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February 08, 2022 8 min read

Starfish crunches are a crunch exercise variation where you start lying down on your back with your arms and legs stretched and pointing away from each other, similar to a starfish.

Compared to regular crunches, starfish crunches work your obliques and lower abdominal muscles more.

Starfish crunches are mostly done to strengthen your core muscles. Whether you should add starfish crunches or alternatives to your routine depends on things like your personal situation, personal preference, and training goals.

To do the exercise you then raise one arm and one leg and move them toward each other with the help of your core muscles. These types of exercises really target your abdominal muscles. In this article, we'll take a look at how starfish crunches can help you build a stronger core.

core muscles anatomy chart

Building a Stronger Core

Your core muscles are some of the hardest working ones in your body. These are the muscles around your pelvis, lower back, hips, and abdomen. They are important in movements that require twisting, bending, reaching, pulling, pushing, balancing, and standing. Your core muscles extend from your neck down to your pelvis.

They incorporate muscle groups like: 

  • Traverse abdominis: this wraps around the front and side of your trunk. This muscle stabilises the pelvis. 
  • Internal and external obliques: these extend diagonally from your ribs to your pelvis and allow you to rotate your trunk. 
  • Rectus abdominis: this is commonly referred to as your 'six-pack' muscle. You use this muscle to bend forward. 
  • Multifidus: this is the back muscle that supports your spine. 
  • Erector spinae: this is the back muscle that extends your trunk and helps you stand up straight. 

Benefits of a Strong Core 

A strong core gives you better stability and balance for athletic activities as well as daily tasks. Building strong muscles in this area can also help you avoid injuries and chronic low back pain. To improve your core strength, you need to perform specific exercises that target your abdominal muscles. Starfish crunches are intermediate exercises that will help you strengthen your abdominal muscles.

The relationship between your abdominal muscles and your core is something like the relationship between your biceps or triceps and your arms: one is a muscle and the other is an area made up of multiple muscles.

By exercising your core, you are trying to focus on what is happening in the center of your body. 

Starfish crunches will certainly help you create abdominal hypertrophy and directly load your rectus abdominis. If you plan to do this type of workout with the proper form and on a consistent basis, you will feel a deep abdominal burn, which is something that can help you build an impressive visually appealing six-pack.

Achieving a six-pack requires hard work and getting to a low body fat percentage. If you're serious about chiseled abs, the Ultimate Shred Stack can help you lose weight while increasing your muscle mass. 

Core training can help you to stand a little taller because a strong core improves your posture, as has been measured by significant improvements in postural stability tests. Also, a strong core can help you build muscle in other areas. If you have a weak core, it can cause a forward pulling and a rounding of the shoulders. Core exercises will give your chest muscles a much better shape.

Engaging Your Core 

Knowing the exercises that will work your core is one thing, but if you learn how to engage it properly, you'll know how to work your core along with whatever muscle you are trying to train.

As you start to engage your core more often, it will soon become almost a subconscious action that will help you maintain an appropriate position and posture and also give you more support, balance, control, and strength overall. 

Engaging your core means that you are trying to brace your body as you would if somebody is about to punch you in the stomach. There is quite a simple way for you to learn how to do it while you are doing your warm-up. We’ll take a look at this simple process in more detail below.

How to Engage Your Core 

First, lay on your back with your knees bent and feet flat. Press your back into the ground and try to slide your hand under your lower back. Try to prevent your hand from passing through the gap by pressing down slightly and tensing your core muscles. Hold this position for up to 10 seconds and rest, and then repeat the exercise three to four times. 

As you get used to this position, try standing and contracting. Once you know what you should be feeling, it becomes easier to contract and engage your core on demand.

Remember that your glute muscles, stomach muscles, and breathing patterns should all contribute to engaging your core. Keep in mind, the contraction should not be so hard that it becomes impossible to contract and breathe at the same time. 

How To Do a Starfish Crunch 


For starfish crunches you will ideally want a yoga mat or other soft surface to lie on. To do a few sets of starfish crunches as a five or ten minute abs workout, just follow all of the step-by-step instructions below.

Here's how to do Starfish Crunches: 

  1. Lie down on your back with your stretched arms and legs spread out so that your body makes a starfish shape (like an X). 
  2. Slowly move up one leg and the arm of the opposite side until they reach the middle while keeping these body parts stretched. These movements should come as much from your core muscles as possible.
  3. Lower your arm and leg through the full range of motion to the position described in step 1 in a controlled motion. 
  4. Repeat the same movement with the opposite arm and leg for as many reps as you can.

Remember to keep your movements slow and controlled to make your obliques and abs really work as hard as possible. Avoid using your arms or legs for momentum.

You want most of the movement to come from your hips and your upper body moving toward each other.

If your core muscles are not feeling tired, your technique needs improvement. 

Some Variations of Starfish Crunches 

Starfish crunches with just your body weight and arms straight up are the standard version of the exercise. There are also a few variations that can make the exercise harder or easier, as some people are not ready yet for full starfish crunches. 

For Less Intensity 

To work up to the full version you can consider only raising your body parts a small amount. If that is still too challenging, you can start with lying down on your back, and pressing your lower back against the ground with the help of your ab muscles.

If your oblique muscles are the thing holding you back, you can start with side planks or even knee side planks. All of these variations will help you train similar muscles but at a less challenging level.

For More Intensity 

Bodyweight starfish crunches can also become too easy. At this point, you may need to turn to other exercises or make starfish crunches harder to keep seeing a lot of muscle growth and strength progress. Making starfish crunches harder at the right points in your training journey can also speed up progress compared to doing the regular bodyweight variation over and over.

The main way to do this is by doing weighted starfish crunches.

This is basically doing the same exercise but while holding extra weights like dumbbells, kettlebells, weight plates, etc. in your hands to make starfish crunches more challenging. You can also wear ankle weights. 

Muscle Groups Worked 

If you do them right, starfish crunches are mainly a core muscle (obliques and abs) isolation exercise. Your hip flexor and back muscles may have to work to a certain extent to raise your legs and arms. The way you build muscle in places like your core is by engaging these muscles so that they get damaged enough. 

This may sound counterintuitive, but this type of hypertrophy allows your body to repair these muscles and be better prepared for future training. If you continually do exercises with the same amount of weight, this same effort may not damage your muscles enough to promote extra muscle growth as your muscles become stronger.

By adding extra resistance to exercises like a starfish crunch you are better able to damage the muscles in a shorter amount of time.

If you don’t overdo it, give your body enough nutrients and give your muscles enough rest. This can in turn lead to faster and more core muscle gain. Depending on your personal situation, workout plan, and training goals, starfish crunches may be a beneficial addition. 

Benefits of Starfish Crunches 

If you enjoy doing starfish crunches, they can be very useful, but there are also plenty of other exercises that can also offer you a lot of similar benefits. If you do decide to start doing more starfish crunches, always provide your body with enough nutrients, rest, and sleep to repair and grow your muscles. Always remember that weightlifting and cardio  can both burn calories.

Many people can benefit from adding starfish crunches to their workout routine. You may need to make the exercise more challenging with crunch equipment to keep seeing a lot of muscle growth and to gain strength more quickly.

You may question how useful starfish crunches can be, but adding them to your routine can offer you these specific benefits: 

  • Stronger muscles: Starfish crunches are a type of resistance training that can help you strengthen your ab muscles. 
  • Aid in losing weight: Doing starfish crunches uses more energy than your regular daily activities. Extra muscle mass also helps with burning more calories. Both of these aspects can help with weight loss. 
  • Improves mood: Exercise like starfish crunches promotes the release of substances that can help you feel better. 
  • May reduce or prevent back pain: Core strengthening exercises like starfish crunches can reduce or prevent back pain.
  • No equipment or location required: Since starfish crunches are a bodyweight exercise you don’t need any special equipment. 
  • Improves sleep: Exercises like  starfish crunches can improve the quality and duration of your sleep which also offers many added benefits. 
  • Slows down aging: Starfish crunches can help slow down the progress of certain aging markers that are correlated with negative health effects. 

A Few Potential Risks 

The main thing to keep in mind is that starfish crunches can be hard on many of your more sensitive body parts such as your back, hips, hip flexors, shoulders, and neck, even if you are doing the exercise with the proper form. If you are weak or sensitive in these body parts, you may need to do other strengthening exercises first. 

Especially if you have any back pain, you may want to talk to your personal trainer before implementing starfish crunches into your workout routine.

If you feel pain in any part of your body, it may be a sign you are overdoing it.

In that case, you may need some rest or a less intense workout schedule. Remember that consistency is an important factor for any workout plan. The more you enjoy any given exercise, the easier it becomes to do it consistently.

Muscular guy doing sit ups at gym with other people in background

Starfish Crunch Alternatives 

If you are not quite ready for starfish crunches, or if you are looking for other moves to strengthen your core and especially your lower abs, here are some other exercises that will also specifically target your abdominal muscles and give you a great ab workout:

  • Reverse crunches
  • Sit-ups
  • Bicycle crunches
  • Planks
  • Hanging knee raises
  • Hanging leg raises
  • Flutter kicks

Overall Findings

If you follow a well-designed strength training program, and if you try to eat as well as you can, you can quickly gain impressive amounts of muscle and strength. But usually after a few months of doing starfish crunches, your progress may slow down considerably. You will need to create a long-term plan to keep getting stronger.

Be sure to do a bit of research into which type of diet might be best for your specific needs. There are so many different types of wellness diets that you will need to select one that matches your goals of either  bulking your body up a lot more, or of shredding excess body fat and slimming down as much as you can.

By simply including starfish crunches and other bodyweight exercises in your core workout routine, you can improve your core strength and your quality of life.

Strengthening and maintaining a healthy core is key to improving athletic performance, performing daily activities, and preventing injuries.

The starfish crunch is an excellent ab exercise that is sure to get your abs burning. You can do them individually, add them to a resistance training session, or include them in your regular workout.