Stomach crunches offer a variety of benefits -- they can help strengthen the abdominal muscles, improve your posture and reduce lower-back pain. You can perform crunches almost anywhere, even while you are still in bed. In fact, a mattress is ideal because it cushions your back and provides adequate support while performing abdominal exercises. Talk to your doctor before doing crunches from bed, especially if you have neck or back problems.
Target your rectus abdominis muscles by doing standard crunches. Lie face-up on your bed with your knees bent into a 90-degree angle and your feet flat on the mattress. Position your hands lightly on either side of your head, fingers resting on your neck. Press the small of your back into the mattress, contract your abdominals and roll your shoulder blades up off the bed. Continue curling your torso upward until your shoulders are about 4 inches off the bed. Hold the contraction for a few seconds and then slowly return to the starting position. Repeat for a total of 12 repetitions.
To boost the intensity of the exercise, hold dumbbells against your chest while you perform crunches in bed or raise your feet about 6 inches off the mattress as you crunch. You can also target the oblique muscles on the sides of your abdominals by doing bicycle crunches where you lift your torso and bring your elbow toward the opposite knee. Continue alternating, pedaling your legs as if you are riding a bike. Or, do reverse crunches, which work your deep transverse abdominis muscles, by lying on your back and lifting your knees up above you at a 90-degree angle. Crunch in reverse by lifting your hips up off the bed and bringing your knees toward your head.
For best results, keep your lower back pressed against the mattress throughout the entire workout. Curl your body forward as you lift, as if you are trying to touch your belly button to your spine. Contract your abdominals as you lift to prevent arching your back, which can lead to back pain. Exhale during the exertion part of the crunch, as you lift your body upward. Inhale as you return your torso to the starting position.
Never lock your fingers behind your head or tug on your neck when you perform crunches, which can cause neck pain and injury. Always crunch slowly. Performing crunches at a fast pace recruits the use of the hip flexor muscles in the upper thighs, which forces your pelvis to tilt and places stress on the lower back. Only exercise on a firm mattress. Mattresses that are too soft can make crunches more difficult or cause your spine to curve. Immediately stop exercising if you experience any pain or extreme discomfort. Take a break or try the crunches from a more stable surface such as the floor or an exercise bench.