A negative repetition (negative rep) is the repetition of a technique in weight lifting in which the lifter performs the eccentric phase of a lift. Instead of pressing the weight up slowly, in proper form, a spotter generally aids in the concentric, or lifting, portion of the repetition while the lifter slowly performs the eccentric phase for 3–6 seconds. Negative reps promote hypertrophy greatly because they allow the muscles to experience extreme trauma. Everyone can train with more weight doing negative reps. Negative reps should generally not be used more than twice a week.
The proper method and loading for performing a negative rep is not always well known. Each negative-accentuated rep should last somewhat longer than the negative phase of a regular movement. Depending on the range of motion of the exercise, this could be anywhere from 3 to 6 seconds.
The initial load used for negative training should be approximately 105% of your regularone rep max for the exercise, e.g. if you can bench 200 pounds, use 210 pounds for negative reps. You can increase this load if you are able to get more than 6 reps with that weight (6 reps is the most you should do with negative training - if you can do more reps, you aren't using enough weight for it to be maximally effective).