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Scott W. Cheatham and Russell Baker

body part using a 50% overlapping (distal to proximal) pattern with a relative elongation or stretch force range of 50% to 90% of the band length. 1 After application, the client performs up to a 2-minute “tissue flossing” intervention that may include various active and passive movements of the

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Scott W. Cheatham and Russell Baker

the mechanical properties of different KT brands. Three recent studies (2016–2019) have measured the material and mechanical properties of 23 different KT tape brands at different elongation lengths (25%–400% of resting length). 3 – 5 These studies used mechanical devices to test the tape and found a

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Keitaro Kubo, Hiroaki Kanehisa, and Tetsuo Fukunaga

The purposes of this study were to compare the elasticity of tendon and aponeurosis in human knee extensors and ankle plantar flexors in vivo and to examine whether the maximal strain of tendon was correlated to that of aponeurosis. The elongation of tendon and aponeurosis during isometric knee extension (n = 23) and ankle plantar flexion (n = 22), respectively, were determined using a real-time ultrasonic apparatus, while the participants performed ramp isometric contractions up to voluntary maximum. To calculate the strain values from the measured elongation, we measured the respective length of tendon and aponeurosis. For the knee extensors, the maximal strain of aponeurosis (12.1 ± 2.8%) was significantly greater than that of the patella tendon (8.3 ± 2.4%), p < 0.001. On the contrary, the maximal strain of Achilles tendon (5.9 ± 1.4%) was significantly greater than that of aponeurosis in ankle plantar flexors (2.7 ± 1.4%), p < 0.001. Furthermore, for both knee extensors and ankle plantar flexors there was no significant correlation between maximal strain of tendon and aponeurosis. These results would be important for understanding the different roles of tendon and aponeurosis during human movements and for more accurate muscle modeling.

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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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Eric Winters, Steven Doty, and Sean Newell

Objective:

To explore changes in bovine Achilles-tendon elasticity relative to 3 thermal conditions.

Design and Setting:

Posttest-only design with assignment by convenience. Manufactured-apparatus-clamped excised tendon, delivered tensile stress, and provided strain measures. Stress was increased at 1-minute intervals. Strain was observed for each level of stress. Before testing, cold-group tendons were submerged in cold water for 20 minutes. Heat-group tendons were tested in the presence of an ultraviolet lamp. A third group of tendons was tested at room temperature.

Subjects:

Frozen bovine Achilles tendons provided by a meat-rendering factory and segmented into 3 longitudinal strips.

Measurements:

Stress and strain were sequentially measured. Elastic region was identified, elastic-region Young's modulus determined, and elastic limit calculated.

Results:

Young's modulus for cold was 0.956 gigapascal (GPa; ± 0.0621); room temperature, 0.753 GPa (± 0.0624); and heat group, 0.487 GPa (± 0.0407). Significant differences were identified between each of the 3 conditions.

Conclusions:

A direct relationship was observed between imposed thermal energy and tendon elasticity. Thermal energy does not affect the elastic limit.

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Andrea Lucena Reis, Thaís Lucena Reis, Lucas Soares de Aguiar, José de Jesus Soares Reis, Thiago Lucena Reis, Lysleine Alves Deus, Rodrigo Vanerson Passos Neves, Hugo de Luca Corrêa, Fernando Sousa Honorato, Thais Branquinho de Araújo, Victor Lopes Silva, Bernardo Neme Ide, and Thiago Santos Rosa

aiming to measure the force obtained from elastic tubes using elongation percentage. 68 , 12 – 14 However, these studies have shown correlations and did not present statistical analysis of validity and reproducibility. Thus, more accurate analysis and the development of predictive equations for the

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Laura C. Slane, Stijn Bogaerts, Darryl G. Thelen, and Lennart Scheys

anatomical landmarks of the notch of the tibial tuberosity and the distal edge of the patella. 32 Using the synchronized goniometer data, this distance was then expressed as a function of the knee angle. Consequently, the whole tendon percent elongation was computed as the change in the bone

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Paige E. Rice, Kiisa Nishikawa, Kevin A. Zwetsloot, Amelia S. Bruce, Caroline D. Guthrie, and Sophia Nimphius

disciplines both entail muscle–tendon unit elongation to store elastic strain energy that is subsequently recovered upon shortening to enhance concentric performance. However, the modalities of dancing and running likely necessitate different muscle–tendon mechanics. Muscle–tendon interaction is not only

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Kosuke Fujita, Masatoshi Nakamura, Hiroki Umegaki, Takuya Kobayashi, Satoru Nishishita, Hiroki Tanaka, Satoko Ibuki, and Noriaki Ichihashi

, instead of muscle tendon unit stiffness as used in our study. We used the passive torque at the final angle during passive knee extension as the index of stretch tolerance, with an increase in this index indicating alteration in subjects’ sensory perception of muscle elongation. 17 – 19 It is well known

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Michael F. Joseph, Katherine Histen, Julia Arntsen, Lauren L’Hereux, Carmine Defeo, Derek Lockwood, Todd Scheer, and Craig R. Denegar

Context:

Achilles tendons (ATs) adapt to increased loading generated by long-term adoption of a minimalist shoe running style. There may be difference in the chronology and extent of adaptation between the sexes.

Objective:

To learn the chronology of AT adaptations in female and male runners who transitioned to a minimalist running style through a planned, progressive 12-wk transition program.

Design:

Prospective cohort study of well-trained, traditionally shod runners who transitioned to minimalist shoe running.

Setting:

Repeated laboratory assessment at baseline and 3, 12, and 24 wk after initiating transition program.

Participants:

Fifteen women and 7 men (of 29 enrolled) completed the study.

Main Outcome Measures:

The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force elongation curve and its derivatives at each time point.

Results:

Greater adaptations were observed in men than in women, with men generating more force and having greater increases in CSA, stiffness, and Young’s modulus and less elongation after 12 wk of training.

Conclusion:

Men demonstrated changes in AT properties that were consistent with increased loading of the triceps surae during exercise. The women demonstrated far smaller changes. Further investigation is warranted to understand when adaptations may occur in women and the implications of altered AT mechanical properties for performance and injury risk.