Swing slow back, four to five times faster through
The instructor explains that a golf swing starts from a completely stopped position, so the backswing has to be very slow because there is zero momentum to work with. He puts the backswing at about one mile per hour and the downswing at about four to five miles per hour.
Channel: Golf with Aimee
Watch official source at 0:09Why this context matters
Given in a lesson answering a student's question about swinging too fast.