Jennifer F.
Hi! It’s not harmful but I would take caution to doing high intensity cardio before lifting weights for a couple of reasons. If you do heavy cardio before lifting, you might not be able to lift as much weight, with the proper form, due to exhausting yourself with cardio. If you plan to do intense cardio AND weightlifting in the same day, I would break them up into two different sessions or lift weights then do the cardio.
