Even the best coaches and athletes often make a mistake when doing eccentric training. Eccentric training is not the same as “focusing on the eccentric phase” or “increasing the time of the eccentric phase by slow movements”.
Let’s start with the basics.
Concentric vs Isometric vs Eccentric
Concentric muscle movement
Maybe you’ve heard about the three different muscle movements: concentric, isometric and eccentric. Although this idea works for every muscle and exercise, let’s look at a bicep dumbbell curl to train the bicep muscle.
When training the biceps with a bicep curl, you tend to think of lifting a weight. In this case, lifting a weight against gravity is called a concentric muscle movement. Also called the upward phase. Your muscle shortens its length and accelerates a weight towards the ceiling. As an example, your maximal weight (1RM) could be 15 kg.
Isometric muscle movement
The second type of muscle “movement” is no movement or isometric movement. During the bicep curl, you could keep your elbow statically in a 90 degree angle and stop moving the weight. Your muscle would not shorten or lengthen. Your trainer could handle you a weight that you could keep still in this position for a short period. The maximal weight would be a bit higher than the 15 kg in your previous concentric muscle movement. Let’s say 17,5 kg. In other words, you are a bit stronger when you don’t need to move the weight upward.
Eccentric muscle movement
The third movement is the opposite of the concentric movement. You don’t lift the weight towards the ceiling, but instead lower the weight to the starting position. Also the downward phase. This movement is called an eccentric muscle movement. Your muscle will lengthen with the aim of slowing down the drop due to gravity.
You are much stronger in the eccentric downward movement then in the concentric upward movement. In our example, when your maximal lifting weight is 15 kg, you are probable also able to lower 20 kg in a controlled manner. Try it if you don’t believe me! The difference can be about 25-30%. Without diving into the details, you could say it is therefore easier to train with heavy weights in the eccentric movement than in the concentric movement. Because heavier weights will cause more muscle damage in eccentric movements, it could also lead to more and faster training progress.
What happens in the muscle during eccentric training
During an eccentric movement, you lengthen your muscle and lower the weight. While you control the weight’s descent, your muscle generates force and remains under tension.
Remember the actin and myosin components in your muscle? Actin is like a long thin rope attached to one end of your muscle. Myosin is similar to a pair of strong hands, attached to the other end of your muscle. During a concentric muscle contraction, the myosin hands grab onto the actin rope and start pulling, like a tug-of-war game. As a result, your muscles shorten.
During an eccentric movement, actin and myosin at first hold on to each other like stretching a rubber band. This stretch is an additional trigger for adaptation. Titin, a muscle protein, plays an important role in the muscle stretch.
You’ve also probably heard that you can’t produce as much force during a concentric movement compared to an eccentric movement. Although the exact reason may not be fully understood yet, it’s not hard to imagine why this could be the case. When you’re in a tug-of-war game, bringing the rope in requires you to “cycle” your hands: you need to let go one hand (myosin) before you can attach it further down the rope (actin). In muscle terms, this actin-myosin cycling is called a cross-bridge cycle. This cross-bridge cycle happens during concentric movements.
During a concentric movement, when you only have one hand attached to the rope, you can’t produce as much force as when you have both hands attached to the rope. As a result, you’re temporarily less strong. The faster you need to bring in the rope, the more often you only have one hand attached to the rope, the less force you can produce. This is what the force-velocity curve is about: the faster you move concentrically, the less strong you are.
During an eccentric movement, more hands are attached to the rope and you can produce more force. In fact, the faster your eccentric movement, the more force you can produce.
So far the muscle theory, here’s where it goes wrong in practice..
Eccentric training misunderstood
Eccentric training is often misunderstood. Eccentric training is not the same as “focusing on the eccentric phase” or “increasing the time of the eccentric phase by slow movements”. Since you are much stronger in an eccentric movement, only focusing on the eccentric phase or increasing the time of the eccentric phase does not create an eccentric training stimulus. Eccentric training should by definition be performed with weights that are close to or above the maximal concentric lifting weight (1RM). And that’s when a practical problem appears. Because if your can’t lift the weight, then how on earth can you lower it?
Technology comes in handy. Although technology might be a big worth for a yo-yo. I am indeed talking about that yo-yo you used to play with as a child. Kynett made a yo-yo for grown-ups that want to do real eccentric training. Place the yo-yo to a wall, tree or anchor it to the ground and start pulling the cord.
When you pull out the cord, the flywheel starts rotating. Ones you pulled the cord out fully, the flywheel will have speed, kinetic energy. This energy will keep the flywheel spinning and will therefore start pulling the cord back, just like your yo-yo does. The harder you pull, the harder the flywheel will pull back after the cord is fully unwind. It is now your job to resist the pull back of the flywheel by doing an eccentric movement.
The smart reader will now say that it is impossible to create an eccentric overload since the energy of your concentric pull is equal to the energy of your eccentric pull. Overall that is true. But by resisting only slightly in the first part of the eccentric movement, you can absorb all the energy over a smaller period of time. Therefore the peak force in the latter part of the eccentric movement of the exercise is much higher than the energy created in the concentric movement. This results in eccentric training as it should be. Here are 4 other ways to create eccentric overload in flywheel training:
For those of you who do not want to invest in a yo-yo, there are 2 other options.
- Invest in two personal coaches that can lift a weight so you can lower it.
- Use your whole body to lift a weight. Then only use a specific muscle to lower it. For instance: lift a dumbbell via a “clean” (exercise) with your legs to shoulder height. Then do the eccentric phase of a dumbbell curl with only your biceps.
Would you like to know more about flywheel training? Read all flywheeltraining articles!
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Founder of Molab, Human Movement Scientist and Freelance Content Marketer.