How would you say "on Saturday mornings"? (That is, I run on Saturdays, in the morning.)

- I run on Saturday mornings.
- Я бегаю ...

- каждую субботу утром is not the same thing - that's every Saturday morning
I am talking about a general habit, but not necessarily "every" Saturday.

Are any of these acceptable? Do they need punctuation to make them better?

- по субботам утром | по субботам, утром | по субботам — утром
- утром по субботам | утром, по субботам | утром — по субботам
- по утрам в субботу | по утрам, в субботу | по утрам — в субботу
- в субботу по утрам | в субботу, по утрам | в субботу — по утрам

Is there another/better way of saying it?