertion and midportion. Intra-tendinous-morphology was quantified by performing spatial frequency analysis assessing eight parameters at standardized ROIs. Increased values in five parameters suggest a higher structural organization, and in two parameters higher fiber density. One parameter represents a quotient combining both organization and fiber density. RESULTS: Among athletes, only ball sport athletes exhibited an increase in one summative parameter at pre-insertion site compared to athletes from other sport categories. When compared to athletes, controls had significantly higher values of four parameters at pre-insertion and three parameters at midportion site reflecting differences in both, fiber organization and density. CONCLUSIONS: Intra-tendinous-morphology was similar in all groups of adolescent athletes. Higher values found in non-athletes might suggest higher AT fiber density and organization. It is yet unclear whether the lesser structural organization in young athletes represents initial AT pathology, or a physiological adaptive response at the fiber cross-linking level.


Assuntos
Tendão do Calcâneo/diagnóstico por imagem , Tendão do Calcâneo/fisiologia , Adaptação Fisiológica , Atletas , Esportes/fisiologia , Ultrassonografia/métodos , Tendão do Calcâneo/anatomia & histologia , Adolescente , Estudos Transversais , Feminino , Humanos , Masculino
15.
PLoS One ; 14(3): e0213347, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30849114

RESUMO

In this study we investigated the relationships between muscle-tendon parameters and average/peak values of velocity, force and power in sprint running focusing on the acceleration phase. Eighteen male sprinters (100 m PB: 10.66±0.51 s) participated to the study. Instantaneous values of horizontal velocity (v) were recorded by means of a radar and instantaneous values of force (F) and power (P) were calculated based on these data. Muscle thickness, fascicle length and pennation angle of knee extensors and plantar flexors, as well as Achilles tendon length and CSA, were measured by means of ultrasonography. In the first 20 m of the sprint average and peak speed were 6.31±0.59 and 8.88±0.98 m·s-1, respectively; force was highest at the start of the sprint (Fpeak = 10.02±1.43 N·kg-1) and power peaked about 1 s after the start (26.64±5.99 W·kg-1). Muscle-tendon parameters showed stronger correlations with peak values of power (R range: 0.81-0.92), force (R range: 0.56-0.84) and speed (R range: 0.53-0.85) than with average values of velocity over the 20 m distance (R range: 0.41-0.61) (R <0.47 = NS; R >0.71 = P < .001). These data underline that the influence of muscle tendon parameters on sprint performance could be better appreciated when peak values of power can be calculated rather than by considering the simple measure of average velocity (e.g. distance/time).


Assuntos
Aceleração , Tendão do Calcâneo/fisiologia , Músculo Esquelético/fisiologia , Corrida/fisiologia , Tendão do Calcâneo/diagnóstico por imagem , Adulto , Desempenho Atlético/fisiologia , Fenômenos Biomecânicos , Humanos , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/fisiologia , Masculino , Músculo Esquelético/diagnóstico por imagem , Ultrassonografia , Adulto Jovem
16.
J Orthop Res ; 37(4): 805-811, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30737834

RESUMO

As cytotoxic (CD8+ ) T cells seem to impair shaft fracture healing, we hypothesized that depletion of CD8+ cells would instead improve healing of cancellous bone. Additionally, we also tested if CD8-depletion would influence the healing of ruptured Achilles tendons. Rats received a single injection of either anti-CD8 antibodies or saline and put through surgery 24 h later. Three different surgical interventions were performed as follows: (1) a drill hole in the proximal tibia with microCT (BV/TV) to assess bone formation; (2) a screw in the proximal tibia with mechanical evaluation (pull-out force) to assess fracture healing; (3) Achilles tendon transection with mechanical evaluation (force-at-failure) to assess tendon healing. Furthermore, CD8-depletion was confirmed with flow cytometry on peripheral blood. Flow cytometric analysis confirmed depletion of CD8+ cells (p < 0.001). Contrary to our hypothesis, depletion of CD8+ cells reduced the implant pull-out force by 19% (p < 0.05) and stiffness by 34% (p < 0.01), although the bone formation in the drill holes was the same as in the controls. Tendon healing was unaffected by CD8-depletion. Our results suggest that CD8+ cells have an important part in cancellous bone healing. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.


Assuntos
Tendão do Calcâneo/fisiologia , Regeneração Óssea/imunologia , Linfócitos T CD8-Positivos/fisiologia , Osso Esponjoso/fisiologia , Animais , Osso Esponjoso/diagnóstico por imagem , Masculino , Ratos Sprague-Dawley , Microtomografia por Raio-X
17.
J Orthop Res ; 37(3): 562-573, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30720208

RESUMO

Conservative (non-operative) treatment of Achilles tendon ruptures is a common alternative to operative treatment. Following rupture, ankle immobilization in plantarflexion is thought to aid healing by restoring tendon end-to-end apposition. However, early activity may improve limb function, challenging the role of immobilization position on tendon healing, as it may affect loading across the injury site. This study investigated the effects of ankle immobilization angle in a rat model of Achilles tendon rupture. We hypothesized that manipulating the ankle from full plantarflexion into a more dorsiflexed position during the immobilization period would result in superior hindlimb function and tendon properties, but that prolonged casting in dorsiflexion would result in inferior outcomes. After Achilles tendon transection, animals were randomized into eight immobilization groups ranging from full plantarflexion (160°) to mid-point (90°) to full dorsiflexion (20°), with or without angle manipulation. Tendon properties and ankle function were influenced by ankle immobilization position and time. Tendon lengthening occurred after 1 week at 20° compared to more plantarflexed angles, and was associated with loss of propulsion force. Dorsiflexing the ankle during immobilization from 160° to 90° produced a stiffer, more aligned tendon, but did not lead to functional changes compared to immobilization at 160°. Although more dorsiflexed immobilization can enhance tissue properties and function of healing Achilles tendon following rupture, full dorsiflexion creates significant tendon elongation regardless of application time. This study suggests that the use of moderate plantarflexion and earlier return to activity can provide improved clinical outcomes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.


Assuntos
Tendão do Calcâneo/lesões , Articulação do Tornozelo/fisiologia , Imobilização/métodos , Traumatismos dos Tendões/terapia , Tendão do Calcâneo/fisiologia , Animais , Masculino , Ratos Sprague-Dawley , Recuperação de Função Fisiológica
18.
Phys Ther Sport ; 36: 110-115, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30716561

RESUMO

OBJECTIVES: To determine normal temperatures over the Achilles tendon over nine weeks. DESIGN: A prospective cohort study with nine weeks of observation. SETTING: University's Human Biomechanics and Physiology Laboratory. PARTICIPANTS: Male or female competitive runners running at least 25 miles per week who did not report pain in the region of the Achilles over 9 weeks of data collection. MAIN OUTCOME MEASURE: Thermal images taken at the same time and day of the week, were used to measure the temperature of the skin over the Achilles tendon. RESULTS: Seventeen athletes were eligible for analysis. The Achilles tendon temperatures were right 28.7 °C ±â€¯1.3 °C, left 28.8 °C ±â€¯1.3 °C. ICC demonstrated a very high consistency and minimal variations in temperatures (right 0.86 (95% CI = 0.58, 0.98), left 0.79 (95% CI = 0.38, 0.97). The mean difference between sides over the season was 0.50 °C ±â€¯0.43 °C (p = 0.681). A decreasing trend in the Achilles tendon temperatures as the season progressed was observed. CONCLUSION: This is the first report of normal thermal profiles over an extended period. Variations in Achilles temperatures left to right, and over time were not significant. The decreasing temperature trend over the season warrants further investigation.


Assuntos
Tendão do Calcâneo/diagnóstico por imagem , Tendão do Calcâneo/fisiologia , Temperatura Corporal/fisiologia , Corrida/fisiologia , Termografia , Adolescente , Adulto , Atletas , Estudos de Coortes , Feminino , Humanos , Masculino , Adulto Jovem
19.
Acta Orthop Traumatol Turc ; 53(2): 145-149, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30638781

RESUMO

OBJECTIVE: The aim of study was to analyze the association between Quadriceps Angle (QA) and plantar pressure, navicular height (NH), and calcaneo-tibial angle (CTA). METHODS: A total of 64 volunteers (mean age: 22.25 ± 2.54 (range:19-33)) participated in this cross sectional study. EMED-m (Novel GmbH, Germany) electronic pedobarograph was employed for dynamic plantar pressure measurement using two step protocol. The angle between the vertical axis of calcaneus and the long axis of Achilles tendon for CTA. The height of navicular tubercle from the ground was measured while the subject was standing on both feet for NH. QA was measured while the subject was standing in a relaxed posture where both feet bearing equal weight. RESULTS: There were significant negative correlations between QA and maximum force (MxF) under the 4th. metatarsal head (MH4). The QA was also significantly correlated with MxF and force-time integral (FTI) under the bigtoe (BT). FTI under the 3rd. metatarsal head (MH3), MH4 and 5th. metatarsal head (MH5) were significantly negatively correlated with QA. Pressure-time integral (PTI) under the MH4 and MH5 were found to be significantly negatively correlated with QA. A significant correlation was also found between QA and NH (p < 0.0001), whilst there was no correlation between QA and CTA. Regression analysis showed that NH was appeared as the major contributor for the QA (ß = -0.49, p < 0.001) in the dynamic condition, followed by BT-FTI (ß = 0.37, p < 0.001) and MH5-MxF (ß = -0.21, p < 0.037). CONCLUSION: These findings may imply that the NH which can at least be controlled by appropriate shoe inserts may affect QA. This way, loading pattern of both plantar region and whole lower extremity may be altered. LEVEL OF EVIDENCE: Level III, Diagnostic Study.


Assuntos
Tendão do Calcâneo , Placa Plantar , Pressão , Músculo Quadríceps , Ossos do Tarso , Tendão do Calcâneo/anatomia & histologia , Tendão do Calcâneo/fisiologia , Adulto , Fenômenos Biomecânicos , Estudos Transversais , Feminino , Pé/fisiologia , Voluntários Saudáveis , Humanos , Masculino , Ortopedia/métodos , Placa Plantar/anatomia & histologia , Placa Plantar/fisiologia , Postura , Músculo Quadríceps/anatomia & histologia , Músculo Quadríceps/fisiologia , Análise de Regressão , Rotação , Sapatos , Ossos do Tarso/anatomia & histologia , Ossos do Tarso/fisiologia
20.
Sports Health ; 11(2): 157-162, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30601077

RESUMO

BACKGROUND:: Tendon overuse injuries are an issue in elite footballers (soccer players) and may affect tendon function. Achilles and patellar tendinopathy are the most frequent pathologies. Tendon stiffness, the relationship between the force applied to a tendon and the displacement exerted, may help represent tendon function. Stiffness is affected by training and pathology. Nevertheless, information regarding this mechanical property is lacking for elite soccer athletes. HYPOTHESIS:: Achilles and patellar tendon stiffness assessed using myotonometric measurements will be greater in elite soccer athletes than in control participants. STUDY DESIGN:: Cross-sectional study. LEVEL OF EVIDENCE:: Level 4. METHODS:: Forty-nine elite soccer athletes and 49 control participants were evaluated during the 2017 preseason. A handheld device was used to measure Achilles and patellar tendon stiffness. Dominant and nondominant limbs were assessed for both groups. RESULTS:: A significantly stiffer patellar tendon was found for both the dominant and the nondominant limb in the elite soccer athletes compared with the control group. Nevertheless, no differences were found in Achilles tendon stiffness between groups. When comparing between playing positions in soccer athletes, no significant differences were found for both tendons. CONCLUSION:: Greater patellar tendon stiffness may be related to an improvement in force transmission during muscle contraction. On the other hand, it seems that after years of professional training, Achilles tendon stiffness does not change, conserving the storing-releasing function of elastic energy. The nonsignificant differences between positions may be attributable to the years of homogeneous training that the players underwent. CLINICAL RELEVANCE:: The present study shows another technique for measuring mechanical properties of tendons in soccer athletes that could be used in clinical settings. In the future, this technique may help clinicians choose the best exercise protocol to address impairments in tendon stiffness.


Assuntos
Tendão do Calcâneo/fisiologia , Biometria/métodos , Ligamento Patelar/fisiologia , Futebol/fisiologia , Tendão do Calcâneo/lesões , Adulto , Fenômenos Biomecânicos , Estudos Transversais , Transtornos Traumáticos Cumulativos/fisiopatologia , Humanos , Contração Muscular , Ligamento Patelar/lesões , Futebol/lesões , Tendinopatia/fisiopatologia , Adulto Jovem
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