Mechanical properties of tendon and aponeurosis of human gastrocnemius muscle in vivo

Load-strain characteristics of tendinous tissues (Achilles tendon and aponeurosis) were determined in vivo for human medial gastrocnemius (MG) muscle. Seven male subjects exerted isometric plantar flexion torque while the elongation of tendinous tissues of MG was determined from the tendinous movements by using ultrasonography. The maximal strain of the Achilles tendon and aponeurosis, estimated separately from the elongation data, was 5.1 ± 1.1 and 5.9 ± 1.6%, respectively. There was no significant difference in strain between the Achilles tendon and aponeurosis. In addition, no significant difference in strain was observed between the proximal and distal regions of the aponeurosis. The results indicate that tendinous tissues of the MG are homogenously stretched along their lengths by muscle contraction, which has functional implications for the operation of the human MG muscle-tendon unit in vivo.

Download Full-text

Gender Difference in Architectural and Mechanical Properties of Medial Gastrocnemius–Achilles Tendon Unit In Vivo

Life ◽

10.3390/life11060569 ◽

2021 ◽

Vol 11 (6) ◽

pp. 569

Author(s):

Liqin Deng ◽

Xini Zhang ◽

Songlin Xiao ◽

Baofeng Wang ◽

Weijie Fu

Keyword(s):

Mechanical Properties ◽

Gender Differences ◽

Gender Difference ◽

Achilles Tendon ◽

Medial Gastrocnemius ◽

Regular Exercise ◽

Training Experience ◽

Exercise Habits ◽

Vertical Stiffness

This study aims to explore whether gender differences exist in the architectural and mechanical properties of the medial gastrocnemius–Achilles tendon unit (gMTU) in vivo. Thirty-six healthy male and female adults without training experience and regular exercise habits were recruited. The architectural and mechanical properties of the gMTU were measured via an ultrasonography system and MyotonPRO, respectively. Independent t-tests were utilized to quantify the gender difference in the architectural and mechanical properties of the gMTU. In terms of architectural properties, the medial gastrocnemius (MG)’s pennation angle and thickness were greater in males than in females, whereas no substantial gender difference was observed in the MG’s fascicle length; the males possessed Achilles tendons (ATs) with a longer length and a greater cross-sectional area than females. In terms of mechanical properties, the MG’s vertical stiffness was lower and the MG’s logarithmic decrement was greater in females than in males. Both genders had no remarkable difference in the AT’s vertical stiffness and logarithmic decrement. Gender differences of individuals without training experience and regular exercise habits exist in the architectural and mechanical properties of the gMTU in vivo. The MG’s force-producing capacities, ankle torque, mechanical efficiency and peak power were higher in males than in females. The load-resisting capacities of AT were greater and the MG strain was lesser in males than in females. These findings suggest that males have better physical fitness, speed and performance in power-based sports events than females from the perspective of morphology and biomechanics.

Download Full-text

Differential displacement of the human soleus and medial gastrocnemius aponeuroses during isometric plantar flexor contractions in vivo

Journal of Applied Physiology ◽

10.1152/japplphysiol.00084.2004 ◽

2004 ◽

Vol 97 (5) ◽

pp. 1908-1914 ◽

Cited By ~ 111

Author(s):

Jens Bojsen-Møller ◽

Philip Hansen ◽

Per Aagaard ◽

Ulla Svantesson ◽

Michael Kjaer ◽

...

Keyword(s):

Knee Joint ◽

Achilles Tendon ◽

Plantar Flexion ◽

Human Locomotion ◽

Muscular Contraction ◽

Triceps Surae ◽

Medial Gastrocnemius ◽

Plantar Flexor ◽

Flexion Moment

The human triceps surae muscle-tendon complex is a unique structure with three separate muscle compartments that merge via their aponeuroses into the Achilles tendon. The mechanical function and properties of these structures during muscular contraction are not well understood. The purpose of the study was to investigate the extent to which differential displacement occurs between the aponeuroses of the medial gastrocnemius (MG) and soleus (Sol) muscles during plantar flexion. Eight subjects (mean ± SD; age 30 ± 7 yr, body mass 76.8 ± 5.5 kg, height 1.83 ± 0.06 m) performed maximal isometric ramp contractions with the plantar flexor muscles. The experiment was performed in two positions: position 1, in which the knee joint was maximally extended, and position 2, in which the knee joint was maximally flexed (125°). Plantarflexion moment was assessed with a strain gauge load cell, and the corresponding displacement of the MG and Sol aponeuroses was measured by ultrasonography. Differential shear displacement of the aponeurosis was quantified by subtracting displacement of Sol from that of MG. Maximal plantar flexion moment was 36% greater in position 1 than in position 2 (132 ± 20 vs. 97 ± 11 N·m). In position 1, the displacement of the MG aponeurosis at maximal force exceeded that of the Sol (12.6 ± 1.7 vs. 8.9 ± 1.5 mm), whereas in position 2 displacement of the Sol was greater than displacement of the MG (9.6 ± 1.0 vs. 7.9 ± 1.2 mm). The amount and “direction” of shear between the aponeuroses differed significantly between the two positions across the entire range of contraction, indicating that the Achilles tendon may be exposed to intratendinous shear and stress gradients during human locomotion.

Download Full-text

Elastic properties of human Achilles tendon are correlated to muscle strength

Journal of Applied Physiology ◽

10.1152/japplphysiol.00624.2004 ◽

2005 ◽

Vol 99 (2) ◽

pp. 665-669 ◽

Cited By ~ 63

Author(s):

Tetsuro Muraoka ◽

Tadashi Muramatsu ◽

Tetsuo Fukunaga ◽

Hiroaki Kanehisa

Keyword(s):

Mechanical Properties ◽

Muscle Strength ◽

Achilles Tendon ◽

Elastic Energy ◽

Plantar Flexion ◽

Triceps Surae ◽

Medial Gastrocnemius ◽

Myotendinous Junction ◽

Men And Women ◽

The Difference

The purpose of this study was to investigate whether the mechanical properties of the Achilles tendon were correlated to muscle strength in the triceps surae in humans. Twenty-four men and twelve women exerted maximal voluntary isometric plantar flexion (MVIP) torque. The elongation (ΔX) and strain of the Achilles tendon (ε), the proximal part of which is the composite of the gastrocnemius tendon and the soleus aponeurosis, at MVIP were determined from the displacement of the distal myotendinous junction of the medial gastrocnemius using ultrasonography. The Achilles tendon force at MVIP (F) was calculated from the MVIP torque and the Achilles tendon moment arm. There were no significant differences in either the F-ΔX or F-ε relationships between men and women. ΔX and ε were 9.8 ± 2.6 mm and 5.3 ± 1.6%, respectively, and were positively correlated to F ( r = 0.39, P < 0.05; r = 0.39, P < 0.05), which meant that subjects with greater muscle strength could store more elastic energy in the tendon. The regression y-intercepts for the F-ΔX ( P < 0.01) and F-ε ( P < 0.05) relationship were significantly positive. These results might indicate that the Achilles tendon was stiffer in subjects with greater muscle strength, which may play a role in reducing the probability of tendon strain injuries. It was suggested that the Achilles tendon of subjects with greater muscle strength did not impair the potential for storing elastic energy in tendons and may be able to deliver the greater force supplied from a stronger muscle more efficiently. Furthermore, the difference in the Achilles tendon mechanical properties between men and women seemed to be correlated to the difference in muscle strength rather than gender.

Download Full-text

Passive Mechanical Properties of Human Medial Gastrocnemius and Soleus Musculotendinous Unit

BioMed Research International ◽

10.1155/2021/8899699 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Ruoli Wang ◽

Shiyang Yan ◽

Marius Schlippe ◽

Olga Tarassova ◽

Gaia Valentina Pennati ◽

...

Keyword(s):

Mechanical Properties ◽

Achilles Tendon ◽

Three Dimensional ◽

Triceps Surae ◽

Medial Gastrocnemius ◽

Passive Stretching ◽

Slack Length ◽

In Vivo Characterization ◽

Passive Stretch

The in vivo characterization of the passive mechanical properties of the human triceps surae musculotendinous unit is important for gaining a deeper understanding of the interactive responses of the tendon and muscle tissues to loading during passive stretching. This study sought to quantify a comprehensive set of passive muscle-tendon properties such as slack length, stiffness, and the stress-strain relationship using a combination of ultrasound imaging and a three-dimensional motion capture system in healthy adults. By measuring tendon length, the cross-section areas of the Achilles tendon subcompartments (i.e., medial gastrocnemius and soleus aspects), and the ankle torque simultaneously, the mechanical properties of each individual compartment can be specifically identified. We found that the medial gastrocnemius (GM) and soleus (SOL) aspects of the Achilles tendon have similar mechanical properties in terms of slack angle (GM: − 10.96 ° ± 3.48 ° ; SOL: − 8.50 ° ± 4.03 ° ), moment arm at 0° of ankle angle (GM: 30.35 ± 6.42 mm; SOL: 31.39 ± 6.42 mm), and stiffness (GM: 23.18 ± 13.46 Nmm-1; SOL: 31.57 ± 13.26 Nmm-1). However, maximal tendon stress in the GM was significantly less than that in SOL (GM: 2.96 ± 1.50 MPa; SOL: 4.90 ± 1.88 MPa, p = 0.024 ), largely due to the higher passive force observed in the soleus compartment (GM: 99.89 ± 39.50 N; SOL: 174.59 ± 79.54 N, p = 0.020 ). Moreover, the tendon contributed to more than half of the total muscle-tendon unit lengthening during the passive stretch. This unequal passive stress between the medial gastrocnemius and the soleus tendon might contribute to the asymmetrical loading and deformation of the Achilles tendon during motion reported in the literature. Such information is relevant to understanding the Achilles tendon function and loading profile in pathological populations in the future.

Download Full-text

Soleus aponeurosis strain distribution following chronic unloading in humans: an in vivo MR phase-contrast study

Journal of Applied Physiology ◽

10.1152/japplphysiol.01085.2005 ◽

2006 ◽

Vol 100 (6) ◽

pp. 2004-2011 ◽

Cited By ~ 32

Author(s):

Hae-Dong Lee ◽

Taija Finni ◽

John A. Hodgson ◽

Alex M. Lai ◽

V. Reggie Edgerton ◽

...

Keyword(s):

Achilles Tendon ◽

Strain Distribution ◽

Phase Contrast ◽

Plantar Flexion ◽

Voluntary Contraction ◽

Triceps Surae ◽

Medial Gastrocnemius ◽

Contrast Study ◽

Ankle Plantar Flexion

The in vivo strain properties of human skeletal muscle-tendon complexes are poorly understood, particularly following chronic periods of reduced load bearing. We studied eight healthy volunteers who underwent 4 wk of unilateral lower limb suspension (ULLS) to induce chronic unloading. Before and after the ULLS, maximum isometric ankle plantar flexion torque was determined by using a magnetic resonance (MR)-compatible dynamometry. Volumes of the triceps surae muscles and strain distribution of the soleus aponeurosis and the Achilles tendon at a constant submaximal plantar flexion (20% pre-maximal voluntary contraction) were measured by using MRI and velocity-encoded, phase-contrast MRI techniques. Following ULLS, volumes of the soleus and the medial gastrocnemius and the maximum isometric ankle plantar flexion (maximum voluntary contraction) decreased by 5.5 ± 1.9, 7.5 ± 2.7, and 48.1 ± 6.1%, respectively. The strain of the aponeurosis along the length of the muscle before the ULLS was 0.3 ± 0.3%, ranging from −1.5 to 2.7% in different locations of the aponeurosis. Following ULLS, the mean strain was −6.4 ± 0.3%, ranging from −1.6 to 1.3%. The strain distribution of the midregion of the aponeurosis was significantly influenced by the ULLS, whereas the more distal component showed no consistent changes. Achilles tendon strain was not affected by the ULLS. These results raise the issue as to whether these changes in strain distribution affect the functional properties of the triceps surae and whether the probability of strain injuries within the triceps surae increases following chronic unloading in those regions of this muscle complex in which unusual strains occur.

Download Full-text

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.

Download Full-text

Can in Vivo Medial Gastrocnemius Muscle–Tendon Unit Lengths be Reliably Estimated by Two Ultrasonography Methods? A Within-Session Analysis

Ultrasound in Medicine & Biology ◽

10.1016/j.ultrasmedbio.2017.09.018 ◽

2018 ◽

Vol 44 (1) ◽

pp. 110-118 ◽

Cited By ~ 4

Author(s):

Francesco Cenni ◽

Simon-Henri Schless ◽

Lynn Bar-On ◽

Guy Molenaers ◽

Anja Van Campenhout ◽

...

Keyword(s):

Gastrocnemius Muscle ◽

Medial Gastrocnemius ◽

Session Analysis ◽

Medial Gastrocnemius Muscle

Download Full-text

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.

Download Full-text