My soon to be 7 year old boy has been doing a lot of pull ups lately. he swings a lot on monkey bars too. are pull ups at his age inadvisable?

Go for it: There's a concern that lifting very heavy weights while the epiphyses are immature may cause bleeds there that will stunt growth. Boys have been doing chin-ups for years to their considerable benefit and in 40 years in medicine, I've never heard of a mishap beyond falling off. Stop worrying, follow common sense, and I'm glad Junior is exercising. More boys should follow his example.