Rapid Eccentric Isometrics: The New Plyometric

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Maximize Performance with Rapid Eccentric Isometrics: The New Plyometric

Dr. Joel Seedman, Ph.D.

Key Points

-Rapid Eccentric Isometrics (REI’s) are similar to standard eccentric isometrics, however, the negative is performed at maximal velocity

-REI’s are a highly advanced and potent training tool.  It’s essential you’ve mastered standard eccentric isometrics (EI’s) before implementing REI’s into your training

-REI’s take proprioceptive feedback a step further than standard eccentric isometrics by maximizing the dynamic response of muscle spindles

-The neuromuscular benefits in terms of potentiation, rate of force production, and rate of force absorption, are difficult to replicate with other training modalities including plyometrics

-Similar to standard EI’s, REI’s can be employed on the 7 basic human movement patterns as well as additional isolation exercises.

Eccentric Isometrics: Quick Recap

As many of you know I’m a huge fan of eccentric isometrics (EI’s) so much so that I'm writing an entire book about them. Their ability to enhance technique, muscle function, and movement mechanics, as well as their potential for building strength and hypertrophy are tough to beat.  In fact eccentric isometrics comprise a large portion of the training I have my athletes perform.

Another similar technique I use on a frequent basis especially with my advanced athletes is Rapid Eccentric Isometrics (REI’s). 

REI’s are similar to standard eccentric isometrics (EI’s) except for one key difference.  Instead of performing a slow negative before pausing in the stretched position, the lifter performs a rapid eccentric movement facilitated by powerful antagonist muscle contraction.

Here’s what it looks like.


Before going any further there is something that needs to be made very clear.  Rapid eccentric isometrics are an advanced training technique that provides a highly potent training stimulus when performed properly.  However, when executed with anything short of textbook mechanics and precise form they can be utterly disastrous and downright dangerous.  

In fact, this is something I only implement with athletes who I’ve spent significant time training (minimum of 3-6 months) using standard eccentric isometrics.  Furthermore they must consistently demonstrate their ability to perform traditional EI’s with movement mechanics that are nothing short of perfection.  Finally they must be able to do so under eyes-closed conditions with relatively heavy loads (80-90% of their 1 RM) for each of the seven basic movement patterns.  Only then have they successfully demonstrated their physical preparedness to properly handle rapid eccentric isometrics.

With that said if you have not been training with standard eccentric isometrics and have not implemented the techniques I laid out in my previous articles addressing this topic, that’s your first step (Read More About Eccentric Isometrics Here).  I also highly recommend you address proper foot and ankle mechanics before touching these.

If in fact you’ve been using eccentric isometrics consistently and have adequately prepared your body, then you may be ready to gradually work REI’s into your program.  

Before heading into the practical application lets go over the basic neurophysiological principles of this advanced training technique.

Scientific Principles of EI’s and REI’s

Standard Eccentric Isometrics (EI’s) allow fine-tuning of movement mechanics.  This is due to the emphasis of a slow eccentric stretch, which enhances proprioceptive feedback from muscle spindles.  If movement mechanics are flawed, this technique will allow the lifter to tune into these errors and make the necessary corrections. 

When it comes to mastering movement the key is muscle spindles/intrafusal muscle fibers.  Muscle spindles are sensory receptors found within muscles that provide information about body positioning and overall kinesthetic awareness.   As previously discussed, muscle spindles respond to stretch. However this can be broken down further.  Specifically, muscles spindles respond to degree or amount of stretch (static response) as well as rate or velocity of stretch (dynamic response).

In fact muscle spindles have specific intrafusal fibers and sensory neurons devoted to different types of stretching/eccentric movements.  Secondary (II) sensory neurons innervate static intrafusal fibers providing information solely pertaining to the static response (degree of stretch).  However, primary (1a) neurons innervate all muscle spindles (dynamic and static intrafusal fibers) essentially providing information pertaining to both the dynamic (rate of stretch) and static response.

Furthermore the axons involved in the dynamic response are exceptionally large producing some of the fastest conducting action potentials in the central nervous system.  In other words the dynamic response provides both the strongest and quickest somatosensory feedback ultimately producing heightened levels of proprioception and sensory-integrated movement. 

Furthermore, the more rapid the stretch is the greater the dynamic response.  In order to produce maximal levels of sensory feedback from muscle spindles this essentially means producing eccentric contractions at very high velocities.

However, any eccentric action that occurs this rapidly will be difficult if not impossible to consciously make adjustments to while the movement is occurring.  Therefore performing rapid eccentric isometrics before proper motor programs have been established is risky and futile as self-correction with REI’s can only occur after the movement has transpired.

Because of this it is essential that the appropriate motor programs already be established with standard eccentric isometrics.  REI’s are then used to etch this more permanently into the CNS while continuing to recalibrate the body’s proprioceptive mechanisms through muscle spindle re-sensitization.

In essence standard eccentric isometrics (EI’s) provide the lifter with the most user-friendly form of somatosensory feedback while rapid eccentric isometrics (REI’s) provide the most powerful form of feedback.  With this in mind, standard EI’s are best for correcting movement while REI’s are best for reinforcing proper mechanics that have already been established using standard EI’s.

“Movement Mastery” can still be accomplished via EI’s alone but EI’s performed in conjunction with REI’s will expedite this process while simultaneously providing additional performance benefits.

Mastering Movement

As previously described, REI’s fully exploit all mechanisms of muscle spindle recruitment.  Over time this permanently ingrains a motor program so strongly into the CNS that it essentially becomes an automated movement. This is the epitome of “Mastering Movement”. 

At this stage the lifter requires little cognitive resources be allocated for proper movement execution, as the body will automatically default to this.  Much like a professional athlete who has mastered their skill, the lifter no longer needs to focus on movement mechanics but can now attend to other factors that will maximize performance such as load, intensity, power, speed, efficiency, and maximal effort.

This is also the stage at which motor programs begin to have a strong beneficial carryover-effect to other related movements whether that’s another lift, an athletic skill, or a simple task such as walking, jumping, or sprinting.

Exception to the Rule

As I’ve stated multiple times in this article, REI’s are an advanced technique that should only be incorporated once proper form has been learned using standard EI’s.  As true as this is there is an exception to the rule.  In fact I’m going to take a step back here and somewhat contradict myself but you’ll understand why momentarily.  

Neuromuscular Kicker: Final Piece of the Puzzle

To properly illustrate this next issue I’ll use a percentage system.  Although the specific numbers may seem somewhat arbitrary, this format will most easily convey the concept. 

Besides reinforcing movement patterns into your CNS, REI’s do provide a slight yet immediate enhancement in movement technique regardless of your current level of movement efficiency.  This enhancement is semi-automatic requiring very little coaching or cueing. This is most likely due to the intensified proprioceptive feedback from dynamic intrafusal fibers. 

Now, lets say this automatic enhancement in technique is 10%.  For most lifters this 10% enhancement in technique does not outweigh the danger associated with anything but perfect form.   For example if an individual’s technique on a particular lift is approximately 60% correct then the REI’s may actually help bump this up to 70%.  Unfortunately an REI performed at even 70% of perfect execution is still highly dangerous with significant potential for injury.

Now here’s where things get interesting. If in fact the athlete appears to be very close to obtaining perfect form and is roughly at 90% movement efficiency for that movement pattern this is where REI’s can be the last piece of the puzzle to clean up and remedy the final issues.  That 10% improvement just put the athlete at 100%.

In essence REI’s act as a kinesthetic kicker representing the final piece of the puzzle for perfecting the athlete’s movement mechanics and proprioception.

How Quickly Can Your Muscles Turn On?

When it comes to rate of force development (RFD), and rate of force absorption (RFA), the key question is “how fast can your muscles turn on?” In other words how fast can your nervous system go from 0-100? Various training modalities particularly standard eccentric isometrics are great for teaching your nervous system to get to that 100 mark but REI’s teach you how to get there as quickly as possible which is essential for athletic performance. 

Rate of Force Absorption

One of the key roles of skeletal muscle is to provide force absorption by acting as shock absorbers. When skeletal muscle is unable to absorb impact, these various forces are transferred to surrounding joints and connective tissue not to mention there's a greater risk for musculoskeletal tears.

Rapid Eccentric Isometrics are particularly useful in addressing this issue as the muscles must turn on quickly with proper mechanics in order decelerate and catch a rapidly descending load.

Rate of Force Development

When it comes to rate of force development most athletes and trainers will focus on the concentric portion of movement.  However, if the athlete nails the eccentric phase, the concentric movement will inevitably take care of itself.

In fact, for many explosive movements, producing high levels of force during the concentric phase is determined predominantly by the athlete’s ability to first decelerate the eccentric phase and absorb impact.  The faster and more efficiently this happens the faster they can transition to producing force on the concentric movement ultimately improving amortization efficiency (the transition from concentric to eccentric movement).

REI’s teach athletes the ability to quickly stick this deceleration phase by rapidly activating the nervous system and turning all available motor units on as quickly as possible.

REI’s vs. Plyometrics

Although plyometrics and rapid eccentric isometrics share distinct similarities, there are several performance bonuses unique to REI’s that are difficult to replicate with other training modalities including plyometrics.

First, REI’s can be performed on nearly all movement patterns and exercise variations.  Essentially, if the exercise can be performed in a standard eccentric isometric fashion then it can be performed as an REI.  With this in mind the variations and exercise possibilities are limitless.   Most plyometrics on the other hand must be altered to adjust for airborne movements often times limiting a majority of the drills to bodyweight or medicine ball variations.

Second, the amortization phase of explosive movements is isolated during REI’s allowing individuals to master the transition phase between the concentric and eccentric phase.  In fact this is essentially where the isometric is occurring (after the eccentric and before the concentric).  Although it may seem like an oxymoron, a rapid eccentric isometric can be thought of as a deconstructed plyometric performed in an isometric fashion as the amortization phase is isolated and held for the duration of the isometric. 

The third factor that differentiates REI’s from traditional plyometrics is the ability to maximally activate reciprocal muscle groups.  During many plyometric drills much of the force responsible for creating eccentric movement is either external loading (i.e. loaded object), gravity, or a combination of these two factors.  REI’s on the other hand rely less on gravity and external loading for creating the rapid eccentric movement and more on reciprocal muscles/antagonists rapidly pulling the body into position. 

Now this is not to suggest that REI’s should replace plyometrics but instead should be used in conjunction with traditional plyometric training to maximize performance and function.


By recruiting antagonist muscle groups at maximal intensity during eccentric motions this creates heightened levels of co-contraction in reciprocal muscles ultimately enhancing mobility, stability, and positioning

Furthermore, because increased co-contraction heightens activation of intrafusal fibers/muscle spindles through enhanced levels of stiffness this produces an ideal scenario for maximal reciprocal inhibition on the concentric phase as well as proprioception. Consequently this optimizes power and force output due to increased firing of agonists and relaxation of antagonists.

Neuromuscular Jolt

REI’s provide an intense neural excitation effect and overall jolt to the nervous system.   The amount of force required to decelerate a rapidly moving heavy load is exponentially greater compared to slow or moderate pace eccentrics. Although this impact is very brief and lasts only a split second, the effect it has on high threshold motor unit recruitment is unusually strong. 

After several repetitions of this you’ll notice a heightened sense of focus, adrenaline, energy, and neural drive.  The acute and chronic impact this has on measures of performance and neuromuscular recruitment is potent to say the least.

Several other prominent strength coaches have utilized similar techniques with their athletes as well.   Charles Poliquin implements a biceps hypertrophy principle in which he suggests performing rapid eccentric movement during curls to wake up survival fibers that normally would not be recruited.  Jay Schroeder employed similar yet more extreme principles for producing record-breaking Combine numbers in NFL superstar Adam Archuletta.

REI’s take these techniques a step further by combining sensory integrated muscle activation with basic human movement patterns for full-body neuromuscular re-education

Proper Execution

Correct execution of rapid eccentric isometrics is both simple and complex.  The isometric contraction (in the stretched position) as well as the concentric movement are nearly identical to standard eccentric isometrics.  The primary difference is the actual eccentric phase leading up to the isometric hold.   Rather than slowly lowering the load you’ll be firing your antagonists rapidly to pull the load into position with great speed. 

As you approach the fully stretched position, you immediately decelerate the load while continuing to fire the antagonist muscles at maximal effort.  As you hold this isometric contraction for 2-5 seconds you should sense every muscle in your body activating at maximal intensity while feeling like a coiled spring ready to launch the weight back into the starting position on the subsequent concentric phase.

The most important factor is to ensure you are not dropping the weight or letting it free-fall but instead are actively pulling/pushing into position as quickly as possible.   Although these two techniques (free fall vs. rapid reciprocal pulling) may appear somewhat similar to the naked eye, neuromuscularly they are very different.  In fact they are polar opposites.  One involves little tightness and low levels of co-contraction while the other involves maximal tightness and maximal co-contraction.

Loading Parameters

Because REI’s focus on speed of movement, loads should be light enough to allow for this to occur at maximal or near maximal speeds with perfect form.   I typically recommend loads ranging from as little as 10% to as high 70% of your 1RM.    When first venturing into this type of training, very light loads often using just an empty barbell or bodyweight will suffice. 

Repetition Guidelines

As with most power movements a repetition range of 2-5 will be best.   In fact the first 1-2 repetitions may lack maximal power as the lifter will need time to find their neuromuscular rhythm and kick-start their nervous system.  Typically reps 2-5 will be the most powerful.  After 5 repetitions fatigue accumulation will become a significant factor minimizing power output as well as disrupting proprioceptive feedback and movement mechanics. 

On a similar note I often have my athletes perform many of their REI sets using progressive neural ramping within a given set.  For example if an athlete is performing a set of 4 REI reps I may have them perform their first repetition at 60% max speed on the decent, 80% max speed on the second, then finally 100% maximal speed for the remaining two repetitions.  This allows the lifter to build up confidence by finding their neural groove and neuromuscular rhythm before moving at maximal eccentric speeds.

Eyes Closed

Similar to standard eccentric isometrics, REI’s can also be performed under eyes closed conditions.  However this requires very high levels of movement competency.   Once you’re able to perform proper REI’s on all movement patterns under eyes closed conditions you’ll most likely have mastered your body movement mechanics for a majority of activation patterns.

Revisiting the 7 Basic Movement Patterns


Any and all squatting variations can be used here.  As you rapidly descend, focus on firing your hip flexors and hamstrings to pull you into position.  Accommodating resistance in the form of bands works particularly well when performing rapid eccentric isometrics with barbell back squats.  The increased velocity the bands produce during the rapid eccentric movement requires even greater decelerating forces with every muscle in the body working overtime to absorb impact at the stretched position.  Just remember to stick the eccentric catch at the bottom rather than gradually slowing down or collapsing.

Horizontal Pull

Any rowing exercise performed with free weights works perfectly for REI’s.  Most machines and cable rows on the other hand are not as conducive to rapid eccentrics isometrics as the cam/pulley system has a semi-fixed speed of release making it difficult to fully dictate the speed of the eccentric movement.  While performing any of these rowing variations focus on pressing the weight away from you as violently as possible on the eccentric movement.  The negative movement will feel more like an explosive chest press rather than an eccentric row.  The pectorals, anterior deltoids, and triceps will be maximally recruited as you launch the weight away from your body.

Horizontal Push

Most compound chest pressing movements will work with rapid eccentric isometrics. Neutral grip dumbbell presses on a flat or incline bench tend to be the most user friendly.   Here are a few of my collegiate and NFL athletes including Minnesota Vikings quarterback Taylor Heinecke demonstrating them. 

Barbell bench press variations can be very effective as the natural catch position is typically 1-2 inches above chest height.  However, it is essential proper scapula positioning and shoulder packing be maintained.   Technique with standard EI’s must be impeccable on barbell bench press variations before attempting them with REI’s. 


Although barbell or dumbbell lunges can be used here I recommend incorporating contralateral arm drive.

Because the lunge/stride movement simulates the contralateral cross-crawl effect of human movement (opposite arm activating opposite leg), coordinating the upper extremities with the appropriate motions of the lower body is critical.  Few exercises have such a profound impact on gait, running stride, and sprint mechanics.

As you start in the top position, the biceps, anterior deltoids, and upper chest of the front arm will drive forward and up to activate the hip flexors and hamstring of the front leg.  At the same time the triceps, lats, and rear deltoids of the opposite arm will drive down and back, simultaneously causing increased firing of the glutes in the rear leg.  These mechanics will rapidly accelerate your body into the bottom of the lunge requiring intense recruitment to initiate the deceleration phase as well as maximize co-contraction of reciprocal muscles.  Still confused?  Check out the video.

Vertical Pull

The main exercise for REI vertical pulling will be pullup/chinup variations.  During the eccentric phase as you push yourself down rapidly using your shoulders and triceps you should feel as though you are doing an explosive overhead press.   Make sure your shoulders don’t get pulled out of position as you reach the bottom.  Remember this isn’t a kipping pullup. Keep your core tight, body aligned from head to toe, and avoid swinging. 

The pullup/chinup can be a tricky one to nail with rapid eccentric isometrics. With that said, pullover variations performed in an REI fashion are a worthy substitute (as well as a great option in general) for achieving rapid eccentric lengthening of the lats in an overhead position.  Here's NFL quarterback Taylor Heinicke using them to prep for the season.  Notice the improvement in his low back and spinal position after the first few reps as the rapid eccentric isometric forced his core musculature and spinal stabilizers to quickly recalibrate and resist extension. 

Vertical Push

Any free weight overhead pressing movement will do the job here.  Similar to horizontal presses, dumbbell’s are generally the most user friendly. The kneeling variation shown below forces proper thoracic positioning ensuring all extension occurs from the T-spine rather than the cervical or lumbar regions.  Perform this incorrectly and you’ll know instantaneously as you’ll be focusing all your attention on avoiding a sudden plummet off the bench.

If you really want to maximize the effectiveness of REI’s in terms of movement mastery, rate of stabilization development, and kinesthetic awareness try performing REI’s with bottoms up movements in an eyes closed fashion.  Once you’re able to successfully do these with at least 50% of your 1RM overhead dumbbell press (if your max weight is 80 lbs. on dumbbells then you would use 40 lb. kettlebells) then your overhead pressing as well as a majority of your body mechanics will most likely be mastered to the maximum.


Rapid Eccentric Isometrics can be applied to a majority of hinging movements including RDL’s, good-mornings, and band pull-throughs.  As you drive your torso down and your hips back, focus on rapidly pulling yourself into position by aggressively firing your hip flexors.  Remember, the harder you activate the antagonists muscles (hip flexors in this case) on the eccentric movement, the greater tension you’ll create in the glutes (via co-contraction), ultimately producing incredible amounts of power in the subsequent hip extension phase.

These do wonders for jump performance, sprint speed, Olympic lifts, and overall hip drive.  Because they emphasize actively pulling into the hinge position, REI’s also represent an excellent tool for reinforcing proper swing technique. In fact when performed correctly hinging REI’s should feel similar to kettlebell swings, albeit one with an isometric contraction.

If you really want to learn to master your lower body mechanics, try this incredibly challenging yet effective single leg RDL performed in a rapid eccentric isometric fashion as shown by one of my awesome clients Leslie Petch. It’s also highly effective for improving rate of stabilization development which is critical for performance.

Olympic Lifts

REI’s are also incredibly effective when applied to hang versions of Olympic lifts such as hang cleans and hang snatches from below the knee. 

By performing an RDL in a rapid eccentric isometric first, this primes the CNS for heightened activation ultimately producing maximal power output on the concentric lifting phase.  If you have trouble priming your nervous system on Olympic lifts and struggle with hip drive, REI’s applied to cleans and snatches does wonders.

Core Training

Although most core stabilization exercises are not conducive for implementing rapid eccentric isometrics, one that’s particularly useful is REI’s using the abdominal wheel rollout as demonstrated by one of my awesome clients Ben Lai.  If you’re looking for an exercise that truly maximizes rate of core stabilization and spinal rigidity by resisting extension forces acting on the spine this one’s a tough one to beat. 

Just make sure you don’t overstretch the movement or allow the hips to sag as that would produce enormous stress on the spine. Focus on keeping the hips tall with a hollowed core by activating the hip flexors not the hip extensors.  In other words don’t squeeze your glutes (a common myth perpetuated by the fitness industry) whether that’s on the REI ab rollout or any other anti-extension core exercise. 


I have three methods I’ll employ when using REI’s.

First, I’ll use them as a neural primer to prepare the body for heavier loads.  For example if I’m having an athlete who has a 455lb max squat perform REI barbell squats, I would have them warm-up with an empty bar for 3-5 reps using standard EI’s.  After waiting 30-45 seconds I would have the athlete use the same load but perform 3-5 REI’s.  I would continue using this staggered protocol (standard EI set followed by REI set) progressing to 135, 185, then 225, and eventually moving to standard squat sets as the weights begins surpassing their heaviest tolerable load for REI’s.  This method does wonders for preparing the body for heavier loads as you’re literally forced to activate survival fibers you might not normally recruit.

For the second method you simply use REI’s for a speed and power day.  The protocol is similar to the above however after progressing up in weight you would perform 3-5 sets of REI’s with your heaviest capable load (i.e. 3-5 sets of 2-5 reps using 225 lbs if using the above scenario).

The final method employs neuromuscular potentiation.  After performing your typical heavy squat routine, preferably with several intense sets of standard eccentric isometrics you’d then decrease the load to approximately 50% of your 1RM and perform several sets of REI’s.  This method takes advantage of post activation potentiation produced from intense loading.  Your nervous system will be accustomed to heavier loads from prior sets and once you reduce the weight, your body will be capable of moving at even greater velocities ultimately maximizing the speed of REI execution.

Additional Benefits of Rapid Eccentric Isometrics

Aim and Fire

Because REI’s happen so rapidly and decisively they are excellent for enhancing movement accuracy and precision of motor control.  Essentially you have a pre-determined target or movement path that must be nailed to a T.     

Recalibrating Muscle Spindles

Although there are multiple components that contribute to muscle dysfunction, poor muscle spindle sensitivity is a key player.  In fact most athletes and general populations have muscle spindles that are either desensitized (lack of sensitivity) or hypertonic (overly sensitive to stretch).   In the long run both of these issues can lead to spasticity of the muscles which can have severe detrimental effects on performance and strength not to mention overall health and physiological function.  Eccentric Isometrics particularly when performed in conjunction with REI’s help reset/recalibrate the muscle spindles to their appropriate levels of sensitivity.


Because REI’s hyper-activate the CNS they elicit numerous benefits for athletes and lifters alike ranging from increased power, speed, and strength as well as significant hypertrophy effects.  The hypertrophic response is due to brief yet very high amounts of mechanical tension and micro trauma/muscle damage produced from the rapid eccentric phase.  In fact Olympic weightlifters are known for their incredible thigh development much of which can be attributed to catching and decelerating heavy loads in the catch/stretched position of their squat.  

Olympic Lifts.

On a similar note, catching and decelerating a rapidly moving load on the eccentric movement makes REI’s especially useful for enhancing Olympic weightlifting movements.  Variations of the squat performed as an REI will do wonders for improving the bottom catch position of the clean or snatch.   In fact the snatch-balance drill used in many weightlifting circles closely resembles many of the characteristics of rapid eccentric isometrics. 

Besides teaching the lifter to rapidly pull themselves into the squat, REI’s will also reinforce the idea of sticking the catch rather than relaxing at the bottom and letting your body excessively collapse – a common problem seen in many weightlifters.

Final Notes

Rapid Eccentric Isometrics should never replace standard eccentric isometrics. Instead they are performed in addition to.  In reality standard eccentric isometrics should still constitute a majority of your training while periodically incorporating REI’s.

For more on eccentric isometrics and rapid eccentric isometrics stay tuned for my book release in the coming months.