How To Do It:
Grab a medicine ball, dumbbell, or weight plate and sit on the floor with your hips and knees bent 90 degrees. Hold the weight straight out in front of you and keep your back straight (your torso should be at about 45 degrees to the floor). Explosively twist your torso as far as you can to the left , and then reverse the motion, twisting as far as you can to the right . That's one rep, do 3 sets of 8-12 at the end of your workout.
The strength you need to paddle a raft is generated in your core, not your arms or shoulders. Build paddle-worthy obliques and incredible rowing muscle with this simple move.