Final answer:
The term that describes an isometric contraction is static tension, where the muscle increases in tension without changing length and does not visibly move a load.
Step-by-step explanation:
The term that describes an isometric contraction is static tension. During an isometric contraction, the muscle produces tension without a change in the length of the muscle or the angle of the skeletal joint. This type of contraction often occurs when a force is applied against a load that is greater than the force the muscle can produce. As a result, the muscle does not move the load, but tension increases within the muscle. This contrasts with isotonic contractions such as concentric and eccentric contractions, where the muscle length changes to move a load. A concentric contraction involves muscle shortening, such as lifting a weight upward, while an eccentric contraction involves muscle lengthening, such as lowering a weight in a controlled way. Isometric contractions are crucial for posture and joint stability, even though there is no movement visible as in isotonic contractions.