Final answer:
The effect of pronation distortion typically results in tight and overactive muscles. It specifically leads to overactivity in muscles like the peroneal, posterior tibialis, gastrocnemius, and lumbar extensors, while causing other muscles to become underactive.
Step-by-step explanation:
The effect of pronation distortion on muscles can lead to a condition in which certain muscles become overly tight and overactive. This postural distortion often results in the overactivity of the peroneal, posterior tibialis, and gastrocnemius muscles, as well as the lumbar extensors. As these muscles become tight, they cause a chain reaction that makes other muscles underactive, like the gluteus medius and the anterior tibialis. Pronation distortion syndrome can contribute to an increased risk of injury, especially in the knees and lower back, due to the improper alignment and functioning of related muscles and joints.
Therefore, the correct answer to the question is: 1) It causes overactive muscles.