Weight & Resistance Exercise
RESISTANCE TRAINING SYSTEMS
These are the classical barbells, dumbbells and circular weights. They may include other equipment but the feature is that they are not connected to walls or machines that alter resistance and force.
Pin Loaded Machines
Working on the lever and cable techniques, this allows easy change of resistance without the need of reloading training equipment. All the weights are connected to the machine, the user only needs to move the pin to the appropriate position on the weight.
Isokenetic machines called ergometers exert a force equal to that provided by the trainer. Machines such as Cybex work in this manner.
More advanced body builders and resistance trainers will tend to use only free weights. Machines tend to be used more by introductory levels as they help control movement a lot better. Once the movement and technique are correctly learnt, most resistance people will move to mainly or even solely free weights.
This is important for long term strength gains. Testosterone (predominant male hormone) plays a key role in muscle hypertrophy. This leads to an increase in muscle protein synthesis. The results are increased strength and muscle size.
Correspondence Course in Resistance Exercise (click for details)