"When using [the seated torso rotation machine], the pelvis does not move as you rotate your upper body, which can place excessive twisting forces on the spine," says Jessica Matthews, a certified fitness instructor and exercise physiologist for the American Council On Exercise. "Plus, the main reason people use this machine is because they think it will help work off their love handles, but the reality is that it won't help reduce fat in that area of the body."
A rotational exercise like wood chops, using a medicine ball or cables, is a great alternative move that will challenge your midsection while sparing your spine in the process. The key is to focus on bracing the core throughout the entire movement, Matthews says.
To do wood chops (pictured), begin in a split stance with left foot forward, holding a medicine ball. Brace abs in tight and reach ball overhead and to the left, keeping torso steady. Slowly bring ball down and across to right hip. Keep abs engaged and body still, return to start.