Eccentric Contraction 

From the earlier mnemonics we can see that:

Eccentric - Lengthen and down movement. 

Contraction - Tension. 

From this we can understand that:

Eccentric contraction is lengthening of the muscle in tension, or:

Eccentric contraction = Lengthening of the muscles 

Eccentric contractions occur when you:

1. Move a dumbbell in a bicep curl downwards away your body.

2. When you squat down to a low position. 

Note: Your quadriceps (quads) are made up of four muscles hence quad. 

3. Doing a press up and moving your nose gradually towards the floor.