Adrea Gibbs is a freelance contributing writer with more than 20 years of experience writing for a variety of publications. She has also written several books.

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Sit ups are an exercise you either love or hate. There really aren't many people who fall in between, but they do target an area of the body most people want to have look better, particularly when it comes to wearing anything form-fitting. With a rapidly changing repertoire that no longer includes the long-standing sit up as we know it, crunches, planks, and standing abdominals have replaced it in the interest of health, safety, and functionality.

Traditional Sit Up

Sit ups have fallen out of favor because of the potential for injury and engagement of the hip flexors as opposed to just isolating abdominal muscles. Many people still use them as part of their exercise regimen; however, you need to pay careful attention to areas of the exercise that can be cause for injury.

To perform a traditional sit up:

Lie on the floor with your hands clasped behind your neck or across your chest. And your knees and place your feet flat on the ground.
Contract your abdominals and lift your torso up from the floor to your knees, returning to your original position.

Of the two arm positions, crossing the arms over your chest is a better choice, as it alleviates the possibility of pulling on and straining the neck in the upward phase of the exercise.

Crunches - The New Sit Ups

Many will remember doing the sit ups as described above in P.E. classes, but things have changed considerably. The science of kinesiology has gone a long way in determining the best possible methods to perform many exercises, sit ups among them. The traditional sit up has been replaced by modifications that are now more commonly referred to as crunches. Crunches reduce stress and strain, particularly of the neck, that was long associated with traditional sit ups.

There are several things to keep in mind as you perform all the crunch exercises below. You will see several phrases or variations of phrases repeated within the directions that are critical to both executing the exercise correctly and in reducing the potential for injury. As with any exercise, be sure to properly warm up and cool-down.

Contract Your Abdominals

When you contract your abdominals, it should feel like a girdle or wide belt has tightened around your ribs, waist, and lower midsection. To achieve this successfully, think about pressing the belly button back toward the spine, drawing inward. You can practice contracting the abdominals almost anywhere: when seated, standing in line, cooking, or even driving the car. Doing this small action will activate the key muscles being strengthened through the different exercises and increase the overall stabilization of the spine.

Inhale or Exhale

As simple as this may seem, breathing is key to successful exercise. Inhaling or exhaling on the indicated phases of the exercise will not only oxygenate your system but allow you to better control all your movements. Equally important is being able to breathe normally when holding a position because it shows you can maintain form without straining.

Hold

When you challenge yourself by adding an extra count or two to the holding phase of an exercise, you increase the intensity while strengthening your body. It is critical you only hold for as long as you can successfully retain your alignment, so when position starts to change, even slightly, return to the starting position in a slow and controlled manner for maximum effect.

Alignment

This refers to the positioning of your body. Typically, it will mean that the head, neck, spine, and depending on the exercise, hips, knees, and feet are in a line. Maintaining position will give you the most benefit and limit and potential injury during the exercise.

Neutral

This is the position your body will naturally fall into without force. When standing, it should mean that the head, neck, shoulders, hips, knees, and feet are aligned. When lying down it is the same, usually with a small curve upward in the lower back.

As with any exercise if you have any issues that will impact proper execution, talk to your doctor or health care professional. Be advised the exercises listed are suggestions of those that will assist in strengthening the core musculature, but each individual exerciser participates at his or her own risk.

The Basic Crunch

The basic crunch has replaced the sit up because it is safer. It also isolates your abdominal muscles better than sit ups do. Positioning is similar to a sit up, and the movement is just a modification of the exercise. Use the instructions in this article about crunches to learn to perform the basic exercise.

Tips

Following those basic instructions, you will be well on your way to doing a solid crunch. Focus on bringing your ribcage toward the hips and keeping your head, neck, and shoulders relaxed. While doing the exercise, keep this information in mind:

Using proper form is necessary to prevent stress to the lower back.
Do not pull on your neck if you choose to place your hands behind your head. This can cause injury to the neck and back.
Do not do the exercises too quickly. If the movement is rushed, you will use muscles in the hips to perform the action instead of the abdominals. It will also cause your hips to tilt, increasing stress to the lower back.
Do not push yourself until you hurt. You want to build stamina and strength over time, so give yourself that latitude. Do the crunch correctly first, then add repetitions.
If you become dizzy, disoriented, or out of breath, rest. If this is a persistent problem, stop doing the exercise and check in with your doctor.

Variations on the Crunch

The following positions allow for variety throughout the exercise ad work slightly different supporting muscles.

Elevated Bent Knee Crunches

Lie flat on your back on a floor mat.
Bend your knees so your feet are also flat on floor, about 12 to 18 inches from your seat.
Cross your arms over your chest, lightly holding opposite shoulders if possible. Contract your shoulder blades, pulling them together without allowing your back to arch. Alternatively, place your hands at the base of the head with your elbows pointed out to the sides. Maintain this starting position throughout exercise.
Lift your feet off the floor until your knees are over your hips and lower legs parallel to the floor.
Exhale a single breath through next steps.
Contract your abdominals.
Drop your chin slightly toward your chest, lifting your shoulders from the floor in a curl, one vertebra at a time, as you squeeze the ribcage together and toward your hips.
Keep your neck relaxed and your lower back, tailbone, and feet in contact with the floor mat.
Curl until the upper part of your back is off the floor, contracting your abdominals, for several seconds.
Start to inhale and lower slowly back to the starting position, maintaining neck and back alignment, with your lower back, tailbone, and feet remaining in contact with the floor.
Repeat 10- 15 times.
Rest.
Work up to three sets, then add repetitions or additional sets to your workout.

Straight Leg Crunches

Follow steps 1 to 3 for Elevated Bent Knee Crunches.
Extend your legs straight up so your ankles and knees are aligned over your hips.
Continue with steps 5 to 13 for Elevated Bent Knee Crunches.

Straight Leg Crunch With Arm Reach

Follow all steps for Straight Leg Crunches except while retaining proper upper body positioning and keeping head and neck relaxed, reach arms upwards and as you lift upward, looking to close the gap between your fingers and toes.

Oblique Crunches

This variation targets the side muscles associated with the abdominals. This series sets up the same way as the basic, bent knee, and straight leg crunches, but the torso action crosses the body instead of flexing forward.

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Basic Oblique Crunches

Lie flat on your back on a floor mat.
Bend your knees so your feet are also flat on floor, about 12 to 18 inches from your seat.
Cross your arms over your chest, lightly holding your opposite shoulders if possible. Contract your shoulder blades, pulling them together without allowing your back to arch. Alternatively, place your hands at the base of the head with elbows pointed out to the sides. Maintain this starting position throughout exercise.
Exhale a single breath through the next steps.
Contract your abdominals.
Drop your chin slightly toward chest, lifting your right shoulder toward your left hip, lifting up from the floor in a curl one vertebra at a time as you squeeze the bottom of the right ribcage together and toward your left hip, effectively crossing the body.
Keep your neck relaxed and your lower back, tailbone, and feet in contact with the floor mat.
Curl until the upper right part of your back is off the floor, contracting abdominals for several seconds. Focus on the left side of the body with your hip to shoulder maintaining contact with the floor.
Start to inhale and lower slowly back to the starting position maintaining neck and back alignment. Keep your lower back, tailbone, and feet in contact with the floor.
Repeat the same side or alternate your right and left sides, repeating each side 10-15 times.
Rest.
Work up to three sets, then add repetitions or additional sets to your workout.

Elevated Bent Knee Oblique Crunches

Follow steps 1 to 4 from Basic Oblique Crunches.
Lift your feet off the floor until your knees are over your hips and your lower legs parallel to the floor.
Follow steps 4 to 12 Basic Oblique Crunches.

Straight Leg Oblique Crunches

Follow steps 1 to 4 from Basic Oblique Crunches.
Extend legs straight up so ankles and knees are aligned over hips.
Follow steps 4 to 12 Basic Oblique Crunches.

Cross-legged Crunches

Follow steps 1 to 2 from Elevated Bent Knee Oblique Crunches.
Place your left ankle on top of your right knee.
Point your left knee out to the left side.
Exhale a single breath through next steps.
Contract your abdominals.
Drop your chin slightly toward your chest, lifting your right shoulder toward your left knee. Lift up from the floor in a curl one vertebra at a time as you squeeze the bottom of the right ribcage together and toward your left hip, effectively crossing the body.
Keep your neck relaxed and your lower back, tailbone, and feet in contact with the floor mat.
Curl until the upper right part of your back is off the floor, contracting abdominals, for several seconds. Focus on the left side of the body, hip to shoulder, remaining in contact with the floor.
Start to inhale and lower slowly back to the starting position, maintaining neck and back alignment, with your lower back, tailbone, and feet remaining in contact with the floor.
Repeat same side 10-15 times.
Switch sides and repeat.
Rest.
Work up to three sets, then add repetitions or additional sets to your workout.

Bicycle Crunch Simple

Follow steps 1 and 2 for the Basic Oblique Crunch.
Lift your left foot off the floor until your left knee is over left hip, and your lower left leg is parallel to the floor.
Follow steps 3 through 9 for the Basic Oblique Crunch.
Switch legs and repeat to other side.
Continue to alternate side to side 10-20 times.
As your confidence grows and form is retained, make the motion more fluid by switching the arms and legs at the same time, simply tapping the returning toe on the ground before lifting again.
Rest.
Work up to three sets, then add repetitions or additional sets to your workout.

Bicycle Crunch Advanced

Advance to this variation once you are comfortable with Bicycle Crunch Simple step 6.

Follow steps 1 through 6 for the Bicycle Crunch Simple except instead of lowering your legs to the ground, extend the returning leg straight out to a position parallel to the floor.
Alternate to the other side.
Continue to alternate side to side 10 to 20 times.
Rest.
Work up to three sets, then add repetitions or additional sets to your workout.

Reverse Crunches

Reverse crunches are powerful because they isolate your abdominal muscles. You can follow these steps to perform them.

Wrap-up on Sit-ups

With fitness continually finding new, better, and different ways for individuals to stay healthy and fit, much comes back to the very basic premise of knowing your physical and mental capabilities, paying attention to and listening to your body, and being cognizant of proper execution of exercises for maximum benefit and reduced risk. There are many great exercises targeting the abdominals. What is most important is that you find something that works well for you.