June 26, 2011

Negatives For Positive Results - How To Increase Eccentric Overload Without Overtraining

While there are 3 types of muscular contractions – concentric, isometric, eccentric, in which muscles produce force while either shortening, lengthening, or remaining the same length, there are only 2 types of intended muscular actions – overcoming, yielding.

Concentric contractions consist of a shortening, overcoming action, in which the intent is to produce enough force to overcome the amount of resistance placed on the muscles, while eccentric contractions consist of a lengthening, yielding action, in which the intent is to produce enough force to yield the lengthening action of the muscles, while isometrics can be of an overcoming, or yielding nature (the intent to shorten, without an actual change in length occurring being of an overcoming nature, while the intent to prevent lengthening, without an actual change in length occurring being of a yielding nature).

In terms of motor patterns and motor unit recruitment, overcoming actions follow a hierarchy in that motor units are recruited as needed from smallest (and weakest) to largest (and strongest) based on the perceived demand. The greater the demand is perceived to be (which can be consciously controlled based on intention), the greater amount of motor units that will be recruited.

Yielding actions do not follow this hierarchy, as they are perceived as potentially dangerous and threatening by the nervous system, as it has no clue as to why a muscle is being stretched under load, all it knows is it that to prevent a potentially catastrophic injury, it must favor the recruitment of the muscle fibers which are capable of producing the highest levels of force – the fast twitch muscle fibers (which also happen to have the greatest size and strength potential).

On a pound for pound basis, there are less total fibers recruited during a yielding action in comparison with an overcoming action, resulting in higher forces being exerted on the fewer motor units recruited, which will encourage greater biological adaptations. Therefore, the stress per fiber is greater, resulting in greater muscle damage (micro-trauma/tearing), and this happens to be why eccentrics cause more discomfort and soreness in the trained musculature during the acute recovery period (AKA, DOMS – delayed onset muscle soreness) than concentrics and isometrics.

The soreness and discomfort produced from eccentric training is commonly, and incorrectly, associated with strength and size gains, ultimately leading to ineffective usage of eccentrics. Size and strength gains are primarily the result of the activation of cell signalling via several pathways (EPK, PKB, etc), as well as the activation of the mTOR pathway, and the production of local growth factors like IGF-1, not because muscles are damaged, it’s more so that muscles just happen to be damaged in the process that triggers this cascade of events. In fact, excessive damage resulting from a high volume of eccentrics can actually retard the repairing and rebuilding process, so the use of eccentrics must be progressed carefully because of the greater toll they take on the body.

To reap the full benefits of eccentric training, a small amount of eccentric overload is needed (enough to stimulate, but not so much that you cause excessive damage). When overloaded, eccentrics provide the greatest neural adaptation (which is the primary cause of strength gains) because they force the nervous system to learn to increase its capacity to recruit motor units faster, and not just any motor units, the high threshold motor units, since they are the ones which are preferentially recruited during eccentric contractions. This increased recruitment and stimulation of fast twitch muscle fibers is the greatest benefit that eccentric loading can provide, and the benefits of increased capacity to recruit the fast twitch muscle fibers carry over to all other types of training.

Because of the nature of the motor pattern, most people can generally handle upwards of 30% more weight eccentrically than concentrically (up to 130% of concentric max, although it’s been suggested that a well trained individual may be able to handle upwards of 175% of concentric max eccentrically). Therefore, a load provides sufficient overload concentrically will not have the same overloading effect eccentrically (because muscles are essentially stronger eccentrically, they need to handle greater loads to get the same effect).

For example, if a muscle is roughly 30% stronger eccentrically, this means:

·         100% of concentric max will provide roughly 77% of eccentric overload (77 + 30% = 100.1, for those who did the math and are thinking that things aren’t adding up. 30% is relative, and differs based on whether it’s being added to, or subtracted from)
·         90% of concentric max will provide roughly 69% of eccentric overload
·         80% of concentric max will provide roughly 62% of eccentric overload
·         70% of concentric max will provide roughly 54% of eccentric overload

Because a load of at least 70% of relative max is needed to provide sufficient overload, the weight needs to be at least equivalent to 91% of concentric max (70 + 30% = 91):

·         97% of concentric max will achieve roughly 75% of eccentric overload
·         104% of concentric max will achieve roughly 80% of eccentric overload
·         110% of concentric max will achieve roughly 85% of eccentric overload
·         117% of concentric max will achieve roughly 90% of eccentric overload

In some cases the margin may be greater 30%, while in others it may be smaller, but in either case it’s painfully obvious that a greater load is needed than that which is being used to overload a muscle concentrically, to overload a muscle eccentrically. Most people fail to understand the concept of overload, or misinterpret what it actually means, and end up failing to take advantage of the opportunity for gains that eccentric training offers.

With concentric training you can overload the muscle or increase the amount of tension the muscle is under, by increasing the perceived demand (as stated earlier), irrespective of how much weight in relation to maximum is being used, which is done by consciously trying to lift the weight with maximum effort. With eccentric training however, overload is directly related to the weight in relation to maximum that is being used, not the speed in which you allow the muscles to be lengthened under load. The only implication that the speed in which a weight is lowered has is to quantify progression, and gauge whether or not it is safe to perform another rep.

Since anything under 70% of relative maximum will not provide optimal overload, and loads need to be in excess of 90% of concentric max to have any real value from an eccentric overload perspective, this doesn’t really allow for many practical applications, because loads at that level of intensity don’t allow for many reps to be performed (obviously loads in excess of 100% of concentric max don’t allow for any concentric reps to be performed).

In most cases 91% of concentric max represents around ones 4 rep maximum, meaning that it likely isn’t possible to perform 4 reps at that intensity twice (or more) during the same workout (if you can duplicate your performance, it likely wasn’t a true rep max).

Also needing to be taken into consideration is that a maximum performance generally doesn’t include an enhanced eccentric component, as the increased time under tension undoubtedly affects the ability to perform the maximum amount of reps at a given intensity. The longer each rep takes to complete, the less total reps that can be performed, regardless of the load. Therefore, to perform the same amount of reps while emphasizing the eccentric component of each rep in an attempt to maximize overload, less weight is going to have to be used, but this is not a viable option because lowering the load in favoring of increasing the time under tension does not provide sufficient eccentric overload.

This leaves sets of 3 reps or less, using loads in excess of 90% of concentric max, as the only real means of practically applying eccentric overload, but the heavier the weight is in relation to concentric max, the greater toll it takes on the neuromuscular system, and the less likely you’ll actually be able to lift it through the concentric range to perform a second or third eccentric repetition. Therefore, process of elimination leads us to one logical solution, and that is to only bother focusing on performing one rep at a time, using as much weight as possible, and lowering for as long as possible, repeating that sequence no more than 5 times per workout (3-4 being optimal) for the trained musculature (anymore than 5 reps with loads in excess of 95% of concentric max is when the risk begins to outweigh the reward anyway). The question now becomes how to implement these 3-4 eccentric overload reps into a program?

Effective practical application for eccentric overload

When?: At the beginning of the workout is when you’ll be able to handle the greatest loads, for the greatest duration, which is the whole point of overload in the first place. The fast twitch fibers that are recruited during eccentric overload, which may not normally be recruited, set the stage for the rest of the workout as they facilitate the use of greater loads for concentric work that follows, which further stimulates the activated muscle fibers.

How?: The 3-4 overload reps can be used as standalones performed back-to-back-to-back(-to-back) before moving on to the rest of the scheduled workload, or used concurrently with concentric work.

When used concurrently, the eccentric repetition can be performed as the first rep of the set, at which point the ‘overload’ is removed, the same way you would when performing a drop set, and the rest of the reps are performed as scheduled, or alternated back and forth as part of a contrast method. In either case the goal is to be able to use more weight than you normally would for the same amount of reps, or perform an extra rep with the same load you had planned to use, because of the additional fast twitch fiber activation. An example of the eccentric overload drop set looking like this:

Rep 1: eccentric rep w/ 100-110% of concentric max, concentric rep with 90% of concentric max
Rep 2: full range rep w/ 90% of concentric max
Rep 3: full range rep w/ 90% of concentric max
Rep 4: full range rep w/ 90% of concentric max

It should go without saying that a power rack is needed, and the only exercises suited for this type of work are those in which a barbell is used, in which case you would simply lower the bar onto the rack, remove the eccentric overload, get back in and finish the set. The major difference with a contrast method is you do not finish the set right away after performing the eccentric overload. Obviously if you have a training partner this is much easier and a lot more practical.

If performing more than 4 sets, staggering the eccentric overload reps (since you don’t want to be performing more than 4 eccentric overload reps) by combining the drop set method above with the contrast method above and alternating between sets which begin with an eccentric overload rep with a traditional set in which no eccentric overload is added, is best. An example looking like this:

Set 1: eccentric overload on first rep
Set 2: no eccentric overload
Set 3: eccentric overload on first rep
Set 4: no eccentric overload
Set 5: eccentric overload on first rep
Set 6: no eccentric overload

Intensity?: While some muscles may be capable of handling 30% greater loads eccentrically than concentrically, it isn’t absolutely necessary to lift such great loads to reap the benefits of eccentric overload and fast twitch fiber recruitment. As long as you’re using over 90% of concentric max you’ll get the full effect. If using a drop set, or contrast method, aim for 10-20% more weight for the eccentric repetition than what you will be using concentrically (unless using the overloaded eccentric to activate the fast twitch muscle fibers prior to speed/dynamic work which is typically performed with 45-55% of max, and 10-20% more than that won’t do much in terms of providing any eccentric overload whatsoever).

Work:rest? Because of the high intensity nature of eccentric overloads, they should not be used exclusively, but rather for 3 weeks at a time at the most, with a better option being to spread them out over several weeks using a 2:1 ratio in terms of ‘regular’ training to eccentric overload training. Also, the results from eccentric training have a delayed effect, so 3 weeks should be given between the last eccentric overload session and any testing done to gauge progression (this also means that eccentric overload training should cease at least 3 weeks before an event in which strength need to be demonstrated).

This type of training is not suited for beginners, or those with relatively little training experience, as it can damage the connective tissue, which in turn increases the risk of muscle injury. Therefore one should have at least two full quality years of training under their belt before attempting this type of training, as it’s not even remotely necessary at that stage in the game to rely on a method like this to get results.

Progression: As stated above, the only implication that the speed in which a weight is lowered has is to quantify progression, and gauge whether or not it is safe to perform another rep, meaning that there should be a predetermined amount of time in which the weight is to be lowered, and if the weight is lowered faster than the predetermined time, that would indicate that the load is too great. The preset time should be determined by the amount of weight being used and the range of motion of the movement (the greater the range of motion, the longer the eccentric should be), with the goal being to work up a 10 second yielding action, but if it is possible to lower for longer than that, then it’s time to increase the weight.

A word of caution for athletes
Eccentric actions can be subdivided into two separate categories: slow eccentric actions (which is what the content up to this point has centered around), and fast/rapid eccentric actions (which need not be neglected for those training for sport).

Exclusively performing slow eccentric actions increases the possibility of decreasing the ability to generate maximum force instantly, therefore usage of them is best suited early on in a periodized training program because of the delayed training effect, and because of the burden the take on the nervous system. In this case, fast eccentrics by way of plyometrics should used closer to the competitive period.

Eccentric strength, rather the ability to produce force while the involved musculature is lengthening under load, or decelerate, is of paramount importance in many different sports that require advanced jumping, and change of direction ability, such as various track and field events, football, soccer, basketball, downhill ski events, gymnastics events, and figure skating.

Slow eccentric based movements are those done with a barbell as stated above (squats, deadlifts, various presses), but fast/rapid eccentric movements generally require no more than bodyweight (various jumps with the emphasis being on landing, depth push-ups – basically any movement in which the nervous system receives input and is required to instantly react by producing force as the muscle rapidly lengthens). Both types of eccentric loading have a place in a well rounded training program, although when they are used is highly dependent on the individual’s goals.

For simplicity and convenience, fast eccentrics can be combined slow eccentrics as part of a complex. The theory here is that the slow eccentrics tap into the high threshold motor units while the fast eccentrics create muscle fiber damage that leads to the growth of fast twitch muscle fibers while maximizing the neural adaptation.

In this case a set of slow eccentrics (using the eccentric overload technique provided above, or even just a normal set within your 1-3, or up to 5, rep range) would be followed by an exercise that is plyometric in nature. A practical example would be squats followed by drop jumps (aim to perform double the amount of drops than squats per set, ex. 3 reps for squats, followed by 6 drops). The height of the drop is determined by the height of the rebounding jump – increase the height of the drop until there is no longer an increase in the height of the rebounding jump.

If you have any questions about how to properly overload eccentrics, feel free to contact me at ben@paramounttraining.ca. I'm available for online consulting and personalized program design, as well as one on one training if you are located in the Greater Toronto Area (GTA).

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