How to Perform Isotonic Trunk Muscle Exercises

A stability ball crunch is another isotonic exercise for the trunk muscles.
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If you are trying to get toned and strong trunk muscles, isotonic exercises are one way to go. The term isotonic refers to exercise involving movement of the muscles. These exercises shorten and lengthen the muscles, while putting joints through a full range of motion. They are the opposite of isometric exercises that involve muscle contraction but no movement of the joint or lengthening of the muscle. For trunk exercises, you want to target the muscles of your abdomen, back and chest, which help move your spine.

Crunches With Heel Push

Step 1

Lie on the floor with your knees bent and heels resting on the floor. Raise your toes. Place your hands behind your head for support.

Step 2

Push your heels into the floor. Slowly raise your shoulders and contract your abdominal muscles while exhaling. Continue until your lower back comes up slightly.

Step 3

Return to the starting position slowly as you inhale. Repeat for eight to 12 repetitions.

Seated Lat Pulldown

Step 1

Sit on the bench at the lat pulldown machine. Grab the bar with your hands slightly wider than shoulder-width apart. Face your palms forward. Lean back slightly but do not arch your back.

Step 2

Exhale as you slowly pull the bar down toward your chest. Keep your elbows underneath the bar and squeeze your shoulder blades together as you pull.

Step 3

Inhale as you slowly return to the starting position. Repeat for eight to 12 repetitions.

Windshield Wipers

Step 1

Lie flat on your back. Extend your legs upward until they are at a 90-degree angle with your hips. Extend your arms out to the side, placing your hands palms down on either side of your body for balance.

Step 2

Keep your legs straight and slowly move them to the left side as far as you can. Keep your upper body flat on the floor. The movement is from the trunk. Return your legs to center. You can keep your legs bent if this is too challenging.

Step 3

Move your legs to the right side. Slowly return to center. This completes one repetition. Repeat for eight to 12 repetitions.

Stability Ball Pushup

Step 1

Get into pushup position with your lower legs and the tops of your feet resting on a stability ball.

Step 2

Inhale as you slowly lower your upper body until your chest comes close to touching the floor. Your elbows should point out to either side.

Step 3

Exhale as you push up slowly to the starting position. Focus on contracting the muscles of your chest through the movement. Repeat for eight to 12 repetitions.

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