In general, when science is done, recruitment requirements force the experimenters to bucket the participants. One thing that often happens is an open bucket, say 35+.
The resulting science is then reported as “When you cross 35, your chances of being pregnant immediately drop” or “The brain stops developing at 18” and so on.
Almost nothing in the body is really like this, though. You can quit smoking later in life and it will help. You can eat better later and it will help. You can exercise and it will help. Very few things are “the damage is done”.
The only constraints are that the later you start the more risks you face. E.g. if you first deadlift in your 50s and you decide to follow Starting Strength you’re going to have trouble.
The resulting science is then reported as “When you cross 35, your chances of being pregnant immediately drop” or “The brain stops developing at 18” and so on.
Almost nothing in the body is really like this, though. You can quit smoking later in life and it will help. You can eat better later and it will help. You can exercise and it will help. Very few things are “the damage is done”.
The only constraints are that the later you start the more risks you face. E.g. if you first deadlift in your 50s and you decide to follow Starting Strength you’re going to have trouble.