As passionate trainers we all want to learn about the best training methods, the coolest exercises or the most effective training programs. However, we disregard that you can literally lose 50% of the benefit of these advanced tools if you don’t get one thing right: performing the reps optimally. 

Think about it, a set is nothing more than an ensemble of repetitions. You can have the best loading scheme in the world, if each rep is done inefficiently, you won’t get maximum results. As my friend Stéphane Cazeault would say: “The rep is king”.

While there is a myriad of possible styles of repetitions, and they can all serve a specific purpose, when it comes to the bulk of my training the style of repetition I like to use is something I call “the perfect rep”. I use other styles, for special reasons, but this is the style I prefer to use on most big lifts.

It combines all the elements to maximize muscle growth and strength gains.

I understand that various types of readers come to my web page. Some are simply looking for tricks to enhance their training while others want to learn the science.

With that in mind I will start with the practical info so that you’ll be able to apply it in the gym immediately. For those of you who want to go more in-depth, I have included the “sciency” stuff at the tail end of the article.

The perfect rep

The perfect rep has 4 specific elements:

  1. A slow eccentric action for 3/4th of the eccentric (lowering) range of motion.
  2. A rapid eccentric action for the last 1/4th of the range of motion.
  3. An explosive turnaround (switching from lowering to lifting as fast as possible).
  4. An accelerative (trying to accelerate) concentric action.

Basically, you control the descent for most of the eccentric range of motion, going down in 4-5 seconds. This will increase mTor activation, triggering protein synthesis/muscle growth. Then, you want to accelerate on that last portion of the eccentric phase, this will allow you to catch the stretch reflex, allowing you to lift more weight. It will also cause more muscle damage which is another way to stimulate growth.

Then you want an explosive concentric, or at least try to accelerate as much as you can: this maximizes force production (F = ma) leading to a greater activation of the growth-prone fast twitch fibers.

This rep style is best done when the concentric phase is preceded by an eccentric (so deadlifts, for example, are not well suited for this rep style).

But one important thing: Since you will be trying to “rebound” from the bottom, the tendency will be to release muscle tension to be more of a whip than a baseball bat. If you lose your tension you will also lose your spring and the risk of injury will be greater. So, stay tight.

And now the “sciency” stuff.

Eccentric action training

The eccentric action of a muscle refers to a resisted lengthening of that muscle; a muscle exerting force while it is being lengthened. This type of action has also been called the yielding action (as opposed to the overcoming action which refers to the actual lifting of the resistance) as well as the negative action.

Eccentric action is present in most free-weight and machine exercises. However, since concentric strength potential is lower than the eccentric strength potential, the yielding portion of a movement is rarely fully stimulated. In other words, the relative weakness of the overcoming portion prevents a complete overload during the yielding portion of the exercise.

As I will explain, it is the yielding portion of an exercise which gives us the greatest bang for our buck. So, an individual seeking maximum results should plan training methods emphasizing eccentric overload.

Eccentric stress as a superior stimulus for strength improvements

It’s been a while since we’ve known that the yielding (eccentric/negative) portion of an exercise is responsible for more strength gains than the overcoming (concentric/miometric/positive) portion.

For example, a study by Hortobagyi and coworkers found that the total maximal strength improvement from eccentric-only training was higher than a concentric-only program followed for 6 weeks.

Total maximal strength refers to the sum of maximum concentric, isometric, and eccentric strength. In that study, eccentric training resulted in a mean improvement of 85%, while concentric training led to an improvement of 78%.

Furthermore, this study used submaximal yielding actions and maximal overcoming actions. Surely this tells us a lot about the potential of yielding strength training, at least where maximum strength gains are the concern.

It is of note that these results are in accordance with the body of scientific literature on the subject. For example, a study by Higbie et al. (1996) found a combined strength increase (concentric strength improvement + eccentric strength improvement) of 43% with an eccentric-only regimen compared to 31.2% with a concentric-only regimen.

We should also note a study by Hilliard-Robertson and coworkers which concluded that “A resistance training protocol which includes eccentricas well as concentric exercise, particularly when the eccentric is emphasized, appears toresult in greater strength gains than concentric exercise alone”.

This is in accordance with an early study by Komi and Buskirk (1972) who recorded greater strength increases after an eccentric training regimen than after a concentric-only regimen.

It was also found that omitting eccentric stress in a training program severely compromised potential strength gains (Dudley et al. 1991).

Eccentric stress as a superior stimulus for muscle growth

The above-mentioned study by Higbie et al. found that eccentric-only training led to an average muscle size gain of 6.6% over 10 weeks while a concentric-only program led to gains of only 5%. While the difference may not seem to be huge, any bodybuilder who knows his stuff understands that 2% more muscle over a 10-week period can be visually important, especially in the long run.

These results are backed by another recent study (Farthing and Chilibeck 2003), which concluded that “eccentric training resulted in greater hypertrophy than concentric training.”

One recent study (LaStayo et al. 2003) even found accentuated eccentric training to cause 19% more muscle growth than traditional strength training over 11 weeks!

Another study concluded that “eccentric muscle actions are a necessary stimulus for muscle hypertrophy” (Cote et al. 1988).

Why is eccentric training effective?

Eccentric training allows one to stimulate greater strength and size gains than pure concentric training. Why is that? There are five major reasons why:

  1. There is a greater neural adaptation to eccentric training than to concentric training (Hortobagyi et al. 1996).
  2. There is a more important force output produced during a maximal eccentric action (greater overload) because you can use a higher external load (Colliander and Tesch 1990).
  3. There is a higher level of stress per motor unit during eccentric work. Less motor units are recruited during the eccentric portion of a movement, thus each of the recruited motor units receive much more stimulation (Grabiner and Owings 2002; Linnamo et al. 2002). Furthermore, since the nervous system seems to recruit less motor units during a maximal eccentric action, the potential for improvement could be greater than with maximal concentric action.
  4. There is some evidence that maximal eccentric actions will preferably recruit fast twitch muscle fibers, which are more responsive to muscle growth and strengthening (Nardone et al. 1989, Howell et al. 1995, Hortobagyi et al. 1996).  In fact, eccentric training may stimulate an evolution towards a faster contractile profile (Martin et al. 1995).
  5. Most of the micro-trauma to the muscle cells incurred during training is a result of the eccentric action (Brown et al. 1997, Gibala et al. 2000). It has been established that this micro-trauma acts as the signal to stimulate the muscle adaptation process (Clarke and Feedback, 1996).
  6. MTor activation seems to be greater with both eccentric actions and loaded stretching. MTor is the trigger that initiates protein synthesis/muscle building.

Further benefits of eccentric training

For most of us, strength and size gains are the name of the game. However, the positive effects of negative training don’t stop there. We could also note the following “fringe” benefits:

  1. Greater cross-education (Hortobagyi and Lambert 1997). Cross-education refers to transfer of strength gains from one limb-side to the other. In practical terms it means that if you were to work only your right arm using eccentric actions, some of the strength gains would transfer to the left arm. This can be very beneficial to prevent excessive strength loss if one limb is immobilized.
  2. Eccentric training is also a superior method to treat tendinosis when compared with concentric exercise (Mafi et al. 2001). So, it could be argued that this form of training is adequate for use by injured athletes and that it is relatively safer than concentric training even if the loads used are greater.
  3. A last point of interest is that strength gains from eccentric training are maintained longer during a period of detraining than the gains from concentric-only training (Collinder and Tesch 1992, Housh et al. 1996), which may be very important for athletes who cannot train as much during the season as they can in the off-season.

In layman’s terms please

The last few paragraphs were very dense in scientific information, but practically, what does it all mean?

  1. If you de-emphasize the yielding portion of your strength exercises (lowering the bar very fast, not contracting your muscles during the eccentric portion, etc.) you might as well not be training at all (at least, if maximum strength and size are important to you). Be careful though, it doesn’t mean that you should accentuate/emphasize the eccentric stress in all of your exercises, just that some exercises should target a very large eccentric overload.
  2. Accentuating the eccentric stress during a session will lead to more strength gains. The reasons are related to structural as well as neural adaptations.
  3. The eccentric portion of a movement is the main stimulus for muscle growth as it is the cause of most of the micro-trauma inflicted on the muscles, which acts as the signal to kick the muscle building process into overdrive.
  4. One more benefit that I have found from experience is that overloading the eccentric portion of an exercise allows one to get used to holding big weights and controlling them. This can have a very important confidence-building effect when attempting to lift maximum weights.


The preceding information helps explain how emphasizing the eccentric by going slower will be good for muscle growth and might have a positive impact on strength. But why accelerate at the end of the range of motion to catch the stretch reflex? Because I believe that a lot of the muscle damage caused during the eccentric phase actually occurs at the turnaround point (when you switch from eccentric to concentric).

The more force/tension you produce at that point, the greater the impact on muscle damage. So, I believe that by accelerating on that last portion of the eccentric phase and then trying to reverse direction as fast as possible, you will produce more muscle damage creating a strong growth stimulus.

Furthermore, Louie Simmons has shown that the faster you are going when you change from eccentric to concentric, the more force you produce. So that will help you lift more weight and get stronger.

What about the concentric

To make the concentric portion of an exercise as effective as possible one should increase the level of intramuscular tension during the overcoming action. To maximize this tension one must produce a very high level of force. The more force you have to produce,the more tension will result.

Remember that F=ma (Force = mass x acceleration). Once this is understood, it becomes clear that there are three ways of maximizing force output and thus intramuscular tension:

  1. Lift very heavy loads relatively slowly (high “mass” factor)
  2. Lift light loads with a lot of acceleration (high “acceleration” factor)
  3. Lift moderate loads with good acceleration (both factors are moderate)

For the concentric portion, the key to remember is that regardless of the load used, you should try to lift the bar withas much speed as possible. That is, of course, with that repetition style. Slower concentric actions also have their place for other specific purposes.

Christian Thibaudeau

Written by Christian Thibaudeau

Christian Thibaudeau has been involved in the business of training for over the last 16 years. During this period, he worked with athletes from 28 different sports. He has been “Head Strength Coach” for the Central Institute for Human Performance (of…