KEEP YOUR LEFT ARM STRAIGHT - ONE PIECE TAKEAWAY
4m
In the golf swing your lead arm stays fairly straight. Not because you keep it straight. It stays straight because of what your trail arm does. As you start the club back. Your wrists begin to hinge. As they hinge your trail arm is always trying to push your lead hand away from you. So the pushing away with the trail arm is what keeps your lead arm fairly straight. That keeps the tension out of your lead arm and lets it accelerate through the ball.