Where to put the phone

On your back, phone low and to the side so the legs are visible from the floor to vertical.

Stand at roughly 45° to the phone. The counter still reads the cycle from the front or the side; the angle only decides how much technique detail the camera can see.

What closes a rep

Raise the legs toward vertical, lower them back down. The rep closes at the bottom.

What makes the counter wait

Keep the legs long. Deep knee bends turn the movement into a reverse crunch, which lives in the library separately.

One tip

Hands under the hips are fine and stay out of the way of the read.

After the set

Every set ends with the same recap: reps counted, time, pace, the longest run, pauses, whether the second half held up, and the camera angle the phone actually saw. Technique detail is measured for the recap and never used to refuse a rep. Why we count and do not grade →