In the first week of my Swim Faster program, we work on relaxation and rotation. These are two key principles in good freestyle.
Relaxation is essential. There are moments in the stroke when you use key muscles, but there are also moments when you need to be relaxed. Part of your body is working, while the other part recovers.
Relaxation is also about feeling positive in the water. If you’re about to embark on a 1.2 mile swim for a half-tri, you need to know you can finish the swim. Starting with a relaxed state of mind really helps stay relaxed throughout the swim and finish the distance. When I start a long distance swim, I start by thinking “I could do this all day.” Then I build into a strong, but still relaxed swim.
Body rotation is also key to good freestyle. It makes your stroke more efficient, and it helps to avoid shoulder injuries. I ask swimmers to imagine a rod that extends through the center of their body from the middle of the head down through the pelvis. All of your body rotation moves around this axis. It should be pointing straight down the pool at all times to avoid unnecessary drag.
If you watch a good swimmer, you notice that their shoulders continually rock back and forth around this axis. While one arm is underwater, pulling the swimmer forward, the other arm is recovering the stroke in a relaxed manner. Keeping your recovery arm and hand relaxed is important.
In my swim program I start with these two ideas. Everything else in a good freestyle stroke starts with relaxation and rotation.