These control actions have been classified into groups, dependent on the type of muscular activity.
Isotonic (same tone) – which describes muscle actions involving movement i.e. eccentric and concentric
Concentric – a muscle generates force and shortens (when raising/lifting a weight)
Eccentric – a muscle generates force and lengthens (when lowering a weight)
Isometric – a muscle generates force and stays the same length (holding a load/weight)
Isokinetic (same speed) – muscle actions involving movement taking place at a constant speed