The ancient symbol “yin-yang” is said to express the Chinese philosophical concept that describes how apparently opposite or contrary forces may actually be complementary, interconnected, and interdependent in the natural world. This connection perfectly describes the relationship between the concentric and eccentric muscle actions. Lengthening versus shortening, force creating versus force absorbing, and energy dependent versus fatigue resistant: all demonstrate the literal tension between two apparently conflicting but interrelated processes.
In the battle for recognition, however, the concentric activity of muscle is the clear winner. Concentric muscle action gets the credit for virtually everything we do in the world, while eccentric activity toils in the background, working tirelessly but completely unnoticed. We always speak about lifting weights, with little emphasis on how we lower them back down.Eccentric activity toils in the background, working tirelessly but completely unnoticed. We always speak about LIFTING weights, with little emphasis on how we lower them back down. Click To Tweet
There are now new technologies available that provide resistance for the eccentric movement. This article will discuss the principles of applying resistance during the eccentric lowering phase with emphasis on supplying this resistance safely and effectively.
The best way to fully differentiate between these two distinct muscle functions is to examine them when they are under conditions of maximal stimulation. In other words, expose them to different degrees of loading and then maximally stimulate them to contract. This is exactly what is done when physiologists create the load-velocity curve to describe muscle activity.
Basically, the testing apparatus should isolate the joint that the muscle acts through and begin in the mid-range position. At about half of its full length, maximally stimulate the muscle (in the laboratory by stimulating the involved nerve). With no load, the muscle will contract almost violently at a high velocity. A curve is constructed by repeating the maximal stimulation by incrementally increasing the weights applied to the involved limb. Very predictably, as the weights are gradually increased, the speed at which the muscle shortens begins to decrease.
The curve of these successive trials typically describes a classic parabolic form. Eventually, a point is reached where the weight equals the contraction force of the muscle. Finally, there is some threshold at which the muscle cannot move the weight at all, which is approximately the one repetition maximum (1RM). Up to this point, the relationship between the weights and the muscle force has been very dynamic, with significant differences as the weights were increased.
The Myth of Lengthening
As the weights being applied to muscle in mid-range are increased further, conditions change markedly. When the applied weights actually exceed the force-producing capacity of the muscle, the muscle is then forced to lengthen. This lengthening is radically different from the shortening that occurs with the lighter weights. At just 10% above the 1RM, the velocity of lengthening is barely perceptible. At 20%, 30%, 40%, or even 50% of added weight above the 1RM, the muscle yields very little and lengthens very slowly. When the applied weights get relatively extreme, at 70%, 80%, and 90% above the maximum, the muscle basically gives way, and the velocities increase at a logarithmic pace.
This behavior suggests that the muscle is trying to resist lengthening under these conditions. Everything points to the conclusion that the maximally stimulated muscle under conditions of significant overload tries not to lengthen; in fact, the reality is that muscles cannot themselves lengthen. Every muscle, when stimulated, responds by shortening—and when not stimulated, simply remains unchanged. Only by applying an external tension to pull the two ends of the muscle apart does the muscle lengthen. Muscles cannot lengthen—they can only be lengthened.Everything points to the conclusion that maximally stimulated muscles under conditions of significant overload try NOT to lengthen. Muscles cannot lengthen—they can only BE lengthened. Click To Tweet
When you look at a combined graph of the concentric shortening and the eccentric lengthening, it is striking how dissimilar the two curves are from one another. On the one hand, the parabolic concentric curve demonstrates the dynamism of the shortening action, while the barely mobile eccentric graph almost appears static.
The extremely small amount of lengthening caused by ever-increasing amounts of overload suggests that the function of the eccentric muscle activity is, indeed, not to lengthen the muscle but rather to keep it from lengthening under the applied load. In terms of the involved movement, as in the biceps for example, it is more accurate to say that the eccentrically loaded biceps is no longer flexing the elbow, but rather keeping the elbow from extending.
There is, in fact, one other curve that bears a striking resemblance to the eccentric curve: the “stress-strain” curve used routinely in material science.
The stress-strain curve describes the bending of a solid material such as wood, plastic, or metal when it is subjected to a gradually increasing force or stress. There is some minimal level of load applied that causes an unavoidable bending or deformation (strain) of material being studied. It appears that all materials, to different degrees, behave very similarly to a bending force.
Initially, materials bend just slightly, and then as the external force increases, they bend more. Under lighter loads of applied force, the material will return to its original shape when the force is removed. This phase of force application is called “the elastic range.” There, however, begins a level of loading that can actually disrupt the molecular integrity of the material so that when the bending force is removed, the material is permanently deformed. This type of material change is call “plastic deformation,” and aptly, this range of force application is called the “plastic range.” Further loading beyond the “plastic range” is catastrophic and causes macro-damage and material failure, called the “failure zone.”
The importance of comparing the stress-strain curve to the eccentric force-velocity curve is that it implies a therapeutic range for applying overload resistance. The “minimum effective dose” of overload begins at the 1RM for that muscle. You can then apply higher levels of resistance, sometimes as high as 60% or 70% above the 1RM, and although temporary deformation will occur, no structural muscular damage will happen. There is, however, some level where tissue damage and potential harm will occur. This should, of course, be avoided if at all possible.The importance of comparing the stress-strain curve to the eccentric force-velocity curve is that it implies a therapeutic range for applying overload resistance. Click To Tweet
In this activated, eccentric condition, the muscle behaves like a stiff, passive spring that will initially absorb an outside force by elastic lengthening. The elastic property allows muscle to stretch under a certain amount of overload resistance, absorb the energy, and then release the energy and return to its resting length. Beyond these levels of resistance, there is potential damage to the muscular tissue.
The Molecular Basis of Muscle Function
In order to appreciate how these observations of muscular behavior relate to the actual muscle itself, the molecular basis of concentric and eccentric function needs to be understood.
These two contrasting functions of the same muscle have similarly contrasting molecular mechanics. The classic “Sliding Filament Theory,” developed in the 1950s, has done an adequate job of describing the observed function of muscle during concentric contractions.
The thick filament with its myosin molecules and the thin filament with its actin molecules slide past each other to decrease the length of the sarcomere and hence shorten muscle length. Unfortunately, this model of muscle function had no explanation for the observed properties of enhanced eccentric muscle action. It was not until relatively recently that researchers proposed a new theory that included the eccentric function of the muscle (Nishikawa, 2012). This new theory was called the “Winding Filament Theory.”
There were two major changes to the model that explained the behavior of eccentric muscle action. First, the thick and thin filaments were not described as being simply chains of myosin and actin, respectively. In the Winding Filament theory, the thick filament has as its primary constituent the largest molecule in the human body, titin. Titin extends the full length of the sarcomere and has unique elastic properties. In this model, the myosin molecules are aggregated on the surface of this molecule for their interaction with the actin molecules.
Similarly, the thin filament is not merely a chain of actin molecules. In this case, the core molecule of the thin filament is called nebulin. Although not as marked, nebulin likewise has elastic characteristics, and similarly the actin molecules are situated on the surface of the nebulin molecule for their attachments to the myosin molecules.
Another major difference of the Winding Filament theory, as the name implies, is that the thick and thin filaments do not simply slide past each other. It is here we are reminded that the contractile proteins are helically shaped. This means that instead of simply passing by each other as the sarcomere shortens, they actually wrap around one another and intertwine. While in the shortened state (the beginning of eccentric lengthening), the two molecules are almost indistinguishable as one.
Eccentrics and the Stretch-Shortening Cycle
It is not intuitively obvious how this spring-like molecular quality relates to the function of the whole muscle in the real world. How can the molecule resist the large physical forces encountered in the real world, and how can molecular stretch result in the long ranges of motion required in some overloaded conditions?
The answer is in the arrangement of the titin and nebulin molecules in the muscle itself. First of all, to be able to resist the larger forces, the molecules, like the myofilaments, work together in the cross section of the entire muscle. In cross section, all the molecules work together when force is applied across the muscle. This arrangement of the elastic molecules in cross section is called a parallel arrangement. This is analogous to stretching a rubber band: it is fairly simple to stretch one rubber band, but if you link 10 or 15 rubber bands together in your fingers, stretching them altogether can be difficult. The cross section of the muscle represents the action of many elastic molecules working together.
The question then becomes, how can the stretching of a molecule allow the muscle to extend for the longer lengths seen in actual human function? To explain this, it has to be emphasized that these molecules exist in the sarcomere, and the sarcomeres are connected end-to-end over the length of the muscle in the myofilaments of the myofibers.
Once again, the rubber band analogy can explain the ability to create length. In this case, instead of holding many rubber bands together to increase their resistance to lengthening, imagine forming a chain of rubber bands looped together end-to-end like the sarcomeres—a single rubber band can only be stretched a short distance, but this chain of rubber bands linked together can be stretched for a much longer distance. This looping together of the rubber bands is called “putting them in series.” The behavior of elastic elements working together either in parallel or in series is described in formulas used in Hook’s Law.
What, then, is the function of these spring-like muscles in human function? It is underappreciated that many common human movements expose the muscles to surprisingly high levels of force. Basic walking is just falling forward while standing on one foot and catching ourselves as we land on the other. Although this seems like an extremely low impact activity, each step requires the body to absorb 1.5 times body weight at each heel strike.It is underappreciated that many common human movements expose the muscles to surprisingly high levels of force. Click To Tweet
The simple act of going down stairs exerts a foot strike that receives 3.5 times body weight of force. In faster activities, the forces go up proportionately. Running, which is basically jumping from one foot to the other, generates an impact force of 2.5 times body weight. To jump, an athlete has to convert their horizontal speed to vertical distance by solidly planting a foot against the ground with a force that can exceed seven times body weight.
The high forces are not just experienced when gravitational forces are encountered but are also present when the muscles must resist the high momentum forces of objects moving at high velocities. Examples of high momentum forces include the acceleration of the low leg during sprinting, the wind-up of the pitcher’s arm, and the back swing of sports equipment such as bats, clubs, and rackets.
Although much has been made about the stretching of the molecules, there is, of course, a time when the molecules “snap back”—i.e., shorten—to their original length. Enhanced force production can occur when the shortening of the titin-nebulin complex is coordinated with the shortening that normally occurs during muscle contraction. The key element of harnessing the absorbed elastic energy is the rate of loading.
For elastic stretch to be utilized in coordination with muscular contractile force, the muscle must be stretched very rapidly and at a high force level. Only then can the two forces combine to produce much more force than either alone. This combined force, the stretch-shortening cycle, is exploited in virtually all force-producing activities, especially in sports.
Running, jumping vertically, and jumping horizontally are all lower-extremity movements critical to sports that rely on the stretch-shortening cycle for maximum force output. Similarly, the acquired momentum of a pitcher’s shoulder stretch, a golfer’s back swing, and a batter’s wind-up all rapidly stretch the eccentrically active involved muscles and then release the stored energy in conjunction with concentric force to maximize resultant effect on ball velocity. Less obvious is the muscle stretching that occurs at the start of a sprint or a standing jump, where the effort against the inertia of the body causes the muscles to stretch slightly before propelling the body forward or upward. This exploitation of the stretch-shortening cycle is critical to virtually every land-based athletic activity.
The key question for athletic performance is whether the valuable properties of the stretch-shortening cycle can be improved through enhanced eccentric resistance training. This question was first addressed by Lindstedt in 2001. Eight weeks of eccentric overload training resulted in a stiffening of the “muscle spring.” He concluded that “not only did eccentric training result in an apparent protection from muscle damage (which would have been severe in naïve subjects exercising at this high intensity), but, significantly, there was a shift in the muscles’ fundamental spring property.”
The increase in the stretch-shortening cycle through accentuated eccentric training was further noted in a review by Douglas in 2017 that concluded, “Eccentric training is a potent stimulus for enhancements in muscle mechanical function, and muscle-tendon unit… architectural adaptations.”
Eccentrics and Muscle Hypertrophy
There is yet another underappreciated role of eccentrics in musculoskeletal health, but it does not involve locomotion. Eccentric muscle actions are the unique source of the signal for mechanotransduction. All musculoskeletal tissues structurally respond to the forces they encounter, either through hypertrophy from high external loading or atrophy in the absence of it. The threshold to create structural adaptation depends on the duration, magnitude, and rate of loading.This was demonstrated in tissue preparations that, when stimulated with concentric muscle force, did not result in high levels of protein synthesis. Only after eccentric activation of muscles did the cascade of protein synthesis occur. It was assessed that tissue deformation is required for significant structural adaptation (Burkholder, 2007).
It is well recognized that mechanical force affects the muscle itself. Increased protein synthesis in muscle occurs not only in the normal maintenance of muscular tissue but also in response to the challenge of supramaximal loads. There are force-sensing structures in the sarcolemma of the muscle cells that can detect the deformation of the cell wall. When triggered, they initiate a cascade of messaging signals that increase the synthesis of contractile proteins.
In the maintenance of muscular tissue, there is a constant balance between muscle protein synthesis and degradation. This represents the normal homeostasis of muscle, and the application of force plays a key role. Too little mechanical stimulation, and the balance tilts toward breakdown of contractile proteins, while increased stimulation leads to its accumulation. In homeostatic control, there is an upper limit of muscle size that can be reached that is basically that individual’s genetically determined muscular size.
As shown in an earlier section, eccentric loading can introduce a superphysiologic signal that invokes a different adaptation process: repair and regeneration. At higher eccentric loads, physical disruption of the muscle fibers can occur and and create areas of micro-injury. Injury is the stimulus for the repair and regeneration processes to proceed. In the muscle, which has innumerable stem cells (satellite cells), this injury stimulates the formation of not only additional myofilaments that increase the force production of the affected muscle but also reconstruction of the cytoskeleton for increased muscle size.
The classic “delayed onset muscular soreness” associated with eccentric loading is directly related to the inflammatory phase of this response. Once inflammation subsides, the process of structural repair can begin, with stem cell migration and protein synthesis. The stem cells provide the substrate required to rebuild and renovate musculoskeletal tissue. The higher the eccentric load applied, the longer the recovery period. The minimum recovery period should be no less than 3-4 days for lighter eccentric loads that approximate the 1RM. For eccentric loading of 50%–80% above the 1RM, recovery can take up to seven days and can be as long as two weeks.
The unique ability of eccentric overloads to create hypertrophy and strength gains was demonstrated in the Lindstedt eccentric studies where “following 8 weeks of training, both muscle strength and cross-sectional area (of biopsied muscle fibers) increased by ~40%.” Subsequent reviews by De Souza Teixeira and the 2017 review by Douglas all reported improved strength gains with eccentric resistance exercise.
Considerations of Eccentric Resistance Application
Thus, in the past few sections, it has been demonstrated how supramaximal eccentric loading is an essential stimulus to increase muscle hypertrophy and improve the elastic behavior of the stretch-shortening cycle. Eccentric training can clearly be beneficial for athletic performance; however, there are practical obstacles to pursuing this course of treatment.
There are three requirements for safe and effective eccentric overload training:
- The first and most important is that you must never apply a load at such a magnitude or at such a velocity that it could result in physical disruption of the muscle itself.
- In the goal of structural adaption, you should be able to increase the resistance you apply in incremental amounts over an appropriate period of time.
- The concentric and eccentric actions are synergistic, and their resistance training should ideally be done concomitantly.
To apply the load safely, as stated in the first requirement, there are two types of external resistance that are not optimal. One is force through a motorized resistance arm that is insensitive to the user’s effort. In this application, a motor pushes a platform, and a subject exerts maximum force against the motor-driven movement arm while the user’s effort is recorded on a force plate. In this closed system, the velocity of the movement arm is fixed and unaffected by the user’s efforts, and the amount of force that the movement arm exerts against the user is essentially infinite, in that no matter how hard the user resists the movement arm, it will continue to apply a high level of force.
There is only one uncontrolled variable in this scenario: the tension in the user’s muscle. As the muscle is forced to lengthen, the internal muscle tension goes higher and higher. In this situation, there is no external control to prevent the tension from exceeding the integrity of the muscle tissue, and unintended overloads can occur.
In addition to high force risk, motorized resistance cannot be increased in incremental amounts, violating the second principle. The basic premise of resistance training in general is the biologic principle of “stimulus response.” The external force stimulates a reponse in the muscle it acts upon. For the adaptation to occur, there must be a period of time for the biologic process to take place. After this recovery period and once the adaptation has occurred, the original stimulus is insufficient to create further adaptation. At this point, the original level of external force is inadequate to cause further structural adaptation. This is the basis of the principle of “Progressive Resistance Exercise” (PRE). It is just as important to apply the principle of PRE to the eccentric phase as it is to the concentric phase.
High-velocity lifting movements pose different risks when the weight is moving concentrically versus eccentrically. When a lifter applies force to a weight concentrically, the energy is transferred into weight, which increases its momentum. Since the weight is moving ahead of the lifter, the increased momentum of the weight does not pose a direct danger. More exertion by the lifter merely accelerates the weight.
The greatest risk of injury is during the lift’s eccentric phase, when the direction of the weight’s movement is against the direction of applied force. In this situation, not only does the lifter have to brake the force of the weight itself but also the additional force created by the weight’s kinetic energy. The formula for the kinetic energy of a mass is:
Kinetic Energy = ½ mass x velocity^2 (velocity squared)
Therefore, a weight traveling at high velocities against the direction of applied force has the potential of delivering many multiples of its resting weight to the eccentrically lengthening muscle. Since the goal of supramaximal eccentric strength training is to deliver a precise amount of force to the elastic zone of muscle lengthening, an uncontrolled speed of descent could easily result in overshooting this desired amount of force, thus risking injury. An example of this is the bench press movement, where the weight is resisted after being allowed to drop suddenly, and the lifter suffers a pectoralis muscle tear at the bottom of the movement (Provencher MT, 2010).
The other less-than-ideal method of eccentric loading is plyometrics with added resistance, such as jump squats. Similar to high-velocity weight lifting, the concentric, or jumping up, portion does not necessarily involve potential danger other than the risk of falling. However, if the landing is done with added resistance, the added kinetic energy of the additional weight can significantly increase the forces absorbed on landing, again risking injury. Additionally, plyometric loading lacks the ability to increase the resistance in accurate incremental amounts that adhere to the principle of progressive resistance exercise.Simultaneous training of concentric and eccentric muscle function is the most efficient and effective method to increase muscular strength. Click To Tweet
As stated previously, there is a synergy between the concentric and eccentric actions in real-world activities. During the stretch-shortening cycle, both muscle functions are literally on the same molecular framework and work in conjunction with each other. It would therefore be maximally beneficial to perform both concentric and eccentric training in the same movement. This means that an ideal repetition for effective strength training involves a concentric component that is 50%–80% of the 1RM, which then converts to an eccentric resistance that is at least equal to the 1RM. Simultaneous training of concentric and eccentric muscle function is the most efficient and effective method to increase muscular strength.
Considerations of Movements for Eccentric Overloads
Finally, there are clearly some exercise movements that are safer for applying eccentric overloads than others. The danger arises if, during supramaximal loading, the lowering movement pathway is forced to deviate from the track of the concentric movement. The pathway of the movement should be the same for the lighter concentric resistance as for the the heavier eccentric loads.
Virtually all selectorized, single-station machines avoid this risk. The trunk is stabilized in a seat, and the limbs are held in position by pads. The track of motion for the concentric raising of a weight is the same track as for the lowering of the heavier eccentric weight. This consistent positioning ensures that, over a training program with increasing weights, the muscle can adapt and strengthen in a progressive, consistent manner.
There are some free weight exercises that are not ideal for eccentric loading. Clearly, unilateral movements are difficult because the added weight can disrupt the lifter’s balance. There are technical aspects of applying eccentric overloads with dumbbells in general, which make them less effective. Obviously, Olympic lifts with their complex movement patterns are impractical, and eccentrics offer no advantages to improve the performance.
Finally, there could be concerns with the performance of front squats. If it is difficult for an individual to maintain the front squat position, where the line of gravitational pull goes vertically from the barbell through the heels on the ground, the barbell could move in front of this vertical line and create a bending force across the lumbar spine. Accentuated eccentric resistance for front squats should be reserved for lifters experienced with this movement.
However, the majority of basic barbell movements could incorporate accentuated eccentric loading. The basic principle is to place the point of application of the barbell along the gravitational line down to where the body is supported (figure 7). The nature of free weight exercises is such that it is difficult to perform the exercise unless this line is carefully followed.
Of course, in the bench press, the vertical line drops through the shoulders onto the bench. Therefore, most barbell movements can be performed with eccentric overloads (if the safety principles above are followed). Some care is needed with the deadlift as it is sometimes necessary to translate the bar anteriorly to avoid the knees.
Application of Enhanced Eccentric Resistance Training to the Barbell Squat
Training the eccentric portion of the squat is extremely important for absorbing high forces and preventing injury when someone jumps from a height or is placed under a heavy load. In addition, improvements of the stretch-shortening cycle in eccentric squats can result in improvements in the speed and power of most athletic activities. The squat is widely considered to be the single most important movement to train.
The hamstring muscle group plays a major role in the squat’s eccentric movement. By attaching to the ischium, the hamstrings have a long lever arm to exert an effect on hip joint movement. In the case of going deeper into the squat position, the ischium rotates further and further posteriorly, thus effectively lengthening the hamstring muscles. In order to control the deepness of the body’s descent, the hamstrings eccentrically resist lengthening and therefore resist the flexion of the hip joint. The primary role of the hamstrings is not to contract and create hip extension (that’s the job of the gluteus maximus) but to resist and control hip flexion.
A recent issue of the Journal of Functional Morphology and Kinesiology (volume 4/2, 2019) focused on the mechanisms of eccentric muscle exercise adaptations and the emerging applications of this unique form of exercise. In this compilation, accentuated eccentric loading (AEL) was described as an attractive strategy for applying additional stress to the muscle while maintaining the concentric stimulus. The review (Suchomel TJ, 2019) accurately found a paucity of literature on this form of training. In fact, the absence of literature speaks directly to the problem that, until very recently, there was no training equipment developed to provide this important form of resistance.The absence of literature on accentuated eccentric loading (AEL) speaks directly to the problem that, until recently, there are no training equipment developed to provide this form of resistance. Click To Tweet
In this section, AEL will be described as it is performed on this new technology. The Myonics system (Myonics LLC, Jacksonville, Florida) employs an assistance cable that is attached to the barbell. The cable rises from a new generation of computer-controlled, motion-sensitive motors that can track the movements of the barbell and hence the lifter. The motors can detect if the lifter is moving up or down and are programmed to provide a precise amount of assistance when the lifter reaches certain positions.
In the above scenario, the lifter loads the bar with 250 pounds and then unracks it, and the 250 pounds is lowered in the eccentric phase. Upon stopping at the bottom, the assistance engages, and the effective weight of the bar is only 200 pounds. This weight is raised with concentric strength back to the top position, where the assistance is removed, and the lifter again is supporting the full 250 pounds. Again, this sequence can be repeated for as many repetitions as can be performed.
It is generally recognized that the squat is the single most important exercise to improve overall athletic performance. Combining the muscles of knee, hip, and spine extension, it has functional significance in all land-based athletic activities. As was shown in an earlier section, there are many athletic functions that can be improved by enhancing the stretch-shortening cycle of the lower extremities. Thus, training to improve the eccentric capabilities of the squat will bring additional benefits to athletes.
The implementation of this form of resistance involves many related variables that can complicate the decision-making. These include the amount of eccentric overload resistance, the amount of concentric resistance, the percent difference between the concentric and eccentric loads, and the pace of each movement. Having worked with this system for a number of years, I have arrived at the most practical system for managing these variables.
The system works by using a predetermined percentage difference between the eccentric and concentrics weights. In this way, only the heavier eccentric weight would be entered, and the concentric weight would be calculated by the motor’s computer. For example, after warm-up, a lifter whose estimated or tested 1RM is 500 pounds would have this amount loaded on the bar.
With 500 pounds on the bar, this number is entered into a computerized assistance program. If the program calls for a 25% difference between the eccentric weight and the concentric weight, the motor would supply 125 pounds of assistance. Thus, the lifter would lower 500 pounds, and upon reaching the bottom of the lift, the stopping point is detected and 125 pounds of assistance is generated. The lifter therefore only has to exert 375 pounds of force to return the bar back to the starting position. Once the target number of repetitions is achieved, the strategy is to simply increase the eccentric weight loaded onto the bar and maintain the percentage difference between the eccentric and concentric weights. In the example above, if the eccentric weight was raised to 520 pounds and the 25% difference was maintained (130 pounds), the lifter would raise 390 pounds concentrically.The Myonics system follows the three requirements of accentuated eccentric resistance; it improves the squat by accentuating the eccentric muscle function. Click To Tweet
This system follows the the three requirements of accentuated eccentric resistance. First, the amount of weight applied eccentrically never exceeds the eccentric maximum, and the risk of injury is minmized. Second, once the desired training effect is reached, the weight can be incrementally increased for the athlete to continue training under progressively increasing resistances. And finally, this system allows for an appropriate resistance to be used for both the concentric and eccentric weights, and they can be trained concomitantly.
Thus, the most important exercise for improving athletic performance can itself be improved by accentuating the eccentric muscle function. Through this training method, athletes can achieve further improvements in sports and athletics.
Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF
Nishikawa KC, Monroy JA, Uyeno TE, Yeo SH, Pai DK, and Lindstedt SL. “Is titin a ‘winding filament’? A new twist on muscle contraction.” Proceedings of the Royal Society B: Biological Sciences. 2012;279(1730):981–990.
Lindstedt JL, LaStayo PC, and Reich TE. “When active muscles lengthen: properties and consequences of eccentric contractions.” News in Physiological Sciences. 2001 Dec;16:256–261.
Douglas J, Pearson S, Ross A, and McGuigan M. “Chronic Adaptations to Eccentric Training: A Systematic Review.” Sports Medicine. 2017;47(5):917–941.
Burkholder TJ, “Mechanotransduction in Skeletal Muscle.” Frontiers in Bioscience. 2007;12:174–191.
De Souza Teixeira F. “Eccentric Resistance Training and Muscle Hypertrophy.” Journal of Sports Medicine & Doping Studies. 2012;S1(01).
Provencher MT, Handfeld K, Boniquit NT, Reiff SN, Sekiya JK, and Romeo AA. “Injuries to the Pectoralis Major Muscle: Diagnosis and Management.” American Journal of Sports Medicine. 2010;38(8):1693–1705.
Suchomel TJ, Wagle JP, Douglas J, et al. “Implementing Eccentric Resistance Training—Part 1: A Brief Review of Existing Methods.” Journal of Functional Morphology and Kinesiology. 2019;4(2):38.