Final answer:
The property that enables muscle tissue to adjust to extended periods of stress is called hypertrophy, which involves an increase in muscle mass due to more structural proteins.
Step-by-step explanation:
The physiological property that allows muscle tissue in the body to adapt to sustained periods of external stresses is called hypertrophy. Hypertrophy is the process where there is an increase in muscle mass due to the addition of structural proteins. This adaptation occurs when muscles undergo resistance exercise, leading to an increase in the cell diameter of muscle fibers. In contrast, atrophy refers to the loss of muscle mass when structural proteins are lost and muscle appearance decreases, which can happen due to a lack of use or age-related factors such as sarcopenia. Elasticity is the muscle's ability to return to its original length when the tension is relaxed, a quality evident when the muscle recoils back to its initial state. Lastly, plasticity refers to the capacity of muscles to adapt to changes but is not specifically related to muscle mass adaptation under stress.