Curling is a living sport.
In the 1950's brooms were made of corn straw similar to a normal household broom. Over the next two decades, brushes took the place of brooms, and sweeping became much more like scrubbing -- what we use is a "broom" in name only.
During the same period, the methods of delivering the rock have changed as well, going from a "lift delivery" where the stone is physically lifted from the ice, arm swinging back, then forward to the release.
Many Olympic-class Curlers learned this method decades ago, and still practice this method today.
Current teaching is a no-lift delivery, with the sliding foot starting out beside the hack, a push forward, draw back with the sliding foot moving back about a foot behind the hack-line, and then pushing forward. This is how I was taught in February 2010, and how I've delivered, and taught, since.
The sliding foot follows a somewhat curved path, and should end up directly below your breastbone (and center of gravity). It starts at least eight inches off the line of delivery and moves (right for those of us right handers) as you push forward and come out of the hack. Lots of steps going in many different directions, all of which have to end up in alignment for a good delivery.
Less than a year ago, USA Curling released a book titled "The Five Elements of Curling" that makes significant changes in how the curling stone is delivered.
I was fortunate to get a few minutes with John Benton at The Crush in September, he's one of those teaching the new method.
Again, I'm a beginning Curler.
The first step in this new delivery is to place your trailing foot in the hack, then place your sliding foot directly in front of your hack foot. The stone goes right in front of the sliding foot, and before you even begin the delivery, you are in alignment.
The steps in delivering are about the same -- press forward, draw back (and raise up), then push out of the hack and slide with the stone until the release.
It's not the same muscles used in the same way, and for the first three games, it was painful -- especially after driving home and letting those sore muscles cool down.
After six games, I'm starting to feel like this is going to work out, but I'm still looking for proper weight.
Someday I'll be good at this again.