Your muscles already run on electricity. EMS, short for electrical muscle stimulation, sends the same kind of signal from the outside, so your muscles work while you sit still.

1. 1

   Your brain says "squeeze"

   Every move starts with a tiny electrical signal from your brain telling a muscle to tighten.

   The scienceMotor neurons carry an electrical impulse, called an action potential, to the point where nerve meets muscle. That impulse triggers the muscle fibers to contract.

   The science

   Motor neurons carry an electrical impulse, called an action potential, to the point where nerve meets muscle. That impulse triggers the muscle fibers to contract.

2. 2

   Velvoi sends a gentle signal too

   Soft pads inside the shorts sit on your glutes, inner thighs and stomach and send a light pulse through your skin.

   The scienceSurface electrodes deliver low-level electrical pulses that activate the motor nerves under each pad. The muscle responds just as it would to a signal from your brain.

   The science

   Surface electrodes deliver low-level electrical pulses that activate the motor nerves under each pad. The muscle responds just as it would to a signal from your brain.

3. 3

   The muscle squeezes, then lets go

   Over and over, in rhythm, for fifteen minutes, while you sit still.

   The scienceEach program alternates contraction and rest. Repeated contractions over time are what work the muscle. The FDA notes EMS devices may temporarily strengthen, tone or firm a muscle.

   The science

   Each program alternates contraction and rest. Repeated contractions over time are what work the muscle. The FDA notes EMS devices may temporarily strengthen, tone or firm a muscle.