1: Isotonic contractions, muscle contracts and shortens, giving movement. Nearly all the training you do is isotonic.

2: Strengthens a muscle throughout the range of movement. 

3: Isometric contractions, muscle contracts but does not shorten, giving no movement. “Plank” for abs is a good example.

4: Develop static strength to push or pull a heavy object or hold it up. 

5: Isokinetic contractions, the muscle contracts and shortens at constant speed. It is usually slowest at the start.

6: Muscles gain strength evenly all through the range of movement. Fastest way to increase strength.