While big biceps or ultra-defined calves are frequent target areas for fitness buffs, six-pack abs also rank as a top goal. Not only do they look good, but they also contribute to a strong core, which can help in everyday activities by making you stronger and faster. One requirement for strengthening these muscles is a variety of core exercises, like situps and crunches, to work your abs and surrounding muscle groups. Doing several different types of these exercises will ensure a total core workout that will build your overall strength and give your stomach more definition.
Bent-Knee Situps and Crunches
Bent-knee situps and crunches are easily the most recognizable of core exercises, with one key difference between the two. With situps, you raise your upper body and core into a full sitting position with help of your hip flexors, while crunches are done with only a half raise, relying primarily on your ab muscles. However, both exercises work the rectus abdominis, which is the long muscle at the center of the abdomen that forms the six-pack look. These situps and crunches are done by lying on the floor with knees bent, then tightening your core to raise your upper body. While many people place their feet under a stationary object to keep them on the floor during this exercise, you actually get a better workout when your feet are unrestrained. In a study published in the "Journal of Strength and Conditioning Research," researchers discovered that restraining your feet resulted in your hip flexors doing most of the work, rather than your abdominal muscles.
Jack Knife Situps & V-Ups
Jack knife situps, which are very similar to V-ups, offer a more intense core workout that concentrates on the rectus abdominis muscle as well as the obliques and other core muscle groups. This exercise is a bit more difficult than the basic situp or crunch, as you also raise your legs. For the jack-knife, the knees remain bent while you bring them to your chest, but the V-up is done with legs straight out, raising them to meet your outstretched hands and forming a "V" with your body.
Your obliques are the muscles on either side of your abdomen, and exercising these is an important part of working your core. Though the obliques are the primary muscles worked in these type of crunches, the rectus abdominis will also benefit. Oblique crunches are done by lying on the floor with your legs raised and knees bent at a 90-degree angle. With your hands behind your head and your elbows bent, you crunch up, bringing your right elbow to your left knee, then return to the starting position and bring your left elbow to your right knee to work both sides of your abdominal muscles.
Stability Ball Core Exercises
The stability ball offers another variation for core muscle workouts. Using the ball to balance yourself, you can do crunches targeting your abs and obliques. These are done using essentially the same form as a standard crunch, but you lie back on the ball instead of the floor, firmly planting your feet for support. Lift your shoulders and chest to crunch in the middle, tightening your stomach muscles. The benefit of using the ball is that all of your core muscles must be engaged at all times to keep the ball steady, so your abs and obliques are worked even harder.
Reverse crunches can be a bit more challenging, requiring you to keep your legs raised in the air for the duration of the exercise. These target your lower abs and are done by lying flat on your back on a mat. With your hands by your sides, bend your knees into a right angle so your calves are parallel to the floor. Tighten your abs and bring your thighs to your chest while tucking your chin to your chest at the same time. Release the crunch, but keep your legs in the raised position and repeat.
- ACE Exercise Library: Bent-Knee Sit-up / Crunches
- FitDay: Crunches: Tone your Abs with These 3 Exercises
- Runner's World: What Type of Sit-Up Best Isolates Ab Muscles?
- Exrx.net: Jack-knife Sit-up
- Exrx.net: V-up
- Fitness: Feel Stronger and More Energized: The You Can Do It Makeover Workout Plan: Oblique Crunch
- ACE Exercise Library: Stability Ball Sit-ups / Crunches
- Runner's World: Stability Ball Exercises For Runners
- ShapeFit.com: Abs Exercises - Reverse Abdominal Crunches For Six Pack Abs
- Photo Credit Photodisc/Photodisc/Getty Images