What Are In and Out Exercises?

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Last updated on September 11, 2022

For many people, working the core starts and finishes with crunches. While the crunch is a very good exercise to work the abs through its full range of motion, there are others that should also feature in your workout. One of the best is the in and out exercise.

If you’re not doing in and outs, you are missing out on a fantastic core movement.

In this article, we will provide a complete guide to the in and out exercise. We’ll provide a step-by-step guide to the exercise, along with a number of variations to work different areas of the core. We’ll also answer the most commonly asked questions about the in and out exercise.

What is the In and Out Exercise?

The In and Out exercise is a core developing movement that targets the rectus abdominis or abs. This is quite a challenging exercise that you may have to work up to. Begin by performing sit ups and crunches to develop a foundation of strength before moving on to this exercise.

The in and out does not require any equipment so it can be done anywhere and at any time you choose.

Muscle Worked in the In and Out Exercise

Rectus Abdominis

The main focus of the in and out exercise is the rectus abdominis or abs. The abs are a very simple muscle group, yet one that is often misunderstood. It is a flat sheath of muscle that originates on the pubic bone of the pelvis and inserts onto the fifth, sixth and seventh ribs.

The job of the rectus abdominis is to pull the torso towards the lower body. It does this by contracting and pulling the insertion and origin points closer together. This produces what is called spinal flexion, or a forward curvature of the spine.

Contrary to what many people have been told, the rectus abdominis, or abs, is one single muscle. It is not two muscles and it is impossible to separate the upper abs from the lower abs. The sheath of muscle has a single insertion and a single origin point and so when it moves, the entire muscle moves together.

The individual abs that you see on a very lean person’s body are like tendons and are called tendinous intersections. You do not develop these; they have been there since you were born. So you cannot change how they look or change the number of them that you have. In other words, you can’t change a four-pack into a six pack, regardless of which exercises you do.

When To Do the In and Out Exercise

In and Out Reps and Sets

Many people believe that they have to do very high repetitions on their abdominal exercises. This belief seems to stem from the mistaken idea that you can burn off fat from your midsection by doing abdominal exercises. You cannot.

People also tend to believe that the burn that they feel in the abs after doing high reps on an exercise means that the tummy is becoming leaner and firmer. This is also not the case.

When you do ab exercises like the in and out, you are working the muscle only. Even though your workout will burn more calories, just as working your biceps will, it will not preferentially remove fat calories from your stomach area.

As a result of these facts, there is no point doing 100 rep sets of crunches, in and outs or any other exercise. That would be just as pointless as doing bicep curls for a hundred reps with a very light weight.

Because your abs are a muscle just like all of your other muscles, you should train them in the same way. That means using a weight resistance that is challenging. While you should use slightly higher reps when training the abs, you should still not go beyond 30 reps.

I recommend using a rep range between 15 and 30 on the in and out exercise. As you lower the reps, you should increase the resistance. You can add resistance to the  in and out exercise by wearing ankle weights.

Here is an ideal set and rep scheme for the in and out exercise:

  • Set One – 30 reps
  • Set Two – 20 reps
  • Set Three – 15 reps
  • Set Four – 15 reps

You should also train your abdominals with the same frequency that you train your other muscle groups. They need just as much recovery time as your pectorals or deltoids, so training them every day is counter-productive. Limit yourself to working your abs no more than twice per week.

How To Do the In and Out Exercise?

  1. Get down on the floor on your butt with your arms at your sides touching the floor, knees bent and feet together. Plant your feet on the floor in front of you.
  2. Contract your core and maintain an unusual spine position, as you draw both your core and knees in toward your chest.
  3. From this ‘in position’, lean back, maintain a neutral spine position, and extend your legs out. Keep your hands off the floor as you balance in this ‘V’ shaped position. This is the ‘out’ position of the exercise.
  4. Return to the in position by drawing your knees and hands together again. Ensure that your core remains tight throughout the entire movement.
  5. Continue for the required recount rep count.

In and Out Exercise Variations

There are a number of in-and-out exercise variations that you can include for variety. Some of them are less challenging so it is a good idea to start with them and then build up to the more challenging version.

Knee to Chest

How to Do It

  1. Lie face up on the floor with your legs straight.
  2. Lift one leg and bend at a 90 degree angle. Grab the leg behind the hamstring with both hands and hold while you feel a stretch behind the hamstring that you are comfortable with. This will be your neutral position.
  3. Keep your hands in the the same position push you leg like you want to straighten it and hold for 5 seconds before returning to the neutral position.
  4. Repeat this with the other leg.
  5. You have now completed one rep. Continue for the required rep count.

Training Tips

  • Make sure you keep your hands behind your leg steady to get the benefit of the exercise.
  • Rest your head on the floor.
  • Move deliberately and under control.

Bicycle Crunch

How to Do It

  1. Lie on your back on the floor with your fingers at your ears and your elbows flared outward. Lift your legs to form a 90° angle at the knee. Lift your feet into the air.
  2. Lift your shoulders and upper back of the floor as you raise your right elbow diagonally. Simultaneously draw your left knee towards the right elbow and extend the right leg diagonally forward until the right elbow and left knee meet.
  3. Lower back to the start position and then do the same on the other side. Alternate sides to complete the required rep count.

Training Tips

  • Draw in your elbow and opposite knee equally so that they meet in the middle.
  • Do not raise your lower back off the floor.
  • Do this exercise deliberately without rushing.

Fire Hydrant In and Out

How to Do It

  1. Begin on your hands and knees, with your palms on the floor and space to shoulder width apart. Your spine should be in a neutral position: straight but relaxed.
  2. Keeping your right leg bent at a 90-degree angle, raise it out to the side.
  3. Now straight in your right leg until it is fully extended behind you.
  4. Bend your right knee and bring your leg back into its 90-degree position, and then lower it to meet your left leg.
  5. You have now completed one rep. Continue for the required rep count and then repeat on the other side

Training Tips

  • Press your hands into the floor to keep your shoulders from sinking.
  • Squeeze your glutes with your leg fully extended.
  • Avoid lifting your hips as you lift your bent leg to the side.
  • Do not rush; make sure that every repetition is controlled.

Double Leg Lift

How to Do It

  1. Lie face up on the floor with your legs together and your arms down at your sides. Your legs should form a 30-degree angle with the floor, and your toes should be pointed.
  2. Pull in your  abdominals, and lower your legs to the floor.
  3. Keeping your back flat,  pull your abs in again, and lift your legs back up. Continue lifting and lowering your legs for the required rep count.

Training Tips

  • Keep your back flat on the floor throughout the entire exercise.
  • Do not drop your legs; move slowly and with control at all times.
  • Drive the movement from your abdominals.


How to Do It

  1. Lie face up on the floor with your arms extended out from your sides to provide a good base of support. Keeping your legs together, lift them toward the ceiling so that your legs and torso form a 90-degree angle.
  2. Lower your legs to the right, twisting your torso and allowing your hips to turn while keeping your upper torso stationary. Control the motion so that your feet tap the floor.
  3. Reverse the motion, in the legs back to the starting position.
  4. Repeat on the other side. Continue alternating sides for the required rep count.

Training Tips

  • Keep your legs straight at all times.
  • Lower your leaves only as far as you can while still keeping both shoulders on the floor.
  • Keep your hips flexed to 90 degrees throughout rotation; do not allow your legs to drop.


How to Do It

  1. Life face up with your legs straight and your arms extended behind your head.
  2. Simultaneously raise your arms and legs so that your fingertips are nearly touching your feet, while maintaining a flat back.
  3. Lower back down to the starting position, then repeat for the required rep counts.

Training Tips

  • Keep your arms and legs straight at all times.
  • Avoid using a jerking motion as you raise or lower your arms and legs.
  • You can make this exercise more challenging by holding onto a medicine ball and keeping it extended above your body throughout the exercise.


How to Do It

  1. Lie on your back, with your pelvis lengthened along the floor but not jammed right into it. Place your arms along your sides, and fold your knees in toward your chest.
  2. Curl your head and neck off the floor, extending your legs to the ceiling one at a time. Both buttocks should remain anchored to the floor throughout the exercise.
  3. Expand both arms toward your left leg so you can grasp it with both hands while the leg remains straight. At the same time, lower your right leg halfway to the floor.
  4. Starts to switch legs by reaching both of them up to the ceiling so that they cross each other in mid-air.
  5. Take hold of your extended right leg, and lower your left leg halfway to the floor.
  6. Alternate legs for the required rep count.

Training Tips

  • Keep your core muscles engaged and active throughout the entire exercise.
  • Stabilize your shoulders by pressing your shoulder blades down your back.
  • Keep your glutes firmly planted into the floor.
  • Keep your legs straight.
  • Do not pull your shoulders forward while grasping your leg.
  • Do not bend your knees.
  • Do not use your arms to pull your leg toward you; instead use your abdominal muscles to lift your upper body toward your legs.

Benefits of In and Out Exercise

Core Strength

The in and out exercise will strengthen your entire core area. Your core is the base of your body’s power. The stronger it is the more power you will be able to exert through both your lower and upper body. A strong core will also enable you to be more stable, to have a better posture, and to more effectively recover if you stumble or fall.

Rock Solid Abs

Because it directly works your rectus abdominis muscle, the in and out exercise will allow you to develop rock hard abs. Even if you never manage to actually see your abs because they are covered by a layer of fat, they will still be extremely strong, enabling you to withstand pressure to the stomach such as a punch or kick that would probably disable other people.

Improves Hip Flexibility

The in and out exercise fully engages your hip flexors. As a result, you will more effectively be able to carry out such everyday movements as walking, running and kicking a ball. You’ll also be less prone to hip joint injury.

What In and Out Exercises Won’t Do

While the in and out crunch exercise will do an effective job of strengthening and developing your rectus abdominis muscle, it will not help you to lose fat from your tummy. As a result, the fat that may be sitting on top of your abs will stay there if the only thing you do to get rid of it is ab exercises.

You cannot spot reduce body fat. That means that the fat that is stored on your body will come off evenly from every part rather than one specific part, even if you are doing lots of exercises for that part of your body. This is as true of the abdominals as it is for the thighs or the triceps.

In order to get rid of the fat that may be laying over your abdominals, you should combine your ab workout with a reduced-calorie diet. Your goal for that diet should be to consume fewer calories each day in the form of food than you are using up the form of energy. The extra energy that the body needs to meet its demands will be met by stored body fat. As mentioned earlier, this fat will come from all over your body, including, but not exclusive to, your stomach.


The in and out exercise is one of the best things you can do to directly target the rectus abdominis muscle. While it won’t give you six-pack abs ( only a reduced-calorie diet does that), it will allow you to build a tremendous amount of strength in your abs. For the best results, we recommend doing four sets of in and outs with the following rep scheme a couple of times per week:

  • Set One – 30 reps
  • Set Two – 20 reps
  • Set Three – 15 reps
  • Set Four – 15 reps

Combine this workout with a reduced calorie diet that ensures that you are maintaining a daily negative calorie balance and, before long, the world will be able to see the results of all of your hard work on the in and out exercise.

Steve Theunissen has qualified from the International Sports Sciences Association (ISSA) and is a certified Personal Trainer and Nutritionist. He has over 30 years experience in fitness and nutrition and currently working with famous fitness professionals. He is currently living in New Zealand with is wife and daughter.

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