In and Out Abs Exercise – A Better Way To Build Core Stability and Strength

in and out ab exercise

For an exercise that really puts those tummy muscles to the test, ab In and Outs won’t disappoint!

As an advanced movement, you may find you need to build up strength in your core first with gentler exercises such as regular sit-ups and crunches (as movements go, it’s pretty similar to suitcase crunches).

When you’re ready to go, a huge bonus is you won’t require any equipment, just you, a floor and the motivation to work that core!

Our step-by-step guide below should be all you need to get started, plus we’ll dive into some variations, those all important benefits and discuss the muscles worked too.

How to Do In and Out Abs Exercise

To do ab In and Outs;

  • Step 1. Start in a sitting position, arms either side of your body with your legs bent, feet together, flat on the floor in front of you.
  • Step 2. Tighten your core, and keep a straight back as you raise your hands and feet from the floor, and bring your knees up to your chest. You are now in the ‘in’ position
  • Step 3. Gently lean back, keeping your spine straight, as you straighten your legs out in front of you. Imagine the movement as a balancing act between your upper body and legs, with your bottom being the only part of your body that makes contact with the floor
  • Step 4. As your shoulders come close to the floor, hold the position without allowing them, or any other part of your body except your bottom, make contact with the floor. You are now in the ‘out’ position.
  • Step 5. Now lift your shoulders, and bend your legs back into the ‘in’ position. Remember to keep your core tight throughout.
  • Step 6. Repeat the ‘in’, ‘out’ movement for the desired number of repetitions.

If at any point you feel pain, or aren’t able to keep a tight core so that the movement is controlled, stop the exercise. You may like to consider some of the easier variations below to better prepare your core for this more challenging movement.

The video below includes a demonstration of the exercise. To really feel the burn and test your core stability, try varying up the speed. Do a few really slow reps, following by some faster ones, helping to ensure your stabilizing muscles are engaged and being tested.

In and Out Ab Variations

Floor surface

Perhaps an obvious one, but if you’re finding balancing your bodyweight on your bottom uncomfortable, using a yoga mat or cushion is likely to help. Our recent guide on the Pilates head cushions, includes some multipurpose cushions that would be good for such situations.

Master gentler abdominal workouts first

Remember this is an advanced workout for your core so it is important you already have good strength in your abs before you try. Build up to this exercise by working on less intense alternatives such as regular sit ups, T-raises or ab crunches.

Ab pulse ups are another great way to build up that foundational core strength.


As with any exercise, increasing the number of repetitions, providing this doesn’t result in you losing the correct form, makes the workout harder. It is generally thought that increasing the number of repetitions can be better for burning fat.

Slow the pace

Rather than increasing the number of repetitions, you can also advance the exercise by slowing down the movement. This requires your muscles to work under tension for longer, which can help you build the strength in your abs more quickly.

You can also pause on each “in” and “out” to make the abs work harder.

Benefits of Ab In and Outs

Strengthen Core

A strong core brings with it a whole host of benefits for everyday functional movements and is key to good balance, posture and stability.

Popular Bodyweight exercise

Utilising bodyweight alone, In and Out abs are a popular choice of exercise for anyone who wishes to build strength in their core from the comfort of their home or even on holidays without the necessity to find a gym or invest in equipment.

Abs of Steel

The core abdominal strength required for in and out abs make it a great choice for anyone looking to enhance definition of the stomach muscles and build or maintain the ‘six-pack’ look.

Hip Flexibility

The hip flexors work hard during this exercise and these are key to a whole host of everyday movements (walking, kicking, bending, basically any movement of the lower body). Building strength and flexibility in your hips helps to perform these movements with ease and avoid injury.

Muscles Worked During the In and Out Ab Exercise

Unsurprisingly, In and Out abs work predominately your abdominal muscles in your core. Keeping the correct form does require strength in your lower back too, whilst your hip flexors allow the ‘in’, ‘out’ movement. Your quads will also be engaged as you bend and straighten your legs.

As with any exercise that isolates particular muscle groups, to really feel the benefits and strengthen and tone the muscles involved, you’ll need to incorporate the movement consistently and regularly into your fitness regime.

That said, you’ll also need to ensure you don’t overwork your core, so allow your muscles sufficient time to rest by perhaps giving them a day of rest in between. If you are using the exercise as part of a bigger workout, make sure the other exercises don’t also focus on your core.

Related Articles:

Hip Adductor Stretches to Unlock Newfound Movement

How to do X Planks (Exercise Guide)

Dumbbell Leg Extension Tutorial