Does lowering the weight slowly focus on eccentric strength?

First, does specific eccentric strength even exist? We classify muscle contractions as eccentric, isometric, and concentric. But physiologically is there any difference? All muscle contraction is produced by the same biochemical sequence stimulating the same protein molecules to change shape. Is it possible to specifically develop eccentric strength more than concentric? The only specific component to eccentric strength is the stretch reflex.

That being said, people have done research in which a particular training program developed eccentric strength to a greater degree than concentric. How does that happen? Let’s talk about two adaptations that tend to show up in response to eccentric training. Looking at passive, non-contractile muscle components, there is surrounding connective tissue as well as a framework of protein on which the contractile components are anchored. These structures are strengthened most in response to generating high tension. This occurs when they are lengthened under heavy load, which occurs during proper eccentric training. Looking at the active, contractile components, we see in research that more sarcomeres are added to muscle fibers in response to high-effort, lengthened, eccentric muscle contractions. (Sarcomeres are the contractile units of muscle fibers. They’re arranged like links in a chain. But having more sarcomeres is not just like having a longer chain. It makes the muscle fiber stronger and more powerful.) So we see adaptations to eccentric training that do not show up to the same degree in response to concentric training. So eccentric and concentric strength are specific, right? Not exactly.

sarcomere

Those adaptations are not a response to just eccentric muscle contraction, but a response to extremely high muscular force. Eccentric contraction is just one of the requirements for maximizing muscular force. The muscle must be lengthened, there must be adequate time to build up tension, and there must be a high contractile effort which is overcome by the load. So take jogging for example. Every time your foot hits the ground, your quadriceps perform an eccentric muscle contraction. Does that mean you get all the specific adaptations to eccentric training by jogging? No, because those adaptations are not specific to eccentric training. They’re specific to extremely high muscle tension, which does not occur in the quads while jogging.

Eccentric and concentric are not the right categories for classifying strength. Instead think of neurological and structural strength. Structural strength increases in response to extremely high muscle tension. Neurological strength develops in response to sustaining high neural drive. These can be trained together or somewhat separately. For example, let’s talk about a box squat in comparison to a regular deep squat. In the box squat, less depth means the glutes and quads are not lengthened as much. Also because of sitting onto the box, you don’t have to stop the weight. This takes away the high effort eccentric contraction. Because of those two factors, the muscle tension produced in a box squat is not as high, so it is not much of a structural strength stimulus. But if the weight is heavy, you still have to push really hard for a relatively long period of time, which means it trains neurological strength. In a deep squat, the target muscles are thoroughly lengthened, and there is high effort eccentric contraction used to stop the weight at the bottom. This evokes high muscle tension and makes the deep squat a strong structural strength stimulus. Of course this depends on the execution of the movement. If you lower slowly and pause at the bottom, or if you bounce off your calves, you take away from the muscular force peak at the bottom. Now you should definitely train neurological strength with deep squats too, but it’s possible to focus on structural by using light weight and only putting max effort into the bottom of the movement. Again, the way the squat is executed makes a big difference.

Back to our original question. Does lowering the weight slowly focus on eccentric strength? No, quite the opposite. Yes, it means you spend more time in eccentric contraction, but it is not particularly high tension due to the low effort level. People tend to misunderstand the force velocity curve of muscle. That curve reflects the maximum possible tension at a given velocity. It does not reflect all muscle contractions at a given velocity. Not all eccentric contraction is high force. Lowering the weight slowly is actually a way to avoid high muscle tension and not develop structural strength.

The highest muscle tension is produced when a muscle is elongated, contracting with maximum effort level, and lengthening because the opposing force is overcoming the muscle contraction. This can be achieved using negatives with supramaximal weight, but that’s not the only way to do it. You really just need to use a natural lifting tempo, which involves letting the weight gain some momentum on the way down. Then toward the bottom when you turn on your maximum effort level, the process of stopping the weight is when you get the perfect scenario for high muscle tension. You don’t have to do anything fancy to get high eccentric tension. Just get good enough at your lifts to lower the weight with decent speed. Don’t think of this as specifically targeting eccentric strength. Think of it as the best way to get structural strength.

For some supporting physiology on this topic, see the video series on muscle tension.