Sit-ups are a classic ab exercise, however, certified strength and conditioning specialist Max Gordon asserts that "gone are the days of doing a thousand sit-ups a day." He has observed that "some clients respond well to sit-ups and some simply don't like it and it's uncomfortable on their back."
In order to break up the monotony of "thousands of sit-ups" this at-home workout is designed as a fast-paced circuit. Do all four exercises in a row with no break between. The exercises chosen are easier on the lower back, but they target all of the abdominal muscles. Your abs will be burning by the end of the workout.
Start with exercise #1 and progress, in order, through exercise #4, take a rest, and then repeat the circuit two more times. Do each exercise for 30 seconds, completing as many repetitions as possible.
Read more: Circuit Training Benefits
The curl-up exercise works your abs harder than the standard sit-up, even though it's an abbreviation. Once your upper body gets more than halfway through a sit-up your hip flexors kick in to pull you the rest of the way up. When you use your hip flexors it means your abs are doing less work.
With the curl-up, the point is to roll up as far as your abs will let you, then go back down. This makes sure that most of the stress stays on your abs.
HOW TO DO IT: To do this exercise, start in a sit-up position with your arms straight by your sides. Slide your hands forward on the floor and curl your head, neck and shoulders up as you reach forwards.
According to this study in the Journal of Applied Physiology, Nutrition, and Metabolism, your hands should slide forward about about 4 inches, or 10 centimeters, for maximal activation of your abs. Keep going until your entire upper back is off of the ground, then slowly lower back down.
2. Cross-Body Sit-Up
The cross-body sit-up involves a twisting motion, which means it activates the muscles at the sides of your abdomen known as the obliques.
HOW TO DO IT: Start by getting into a sit-up position, then pick up your right leg and cross it in front of your left knee. Then put your left hand behind your head. Reach your left elbow up and across your body towards your right knee. Get as close as possible to your knee, then go back down slowly.
3. Single-Leg Sit-Up
The single-leg sit-up looks almost identical to a regular sit-up. The only difference is that one is leg straight on the floor and the other leg is bent. According to Dan Cerone, a certified personal trainer in New York City, "having one leg straight helps to prevent the hip flexors from contributing too much to the movement." Thus, this version of the sit-up targets your abs even more than the traditional version.
HOW TO DO IT: Start by assuming a regular sit-up position but put your left leg out straight on the ground. Now perform a regular sit-up to your bent right knee. Try to use as little arm swing as possible.
4. Kettlebell Sit-Up
The kettlebell sit-up is a tough exercise but it's totally worth it if you want a nice set of abs.
HOW TO DO IT: For this exercise you need a kettlebell or another easy to grip object. You can hold a gallon jug of water or milk, or something round and heavy like a bowling ball. Grab the kettlebell with both hands and get into a sit-up position. Now curl your shoulders and head off of the ground and slowly move the kettlebell down towards your legs.
Keep sitting up until you are at the top of the sit-up position. Try to keep the kettlebell as close to your chest as possible while you sit up. If you reach the kettlebell too far forwards the weight will help you sit all the way up instead of making your abs do all of the work.
Pull the kettlebell back towards your chest and slowly roll down the mat with your back. Keep your feet flat on the ground as you lower yourself. Keep pulling the kettlebell back towards your chest as you slowly roll all the way back to the ground.
Read more: Kettlebell Exercises for the Abs