Final answer:
Golgi tendon organs are activated during isometric contractions, where muscle tension increases but the muscle does not shorten or lengthen because the force produced cannot move the load.
Step-by-step explanation:
Golgi tendon organs are activated during isometric contractions. This type of contraction occurs as the muscle produces tension without changing the length of the muscle. During an isometric contraction, even though the muscle tension increases, the force produced cannot overcome the resistance, leading to no movement of the load. These contractions help in maintaining posture and stabilizing bones and joints.
Isotonic contractions, on the other hand, involve movement and come in two types: concentric contractions and eccentric contractions. In a concentric contraction, the muscle shortens as it moves a load, such as when lifting a weight. An eccentric contraction occurs when the muscle lengthens while controlling the movement of a load, such as slowly lowering a weight.