The rotary torso machine, also called a torso rotation machine, targets the muscles of your core. However, if you use improper form or don't control the motion, the rotary torso machine loses its effectiveness. This exercise strengthens your core muscles, but it will not specifically burn off fat from your midsection or sides.
The rotary torso exercise machine allows you to rotate your trunk against resistance. This movement targets your side abs, or obliques. Rotary torso machines have different designs. You sit on most torso rotation machines, but you kneel on others. Some machines hold your legs in place while you twist your torso; other machines hold your torso in place while you twist your legs. Selectorized torso rotation machines have an integrated weight stack, while plate-loaded machines hold weight plates for resistance.
Regardless of the design, rotary torso machines target your core muscles. The obliques are the primary movers. They are responsible for spinal rotation -- turning your torso to the side. To target the obliques, you must rotate at the lumbar spine, not at the hips. Although the torso rotation movement targets your obliques, several other muscles engage to assist your core and stabilize your torso. Your hip flexors and upper-back muscles are also involved in the rotary torso exercise.
To use the rotary torso exercise machine, sit down, place your shoulders against the shoulder pads and lightly grasp the handles. Select a weight that allows you to do eight to 12 repetitions. Pull your bellybutton into your spine to activate your rectus abdominis, the main ab muscle, which helps brace your torso. Exhale as you rotate to one side. Pause for a count and then slowly return to center. Perform each repetition slowly and with control.
Do not grasp the handles too tightly. If you do, you are more likely to use your arms to twist, which takes away from the work of your obliques. Do not swing or perform the rotation exercise quickly or with momentum. It is easy to begin swinging back and forth with no control or purpose, but this does not benefit your obliques.
Using the rotary torso machine will strengthen and tone your oblique muscles, but it will not specifically burn fat off the area you are working. Design a complete workout plan that incorporates strength and cardio exercise, in conjunction with a solid nutrition plan, if your goal is to lose weight and burn fat. The rotary torso machine should be one part of an overall exercise routine.