As for movement...why would they limit your character? If you have a problem with your old looking character running like a trackstar, then why would you take athletics?
I'd agree with that statement if it wasn't for athletics not being in the game...
But anyway, with different body types being a feature, I think that we can hope for your character's age impacting your body this time, but I wouldn't count on it effecting movement, not for the player, anyway, it's possible that older NPCs will get special NPC animations to reflect their older age, but older player characters will move normally, and to be fair, that's actually reasonable when you think about it, because I'm fairly certain that character age, if we can change it, will simply be a cosmetic choice, and I wouldn't want to be prevented from customizing my character's appearance how I want by having that choice cause gameplay effects I wouldn't want, and besides, if older characters actually had some penalties with movement (And having them have animations that make them look like they have trouble moving while in gameplay terms still being as fast and agile as younger characters would just look really stupid.), there would need to be some positive effect to balance it out, or no one would want to play old characters, and what kind of benefit would you give to playing an older character?