To better understand the real objective of exercise and get into the proper mindset for high intensity training I’ve found it helps to think of barbells, dumbbells, or exercise machines as “backwards machines”. The purpose of most machines is to make some task easier, like lifting a heavy object, or moving some object more quickly or over a greater distance. The purpose of a barbell, dumbbell, or exercise machine is the exact opposite; to make it harder for you to perform various exercise movements to place a demand on the muscles targeted.
The body movement is the exercise, not making the barbell or dumbbells or the weight stack on a machine go up and down. The whole point of using the weights or machine is to make the specific body movement you are performing harder to get at the muscles you are targeting. If you focus on moving the weight you will tend to alter your body movement to make it easier to do that, which might look more impressive to other people in the gym who don’t know better but makes the exercise less effective. If you focus on your body movement instead and think of the barbell, dumbbell or machine as a “backwards machine” for making your muscles work harder you will make the exercise far more effective.
For example, the RenEx Leg Press pictured here wasn’t designed to allow you to easily make a weight stack go up and down. It was designed to resist hip and knee extension to efficiently load the involved muscles. To focus on making the weights go up and down or to use the machine in a manner that makes it easier rather than harder to do so completely misses the point.
In the same way, cheating during a barbell or dumbbell exercise by altering your body position or offloading the weight onto other muscles misses the point of using the weight to begin with. The purpose of using a weight is to increase the resistance against the target muscles during an exercise. If you’re moving the barbell or dumbbells in a way that makes them easier to lift instead of harder you’re doing the exercise wrong.
Similarly, the skill of performing an exercise can be thought of as a “backwards skill” because the better you are at performing an exercise the harder it is to do.
Don’t confuse being better at an exercise with being stronger. They are completely different things. Being stronger means your muscles are capable of producing more force. Being better at an exercise means you are able to more effectively and efficiently load the targeted muscles. The better you get at doing this, the harder the exercise will be with a particular amount of weight.
It is also important to distinguish between being better at exercise and lifting weights. The goal of exercise is to stimulate increases in muscular strength and all the supporting factors of functional ability. The goal of a competitive lift in powerlifting, weight lifting, and other strength competitions is to lift as much weight as possible. The first is about making the weight harder to lift (increasing the resistance the weight provides), the second about making it easier (reducing the resistance). Unless you are a competitive lifter training to improve your skill in a competitive lift you should always use a barbell, dumbbells, or machine in a way that makes the movement as hard as possible.