What Are Crunches?
Each workout consists of sets of exercises, and people always adjust them to their needs. There is always an exercise that is considered to be the most effective for certain muscle groups. For buttocks and quads, the go-to exercise is a squat, for biceps and triceps, it’s a push-up or a pull-up. Those who dream of rippling biceps pack their workout routine with zounds of exercises that target arms muscles. Those who strive for a Greek god torso try to hone their focus on their chest and abdominal muscles by churning out Russian twists and crunches. Crunches are a calisthenic exercise, which means that they target large groups of muscles and generally don’t require any additional equipment.
A classic crunch involves raising your shoulders and head off the floor, by using the sole force of your core muscles. Although you feel how your abdominal muscles contract during the crunch, it is not the best ab-defining exercise. Performing different types of crunches may improve the result and add to the process of building a six-pack. However, the best option is to combine exercises that focus on your core from different angles and involve different mechanisms of action. Stick around to find out more about what muscles do crunches work, are crunches good for weight loss, how many calories do you burn doing crunches, and how to do crunches properly.
What Muscles Do Crunches Work?
There are different types of crunches, that focus primarily on the same group of muscles, but with the bigger emphasis on different muscles of that group. The classic crunch aims mainly at your rectus abdominis also involving your obliques. The rectus abdominis, or your “six-pack muscles” stretch vertically from the pubic bone upward to the ribs. The obliques, which are divided into internal and external obliques, are also a part of the abdominal muscles group. They stretch on the sides of your torso (6), with internal obliques lying beneath external obliques, and are interconnected with the rectus abdominis. Together the abdominal muscles play the key role in your posture, balance, and movements of your torso and hips.
How Many Calories Do You Burn Doing Crunches?
If your main goal is not to build abs, but to lose weight, you may wonder how many calories do you burn doing crunches. The number of calories that you burn during any physical activity depends on a lot of factors, including your weight, height, sex, age, intensity, and duration of that activity (2). An average 125- (56kg), 155- (70kg), and 185-pound (84kg) person burns around 45, 55, and 66 calories per 10 minutes of moderate-intensity crunches respectively. 10 minutes of vigorous crunches burn 80, 99, and 118 calories (3). In order to estimate how many calories, you personally burn, you can use our calories burned calculator. So, if you want to get a more accurate result, and calculate how many calories you burn doing crunches in a minute, use the following formula:
Number of calories burned per minute = (MET × 3.5 × your weight in kg) / 200
The MET of crunches varies depending on the intensity, and may equal 2.8 (light effort), 3.8 (moderate effort), and rarely 8 (vigorous effort) (8).
To calculate your weight in kg, divide your weight in pounds by 2.2.
So, if you weigh 165 pounds, which is 75 kilograms, 1 minute of performing crunches with moderate effort will burn (3.8 × 3.5 × 75) / 200 which equals 4.9 calories.
An average person performs 30 crunches in a minute, burning around 5 calories. So, in order to calculate how many calories do you burn doing 100 crunches, all you need is to multiply the number of calories you burn in a minute by 3.3, which is how many minutes it takes to perform 100 crunches. An average person would burn 16.6 calories.
What About Other Types Of Crunches?
There are a lot of types of crunches, some of the most popular include bicycle crunches, reverse crunches and crunches on the ball. That is not surprising, as they were rated as some of the best exercises for abdominal muscles (1). As a bicycle crunch, which is also called the bicycle maneuver, was ranked number 1 on the list of best ab exercises, a lot of people take more interest in them. Bicycle crunches are a variation of a classic crunch. Along with rectus abdominis and obliques that are involved in a classic crunch, they also engage your quadriceps and intercostals. Although they incorporate more muscles, they still do not burn that many calories.
So, if you are curious how many calories do you burn doing 100 bicycle crunches, or how many calories do you burn doing crunches on a ball, you may be disappointed to find out that they burn the same number of calories as the classic crunch.
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Are Crunches Good For Weight Loss?
If you are still wondering “How many crunches should I do a day to lose weight?”, here is your answer: one pound (0.45kg) of fat equals 3500 calories (5), so, using the above-given information, you can calculate that in order to burn that amount of fat, an average person must do 21,875 crunches. To shed 1 pound (0.45kg) a week, you need to perform 3,125 crunches a day. This number is quite high, to say the least. Frankly speaking, it sounds impossible and dangerous. Especially considering that you are not likely to perform crunches for a long period of time, and in one workout all the sets of crunches combined usually take from 5 to 10 minutes.
So, in other words, crunches are not as effective at helping you slim down, as they may seem. That is why if you want to lose weight, you should reconsider what tools you use for that, as there are a lot of exercises that promise a much better weight loss effect than crunches. Another important factor that greatly affects weight loss is nutrition. Eat healthy and decrease your caloric intake, and it will undoubtedly propel you to your goal (7).
How To Do Crunches Properly
As with any other type of exercise, it is extremely important to perform a crunch properly. It will not only prevent any possible injuries but will also maximize the benefits from the exercise. Before you get down to crunches, here are some recommendations:
- Avoid rapid and abrupt movements
- Your lower back should remain pressed to the mat throughout the whole exercise
- Do not push yourself too hard
- Stop the exercise whenever you feel any discomfort in your lower back
- Do not begin any new workout plan without discussing it with a health specialist
Now that you followed all the recommendations, you can start performing crunches.
In order to properly do a crunch, follow these instructions:
- Lie down on the exercise mat, with your knees bent and your feet flat on the floor.
- Connect your hands behind your head and spread your elbows to the sides.
- Contract your abdominal muscles, and while keeping your lower back pressed to the mat, lift your shoulders and upper back off the floor, and pull your rib cage toward your pelvis.
- Pause for a second, inhale and slowly pull your back down to the mat. That is one repetition.
During a crunch, avoid the following mistakes (4):
- Lifting your upper back too high off the mat
- Tucking the chin too far into your chest, and trying to use the force of your hands to lift your head and shoulders off the ground
- Not contracting your abdominal muscles throughout the exercise
- Jerking your head off the floor
Crunches are a calisthenic exercise, which focuses mainly on your rectus abdominis, or a “six-pack”, and your obliques. Despite being considered one of the best ab exercises, crunches are not very effective when it comes to burning calories. You can calculate how many calories you burn doing crunches with the formula that we explained above. An average person performs 30 crunches per minute, burning only 5 calories. So if you want to successfully trim a couple of inches, it is better to perform a more high-intensity activity, keeping in mind that your eating habits make up 80% of your weight loss success. Before starting any new exercise routine, or dietary plan, it is highly recommended to consult a doctor.
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!
- American Council on Exercise (ACE)-sponsored Study Reveals Best and Worst Abdominal Exercises (2001, acefitness.org)
- Calculating how many calories are burned in a day (2020, medicalnewstoday.com)
- Calories burned in 30 minutes for people of three different weights (2018, health.harvard.edu)
- Common exercise mistakes (2018, nhs.uk)
- Counting calories: Get back to weight-loss basics (2020, mayoclinic.org)
- Internal obliques (2006, dictionary.webmd.com)
- Start losing weight (2019, nhs.uk)
- The Compendium of Physical Activities Tracking Guide (n.d., prevention.sph.sc.edu)