Level.
The only possible developmental advantage is a bit more natural strength from a maturing body.
Speed and explosiveness is going to go to pot.
Net, everyone on a mission is going to be behind athletically after their mission vs before their mission.
The only people this wouldn't apply to is people who were non athletes and out of shape before.
Then the mission may get them moving mote and eating less. Then they actually improve.
This does not apply to athletes, as their activity decreases greatly.