The term eccentric overload gets tossed around so much that it seems that some are labeling anything eccentric regardless of load or anything that is done on a flywheel device as “eccentric overload”. In reality, most eccentrics done in the weight room are not eccentric overload at all. The term eccentric overload should only be reserved for exercises where an athlete is capable of expressing eccentric forces in excess of 100% of their maximal concentric force producing capabilities.
This takes us to the main point of this piece. Why and how we should be moving beyond submaximal slow eccentrics and toward true eccentric overload.
A Quick Review
To get the basics out of the way, an eccentric contraction can be considered any action that involves the forceful lengthening of a muscle or tendon. Research states that eccentric contractions or eccentric force generating capabilities are up to 50% higher than our maximal concentric force generating capabilities. The idea of eccentric loading capacity nearing 1.5x it’s concentric counterpart is nice, but it is truly hard to see this come to fruition in the weight room.
It’s still difficult for researchers to fully understand why there is this marked increase in eccentric capacities relative to concentric capacities, but many seem to agree on the fact that passive elements during the eccentric activity assist in this, mainly cross-bridge properties and titin.
The force-velocity curve is an easy way (at least for me) to organize thoughts on improving eccentric force generating capacities in the weight room. While the eccentric loads that we may impose in the weight room still won’t match those during sprinting and most change of direction activities, we have to remember that most of what we do in the weightroom is very general and is typically used to either improve neurological factors such as motor unit recruitment, rate coding etc., or architectural changes, such as cross-sectional area, fascicle length, etc. which can directly and indirectly enhance sporting qualities and reduce injury risk.
The problem with the FV curve is that most get stuck on the right side and thus live on the right side. The right side is what is presented in most text books and has been brought to the forefront because of the popularity of VBT in the past few years. The right side is important, but there is much more of the curve to explore beyond the right side, and to truly develop eccentric force generating capacities there is a need to shift our thinking to left side of the curve.
The following sections will be broken up into what I believe are the most logical categorizations of the force-velocity continuum and a way to organize the planning and development of eccentric capacities:
- Submaximal Slow Eccentrics
- Maximal Isometrics (and submaximal to a lesser extent)
- Supraxamimal Slow Eccentrics
- Fast Eccentrics
Submaximal Slow Eccentrics
Submaximal slow eccentrics are what most mislabel as “eccentric overload”. If we have an understanding of where submaximal slow eccentrics fall on the FV curve, we can see it falls well short of eccentric overload and maximal eccentric force generating capacities.
Most weight room exercises are limited by the athlete’s ability to produce concentric force in the weakest range of motion. The squat is a prime example. If we were to test an athlete’s 1RM squat capacity, what we are really testing is the maximal concentric force produced at the weakest joint angles (the bottom-ish of the squat).
With this logic, we can gather that using loads based off of our weakest concentric abilities (i.e. 80% of 1RM) and lifting them slowly may not be the best way to continue to push eccentric adaptations. While hanging out in the region highlighted above for long periods of time will undoubtedly stall eccentric force generating capacities, this area on the curve does have some value:
- Increase muscle mass – It’s no secret that eccentric training can be a great tool to create a hypertrophic response and increase muscle mass. Due to the increased duration of muscular tension that slow eccentric exercises offer we can attempt to increase hypertrophy of the muscle fiber and thus increasing cross-sectional area of the muscle (time under tension is not the end all be all to induce hypertrophy, but it at least plays a part). Along with this increased cross sectional area comes the potential to produce greater force. This can be a major benefit if you have an undersized athlete or the athlete’s sport requires muscle mass as a protection element, but the caveat is that a larger muscle may not always be able to express greater maximal forces or higher rates of force production due to the type (why bodybuilders are not known for their speed and power abilities). There is still a major need to train in a way that would allow the athlete to actualize greater maximal force and high rates of force development.
- Improve coordination and skill – I’m a fan of using slow eccentrics as an early introduction to an exercise or as a remedial fix because it can enhance skill in the exercise being performed. If we’re attempting to teach a barbell squat to someone that just isn’t getting it, a remedial option may be to have them squat to a box with a 3-5 second count on the eccentric portion. Or if we are trying to teach or reteach a weightlifter pulling posture and positions, we may have them clean or snatch pull with normal tempo and include a slow eccentric lower to assist in teaching proper posture and balance.
- Introduction to more intense and/or specific means of eccentric loading. – This is probably why I would use submaximal slow eccentrics with most athletic populations. If your goal is to get to the left side of the curve, the body should to be stressed in a progressive manner to ensure the body is prepared for greater specificity and the intensification of training. It would be unwise to hop directly into supramaximal eccentrics or fast eccentrics due to the potential injurious effects it may have if under-prepared. Submaximal slow eccentrics are an introduction to more intense training down the line.
For these reasons, submaximal slow eccentric training lends itself well to early/mid stage rehab or early in the training plan when athletes can’t yet tolerate maximal or fast loading, but to improve eccentric force generating capacities much beyond the levels of the right side of the curve, we need to think beyond submaximal and slow.
Beyond Submaximal Slow Eccentrics
Before we discuss isometrics, it’s imperative that we distinguish between the two categories of isometrics: yielding and overcoming. Overcoming isometrics are producing force against an immovable object (think isometric mid-thigh pull) while yielding isometrics are isometric pauses with a submaximal weight usually within an eccentric or concentric motion (think pausing during a snatch/clean pull). Typically, overcoming isometrics can be can be subcategorized into maximal and submaximal, while yielding isometrics can only be submaximal… if a yielding isometric was maximal, the isometric contraction would quickly fail and become an eccentric action.
Overcoming and yielding isometrics can fall under this highlighted section and they both have unique attributes that make them useful if the scenario is right. Submaximal isometrics won’t play a major role in developing eccentric capacities in healthy athletes, but they potentially can play a role in the progression of an injured athlete.
Submaximal overcoming isometrics, specifically iso quarter squat and IMTP that require very little range of motion, may be a good tool if an injured athlete’s range of motion is still very limited and we want to provide a larger neuromuscular stimulus than what we maybe could with traditional weightroom exercises that require larger ranges of motion and less external loading.
Yielding isometrics (and isometrics in general) have been getting a lot of attention lately for the ability to manage pain and increase acute strength in certain cases of tendonopathy. This is method of pain management can be especially important if we’re late in a season and resting isn’t really an option. Also, due to the decrease of tendon pain (and the potential potentiation effect) there is shown to be an increase in strength for at least 45 minutes post isometrics which may allow an athlete to train more intensely for that short time frame.
Maximal isometrics are typically better than traditional weightroom exercises for testing maximal force and rate of force development because unlike the deep squat which is a measure of maximal force at the weakest joint angles, with maximal isometrics you have the ability to load and test some of the strongest lower body joint angles. On top of that, typical weightroom 1RM testing is typically reserved for athletes that have a good amount of training experience as well as experience handling near maximal and maximal loads. This is why maximal isometrics may be a better testing and training tool for team sport athletes and young athletes alike.
Sometimes maximal isometrics are looked down upon in a training setting because there is no dynamic movement and the lack of specificity to sporting actions. I do agree that if you have very little time in the weightroom with the athlete, maximal isometrics may not be the best use of time. As a counter to that argument though, first, there is a very high neural demand with maximal isometrics, which is specific to most sports that require any form of high intensity activity. Secondly, that argument is quickly solved by using them in a complex with dynamic movements to potentiate other movement based training items like squats and Olympic lifts. In addition, at specific joint angles isometrics can assist in developing postural strength for jumping and sprinting.
The huge neural stimulus that maximal isometrics provide may also prepare one for more advanced methods like true eccentric overload.
The left side of the curve is where we get into true eccentric overload. To achieve an eccentric overload supramaximal eccentrics are generally done at slower velocities while fast velocities require relatively less external load. This side of the curve is where we can potentially achieve greater changes in muscle mechanical function and changes in musculotendon architecture. More specifically, there are opportunities to recruit higher threshold motor units, and generate increases in volitional activation, the proportion of type II muscle fiber area, musculotendon cross-sectional area, and musculotendon stiffness.
Supramaximal Slow Eccentrics
As mentioned above, recruiting high threshold motor units is a big draw for supramaximal eccentrics. These higher threshold motor units are recruited only when the CNS recognizes that they need to be. Granted, 90% 1RM (or submaximal intensity with maximal intent) is typically enough to tap into these motor units, supramaximal eccentrics may be what is needed for advanced athletes to spur neural adaptations.
Supramaximal slow eccentrics can be tricky (and potentially dangerous) even with highly trained athletes, but if you have access to one or two tools it can become significantly easier and safer. One of the now old school ways of attempting to attain eccentric overload is lowering a supramaximal squat (105-120%) to pins. The only problem is that you can only perform one rep unless you have an army of training partners to lift it back up to the starting position.
An option that is becoming a bit more popular, and takes the above example to a more refined level, is using weight releasers. It still only offers the ability to do one rep at an eccentric overload, but the athlete can continue to finish the remainder of the set at a submaximal load. This first rep at eccentric overload may enhance the output of the subsequent concentric rep(s) due to neural stimulation, elastic energy storage, and contractile alterations. This means that we can create, at least in an acute environment, increased output which may lead to chronic adaptations over time.
Another option, and somewhat more all-athlete friendly option, to attain eccentric overload is a flywheel device. But, just because an exercise is done via flywheel doesn’t mean it’s eccentric overload either. With a fly wheel device we still need to get crafty with techniques used. Techniques to use on the fly wheel device can range from the assisted concentric to subsequently overload the eccentric (the use of a partner or stationary object is needed to assist on the concentric), the strong to weak movement (such as deadlift to RDL), to the 2-1 technique where you move the weight with 2 limbs concentrically and allow 1 limb to perform the eccentric movement.
Fast eccentrics are the money maker when it comes to eccentric development for most athletes. With fast eccentrics, we see similar benefits to supramaximal slow eccentrics, but typically with a preference toward explosive activities and activities that utilize the SSC to a greater degree.
Fast eccentrics can develop increases in RFD, tendon stiffness and in turn the utilization of elastic energy, fascicle length / sarcomeres in series, and a possible increase in type IIx fiber proportion. These are huge when it comes to performance as well as reducing injury.
We have quite a few options when it comes to fast eccentrics. There are the obvious plyometric activities which I think can better develop RFD and stiffness than many weightroom activities, but we can also apply the concept to traditional weight room and flywheel devices as well.
With traditional weightroom exercises I prefer to use fast eccentrics with the intention of reducing risk of injury. With research in recent years on the relationship of fascicle length / sarcomeres in series and a reduction in muscular strains (mainly hamstring), we can continue to provide progressive stress using high velocity eccentrics that in theory will reduce risk to a greater extent.
While these concepts can be used as the basis for the progression of many exercises, here are a couple videos with some thoughts on progressing eccentric hamstring strength in the weightroom with two of the most commonly used exercises.
Important note: Bodyweight nordics aren’t always supramaximal eccentric as I have labelled them. If strong enough (I’m not), they could also be classified as submaximal eccentric if full range eccentric and concentric is achieved.
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