scholarly journals Effects of estrogen on the mechanical behavior of the human Achilles tendon in vivo

2008 ◽  
Vol 105 (4) ◽  
pp. 1035-1043 ◽  
Author(s):  
Adam L. Bryant ◽  
Ross A. Clark ◽  
Simon Bartold ◽  
Aron Murphy ◽  
Kim L. Bennell ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Repeated Measures ◽  
Oral Contraceptive Pill ◽  
Test Session ◽  
Triceps Surae ◽  
Strain Behavior ◽  
Endogenous Estrogen ◽  
Tendon Strain

The purpose of this study was to elucidate the effect of normal fluctuating [non-monophasic oral contraceptive pill (MOCP) users] and low, consistent (MOCP users) endogenous plasma estrogen levels on the strain behavior of the Achilles tendon in vivo. Twenty women (age 28.0 ± 4.2 yr, height 1.67 ± 0.07 m, mass 61.6 ± 6.8 kg) who had been using the MOCP for at least 12 mo together with 20 matched women who were non-MOCP users (age 31.9 ± 7.3 yr, height 1.63 ± 0.05 m, mass 62.5 ± 5.9 kg) participated in this study. Non-MOCP users were tested at the time of lowest (menstruation) and highest (≈ovulation) estrogen, whereas MOCP users, who exhibited constant and attenuated endogenous estrogen levels, were tested at day 1 and day 14 of their cycle. At each test session, maximal isometric plantarflexion efforts were performed on a calf-raise apparatus while synchronous real-time ultrasonography of the triceps surae aponeurosis was recorded. Achilles tendon strain (%) was calculated by dividing tendon displacement during plantarflexion by resting tendon length. Repeated-measures ANOVA revealed a significant ( P < 0.05) main effect of subject group with significantly lower Achilles strain (25.5%) in the MOCP users compared with the non-MOCP users. In conclusion, acute fluctuations in plasma estrogen across the menstrual cycle in non-MOCP users did not alter the strain behavior of the Achilles tendon. Conversely, long-term exposure to attenuated estrogen in MOCP users resulted in a decrease in Achilles tendon strain, which is thought to be attributed to the effects of endogenous estrogen on collagen synthesis. These findings have a number of important functional and clinical implications.

Dynamic viscoelastic behavior of lower extremity tendons during simulated running

2000 ◽  
Vol 89 (4) ◽  
pp. 1352-1359 ◽  
Author(s):  
M. De Zee ◽  
F. Bojsen-Møller ◽  
M. Voigt
Keyword(s):  
Cyclic Loading ◽  
Achilles Tendon ◽  
Testing Machine ◽  
Viscoelastic Behavior ◽  
Muscle Spindles ◽  
Minor Effect ◽  
Velocity Feedback ◽  
Dynamic Creep

The aim of this project was to see whether the tendon would show creep during long-term dynamic loading (here referred to as dynamic creep). Pig tendons were loaded by a material-testing machine with a human Achilles tendon force profile (1.37 Hz, 3% strain, 1,600 cycles), which was obtained in an earlier in vivo experiment during running. All the pig tendons showed some dynamic creep during cyclic loading (between 0.23 ± 0.15 and 0.42 ± 0.21%, means ± SD). The pig tendon data were used as an input of a model to predict dynamic creep in the human Achilles tendon during running of a marathon and to evaluate whether there might consequently be an influence on group Ia afferent-mediated length and velocity feedback from muscle spindles. The predicted dynamic creep in the Achilles tendon was considered to be too small to have a significant influence on the length and velocity feedback from soleus during running. In spite of the characteristic nonlinear viscoelastic behavior of tendons, our results demonstrate that these properties have a minor effect on the ability of tendons to act as predictable, stable, and elastic force transmitters during long-term cyclic loading.

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

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.

Effects of Transducer Mass on Intramuscular Temperature During Ultrasound Treatments

2013 ◽  
Vol 22 (4) ◽  
pp. 296-300
Author(s):  
Daniel Krasinski ◽  
Ashley B. Thrasher ◽  
Michael G. Miller ◽  
William R. Holcomb
Keyword(s):  
Outcome Measures ◽  
Repeated Measures ◽  
Human Performance ◽  
Ultrasound Treatment ◽  
Triceps Surae ◽  
Convenience Sample ◽  
Linear Temperature ◽  
Temperature Standards ◽  
Intramuscular Temperature

Context:A potential variable that could affect rate of temperature elevation with ultrasound is the pressure (mass) that is applied to the transducer head during application. Added pressure could compress the tissue, affecting density and the transmission of ultrasound energy. Little research has been completed to determine the effects of the amount of pressure applied during therapeutic ultrasound in vivo.Objective:To determine the effects of different applied transducer mass on intramuscular temperature during an ultrasound treatment within the left triceps surae.Design:Crossover clinical trial.Setting:Human performance research laboratory.Participants:Convenience sample of thirteen healthy, college-age students.Interventions:Three separate MHz, 1.0-W/cm2 ultrasound treatments were administered 1.5 cm within the triceps surae. The independent variables were the linear temperature standards (0.5°C, 1.0°C, 1.5°C, and 2.0°C above baseline) and the 3 different applied pressures measured in grams (200 g, 600 g, and 800 g).Main Outcome Measures:A thermocouple probe was used to measure triceps surae temperature, and time to reach the temperature standards was recorded during the ultrasound treatments. A 4 × 3 repeated-measures analysis of variance (RM-ANOVA) was used to analyze the differences for temperature points (0.5°C, 1.0°C, 1.5°C, and 2.0°C) and transducer mass (200 g, 600 g, and 800 g) and with respect to time.Results:The results of the RM-ANOVA showed no temperature-point and transducer-mass interaction (F6,72 = 1.69, P = .137) or main effect for mass (F2,24 = 1.23, P = .309). The time required to raise temperature 2°C was 209.1 ± 68.10 s at 200 g, 181.5 ± 61.50 s at 600 g, and 194.9 ± 75.54 s at 800 g.Conclusions:Under the conditions of this study, the amount of mass applied with the transducer during an ultrasound treatment does not ultimately affect the rate of tissue heating.

scholarly journals Considerations on the human Achilles tendon moment arm for in vivo triceps surae muscle–tendon unit force estimates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Denis Holzer ◽  
Florian Kurt Paternoster ◽  
Daniel Hahn ◽  
Tobias Siebert ◽  
Wolfgang Seiberl
Keyword(s):  
Achilles Tendon ◽  
Triceps Surae ◽  
Muscle Forces ◽  
Moment Arm ◽  
Unit Force ◽  
Plateau Region ◽  
Triceps Muscle ◽  
Triceps Surae Muscle ◽  
The Individual

Abstract Moment arm-angle functions (MA-a-functions) are commonly used to estimate in vivo muscle forces in humans. However, different MA-a-functions might not only influence the magnitude of the estimated muscle forces but also change the shape of the muscle’s estimated force-angle relationship (F-a-r). Therefore, we investigated the influence of different literature based Achilles tendon MA-a-functions on the triceps surae muscle–tendon unit F-a-r. The individual in vivo triceps torque–angle relationship was determined in 14 participants performing maximum voluntary fixed-end plantarflexion contractions from 18.3° ± 3.2° plantarflexion to 24.2° ± 5.1° dorsiflexion on a dynamometer. The resulting F-a-r were calculated using 15 literature-based in vivo Achilles tendon MA-a-functions. MA-a-functions affected the F-a-r shape and magnitude of estimated peak active triceps muscle–tendon unit force. Depending on the MA-a-function used, the triceps was solely operating on the ascending limb (n = 2), on the ascending limb and plateau region (n = 12), or on the ascending limb, plateau region and descending limb of the F-a-r (n = 1). According to our findings, the estimated triceps muscle–tendon unit forces and the shape of the F-a-r are highly dependent on the MA-a-function used. As these functions are affected by many variables, we recommend using individual Achilles tendon MA-a-functions, ideally accounting for contraction intensity-related changes in moment arm magnitude.

scholarly journals Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6764 ◽  
Author(s):  
Amelie Werkhausen ◽  
Neil J. Cronin ◽  
Kirsten Albracht ◽  
Gøran Paulsen ◽  
Askild V. Larsen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Achilles Tendon ◽  
Stance Phase ◽  
Training Group ◽  
Triceps Surae ◽  
Control Group ◽  
Tendon Stiffness ◽  
Strain Pattern ◽  
Tendon Strain ◽  
Triceps Surae Muscles

Background During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus. Methods Eleven subjects were assigned to a training group performing isometric single-leg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics. Results Achilles tendon stiffness increased by 18% (P < 0.01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P < 0.01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training. Discussion These results show that a training-induced increase in Achilles tendon stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple in-series models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running.

scholarly journals The effects of triceps surae muscle stimulation on localized achilles subtendon tissue displacements

2021 ◽  
Author(s):  
Nathan L. Lehr ◽  
William H. Clark ◽  
Michael D. Lewek ◽  
Jason R. Franz
Keyword(s):  
Achilles Tendon ◽  
Muscle Activation ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Muscle Stimulation ◽  
Triceps Surae Muscle ◽  
Ankle Angle ◽  
In Series ◽  
Fixed End

The triceps surae muscle tendon unit is comprised of the lateral and medial gastrocnemius (MG) and soleus (SOL) muscles and three in series elastic “subtendons” that form the Achilles tendon. Comparative literature and our own in vivo evidence suggests that sliding between adjacent subtendons may facilitate independent muscle actuation. We aim to more clearly define the relation between individual muscle activation and subtendon tissue displacements. Here, during fixed-end contractions, electrical muscle stimulation controlled the magnitude of force transmitted via individual triceps surae muscles while ultrasound imaging recorded resultant subtendon tissue displacements. We hypothesized that MG and SOL stimulation would elicit larger displacements in their associated subtendon. 10 young adults completed 4 experimental activations at 3 ankle angles (-20°, 0°, 20°) with knee flexed to approximately 20°: MG stimulation (STIMMG), SOL stimulation (STIMSOL), combined stimulation, and volitional contraction. At 20° plantarflexion, STIMSOL elicited 49% larger tendon non-uniformity (SOL – MG subtendon tissue displacement) than that of STIMMG (p=0.004). For STIMSOL, a one-way post-hoc ANOVA revealed a significant main effect of ankle angle (p=0.009) on Achilles tendon non-uniformity. However, peak tendon non-uniformity decreased by an average of 61% from plantarflexion to dorsiflexion, likely due to an increase in passive tension. Our results suggest that localized tissue displacements within the Achilles tendon respond in anatomically consistent ways to differential patterns of triceps surae muscle activation, but these relations are highly susceptible to ankle angle. This in vivo evidence points to at least some mechanical independence in actuation between the human triceps surae muscle-subtendon units.

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