Let’s begin by differentiating between pull ups, pull downs and chin ups. Pull ups are performed with your palms facing away from you and can target the triceps, lats and back muscles, depending on the width of your grip.
Pull downs are performed at a pull down machine, and are just assisted pull ups, in that you are able to select how much weight to work with.
Chin ups are performed with your palms facing towards you and target predominantly the biceps. Chin ups are much easier than pull ups, which is why a lot of beginning bodybuilders follow the path of least resistance and never move on to pull ups. The reason chin ups are easier is because they engage both the biceps and the lats, whereas the pull ups engage only the lats, meaning you are using an extra muscle to help you with the same workout.
The most common mistake people make with pull ups is to keep their elbows forward during the motion. Once again, we do this because we are naturally inclined to minimize effort, and keeping your elbows in this position engages your bicep in addition to your lats – just as with the chin up.
To do a proper pull up, you need to isolate the lats and leave your biceps out of the equation entirely. This means that you need to keep your elbows pinned backward during the entire motion. If you feel your elbows drifting forward, force them backward until your body learns how the exercise should be performed. If you have been doing pull ups with your elbows forward, you will notice that you are unable to do as many now that you are keeping your elbows backward. As with all other movements in the gym it is the correct technique that is paramount, so don’t compromise. Do as many correct pull ups as you can with perfect form and if you fail too quickly, do a drop set by switching to 70% of your weight at the pull down machine. Over time you will build up your strength and perform three full sets of 15 correct pull ups.