Benefits of Negative Reps
Eccentric training, better known as "Negs" or "Negative reps" is performing only the eccentric part of a lift. Almost every exercise there is can be split into the eccentric and concentric phase, the eccentric phase is where the muscles is stretched while the concentric phase is where the muscle contracts.
So in a bicep curl the concentric part of the lift would be curling the bar upwards, and the eccentric part would be lowering the bar back down. In a bench press the eccentric part would be lowering the bar (your pecs would stretch as you did this) while the concentric part would be pushing the bar back up.
Most people pay more attention to the concentric part of the lift than the eccentric, putting all the effort into curling the bar during a bicep curl before dropping it back down with no control. This is because most people believe the concentric part of the lift to be where all the magic happens, with the eccentric part a necessary evil.
In reality both phases are extremely important for anyone trying to get stronger or build bigger muscles (or even perform the exercise correctly). In fact, it is the eccentric part of the lift that is slightly more important when it comes to hypertrophy and strength. So much so that many strength coaches add exclusively eccentric movements into their programming.
How to Perform Eccentric Movements
To perform an eccentric movement you either need a partner, or something like a squat rack or smith machine that can prevent you from getting stuck under the bar (or something similar). For example let's say you are going to perform a negative bench press.
Set yourself up as usual on the bench but use a weight that is between 105 and 120% of your 1rm for the bench press. Obviously if this is the first time performing negatives then 105% would be recommended. Take the bar off the stand with the help of your spotter and bring it over your chest, now slowly lower the bar towards your chest. Fighting the bar all the way.
Once the bar touches the chest your spotter should immediately pull the bar off you, whilst you help them. Pause for around 10 seconds and then repeat.
In this article we will look at what the benefits of negative reps are and how best to incorporate them into your current training program.
Benefit #1. Increased Force
Many studies have found that eccentric training can massively increase force production, which has many carryovers in sport and exercise. A study by Hollander et al (2007) found that eccentric force was 20-60% greater than concentric force in young men . A study by Kelly et al (2015) similar results, with a 120% increase in force .
Benefit #2. Lowered Fatigue
The same study by Kelly et al found that eccentric training also resulted in less fatigue than a regular strength training session . This is probably due to the lengthening movement being more efficient than the contracting movement, and also explains why more force can be produced.
Benefit #3. Increased Hypertrophy
Eccentric training may not produce as much fatigue but it does produce more muscle damage than regular training . This sounds bad but actually the more muscle damage a workout produces the more strength and hypertrophy you can expect (provided you consume sufficient protein).
Studies have shown that eccentric training really does increase muscle size (hypertrophy), for example a study by Pope et al in 2015 found that when combining eccentric training with blood flow restriction muscle fibre size increased significantly .
Benefit #4. Lowered Risk of Injury
People who have heard anything about eccentric training are probably aware of the strength and size benefits. Most gym goers are already sold on the matter after you mention bigger muscles. But one benefit that doesn't get much attention is the effect that negative reps have on your risk of injury.
This seems to be the case with the hamstring muscles in particular, a study in 2011 by Petersen et al found that not only did eccentric training lower the risk of new injuries, it also lowered the risk of recurring injuries .
Another way that eccentric training can lower injury risk is simply getting the performer to improve their technique. Most techniques fail due to being performed incorrectly, or with too much weight. Eccentric training, that involves the slow controlled lengthening of the muscle is a great way to relearn an exercise that you may have previously been performing poorly.
Everyone knows that performing an exercise poorly is one of the easiest ways to injure yourself, and sometimes we don't even know we have an issue. For instance, next time you are performing a bicep curl try to slow down the eccentric part of the lift you might find it almost impossible to then perform the second rep.
This is because you were unwittingly using too much momentum throughout the movement, subconsciously making the exercise easier for yourself.
Benefit #5. Improve Flexibility
As with its effect on injury risk, the effect of eccentric training on flexibility is very underrated. Combining eccentric training with static stretching has been shown to increase flexibility, and even when used on its own eccentric training is still effective .
How to Successfully add Eccentric Training to your Program
The main trick with eccentric training is not to overdo it, adding it to every session or every exercise will increase the risk of overtraining. Pick one exercise that you would like to improve, for example the squat and add a set of 8-10 reps (with 10 seconds rest in between) to your training program. You should limit this to once or twice a week max, and make sure that you are getting enough sleep and protein afterwards because the muscle damage is potentially huge!
 Hollander, D., Kraemer, R., Kilpatrick, M., Ramadan, Z., Reeves, G., Francois, M., Hebert, E., Tryniecki, J. 2007. Maximal eccentric and concentric strength discrepancies between young men and women for dynamic resistance exercise. Journal of Strength & Conditioning Research 21(1): 34-40
 Kelly, S., Brown, L., Hooker, S., Swan, P., Buman, M., Alvar, B., Black, L. 2015. Comparison of concentric and eccentric bench press repetitions to failure. Journal of Strength & Conditioning Research 29(4): 1027-32
 Armstrong, R., Warren, G., Warren, J. 1991. Mechanisms of exercise-induced muscle fibre injury. Sports Medicine 12(3):184-207
 Pope, Z., Willardson, J., Schoenfeld, B., Emmett, J., Owen, J. 2015. Hypertrophic and Strength Response to Eccentric Resistance Training with Blood Flow Restriction: A Pilot Study. International Journal of Sports Science & Coaching 10(5): 919-931
 Petersen, J., Thorborg, K., Nielsen, M., Budtz-Jorgensen, Holmich, P. 2011. Preventative effect of eccentric training on acute hamstring injuries in men's soccer: a cluster-randomized controlled trial. American Journal of Sports Medicine 39(11): 2296-303
 Nelson, R., Bandy, W. 2004. Eccentric Training and Static Stretching Improve Hamstring Flexibility of High School Males. Journal of Athletic Training 39(3): 254-258