I don't think it's too important to explain - most of the actual terraforming lore probably won't make it in - but the gravity of Mars would likely increase by at least 20% post-colonization since it would now have seas, a thicker atmosphere, and a higher mass from throwing asteroids at it.
So does everybody just have terrible muscle atrophy
There was probably a lot of mandatory gene modification early on to make sure people develop and retain muscle mass faster. It's at least partially why Ms. Sommers is so strong.
Keep up the great work though, always glad to see new development!
Thank you!