Order Of Strength
The order of strength describes how much torque (strength) we can produce in the various exercises or tests if the test is the same.
For example if we tested bicep strength we would get the lowest result in a standard isotonic concentric test. If we repeated the same bicep test isokinetically the results would be higher (for peak torque). If we then went on and measured isometrically the results would be even higher (as long as the angle of mechanical and muscular efficiency was chosen).
The eccetric actions always offer the highest levels of torque. Or in other words we are stronger in eccentric actions than in concentric and isometric actions.
Why we are stronger eccentrically is not fully understood one theory is that when the muscle lengthens you have the strength of the contractile elements (the concentric in other words) and added to that is the elasticity of the non contractile elements (Z disks etc. which stretch). This added stretch gives a higher value in eccentric actions.
Remember eccentric actions actually damage the micro fillaments (actin and mysosin) and give delayed onset muscle soreness if done enough.
(Adapted from Davies, 1984)