The butterfly arm exercise lying on a bench helps simulate the pull and recovery motions in butterfly stroke, improving shoulder and back strength without needing water. Here’s how to do it:1. Preparation: Lie face down on a bench, with your head and shoulders extending off the edge, arms straight down towards the ground.2. Pull motion: Start by moving your arms forward as if initiating a pull in the water. Then pull your arms down in a curved path, keeping your elbows high.3. Recovery: After th