We could debate the vagueness of how much human and Viltrumite physiology scale to each other as far as age and sex are concerned, but an athletic 18 year old male human would absolutely physically dominate an athletic 50-60 year old woman. Mark is not close to his physical prime, but he’s likely much stronger than he was in S1.

This is exactly the conclusion I came to as well, and it just seems logical to me. Then again we can’t know what the show runners intended for sure unless they explain their reasoning.