Sit down on a bench and place your forearms on top of your legs at mid-thigh. Make sure your wrists are past your knees so that you have enough clearance for the dumbbells. Grab the dumbbells with your palms facing down (reverse grip). This is your starting position.
Curl the dumbbells up as much as the natural range of motion in your wrists will allow. Then curl the weight back down as deep as you comfortably can. Finally, repeat this entire movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Don't allow the dumbbells to jerk your wrists down as this may result in injury; always be in complete control of the dumbbells
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or use heavier dumbbells.
This exercise is an all-time classic for blasting your forearms into muscle-bulging growth. It is very effective and will build your forearms and strengthen your wrists fairly quick.
Another thing to point out is that this exercise is not the ideal exercise for beginners as it may prove to be somewhat challenging in terms of balance and synchronization. Thus, if you're attempting this exercise as a beginner you may find it awkward at first.
Most exercises that involve dumbbells are more advanced because of the balancing aspect they inherently require a lifter to master.