Anterior cruciate bone-ligament-bone preparations of wild primates tested in tension failed at a higher load and greater elongation, and absorbed more energy, at a fast rate of deformation than at a slow rate. The major mode of specimen failure changed from a predominance of tibial avulsion fractures at the slow rate to ligament disruption at the fast rate. Failure at the two deformation rates commonly occurred by a serial mechanism involving from one to all components of the bone-ligament-bone unit to different degrees. Factors important in ligament-failure properties included: (1) rate-dependent behaviors, (2) geometrical arrangement of collagen fibers, (3) surrounding ground-substance effects, (4) osseous insertion-site effects, and (5) the influence of non-physiological experimental loading conditions and disuse-induced changes in specimens.

Biomechanics of Anterior Cruciate Ligament Failure: An Analysis of Strain-Rate Sensitivity and Mechanisms of Failure in Primates

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jor.1100100205

Tensile properties of the inferior glenohumeral ligament

Elongation mechanism of collagen fibrils and force-strain relations of tendon at each level of structural hierarchy.

The purpose of this study was to investigate the influences of static stretching on the viscoelastic properties of human tendon structures in vivo. Seven male subjects performed static stretching in which the ankle was passively flexed to 35° of dorsiflexion and remained stationary for 10 min. Before and after the stretching, the elongation of the tendon and aponeurosis of medial gastrocnemius muscle (MG) was directly measured by ultrasonography while the subjects performed ramp isometric plantar flexion up to the maximum voluntary contraction (MVC), followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) of MG and tendon elongation (L) during the ascending phase was fitted to a linear regression, the slope of which was defined as stiffness of the tendon structures. The percentage of the area within the Fm-L loop to the area beneath the curve during the ascending phase was calculated as an index representing hysteresis. Stretching produced no significant change in MVC but s...

https://www.physiology.org/doi/pdf/10.1152/jappl.2001.90.2.520

Influence of static stretching on viscoelastic properties of human tendon structures in vivo

The present study examined whether resistance and stretching training programmes altered the viscoelastic properties of human tendon structures in vivo. Eight subjects completed 8 weeks (4 days per week) of resistance training which consisted of unilateral plantar flexion at 70 % of one repetition maximum with 10 repetitions per set (5 sets per day). They performed resistance training (RT) on one side and resistance training and static stretching training (RST; 10 min per day, 7 days per week) on the other side. Before and after training, the elongation of the tendon structures in the medial gastrocnemius muscle was directly measured using ultrasonography, while the subjects performed ramp isometric plantar flexion up to the voluntary maximum, followed by a ramp relaxation. The relationship between estimated muscle force (Fm) and tendon elongation (L) was fitted to a linear regression, the slope of which was defined as stiffness. The hysteresis was calculated as the ratio of the area within the Fm-L loop to the area beneath the load portion of the curve. The stiffness increased significantly by 18.8 ± 10.4 % for RT and 15.3 ± 9.3 % for RST. There was no significant difference in the relative increase of stiffness between RT and RST. The hysteresis, on the other hand, decreased 17 ± 20 % for RST, but was unchanged for RT. These results suggested that the resistance training increased the stiffness of tendon structures as well as muscle strength and size, and the stretching training affected the viscosity of tendon structures but not the elasticity.

A Viidik

Papers

Rheological analysis of soft collagenous tissue. Part I: theoretical considerations.

A rheological model for uncalcified parallel-fibred collagenous tissue.

Rheological analysis of soft collagenous tissue. Part II: experimental evaluations and verifications.