Starfish Crunches: How To Do, Benefits,…

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There are many different ways to improve your current exercise routine. What about doing starfish crunches, what will the effects be?

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.

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.

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

Starfish crunches are typically done to grow and strengthen core muscles like your obliques and abs. For other fitness goals, there are many better exercise options.

Whether you should add starfish crunches or alternatives to your routine depends on things like your personal situation, personal preference, and training goals.

How to do a starfish crunch

For starfish crunches you preferably want a yoga mat or other soft surface to lie on. To do a starfish crunch take the following steps:

  1. Lie down on your back with your stretched arms and legs spread out so that your body makes a starfish (an X) shape.
  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. Especially for the arm movement you want the movement to come from your upper body coming off the ground.
  3. Lower your arm and leg to the position in step 1 in a controlled motion.
  4. Repeat the same movement with the opposite arm and leg.

Keep your movements slow and controlled to make your obliques and abs really work hard and to 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 fatiguing your technique can likely use some improvement.

How to do a starfish crunch

Starfish crunch variations

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 easier or harder.

Some people are not ready yet for full starfish crunches. 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 by 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 will help you train similar muscles but at a less challenging level.

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.

Starfish crunches muscles 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 damaging makes it so your body repairs these muscles, and adds a bit more to be better prepared to exert similar efforts in the future.

If you stick to exercises with the same weight, as your muscles become stronger this same effort may not damage your muscles enough to promote extra muscle growth.

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 good or bad addition.

Starfish crunch benefits

Some people question how useful this exercise can be but adding starfish crunches to your routine can offer you some helpful benefits. Some of the most important ones include:

  1. Stronger muscles: Starfish crunches are a type of resistance training that can help you strengthen your ab muscles.
  2. Can help with losing weight: Doing starfish crunches likely requires more energy than your regular daily activities. Extra muscle mass also helps with burning more calories. Both of these aspects can help with, but are no guarantee for, weight loss. Keep in mind that there are better exercise choices if weight loss is your goal.
  3. Improves mood: Exercise like starfish crunches promotes the release of substances that help you feel good.
  4. May reduce or prevent back pain: Core strengthening exercises like starfish crunches can reduce or prevent back pain (1, 2). If you currently have back pain you do want to be careful and talk to an expert before implementing this exercise.
  5. No equipment or location required: Since starfish crunches are a bodyweight exercise you don’t have to invest in equipment or be in a specific location. That being said, a soft surface like a yoga mat can make the exercise more comfortable.
  6. Improves sleep: Exercise like starfish crunches can improve the quality and duration of your sleep which in turn offers many important benefits.
  7. Slows down aging: Starfish crunches won’t influence how many days have passed since you were born. However, exercise can slow down the progress of certain aging markers that are correlated with negative health effects.

While inevitably many workouts are better for some of these benefits than starfish crunches, it is amazing that you can get so many important benefits from adding one activity to your routine.

Potential risks

The main thing to keep in mind is that starfish crunches can be hard on body parts like your back, hips, hip flexors, shoulders, and neck even if you implement the right technique.

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 primary care provider before implementing starfish crunches into your workout routine.

If you feel pain in any body parts it may be a sign you are overdoing it. In that case, you may need some rest, better lifestyle habits, a less intense workout schedule, or it may be a sign that starfish crunches are not (yet) for you.

Starfish crunch alternatives

While starfish crunches can be a good addition to your workout routine, there are also some alternatives available for training your core muscles. Some of these starfish crunch alternatives include:

  • Reverse crunches
  • Side plank dips
  • Bicycle crunches
  • Lying leg raises
  • Side leg raises on the captain’s chair
  • Compound core exercises

Which one of these options is the best depends on things like your personal situation, training goals, the equipment you have available, etc.


Many people will benefit from adding starfish crunches with the right technique to their routine. You may need to make the regular version more challenging soon with crunch equipment to keep seeing a lot of muscle growth and strength progress.

That being said, for goals besides strengthening your obliques and abs and making them stand out more, there are many better exercise options.

You also need to remember that starfish crunches can be hard on body parts like your back, hips, hip flexors, shoulders, and neck even if you implement the right technique.

If you are sensitive or weak 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 primary care provider before doing more starfish crunches.

Also keep in mind that consistency is an important factor for any workout plan. The more you love the exercise you do the easier it becomes to do it consistently. If doing starfish crunches is a workout you love, great. If not other exercises can also offer a lot of benefits.

If you do decide to implement more starfish crunches make sure you give your body enough nutrients, rest, and sleep to repair and grow your muscles.

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Matt Claes founded Weight Loss Made Practical to help people get in shape and stay there after losing 37 pounds and learning the best of the best about weight loss, health, and longevity for over 4 years. Over these years he has become an expert in nutrition, exercise, and other physical health aspects.