How long / how many lengths (25m lengths) should a teenage boy be swimming for each session? I'm wanting to start building a bit of visible muscle, get fitter and tone up
![Tunisian teen wins surprise Olympic swimming gold American Australia Tokyo North Africa South Africa | The Independent Tunisian teen wins surprise Olympic swimming gold American Australia Tokyo North Africa South Africa | The Independent](https://static.independent.co.uk/2021/07/25/08/Tokyo_Olympics_Swimming_33094.jpg)
Tunisian teen wins surprise Olympic swimming gold American Australia Tokyo North Africa South Africa | The Independent
![Teen told she'd never be able to swim proves doubters wrong - and now has sights set on Paralympics - North Wales Live Teen told she'd never be able to swim proves doubters wrong - and now has sights set on Paralympics - North Wales Live](https://i2-prod.dailypost.co.uk/incoming/article23826867.ece/ALTERNATES/s615/1_Heidi-Rogerson-Swim-Coach-Wes-Billings.jpg)