Final answer:
An isometric contraction develops force without changing the muscle length, as it increases muscle tension but the length remains static due to the resistance of the load.
Step-by-step explanation:
The type of contraction that develops force without changing the length of the muscle is known as an isometric contraction. In an isometric contraction, the muscle increases tension through the shortening of sarcomeres but does not shorten overall or move a load, because the force produced cannot overcome the resistance provided by the external load. This is in contrast to isotonic contractions, where the muscle length changes (shortens or lengthens) to move a load, and tension remains constant throughout the movement. Isotonic contractions are classified as either concentric, where the muscle shortens, or eccentric, where the muscle lengthens.
Isometric contractions are essential in everyday life, helping to maintain posture and stabilize bones and joints. Examples include maintaining an upright head position or trying to lift an immovable object, where the muscle tension increases but the muscle itself doesn't shorten.