Which condition is described as the tightening of muscle fibers leading to pain and discomfort?

The condition described as the tightening of muscle fibers leading to pain and discomfort is accurately referred to as a muscle cramp. A muscle cramp typically occurs when a muscle involuntarily contracts and does not relax, resulting in sudden pain and discomfort. This can happen during physical activity, dehydration, or as a result of electrolyte imbalances.

While a muscle strain involves the stretching or tearing of muscle fibers, resulting in pain, swelling, and limited movement, it does not specifically encapsulate the concept of tightening as the primary symptom. A muscle sprain refers to an injury involving the ligaments that connect bones to one another, while tendonitis is the inflammation of a tendon and is characterized by pain around the affected tendon region rather than a tightening of muscle fibers.

Thus, the correct understanding of muscle cramps aligns best with what was described in the question.