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Josep C. Benítez-Martínez, Pablo Martínez-Ramírez, Fermín Valera-Garrido, Jose Casaña-Granell and Francesc Medina-Mirapeix

) and abnormal vascular structures (neovascularization [NV]), detected with Doppler ultrasound, have been shown to be an important source of patellar tendon pain. 5 – 7 In cases of tendinopathy, several histological findings have been suggested to be the cause of the changes observed in the pathology

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Carly C. Sacco, Erin M. Gaffney and Jesse C. Dean

. While less well studied than tactile enhancement, stochastic resonance can also be used to enhance muscle proprioceptive feedback. Early human 19 and animal 20 experiments found that white noise tendon vibration increases the stretch-sensitivity of muscle spindles embedded in the vibrated

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Christopher Tack, Faye Shorthouse and Lindsy Kass

[“what is the effect of dietary supplements on musculoskeletal tissue (e.g., cartilage, tendon, muscle, ligament) healing compared to placebo or other control?”] and was used to formulate a search of Google Scholar and PubMed to evaluate the quality/volume of the existing literature. This search produced

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Kurt Manal and Thomas S. Buchanan

Tendon develops force proportional to the distance it is stretched beyond its slack length. Tendon slack length is an important parameter for musculoskeletal models because it can greatly affect estimations of muscle force. Unfortunately, tendon slack length is a difficult parameter to measure, and therefore values for it are not often reported in the literature. In this paper we present a numerical method for estimating tendon slack length from architectural parameters of the muscle. Specifically, tendon slack length is computed iteratively from musculotendon lengths determined when a corresponding joint is held at two angles, and from knowledge of the muscle's optimal fiber length. Idealized data generated using SIMM were used to test the tendon slack length algorithm. The method converged to within 1% of the “true” tendon slack length specified in the SIMM model. The advantage of the method outlined in this paper is that it yields subject-specific estimates of tendon slack length, given subject-specific input parameters.

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Annika Kruse, Christian Schranz, Martin Svehlik and Markus Tilp

examination of the most commonly affected plantar flexor muscle-tendon unit and found alterations of both the gastrocnemius medialis and the Achilles tendon when compared with typically developing children. These alterations have included reduced muscle belly length ( 4 ) and volume ( 3 ). However, reports on

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Niell Elvin, Alex Elvin, Cornie Scheffer, Steven Arnoczky, Edwin Dillon and P. J. Erasmus

The etiology of patellar tendinopathy (jumper’s knee) has been attributed to a significant increase in patellar tendon torques associated with jumping. While some investigators have suggested that patellar tendon torques are greater during takeoff, little is known about the relative magnitudes of patellar tendon torques during takeoff and landing. We hypothesized that peak patellar tendon torques are greater in jump takeoff than in landing, and that there is a linear correlation between jump height and peak patellar tendon torque. Seven asymptomatic, recreational male athletes each performed a series of 21 jumps ranging from low to maximal height. A calibrated fiber-optic sensor, implanted transversely within the patellar tendon was used to measure the knee torque during takeoff and landing. There was no significant difference in the peak patellar tendon torque experienced during takeoff and landing within individuals. There was a moderate correlation (r = .64) between maximum takeoff patellar tendon torques and jump height. There was a weak correlation (r = .52) between maximum landing patellar tendon torques and jump height. There was a moderate correlation (r = .67) between maximum 60°/s isokinetic extension torque and maximum jump height. The lack of a strong correlation between jump height and patellar tendon forces during takeoff or landing suggests that these forces may be technique dependent. Therefore, modifying takeoff and/or landing techniques could reduce patellar tendon force and potentially lessen the incidence of patellar tendinopathy.

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Atsuki Fukutani and Toshiyuki Kurihara

Recent studies have reported that resistance training increases the cross-sectional areas (CSAs) of tendons; however, this finding has not been consistently observed across different studies. If tendon CSA increases through resistance training, resistance-trained individuals should have larger tendon CSAs as compared with untrained individuals. Therefore, in the current study, we aimed to investigate whether resistance training increases tendon CSAs by comparing resistance-trained and untrained individuals. Sixteen males, who were either body builders or rugby players, were recruited as the training group, and 11 males, who did not participate in regular resistance training, were recruited into the control group. Tendon CSAs and muscle volumes of the triceps brachii, quadriceps femoris, and triceps surae were calculated from images obtained by using magnetic resonance imaging. The volumes of the 3 muscles were significantly higher in the training group than in the control group (P < .001 for all muscles). However, a significant difference in tendon CSAs was found only for the distal portion of the triceps surae tendon (P = .041). These findings indicate that tendon CSA is not associated with muscle volume, suggesting that resistance training does not increase tendon CSA.

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Christina Davlin and Jody Jenike

Objective:

To present the case of a Division I female college basketball player with a complete Achilles tendon rupture.

Background:

A 19-year-old, female college basketball player ruptured her right Achilles tendon during preseason conditioning. She had no previous history of heel cord symptoms.

Treatment:

The athlete underwent open surgical repair of Achilles tendon. The athlete successfully progressed through a functional rehabilitation program focused on early mobilization and weight bearing. The rehabilitation program was continually modified to address deficiencies and to keep the athlete actively engaged. She was cleared for full, unrestricted activity 15 weeks and 3 days after surgery and returned to game participation in 16 weeks.

Conclusions:

This case provides evidence that early mobilization and weight bearing can be used while still protecting the repaired tendon.

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Taija Finni and Paavo V. Komi

During dynamic activities it is difficult to assess in vivo length changes in human tendon and aponeurosis. The present study compared the outcome of two methods during unilateral squat jump and drop jump performances of four volunteers. Tendinous tissue elongation of vastus lateralis muscle was estimated using either (a) direct measurement of in vivo fascicle length change and muscletendon length estimation (kinematic method), or (b) prediction using a quadratic force function in combination with direct tendon force measurement (force method). In the kinematic method the most critical measures contributing to the 10% uncertainty were the fascicle angle and fraction of the estimated fascicle length. The force method was most sensitive to resting length, with 1% error margin. Both methods predicted the same pattern of tendinous elongation because of the monotonic force/length relationship. The magnitude of length change, however, differed considerably between both methods. Based on the force method, the changes were only 20% (absolute values) or 30% (strain values) of those obtained with the kinematic method. On average, the maximum strains were 5% with the force method and 15% with the kinematic method. This difference can be explained by the fact that the kinematic method characterizes not only the changes in tendon length but also includes aponeurosis strain along the muscle belly. In addition, the kinematic method may be affected by non-uniform distribution of fascicle length change along the length of the muscle. When applying either method for estimating the patterns of tendon and tendinous tissue length changes during human locomotion, the given methodological considerations should be acknowledged.

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Senshi Fukashiro, Dean C. Hay and Akinori Nagano

This paper reviews the research findings regarding the force and length changes of the muscle-tendon complex during dynamic human movements, especially those using ultrasonography and computer simulation. The use of ultrasonography demonstrated that the tendinous structures of the muscle-tendon complex are compliant enough to influence the biomechanical behavior (length change, shortening velocity, and so on) of fascicles substantially. It was discussed that the fascicles are a force generator rather than a work generator; the tendinous structures function not only as an energy re-distributor but also as a power amplifier, and the interaction between fascicles and tendinous structures is essential for generating higher joint power outputs during the late pushoff phase in human vertical jumping. This phenomenon could be explained based on the force-length/velocity relationships of each element (contractile and series elastic elements) in the muscle-tendon complex during movements. Through computer simulation using a Hill-type muscle-tendon complex model, the benefit of making a countermovement was examined in relation to the compliance of the muscle-tendon complex and the length ratio between the contractile and series elastic elements. Also, the integral roles of the series elastic element were simulated in a cyclic human heel-raise exercise. It was suggested that the storage and reutilization of elastic energy by the tendinous structures play an important role in enhancing work output and movement efficiency in many sorts of human movements.