Depending on the bar type used at your gym, grip the bar tightly with both hands perpendicular to the bar. Be sure your grip is not too close together or too spread apart as this puts unneeded stress on your wrists. Depending on which you find more comfortable, you can use an overhand or underhand grip. Also be sure to keep your head in a neutral position and not let it protrude forward anytime during the lift as that can cause stress on your neck and spine.
Once you find a comfortable grip, depending on the machine, lean slightly backwards so that when you begin to pull the bar downward it will come in front of you towards the top of your chest.
How to do:
1. From the starting position described, draw your naval (or belly button) towards your spine to tighten your core for stabilization.
2. Being sure to keep a natural spine alignment and slowly begin to pull the bar straight downward.
3. Once you have pulled the bar down as close to your chest as your flexibility allows, pause for a second and let the weight begin to rise back upwards in a controlled motion.
4. Repeat this movement while always maintaining a slow and controlled speed.