1. Sit tall on a weight bench with your feet roughly hip-width apart.
2. Move one of your feet backward underneath your same-side thigh as far as you can while keeping your heal on the floor and your foot straight.
3. Place one side of the dumbbell, or the bottom of a kettlebell, on top of the knee (not on top of your mid-thigh) of the same foot you just moved backward.
4. Push your toes into the ground and lift your heel as high as you can off of the floor, ending up on the ball of your foot.
5. Slowly lower your heel until it touches the floor to complete the rep. Don’t bounce; control the lowering (eccentric) portion of each rep by allowing your heel to touch the floor gently – without fully resting on the floor – until all reps have been completed.
6. Do all the reps on the same side before switching sides.
Note: Position your working side foot closer to you than if you keep your knee bent at a 90-degree angle. This increases the range of motion and demand, which will make it more productive.
– Nick Tumminello