Mechanical Responses of Tendons to Repeated Extensions and Wait Periods

Abstract

Tendon specimens were repeatedly extended to peak strains of either 2, 3, 4, or 6 percent. During the three 1800 s (30 min.) periods of cyclic extension, the peak loads relaxed with decreases in hysteresis and increases in slack strain. During the two 1800 s wait periods of no extension, the specimens recovered with increases in peak load and hysteresis and decreases in slack strain. However, the recovery during the wait periods was eradicated in the first few subsequent extensions and the relaxation continued as if there were no 1800 s wait periods. Stress-strain responses were well fit with power relations.

Interaction of viscoelastic tissue compliance with lumbar muscles during passive cyclic flexion–extension

“…Hubbard and Chun (1988) observed decreased viscoelastic strength while cyclically loading canine tendons. We did not measure viscoelastic strength, but our results showed a linear reduction in torque within the posterior tissues.…”

Mechanics of feline soleus: II design and validation of a mathematical model

“…Furthermore, Hubbard and Chun (1988) observed that a single stretch of 6% strain can shift L~ by 1%, while at higher forces (-F0) the shifts were only 0.2%. To demonstrate the problems associated with using L T, we plotted the same five SE curves in Fig.…”

“…FACT was defined to be unitless and FL was chosen to have units of F0 thus the 'force' in the FV curve was defined as a unitless 'force index'. The connective-tissue lengths were also normalized to facilitate scaling between muscles but in a manner somewhat different from the approach used by Zajac (1989) and other previous studies (Hubbard & Chun, 1988;Lieber et al, 1992). Connective-tissue (T) data were normalized in terms of F0 for force and L~ for length (connective-tissue length at F0) as opposed to the more commonly used L T (connective-tissue slack length).…”

Viscoelastic constitutive law in large deformations

“…The first test was started 30 min after preconditioning. In order that the specimens were in an identical mechanical situation for each test, a 30 min interval separated each test (Hubbard and Chun, 1988). At the end of the tests, the specimens were reloaded with the 0.3 mm s\ rates of elongation to assess the reproducibility of the tests.…”