Reliability of human Achilles tendon stiffness measures using freehand 3-d ultrasound

Older adults walk slower and with a higher metabolic energy expenditure than younger adults. In this review, we explore the hypothesis that age-related declines in Achilles tendon stiffness increase the metabolic cost of walking due to less economical calf muscle contractions and increased proximal joint work. This viewpoint may motivate interventions to restore ankle muscle-tendon stiffness, improve walking mechanics, and reduce metabolic cost in older adults.

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Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length

Journal of Applied Physiology ◽

10.1152/japplphysiol.91476.2008 ◽

2009 ◽

Vol 106 (4) ◽

pp. 1249-1256 ◽

Cited By ~ 91

Author(s):

Anthony D. Kay ◽

Anthony J. Blazevich

Keyword(s):

Mechanical Properties ◽

Achilles Tendon ◽

Muscle Stiffness ◽

Triceps Surae ◽

Medial Gastrocnemius ◽

Static Stretch ◽

Tendon Stiffness ◽

Neuromuscular Activity ◽

Time Motion ◽

The Impact

The effects of static stretch on muscle and tendon mechanical properties and muscle activation were studied in fifteen healthy human volunteers. Peak active and passive moment data were recorded during plantar flexion trials on an isokinetic dynamometer. Electromyography (EMG) monitoring of the triceps surae muscles, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Subjects performed three 60-s static stretches before being retested 2 min and 30 min poststretch. There were three main findings in the present study. First, peak concentric moment was significantly reduced after stretch; 60% of the deficit recovered 30 min poststretch. This was accompanied by, and correlated with ( r = 0.81 ; P < 0.01) reductions in peak triceps surae EMG amplitude, which was fully recovered at 30 min poststretch. Second, Achilles tendon length was significantly shorter during the concentric contraction after stretch and at 30 min poststretch; however, no change in tendon stiffness was detected. Third, passive joint moment was significantly reduced after stretch, and this was accompanied by significant reductions in medial gastrocnemius passive muscle stiffness; both measures fully recovered by 30 min poststretch. These data indicate that the stretching protocol used in this study induced losses in concentric moment that were accompanied by, and related to, reductions in neuromuscular activity, but they were not associated with alterations in tendon stiffness or shorter muscle operating length. Reductions in passive moment were associated with reductions in muscle stiffness, whereas tendon mechanics were unaffected by the stretch. Importantly, the impact on mechanical properties and neuromuscular activity was minimal at 30 min poststretch.

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Biomechanics and Exercise

Pediatric Exercise Science ◽

10.1123/pes.2015-0033 ◽

2015 ◽

Vol 27 (1) ◽

pp. 34-38

Author(s):

Thomas D. O’Brien

Keyword(s):

Achilles Tendon ◽

Young’S Modulus ◽

Young's Modulus ◽

Plantar Flexion ◽

Tendon Injury ◽

Time Curve ◽

Tendon Stiffness ◽

Prepubertal Children ◽

Experimental Group ◽

Tendon Properties

Children develop lower levels of muscle force, and at slower rates, than adults. While strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strainrelated tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (8.9 ± 0.3 years) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-week RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve) and rate of EMG increase (REI; slope of the EMG-time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively, n.s) which may have implications for tendon injury risk and muscle fiber mechanics. A ~13% decrease in EMD was found after RT for the experimental group which paralleled the increase in tendon stiffness (r = −0.59), however RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of potential importance within the context of the efficiency and execution of movement.

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Patellar and Achilles Tendon Stiffness in Elite Soccer Players Assessed Using Myotonometric Measurements

Sports Health A Multidisciplinary Approach ◽

10.1177/1941738118820517 ◽

2019 ◽

Vol 11 (2) ◽

pp. 157-162 ◽

Cited By ~ 4

Author(s):

Iver Cristi-Sánchez ◽

Claudia Danes-Daetz ◽

Alejandro Neira ◽

Wilson Ferrada ◽

Roberto Yáñez Díaz ◽

...

Keyword(s):

Achilles Tendon ◽

Patellar Tendon ◽

Professional Training ◽

Soccer Players ◽

Patellar Tendinopathy ◽

Control Group ◽

Force Transmission ◽

Level Of Evidence ◽

Tendon Stiffness ◽

Handheld Device

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.

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Effects of long-term athletic training on muscle morphology and tendon stiffness in preadolescence: association with jump performance

European Journal of Applied Physiology ◽

10.1007/s00421-020-04490-7 ◽

2020 ◽

Vol 120 (12) ◽

pp. 2715-2727

Author(s):

Nikolaos Pentidis ◽

Falk Mersmann ◽

Sebastian Bohm ◽

Erasmia Giannakou ◽

Nickos Aggelousis ◽

...

Keyword(s):

Muscle Strength ◽

Achilles Tendon ◽

Muscle Hypertrophy ◽

Muscle Thickness ◽

Pennation Angle ◽

Triceps Surae ◽

Plantar Flexors ◽

Tendon Stiffness ◽

Jumping Performance

Abstract Purpose Evidence on training-induced muscle hypertrophy during preadolescence is limited and inconsistent. Possible associations of muscle strength and tendon stiffness with jumping performance are also not investigated. We investigated the thickness and pennation angle of the gastrocnemius medialis muscle (GM), as indicators for potential muscle hypertrophy in preadolescent athletes. Further, we examined the association of triceps surae muscle–tendon properties with jumping performance. Methods Eleven untrained children (9 years) and 21 similar-aged artistic gymnastic athletes participated in the study. Muscle thickness and pennation angle of the GM were measured at rest and muscle strength of the plantar flexors and Achilles tendon stiffness during maximum isometric contractions. Jumping height in squat (SJ) and countermovement jumps (CMJ) was examined using a force plate. We evaluated the influence of normalised muscle strength and tendon stiffness on jumping performance with a linear regression model. Results Muscle thickness and pennation angle did not differ significantly between athletes and non-athletes. In athletes, muscle strength was greater by 25% and jumping heights by 36% (SJ) and 43% (CMJ), but Achilles tendon stiffness did not differ between the two groups. The significant predictor for both jump heights was tendon stiffness in athletes and normalised muscle strength for the CMJ height in non-athletes. Conclusion Long-term artistic gymnastics training during preadolescence seems to be associated with increased muscle strength and jumping performance but not with training-induced muscle hypertrophy or altered tendon stiffness in the plantar flexors. Athletes benefit more from tendon stiffness and non-athletes more from muscle strength for increased jumping performance.

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Effects of eccentric training on mechanical properties of the plantar flexor muscle-tendon complex

Journal of Applied Physiology ◽

10.1152/japplphysiol.01313.2011 ◽

2013 ◽

Vol 114 (5) ◽

pp. 523-537 ◽

Cited By ~ 42

Author(s):

Alexandre Fouré ◽

Antoine Nordez ◽

Christophe Cornu

Keyword(s):

Mechanical Properties ◽

Achilles Tendon ◽

Plantar Flexion ◽

Triceps Surae ◽

Elastic Component ◽

Plantar Flexor ◽

Eccentric Training ◽

Tendon Stiffness ◽

Series Elastic Component ◽

Series Elastic

Eccentric training is a mechanical loading classically used in clinical environment to rehabilitate patients with tendinopathies. In this context, eccentric training is supposed to alter tendon mechanical properties but interaction with the other components of the muscle-tendon complex remains unclear. The aim of this study was to determine the specific effects of 14 wk of eccentric training on muscle and tendon mechanical properties assessed in active and passive conditions in vivo. Twenty-four subjects were randomly divided into a trained group ( n = 11) and a control group ( n = 13). Stiffness of the active and passive parts of the series elastic component of plantar flexors were determined using a fast stretch during submaximal isometric contraction, Achilles tendon stiffness and dissipative properties were assessed during isometric plantar flexion, and passive stiffness of gastrocnemii muscles and Achilles tendon were determined using ultrasonography while ankle joint was passively moved. A significant decrease in the active part of the series elastic component stiffness was found ( P < 0.05). In contrast, a significant increase in Achilles tendon stiffness determined under passive conditions was observed ( P < 0.05). No significant change in triceps surae muscles and Achilles tendon geometrical parameters was shown ( P > 0.05). Specific changes in muscle and tendon involved in plantar flexion are mainly due to changes in intrinsic mechanical properties of muscle and tendon tissues. Specific assessment of both Achilles tendon and plantar flexor muscles allowed a better understanding of the functional behavior of the muscle-tendon complex and its adaptation to eccentric training.

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Human Achilles tendon glycation and function in diabetes

Journal of Applied Physiology ◽

10.1152/japplphysiol.00547.2015 ◽

2016 ◽

Vol 120 (2) ◽

pp. 130-137 ◽

Cited By ~ 37

Author(s):

Christian Couppé ◽

Rene Brüggebusch Svensson ◽

Mads Kongsgaard ◽

Vuokko Kovanen ◽

Jean-Francois Grosset ◽

...

Keyword(s):

Achilles Tendon ◽

Plantar Pressure ◽

Foot Ulcers ◽

Cross Linking ◽

Diabetic Patients ◽

Foot Pressure ◽

Tendon Stiffness ◽

Material Stiffness ◽

Skin Collagen ◽

Collagen Cross Linking

Diabetic patients have an increased risk of foot ulcers, and glycation of collagen may increase tissue stiffness. We hypothesized that the level of glycemic control (glycation) may affect Achilles tendon stiffness, which can influence gait pattern. We therefore investigated the relationship between collagen glycation, Achilles tendon stiffness parameters, and plantar pressure in poorly ( n = 22) and well ( n = 22) controlled diabetic patients, including healthy age-matched (45–70 yr) controls ( n = 11). There were no differences in any of the outcome parameters (collagen cross-linking or tendon stiffness) between patients with well-controlled and poorly controlled diabetes. The overall effect of diabetes was explored by collapsing the diabetes groups (DB) compared with the controls. Skin collagen cross-linking lysylpyridinoline, hydroxylysylpyridinoline (136%, 80%, P < 0.01) and pentosidine concentrations (55%, P < 0.05) were markedly greater in DB. Furthermore, Achilles tendon material stiffness was higher in DB (54%, P < 0.01). Notably, DB also demonstrated higher forefoot/rearfoot peak-plantar-pressure ratio (33%, P < 0.01). Overall, Achilles tendon material stiffness and skin connective tissue cross-linking were greater in diabetic patients compared with controls. The higher foot pressure indicates that material stiffness of tendon and other tissue (e.g., skin and joint capsule) may influence foot gait. The difference in foot pressure distribution may contribute to the development of foot ulcers in diabetic patients.

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