What do you think you are achieving by “focusing on the eccentric phase”?
Everywhere you look now in the fitness industry, people are talking about eccentric training, and the benefits of the eccentric (lowering) phase of the movement.
But although we are saying the same words, we are not speaking the same language.
When researchers talk about eccentric training, they mean either eccentric-only strength training, or eccentric overload strength training. This means lowering a weight that it too heavy to lift.
In contrast, a lot of strength coaches, personal trainers, and fitness enthusiasts think it means “focusing” on the eccentric phase or “increasing the duration” of the eccentric phase.
Let me explain why these things are totally different when it comes to programming for strength gains.
What are eccentric-only and eccentric overload training?
Eccentric-only training is a type of strength training in which we just use the lowering phase of the exercise.
Eccentric overload training is a type of strength training in which we use both the lifting and lowering phases of an exercise, but we add load (hence the term “overload”) to the lowering phase, either with weight releasers or flywheel devices.
Weight releasers are devices that fit over a barbell, that can be loaded with extra weight.
We attach weight releasers while in the top position, before starting the descent. When we reach the bottom of the lift (after the lowering phase), they detach, and we can return to the top position, lifting a lighter load. Spotters can then reattach the weight releasers on either side, and we can start the cycle again.
Flywheels use a rotating flywheel to provide resistance to movement.
In the lifting phase, we pull on a cord that is attached to the flywheel, which begins to rotate, and stores rotational kinetic energy. Once the lifting phase is complete, we stop, and the cord is pulled back into the flywheel mechanism, until the stored energy is dissipated. By resisting only slightly in the first part of the movement, we can absorb all that energy over a smaller period of time, which makes the peak force in the latter part of the lowering phase of the exercise much higher than in the lifting phase.
Ultimately, both eccentric-only and eccentric overload strength training achieve the same thing, which is to allow a heavier load (or a greater force) in the lowering phase than we would otherwise be able to experience during normal strength training.
But how is it possible for us to lower a heavier weight than we can lift?
How is it possible to use a heavier load in the eccentric phase?
In normal strength training, when we lift 85% of our one repetition-maximum (1RM), that weight “magically” becomes approximately 65% of our eccentric-only 1RM, when we come to lower it.
This is because when we lower a weight under control, the maximum weight (1RM) we can use is approximately 25–30% larger than the heaviest weight we can lift.
In contrast, during either eccentric-only or eccentric overload training, if we use weights in the lowering phase that are 85% of our eccentric-only 1RM, then that weight would correspond to approximately 110% of our 1RM for the lifting phase, if we tried to lift it.
Why are we so much stronger in the eccentric (lowering) phase?
Well, we can lower a heavier weight than we can lift primarily because of the behavior of the giant molecule titin.
During muscle lengthening, titin attaches itself to the actin and myosin myofilaments once a muscle fiber is activated. Once attached, it then resists lengthening like a giant spring uncoiling. Titin does not play the same role when the muscle is shortening, so our ability to produce force is enhanced during eccentric contractions.
But why is using an extraordinarily heavy load so important when writing programs to increase maximum strength?
Why is adding extra load in the eccentric phase so important?
The magnitude of the external weight or force that we use during strength training, along with the speed that we move, determines the tensile force on the muscle-tendon unit.
This tensile force on the muscle-tendon unit has a *different effect* from the mechanical loading that we can subject individual muscle fibers to, by activating them, which is likely a key part of the signaling process that leads to hypertrophy.
This tensile force on the muscle-tendon unit likely produces many of the following adaptations that can increase maximum strength, including:
- Increased tendon stiffness
- Increases in the amount of lateral force transmission inside the muscle, by an increase in the number of costameres linking the fiber to its surrounding collagen layer
- Increases in the activation of the prime mover muscles
- Increases in load-specific coordination
These are all factors that can enhance maximum strength, even without increasing muscular size, and most of them are increased in proportion to the *size of the external force or weight* applied to the muscle (and not the number of active motor units).
Why does “focusing on the eccentric phase” or increasing the length of the eccentric phase not achieve the same thing?
“Focusing on the eccentric phase” means consciously contracting a muscle while lowering the weight (with the mind-muscle connection) during normal strength training. This likely increases muscle activation, but does not alter the external force.
“Increasing the length of the eccentric phase” means taking longer to lower the weight during normal strength training. This increases external force slightly, compared with allowing the weight to drop quickly back to the start, because it involves a smaller downward acceleration and this allows gravity to do its job on the weight more effectively.
Yet, no matter how hard we focus, and no matter how long we draw this eccentric phase out, it is *literally impossible* in this universe for an external force in the eccentric phase (and the tensile force on the whole muscle-tendon unit) to ever be greater than the external force in a concentric phase.
If we did produce a greater force, then we would immediately stop lowering the barbell, and start lifting it again!
Therefore, neither “focusing on the eccentric” nor “increasing the length of the eccentric phase” can produce the extraordinarily large gains in maximum strength that we see after eccentric-only or eccentric overload training, because they are not exposing the whole muscle to enough force.
What is the takeway?
Eccentric-only and eccentric overload training both refer to using an extremely large weight or force in the lowering (eccentric) phase of a strength training exercise, such that this weight or force could not be lifted or produced in normal strength training.
By placing an unusually high amount of tensile force on the whole muscle-tendon unit, these types of training create adaptations that lead to superior gains in maximum strength, which has great advantages for athletes.
In contrast, “focusing” on the eccentric phase, or “increasing the duration of the eccentric phase” during normal strength training do *not* involve these super-heavy loads that cause the adaptations leading to greater-than-normal gains in maximum strength.