What is the difference between "fixed resistance" and "variable resistance"?

What is the difference between "fixed resistance" and "variable resistance"?

John Spencer Ellis (Author, TV Show Host, Trainer and CEO, National Exercise & Sports Trainers Association) gives expert video advice on: How do I design a strength training program?; How often each should I train each muscle group?; How much weight should I use when I train? and more...

The difference between fixed resistance and variable resistance is exactly what their name states. In a fixed resistance exercise, the amount of weight, or the amount of resistance, against the pull or the push is consistent from beginning to end. In a variable resistance exercise, the weight, or the resistance, may increase or decrease throughout the range of motion. This can be done in a couple of different ways. On a machine, for example, there may be a cam that makes a belt go over a larger surface, or a change in the fulcrum in the cam, which will change the amount of mechanical advantage or disadvantage of the machine, which in turn changes the amount of the resistance throughout the range of motion. This will be synchronised with the amount of strength increased or decreased in your joint as you go through the range of motion. Another way of having a variable resistance is in an exercise tube. The more you pull it towards you, for example, the tighter it will become. So, the tighter it will become pulling towards you, that's variable, and increasing resistance during the concentric, or the squeezing part of the motion. So, fixed resistance: constant. Variable resistance: changes the amount of resistance throughout the range of motion.