The kettlebell swing should be respected for it's pure simple physical challenge, so we refer to "heavy" as enough weight that you don't have to worry about swinging it over your head (that would be a crescent swing btw ). .
Before you load up on snatches, go back to the swing and refocus on the fundamentals. It's not uncommon to swing 30% more than you can snatch.

Swings are the foundation kettlebell motion.
* Low impact read more
