Which tissue property describes time-dependent strain and recovery in tissues?

• A. Elasticity
• B. Viscoelasticity
• C. Plasticity
• D. Rigidity

Answer: (B)

Viscoelasticity describes how tissues deform under load with both an immediate elastic component and a time-dependent viscous component, leading to strain that develops over time and partial recovery after unloading. In purely elastic materials, deformation happens instantly and returns fully once the load is removed, with no time delay. In purely viscous materials, deformation keeps increasing with time under a constant load and there’s little to no immediate rebound after unloading. Biological tissues combine these behaviors, so the total strain depends on how long and how quickly you load the tissue, and recovery unfolds over time after the load is removed. This explains phenomena like creep (increasing deformation under constant load) and stress relaxation (decreasing stress under constant strain) seen in tissues such as tendons, ligaments, and cartilage.