Kneel down and set up on the flat bench by placing one forearm across the bench so that your wrist is just a touch past the edge. You should grip the dumbbell with your palm down (reverse grip). Your other arm should be resting on the bench perpendicular to the weighted arm. This is your starting position.
Raise (curl) the dumbbell up with your wrist as much as you can. Then lower it back down as far as the natural range of motion in your wrist will allow. Repeat the entire movement for the desired or prescribed number of repetitions and then switch and do the same with your other forearm.
Perform this exercise in a smooth and fluid motion
Don't allow the dumbbell to drop too fast as this may result in a jerking motion to your wrist that can cause injury
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or get a heavier dumbbell.
This exercise is great for beginners because it will allow your wrists and forearms to get stronger and bigger over time. Then, you can move on to more advanced forearm exercises.
You will feel some soreness in your wrist and forearm for a couple of days after performing this exercise, but that is normal. Stick with it and after a few weeks your forearm muscles as well as wrists will get stronger and more resilient.
In addition, your gripping power will increase which is a great benefit for anyone doing weightlifting because most lifting involves gripping barbells, cable handles and dumbbells.