Skull crushers are a great exercise for triceps workouts, especially if you have access to a spotter.
But, you may want to know, how many skull crushers should I do to build muscle? How many skull crushers should I do to increase strength?
In this workout guide, we will discuss how to do skull crushers and determine the number of reps, sets, and weights you should use for skull crushers based on your fitness goals to ultimately answer your question, how many skull crushers should I do in my workouts?
Let’s dive in!
How Do You Do Skull Crushers?
You can perform skull crushers with various types of resistance, but barbell skull crushers are the most common.
However, if you’re going to do barbell skull crushers—-especially with heavy weights to build muscle or increase strength—it is best to work with a spotter for safety because you will be bringing the weight over your face.
Here are the steps for how to perform skull crushers:
Skull Crushers
- Lie down on a flat bench holding a barbell (or dumbbells) with your arms extended straight up like the end position of the bench press.
- Point your elbows up so that you can lower the barbell backward towards your forehead, only moving your lower arms. Your upper arms should remain completely fixed and perpendicular to the weight bench.
- The barbell should nearly graze your forehead as you bring it back behind your head as slowly as possible.1Schoenfeld, B. J., Ogborn, D. I., Vigotsky, A. D., Franchi, M. V., & Krieger, J. W. (2017). Hypertrophic Effects of Concentric vs. Eccentric Muscle Actions. Journal of Strength and Conditioning Research, 31(9), 2599–2608. https://doi.org/10.1519/jsc.0000000000001983
- Pause, feeling the stretch in your triceps, before you contract your triceps to press the barbell back up and forward to the starting position.
If you do not have a spotter, you can perform the exercise with dumbbells, a cable pulley, or kettlebells rather than a barbell, which will be safer.
However, in all cases with free weights, having a spotter is ideal.
How Many Skull Crushers Should I Do To See Good Results?
Deciding how many skull crusher reps to do is only part of programming skull crushers into your workouts.
The reps of an exercise refers to the number of repetitions of the exercise you do.
So, for example, one rep of the skull crusher exercise involves starting with the barbell or weights up above your chest, then lowering the weight back behind your head, and then lifting it back up.
Another component to consider is the number of sets of skull crushers that you will do.
A set of an exercise is the total number of repetitions that are performed back to back without stopping and resting.
For example, you might do 8 skull crushers in a row, rest for 90 seconds, and then do another 8 skull crushers in a row.
This means that you have done two sets of 8 reps of skull crushers in each set.
Finally, the other key component that significantly impacts how many reps of skull crushers you should do is the weight that you are lifting, also known as the load.
Together, the number of reps, sets, and weights that you lift for an exercise multiplied together constitutes the total training volume or training load of that exercise for a workout.
How Many Skull Crushers Should I Do Based On My Goals?
There are several factors to consider when deciding how many skull crushers you should do.
Your Fitness Level
Deciding how many skull crusher reps to do begins with considering your fitness level or training level.
This leads to questions like: How many skull crushers should beginners do? And how many skull crushers should I do if I have been training for years?
As is likely intuitive, beginners should do fewer reps of an exercise than trained athletes in order to prevent injuries and allow the body to get accustomed to the demands of the movement.
How Much Weight You Are Lifting
The number of reps of skull crushers that you can and should do in a set or workout overall will be largely dependent on how much weight you are lifting.
Here, it is important to distinguish that the amount of weight that you are lifting refers to the relative load or intensity of the weight you are using for you personally.
For example, there is a big difference in lifting 15-pounds vs 30-pounds for skull crushers.
Using just an unloaded EZ curl bar that weighs 15 may be extremely difficult for a beginner and pose essentially very little challenge for an advanced athlete who might be able to do countless reps of skull crushers with that weight.
To determine how many reps of an exercise you should do, the weight that you lift is compared to your one-repetition maximum (1RM) for the exercise, which gives you an idea of the relative load or relative intensity of the weight for you.
Your 1RM for an exercise is the maximum amount of weight that you can lift with proper form for just one complete repetition of that exercise.
For example, with the skull crusher exercise, if you can use a 25-pound barbell for one repetition but not more than that, your barbell skull crushers 1RM is 25 pounds.
Then, if you are lifting 20 pounds in your skull crushers workout, you are lifting 80% of your 1RM.
The strength continuum offers a framework by which you can calculate the appropriate weight to lift based on the number of reps of an exercise you want to do.
The following table shows the percentage of your 1RM you should use for the given number of reps of an exercise based on the strength continuum created by the National Strength and Conditioning Association (NSCA):2TRAINING LOAD CHART. (n.d.). https://www.nsca.com/contentassets/61d813865e264c6e852cadfe247eae52/nsca_training_load_chart.pdf
| Maximum Number of Reps | Percent of 1RM Load |
| 1 | 100% |
| 2 | 95% |
| 3 | 93% |
| 4 | 90% |
| 5 | 87% |
| 6 | 85% |
| 7 | 83% |
| 8 | 80% |
| 9 | 77% |
| 10 | 75% |
| 12 | 70% |
So, to determine how much weight to lift for skull crushers, look at the number of reps you want to do and then determine the relative load that you should use in the column next to your desired number of reps.
For example, if you want to do 12 reps, the recommended load is 70% of your 1RM while if you are only doing six reps, you should use 85% of your 1RM.
This is all a good starting point, but we still have not answered the question: How many skull crushers should I do based on my fitness goals?
Your Fitness Goals
Aside from your training level, your primary training goal is the other key factor that will affect how many skull crushers you should do.
Your training goal helps set the context for how much weight you should lift and how many skull crusher reps you should do for optimal results.
There are three primary strength training goals generally considered when programming exercises:
- Increasing strength
- Increasing mass (building muscle, also known as hypertrophy training)
- Increasing muscular endurance
How many reps of an exercise you should do is largely dependent on these fitness goals, as each goal is best served by a different approach to programming your workouts.
The following table provides recommendations for how many reps to do and how much weight to lift for different strength training goals based on the average guidelines from the American Council on Exercise3How Many Reps Should You Be Doing? (n.d.). Www.acefitness.org. https://www.acefitness.org/resources/everyone/blog/5867/how-many-reps-should-you-be-doing/(ACE) and the National Strength and Conditioning Association4.Sands, W., Wurth, J., & Hewit, J. (2012). The National Strength and Conditioning Association’s (NSCA) BASICS OF STRENGTH AND CONDITIONING MANUAL. https://www.nsca.com/contentassets/116c55d64e1343d2b264e05aaf158a91/basics_of_strength_and_conditioning_manual.pdf
| Training Goal | Sets | Reps | Rest Period | Intensity |
| General Fitness | 1-3 | 12-15 | 30 to 90 seconds | Varies on exercise and ability level |
| Muscular Endurance | 3-4 | >12 | Up to 30 seconds | <67% of 1RM |
| Hypertrophy (building muscle mass) | 3-6 | 8-12 | 30 to 90 seconds | 67% to 85% of 1RM |
| Muscle strength | 4-6 | 3-6 | 2 to 5 minutes | >85% of 1RM |
| Power | 3-5 | 1-5 | 2 to 5 minutes | 85%–100% of 1RM |
From here, you can use the strength continuum table to determine how much weight you should be lifting after you determine how many reps of the exercise you should do based on your training goals.
Let’s walk through an example:
How many skull crushers should I do to build muscle?
According to the table above, if you are trying to build muscle (hypertrophy training), you should do 8 to 12 reps of the exercise.
So, if we want to do 10 reps of skull crushers—which would be right in the middle of the recommended range for building muscle—we would then use the first table to see that for 10 reps of an exercise, the optimal load is 75% of your 1RM.
Let’s imagine that your 1RM for the dumbbell skull crushers is 20 pounds, this means that you would do three sets of 10 reps with 15-pound dumbbells in each hand.
To learn more about the number of reps and sets you should do to build muscle, check out our guide to hypertrophy reps and sets here.
