Answer to Question 1
If they are overstretched or stretched too fast, the spindles send messages to the central nervous system, and through a feedback loop, motor neurons are activated and cause muscle contraction to resist muscle stretch. This is called the stretch reflex.
Answer to Question 2
Greater range of motion around the joints is attained through plastic and elastic elongation.
Plastic elongation is the permanent lengthening of soft tissue. Even though joint capsules, ligaments, and tendons are basically nonelastic, they can undergo plastic elongation. This permanent lengthening, accompanied by increased range of motion, is best attained through proper stretching exercises.
Elastic elongation is the temporary lengthening of soft tissue. Muscle tissue has elastic properties and responds to stretching exercises by undergoing elastic or temporary lengthening. Elastic elongation increases extensibility-the ability to stretch the muscles.
Smooth muscle under microscope
Muscle length versus isometric force
Gluteal muscles of the hip region.
Testing the strength of the facial muscles
Smooth muscle
Lactate fermentation in muscles