I can think of nothing worse, and when I exercise, the first thing I want to do is shower and put clean clothes on. It can't be good for his personal health, all that stale sweat, underarm BO etc.. I would be grossed out by him working in that state all day, let alone actually getting into bed with me. I would insist he shower when he gets back from his run, and puts his "work clothes on" .. I get that the lock down has put all of us under pressure, and into a different frame of mind, and perhaps we all feel a bit more slovenly.. (I had a very lazy day myself yesterday!!) But I live alone, and if I want that kind of day (which is rare), at least it's only me.
Not sure what he was like pre-lock down, but personally, we should all shower after every session of exercise, whether it be at the gym, or at home.. If you are living with someone and they smell, it can be a huge turn off, which could lead to some serious issues about your feelings for that person, and you lose respect for them, which is even worse! He should have more pride.. The odd day you could probably let go, but every day... noooo.. gross!! lol
Please tell him..