Resistance training systems: Negative / eccentric training
In negative / eccentric training, the concentric phase of an exercise is all but removed and all the effort is applied to the eccentric portion of the movement. Potentially this means the client can be exposed to supramaximal loads in excess of their normal repetition maximum. Examples of negative reps include leg extensions where the resistance is raised with two legs but lowered with one, chin/pull ups where the client climbs/ jumps into the top position, and lowers themselves slowly into the extended position or a bench press where two spotters are used to lift the bar into the starting position and the client lowers the bar slowly on his/her own.
Active IQ, Level 3 certificate in personal training, programming personal training with clients (2014)