For abdominal workouts, popular exercises include situps and crunches. These two exercises will work your abdominal muscles, but you perform each differently. Situps and crunches also engage different muscles when executed correctly. Different muscles are engaged during a situp and crunch; consider which works best for your needs and fitness goals before choosing one or the other.
Both situps and crunches require you to lie on your back with knees bent. With situps you may need additional assistance -- either with a partner holding your feet in place or by hooking your feet around a secure object for stability. When executing a crunch you only need to bend forward far enough so that your shoulders are off the ground. Situps require you to lift your entire back off the ground during execution.
The targeted muscles for both situps and crunches are the upper and lower abs; the obliques assist the abdominals to accomplish the movements in both exercises. With a situp you also have additional assistant or synergistic muscles, including the inner hip muscles, quads, thighs and the sartorius -- the long, thin muscle that runs down the entire length of the thigh. Situps require the use of a stabilizer muscle to maintain posture during execution and engage more muscles during execution compared to crunches. This stabilizer muscle is the tibialis anterior -- the spindle-shaped muscle located at the front of the lower leg.
Situps do involve many muscle groups during execution and so are not advised for people with neck, hip or back problems. There is a connection with situps and back pain due to the contraction of the stabilizer muscle. When you perform a situp, your thigh muscles contract and tilt your pelvis forward and down. This increases the compressive forces on the disks in the spine, according to CharlesPoliquin.com. There is more risk involved with performing situps versus crunches because of the involvement of both the targeted and stabilizer muscles. Crunches offer a smaller range of motion, which makes the exercise less of a risk.
Performing a situp requires a further range of motion compared to a crunch. If you're new to abdominal exercises it's best to start with a crunch to strengthen your abdominals and then continue on to situps when you feel comfortable. Both situps and crunches aid in strengthening and toning the abdominal muscles. Your metabolism will see a boost if you perform crunches and situps on a regular basis because of the increase in muscle mass. However, getting a washboard stomach will require strengthening the abs, a nutritional diet and an increase in cardio exercises. Both exercises have variations that increase the intensity such as decline situps and crunches, and exercise ball crunches and situps. Both can be further intensified by including weights. Hold a weighted plate across your chest during crunches or try a dumbbell push situp.