Roll rotation measures movement that looks like the head shaking "no", or like a log rolling in a river.
Roll rotation can be used to help reduce the friction or resistance the body creates moving through the water. It does not represent how the hips or shoulders rotate, but you can use it to help optimize breathing and stroking in Freestyle and Backstroke.
In freestyle, during a breathing stroke, look for the following depending on the desired breathing style:
On non-breathing freestyle strokes, there should be minimal rotation. Look for unnecessary exaggerated movements out from the zero line, identify the cause and work to reduce it. Specifically look for any instances where movement crosses the zero line more than once per stroke. This is unnecessary motion which can be reduced or eliminated.
During backstroke you're always looking for minimal rotation, as the shoulders and hips should be rolling, but the head should remain stable. If you were to compare roll present between non-breathing freestyle and backstroke for a swimmer, the non-breathing freestyle should show quite a bit more roll.
To view roll rotation on the graph:
To see stats for roll rotation, create or select a clip stat. Learn more about creating clip stats.