Jumping jack form check: a live coach on your phone
Jumping jacks are a simple full-body warm-up, and the count is only honest when each rep is a full one: arms all the way overhead and feet clearly wider than your shoulders at the open position, then arms down and feet together. Lazy jacks with half-raised arms or feet that barely part are the usual shortcuts. Filmed from the front, because the movement is sideways.
No equipment needed. Practise at home. Just do the rep properly in front of your phone. Bodyweight squats, push-ups and lunges need nothing at all, and you can check the hinge and press patterns with a very light weight or none: the coach judges your movement, not your kit.
What good looks like
- Start standing tall with your feet together and your arms down by your sides.
- Jump your feet out wider than your shoulders while your arms sweep up overhead.
- Reach your arms all the way up, close to your ears, at the open position.
- Jump back to feet together with your arms down, keeping a steady rhythm.
Common mistakes and how to fix them
Arms stopping at the shoulders
Half-raised arms cut the movement and the warm-up. Reach all the way overhead.
Feet barely moving apart
A tiny hop is not a jack. Land with your feet clearly wider than your shoulders.
Not coming back to the start
If your arms never come all the way down, the rep is half done. Return to your sides every time.
What Formanti checks on your jumping jack
The top of every rep, judged the same way.
- Arms: 125–186°. arms all the way overhead
- Feet: at least 1.9× your hip width apart. feet clearly wider than your shoulders
Your closed
The low point of every rep, judged against the guide ranges.
- Arms: 0–45°. arms back down by your sides
What you hear and see when you are off
Bring your arms all the way down
The coach says: “Arms all the way down”
On screen: Bring your arms all the way down.
Drill: Slow jacks: arms touch your thighs at the bottom of every rep.
Reach your arms all the way overhead
The coach says: “Arms overhead”
On screen: Reach your arms all the way overhead.
Drill: Slow jacks with a 1 second pause when your hands touch overhead.
Jump your feet wider
The coach says: “Feet wider”
On screen: Jump your feet wider.
Drill: Mark two spots on the floor a little wider than your shoulders and land on them.
Drills you can do alone
- Slow-motion jacks: one rep per two seconds with a pause in the open position, to check your arms and feet.
- Step jacks: step one foot out at a time with the same arm movement, if jumping is not comfortable.
How to set up your phone
Phone at chest height, 2 to 3 metres in FRONT of you, whole body in view with room above your hands. Film from the front: the arms and legs move sideways, which only a camera in front of you can read. It all runs on your phone and nothing is uploaded.
New: ranges from standard coaching references, not yet checked against real lifters.
Frequently asked questions
Why film jumping jacks from the front?
The arms and legs move out to the sides, which is face-on to a camera in front of you. From the side the phone cannot see how high your arms go or how wide your feet land.
Does it count fast jumping jacks?
Yes, it counts a rep roughly every half second, so a normal fast pace is fine, as long as your whole body is in view.
More lifts to check
Deadlift · Squat · Push-up · Lunge · Overhead press · Bent-over row · Romanian deadlift · Bicep curl · Tricep extension · Lateral raise · Glute bridge · Pull-up · Dip · Sit-up · Plank · Wall sit