When the tanner stage calculator says that during stage 4 you develop muscles, do you

[Cicero]

Do they develop automatically, without working out? So like, on that tanner stages sticky, they said during phase 4, you begin to develop muscles. So do you have to workout?

[Rayquaza]

You have to stay fit, otherwise the muscle will develop into fat. But don't really take the tanner stage too literally, since everyone's puberty experience is different, it's just a 'guide' to what probably will happen. If you completely laze around through the muscle developing stage, it will develop underneath your skin and won't really show up.

[Neverender]

You develop your basic muscles to an adequate point for survival. Obviously you would have to work out for them to become large but you don't need to work out for the muscles to grow.