Stand up straight and hold a pair of dumbbells to your side. This is your starting position.
Squat down while keeping your back straight and as vertical as possible. Your head should be up as well as if looking into the horizon. Squat down all the way until your legs are past a 90-degree angle. Once at the bottom, push yourself up with your legs and get back into the starting position.
Finally, repeat the entire movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Keep your back straight at all times and as vertical as possible
Don't allow the dumbbells to swing back and forth; keep them fixed to your sides and control them at all times
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or use heavier dumbbells.
Not the most common exercise you will see people doing at the gym, this exercise is very effective for your legs if you are not on a muscle (mass) building phase. It's great for toning and shaping which in turn will give you the much-coveted muscle separation that contributes to the cut and lean beach-body look.
Thus, if you are looking to put slabs of muscle onto your legs this exercise is not for you. To build massive muscles onto your legs you will need to do the big daddy of all leg exercises - the barbell squat.