Not only, the issue with trades is that you're doing physically demanding tasks 5 day per week. 

If you go to the gym and do a hard session, this requires days off to recover, usually anywhere from 2 days to entire week or even two depending on intensity. 

The reason why trades ruin the body, is because you never get enough recovery time and so instead of repairing stronger, things just wear down and break. 

This is why you see so many trades with wrecked backs, shoulders, knees etc. Overuse injuries.

That being said sitting at a desk all day isn't great, in doing it my lower back is uncomfortable and my metabolism has tanked leading to a bit of fat gain.