Muscular Hypotrophy is a symptom exclusive to the Shadow Plague DLC. It increases the strength of the infected by increasing muscle mass, allowing the infected to easy overpower other humans.
- Hypo means not enough and trophy means nourishment, making hypotrophy not enough nourishment. Therefore, Muscular hypotrophy means not enough nourishment for the muscles. It is likely that the developers of Plague Inc. made a typo and meant for the symptom name to be "Muscular Hypertrophy," which would be more accurate to the symptom's effects.
- This symptom could be a take on how vampires have unnatural strength.