Trainer's Tip: Focus on Your Muscles
When performing any exercise that requires you to grab a handle or bar, take your focus off of what you're gripping. For example, when performing a lat pull down, don't think about pulling the bar down towards you. Instead, think about pulling your chest towards the bar.
The problem with focusing on moving the object in your grasp is that most of us will do anything to get it to where it's supposed to go. We're quick to judge the performance of a single rep, set or even the entire exercise based on how well we moved the gripped object. And if we struggle to move it, we'll resort to almost any bad habit to get it there, including leaning back, shrugging the shoulders, jerking the weight, curling the wrists, etc.
By changing your focus to going towards the object and not vice versa, bad habits are usually avoided. You will NOT end up taking away from the targeted muscle's ability to create tension and will continue to isolate the muscle you want to work.
Instead of worrying so much about the end points and whether or not you can get the gripped object there, focus on contracting the muscles throughout the ENTIRE range. A full contraction will determine where the bar will start/stop– not a predetermined perception of what the exercise motion should be.
Remember to control the ENTIRE range on each and every rep. All too often I see folks do great on the concentric contraction (muscle shortening) but lose all focus during the eccentric. On the eccentric contraction (when the muscles lengthen) don't just let the weight fall back to the starting position. Set it there, carefully… with your muscles!
Heed this advice on every exercise and you will maximize the effectiveness of your workout and minimize the risk too.