There are many ways to do oblique exercise. I feel the best exercise system for training the obliques is to do Pilates-based exercises in a variety of positions.
Just lying on your back is not enough, lateral (side) positions also help to stimulate the transverse abdominal muscles and the internal and external obliques at the same time.
Listed below is what I use and believe to be the best oblique abdominal exercise sequence to trim up your waistline.
This oblique exercise works the muscles at the waist, and trunk. It is a very effective exercise for getting rid of love handles, in effect, slimming the waist.
Lying on a mat clasp your hands lightly at the base of your skull. Keep your elbows wide by drawing the shoulder blades together and down. Bend your knees up into a tabletop position (knees directly over hips, shins parallel with the floor and toes pointed).
Draw your head and shoulders off the floor just lifting to the base of your shoulder blades. Feel a fold or bow just under the chest.
Draw in your lower abdominal muscles, inhale in the center, and then exhale as you twist at the waist bringing the right elbow to the left knee as you extend the right leg away from you. Switch elbow to right knee as you extend the left leg long.
Continue switching both legs as you inhale and exhale for 8 repetitions. You should be tired by 6 or 8 repetitions if you are doing them correctly.
Keep your elbows wide not pulling on the neck. Stay lifted from your core rather than just leading with your elbows (this will cause you to rock from side to side).
Maintain a strong core connection with the deepest transverse abdominal muscles, and use the obliques to really execute at the waist.
Move slowly holding the twist at the waist to each side. Think deeper in the abdomen!
This oblique exercise works the deep core muscles, waist, arms, shoulders, thighs, and hips. It is a great way to teach the body to work in a lateral plane.
Lie on your right side with your elbow bent at a 90-degree angle and forearm under your shoulder, fist points forward. Knees are bent at a 90-degree angle with legs and hips stacked.
Draw in your lower abs and tighten your waist to raise your hip and thigh off the floor. Create one long line of energy from the crown of your head through your feet. Keep the shoulders pressing down away from the ears and hold for 6-8 seconds (build more repetitions as you advance rather than holding longer).
For more challenge, extend the legs and raise your hips, thighs, and knees off the floor as you reach to the ceiling with the top hand.
To stretch the side of the spine, opening the space between ribs and hips while lengthening and strengthening the oblique muscles.
Position yourself on the side of your exercise ball, it is under your armpit like a buddy. Bend your legs sitting next to it, then place your hands behind your head with your elbows wide.
Press your ribs and hips up onto the side of the ball stabilizing with your feet against a wall. Bend over the ball with an inhale lengthening the spine, then exhale and really lift up lengthening your spine and lifting your ribs and under the armpit up off the ball.
Keep your elbows wide and lift up through the back top of your head. Keep your chin down, chest up, and abs in!
This oblique exercise is not only for lumbar (low back) mobility but also to stabilize the pelvis. By lifting one leg off the mat makes it a great oblique abdominal exercise. You will definitely feel the muscles of the obliques, hamstrings, and gluteals when performing this exercise.
Lie on a mat with your knees bent and feet hip width apart and ankles directly under your knees. Arms are at your side with palms face down.
From a neutral spine inhale to prepare and as you exhale imagine curling the spine up from the tailbone scooping out the deeper abdominals as the hips lift up to the ceiling. Feel the weight evenly in the shoulders and the feet to keep the hips lifted and level.
While lifted and level in the hips press one foot into the floor and lift the other foot about 1 inch off the mat, then switch without rocking side to side as you alternate legs for 4-6 repetitions.
Inhale at the top and then exhale to deeply peel the spine down from top to bottom.