Changing up your workout routine can make it more interesting. Discover how to do pencil jacks, what muscles they work, and whether they are worth it.
Pencil jacks are a variation of jumping jacks where you do a little jump with your arms straight up in the air between each jumping jack.
This makes the exercise focus slightly more on the front part of your shoulder muscles and calves but it also makes doing the exercise at high speeds a lot more awkward.
In turn, pencil jacks are mostly useful as a warmup or to improve coordination.
If you want to improve muscle endurance and/or cardiovascular health and don’t necessarily like pencil jacks, you likely want to choose regular jumping jacks or one of the alternatives.
How to do a pencil jack
Take the following steps to do a pencil jack:
- Stand upright with your arms beside your body.
- Jump in the air and move your legs sideways and outward. At the same time, move your arms sideways and upward.
- Land with your feet wide apart and your arms pointing upward. You want to land with your legs slightly bent for comfort and injury risk reasons.
- Jump back into starting position by reversing the movement from step 2.
- Jump straight up a small amount while moving your arms forward and upward. Ideally, your arms are vertical at the top of the jump movement and back down when you land.
- Land with slightly less than stretched legs into starting position.

Especially when you first try them out, pencil jacks will likely feel relatively awkward to do.
You can give it a try but even when you are more experienced, pencil jacks will feel awkward to do at high speeds.
To make this exercise somewhat more challenging for your cardiovascular system anyway you can wear a good weighted vest while doing pencil jacks.
Muscles worked with pencil jacks
Some of the muscles you work with pencil jacks include your hip adductors (inner thighs), hip abductors (outer thighs/hips), calves, quadriceps (front thighs), glutes (butt), hamstrings (back thighs), core, and shoulders.
When it comes to muscle engagement, pencil jacks are different from regular jumping jacks in that they focus more on your calves and the front part of your deltoids (main shoulder muscle).
At the same time, you spend less time engaging your inner and outer thighs.
All of these muscle engagement differences between pencil jacks and jumping jacks are mostly relevant in terms of improving endurance in these areas.
Both exercises are generally not hard enough to actually cause muscle growth.
Pencil jack exercise benefits
Pencil jacks will likely not be the most effective exercise available but they do still offer positive effects. Some of these benefits include:
- No equipment or location required: You can pencil jacks no matter what your fitness budget is or in what location you are.
- Better cardiovascular health: Working your cardiovascular system harder with pencil jacks can make this system healthier.
- Muscle endurance improvements: The arm and leg movements in pencil jacks are likely not enough to build muscle. At the same time, they can still help you improve muscle endurance.
- Can help with losing weight: Losing weight requires you to use up more energy than is coming in from food. Pencil jacks make this easier to do by increasing your energy usage.
- Improves mood: Doing intense movements like pencil jacks generally makes your body produce more endorphins. These tend to improve your mood.
- Balance and coordination: The movements in pencil jacks can feel a bit awkward to do. By challenging your coordination skills, you can improve them.
- Improves sleep: You can improve your sleep quality and duration by working out more often. For example, by doing pencil jacks.
Jumping jacks offer these benefits too but if you like the pencil jack movement more you could consider this variation too.
Pencil jack exercise alternatives
It is also definitely possible that you don’t necessarily like doing pencil jacks that much. In that case, you can consider their alternatives instead.
- Jumping jacks
- Side shuffles
- Agility drills
- High knees
- Weighted leg adductions or abductions
- Squats
- Using a rowing machine
To choose between these pencil jack exercise alternatives you want to think about what you are trying to achieve and potentially try out a few different options.
Are pencil jacks a good exercise?
You can say that pencil jacks help you warm up, improve your coordination, and to some extent benefit cardiovascular health and muscle endurance.
However, it is hard to really call this a good exercise.
This is mainly because pencil jacks are awkward to do at high speeds and not that challenging for your muscles.
So if you don’t necessarily like doing pencil jacks more than its more effective alternatives, you likely want to go for these other exercise options instead.
If you do like pencil jacks you can still do them. Pencil jacks typically offer a lot more benefits than doing nothing at all.
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