The 5 Best Ab Exercises—And The Ones That Are Wasting Your Time

Strengthen your core by adding these five must-do exercises to your routine.

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ab exercises woman in black doing twist situps

Not all ab exercises are created equal. In fact, many are simply a waste of workout time. A study conducted at the San Diego State University Biomechanics Lab examined the electromyography (EMG) activity results garnered by popular core exercises. Here’s how they stacked up, along with some of our other favourite (and least favourite) ab exercises:

Don’t waste your time with:

1. The basic crunch

Why: The basic crunch is just that—basic. Don’t waste countless hours on a less-than-stellar exercise that does little to fully engage your abdominal muscles.

2. The ab rocker

Why: The ab rocker was proven to be no more effective than the traditional crunch. Actually, it was shown to be up to 80 percent less effective. Yes, it’s super easy to do, and that’s why it doesn’t work. By supporting your head, this tool actually deactivates the muscles in the neck that would normally support it. This can lead to neck pain as your supporting muscles weaken. There’s a reason these machines are collecting dust in the corner of your gym.

3. The straight-leg sit-up

Why: This old-school exercise is responsible for many back issues. It puts a huge strain on the lower back by provoking you to hurl your upper body forward in an attempt to touch your toes. No thanks.

4. The standing dumbbell side bend

Why: Isolating the obliques in this way is not natural and can add unnecessary strain to your back. (How often do you bend straight to the side to pick something up?) Also, many people use the momentum that the dumbbells create and rock side-to-side instead of properly engaging their muscles. Avoid these unless you want to look you’re rocking to the oldies.

5. The seated twist

Why: Seated twisting machines are a waste of money and space in fitness facilities. They rotate your lower back beyond its safe range of motion and can also lead to injury if you don’t know what weight to use and how to control the movement. I’ve seen many people snap from right to left with some wicked momentum—ouch!

Opt for these five exercises to maximize your workout time instead:

1. The plank

How to do the Plank Challenge
Plank. (Photo, Roberto Caruso.)

Why: It stimulates more abdominal activity than a regular crunch and works the muscles in your back as well.
How: Supporting yourself on your forearms and the balls of your feet, bridge up and position your body in one straight line. Pull your abs in tight and hold for 30-60 seconds.
Kick it up a notch: From the plank position, reach forward with your right hand, hold for a count and slowly return to the starting position. Do the same with your left hand and repeat.

2. The bicycle crunch

Why: In the San Diego study, this exercise was the second highest in terms of strengthening the obliques in participants. It also stimulates more abdominal activity than the traditional crunch including your lower stomach and obliques.
How: Lying on your back, bring your knees up to form a 90 degree angle and keep your hands by your temples. Crunch up and twist across the body while simultaneously performing a bicycle motion with your legs. For example, if you crunch up and to the right you should draw your right knee in and vice versa. Repeat for 20-30 reps total.

3. Side plank

Why: Side planks not only torch your obliques, they also stimulate and tone your glutes, quads, hamstrings, inner/outer thighs and your upper body.
How: Lie on your side with your forearm perpendicular to your body and one foot stacked over the other. Bridge your hip up and hold for 30-60 seconds while maintaining a straight line with your body.
Kick it up a notch: Raise your top leg so that it’s parallel to the ground (this full version of this is called Vasisthasana in yoga).

4. Vertical leg crunch

Why: It stimulated 116 percent more abdominal activity in the study’s participants than the traditional crunch.
How: Lie on your back with your legs up in the air, knees slightly bent. Try to touch your ankles with your hands by contracting just your abs, but keep your chin off your chest. Repeat for 12-16 reps.
Kick it up a notch: Reach towards your toes and hold the position for 15 seconds for a V-sit.

5. Reverse crunch

Why: Engage your lower abdomen and obliques with this move.
How: Lie on your back with your hands tucked under your bum and your knees bent. Bring your legs up until they form a 90 degree angle from your torso. Do a pelvic tilt and pull your knees in towards your chest, squeeze and slowly lower to starting position. Aim for 15-20 reps.
Kick it up a notch: Hold a weight over your head.

Ripped abs plan:

One of the best ways to work the abs is to perform a series of core moves in one continuous circuit. Circuits are efficient and effective, allowing you to get the most out of your efforts. For optimum results, perform this core circuit at the end of your intense training sessions. You want your core strong and ready to back you up when you’re in the thick of a tough workout.

Plank tri-set (regular and sides): 30-60 seconds
Reverse crunch: 15-20 reps
Bicycle crunch: 10-15 reps per side
Vertical chair knee raise: 12-15 reps
Notes: Perform 2-4 total sets or circuits with no rest between exercises and a 1 minute rest between circuits.

Alex Savva is a strength and conditioning expert and a professional member of the Ontario Kinesiology Association.

This article was originally published in June 2016; Updated January 2020.