WHAT IS IT?
The eccentric portion of a rep refers to the the phase in which the working muscle is being lengthened under load. Due to physiological mechanisms, we can handle more force during this phase than we can actively produce during the concentric. Specifically tailoring training to take advantage of this inequality is known as Eccentrics (or Negatives).
After reaching concentric failure, extend the set by utilizing assistance through the concentric portion of the rep while you perform the eccentric under your own control. Assistance can be applied via partner-spotting, self-spotting, and/or changing leverages. In special cases, additional force can be applied to overload the eccentric even further.
Eccentrics can also be utilized on their own, independent of traditional set paradigms, in order to completely eliminate the concentric.
HOW TO TRACK PROGRESSION?
Because this is not a technique necessarily reliant on volume or absolute strength, the best way to track Eccentrics is “time-under-tension” x “total load used” though standardization can be difficult.
WHO SHOULD USE IT?
Eccentrics have application in the realms of sport performance, injury rehablitation, and technical refinement, but using them as an intensity technique should only be done by intermediate to advanced trainees.
WHO SHOULD NOT USE IT?
Beginners (and even most intermediates) have no need to utilize Eccentrics and can make great progress training up to, or under, traditional technical failure. Additionally, trainees who are susceptible to muscle damage and/or soreness from conventional concentric-focused training should err towards avoidance of Eccentrics.
WHEN TO USE IT?
Because Eccentrics create substantial muscular damage, using it before the culminating week of a training block is risky from a recovery perspective. Attempting to push beyond concentric failure by way of supra-maximal Eccentrics should be used sparingly. However, using Eccentrics exclusively (i.e. with no concentric failure) can be a productive use of volume throughout a training block as long as the resulting fatigue is controlled for.
Beyond-failure Eccentrics should be confined to higher intensity training blocks. Eccentrics used to replace traditional sets can be performed carefully in phases with higher volumes due to the lower absolute intensity.
WHEN NOT TO USE IT?
If delayed recovery is a potential hindrance to future overloading training, hold off on adding in Eccentrics (or titrate them in very slowly) until you know fatigue is able to be managed . We should use these VERY cautiously in a conventional progressive program. During periods of intentional reduction/avoidance of muscle damage, Eccentrics are strongly contraindicated.
HOW TO USE IT?
As mentioned above, Eccentrics allow for the handling of more load but are HIGHLY damaging to sarcomeres which creates soreness and local/systemic fatigue. There are a multitude of potential risk vectors including: acute injury (muscle tears), local overreaching (due to sarcomere shearing), human error (from poor spotting), and more.
When used as an intensity technique after concentric failure, 1-3 Eccentric reps will be more than sufficient. Trying to accumulate additional volume will only increase risk of injury and overreaching without the accompanying benefits. The tempo can vary, but as a rule of thumb, it should be at least 3 seconds. In some cases, performing a single max-duration Eccentric rep can be a useful strategy rather than attempting more reps with less duration.
When used as a stand-alone scheme, Eccentrics can be approached in a somewhat similar manner as traditional paradigms though the total volume should be substantially lower (as well as the reps per set). It’s not uncommon to see this as 2-3 sets of 4-6 reps with a definitive intensity (e.g. taken to 1RIR). Obviously, this is a more advanced strategy.
Machines tend to be best for partners to assist due to the controlled nature. Unilateral upper body movements are often best for self-spotting though there are some machines that have in-built mechanisms for self-spotting (like a foot plate that assists when pressed against). Body weight variations can be done readily, and seem to fit the “changing leverages” mold the best as well. As lesser known and utilized (perhaps undeservedly) application of Eccentrics would be performing the concentric as a compound and eccentric as an isolation movement.
Examples:
1)Single Arm Preacher Curls- Perform a set to failure with ~10RM then use your off arm to assist with 2 Eccentric reps (5 sec duration)
2)Machine Chest Press- Perform sets of 4-6 (1RIR) with spotter assistance on the concentric and a 5 sec count on the Eccentrics
3)DB Skullcrushers- Perform the concentric as a neutral grip DB press then perform the eccentric as the skull crusher (I know this is breaking my rules a bit but I like the application)
HOW NOT TO USE IT?
When the weight being used is too dangerous for a spotter’s assistance and/or the exercise mechanics aren’t favorable to extended Eccentrics (think Barbell Bent Over Row), other intensity techniques should be favored. Movements that are axially-loaded or cannot be failed safely are contraindicated. Barbells and dumbbells can be used (though machines and cables are generally preferable), but instability and rep variability will negatively impact the effectiveness of Eccentrics.
Additionally, certain variations should be cut short of a full ROM due to the exponentially increasing risk associated with carrying Eccentrics into the deepest parts of the stretch (think DB Flye or Barbell Preacher Curls).
Examples:
1)Leg Press- Too impractical for a spotter to handle the entirety of the load through the concentric
2)Barbell Bench Press- Impractical for spotters and unsafe failure
3)Smith RDLs- Too much axial loading (and risk) even though you could theoretically make this work mechanistically
BENEFITS OF THE TECHNIQUE:
-Promotes a favorable environment for hypertrophy due to increased (controlled) muscle damage, time-under-tension, and mechanical tension
-Eccentric overloading is a phenomenal technique for accelerating strength adaptations
-Allows for technical refinement and positional comfort
-Can be used to push beyond concentric failure OR as a volumetric replacement for traditional paradigms
-Effective application is relatively broad in terms of exercise selection, modalities, and method
-Easy way to massively spike intensity while keeping total volume low
DRAWBACKS OF THE TECHNIQUE:
-Incredibly taxing on soft tissues and nervous system
-Higher risk of acute injury and overreaching
-Challenging to track progress quantitatively
-Uncontrollable external dependencies with spotter (or self-spotting)