Postoperative Recovery of Triceps Surae Muscle Power in the Cases with Subcutaneous Ruptured Achilles Tendon

Ankle joint quasi-stiffness is an aggregate measure of the interaction between triceps surae muscle stiffness and Achilles tendon stiffness. This interaction may be altered due to age-related changes in the structural properties and functional behavior of the Achilles tendon and triceps surae muscles. The authors hypothesized that, due to a more compliant of Achilles’ tendon, older adults would exhibit lower ankle joint quasi-stiffness than young adults during walking and during isolated contractions at matched triceps surae muscle activations. The authors also hypothesized that, independent of age, triceps surae muscle stiffness and ankle joint quasi-stiffness would increase with triceps surae muscle activation. The authors used conventional gait analysis in one experiment and, in another, electromyographic biofeedback and in vivo ultrasound imaging applied during isolated contractions. The authors found no difference in ankle joint quasi-stiffness between young and older adults during walking. Conversely, this study found that (1) young and older adults modulated ankle joint quasi-stiffness via activation-dependent changes in triceps surae muscle length–tension behavior and (2) at matched activation, older adults exhibited lower ankle joint quasi-stiffness than young adults. Despite age-related reductions during isolated contractions, ankle joint quasi-stiffness was maintained in older adults during walking, which may be governed via activation-mediated increases in muscle stiffness.

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

Scientific Reports ◽

10.1038/s41598-020-76625-x ◽

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.

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Impact of seated and standing positions on triceps surae muscle activation in unilateral Achilles tendon rupture

Translational Sports Medicine ◽

10.1002/tsm2.117 ◽

2019 ◽

Vol 3 (1) ◽

pp. 3-8

Author(s):

Jennifer A. Zellers ◽

Annelie Brorsson ◽

Karin Grävare Silbernagel

Keyword(s):

Achilles Tendon ◽

Muscle Activation ◽

Tendon Rupture ◽

Achilles Tendon Rupture ◽

Triceps Surae ◽

Triceps Surae Muscle

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Peer Review #2 of "Do triceps surae muscle dynamics govern non-uniform Achilles tendon deformations? (v0.1)"

10.7287/peerj.5182v0.1/reviews/2 ◽

2018 ◽

Keyword(s):

Achilles Tendon ◽

Peer Review ◽

Triceps Surae ◽

Triceps Surae Muscle ◽

Muscle Dynamics

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

Journal of Experimental Biology ◽

10.1242/jeb.242135 ◽

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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