Final answer:
An isometric contraction occurs when a muscle cell produces tension without shortening, typically during activities that require maintaining posture or joint stability.
Step-by-step explanation:
When a muscle cell generates tension without shortening, a(n) isometric contraction occurs. These contractions result in increased muscle tension but maintain the length of the muscle and do not change the angle of a skeletal joint. For example, trying to lift an immovable object would engage isometric contractions as sarcomeres shorten and muscle tension increases, but the elbow joint angle would remain the same. This type of contraction is also crucial for activities such as maintaining posture and joint stability.