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What are eccentrics and why do they matter?

Updated: Aug 24, 2022

When performing any type of strength training or power producing exercise, there are two main phases to the movement.

The CONCENTRIC phase and the ECCENTRIC phase.

The concentric phase is the part of the exercise in which the targeted muscle is shortening. Such as the “up” phase of a push up or pull up.

The eccentric phase occurs when the targeted muscles are lengthening while under staying under control. Such as when lower your butt to the floor during a squat or lunge.

Research shows we not only gain more strength and hypertrophy (size) during the eccentric phase but focusing on this phase also leads to reduced injury in sport amongst other benefits.

Benefits of Eccentric Strengthening

Faster Muscle Gains

As we discussed, during the eccentric phase, the muscle is lengthening while controlling the resistance. When lowering the dumbbell during a bicep curl, the bicep and brachialis muscles are lengthening or “stretching”. During this time is when the bicep and brachialis have the greatest force production. The rate at which protein molecules, known as actin and myosin, detach from one another is greatly inhibited during the eccentric phase compared to the concentric phase. This leads to a great amount of force production resulting in increased strength and size of the muscle overtime.

Increased Calorie Burning

Eccentric strengthening is also known to boost metabolism leading to a greater caloric deficit during your workouts – hence why strength training can be just as effective if not more so at losing weight compared to general cardio-type exercises. Studies show that slowing down the eccentric phase of your exercise can significantly increase your resting metabolic rate. So even when at rest or sleeping, your eccentric workouts are still helping you achieve your weight loss goals.

Increased Flexibility

There’s a popular saying going around the fitness world lately – that phrase is “strengthen to lengthen”. This is referring to using eccentric exercise to help increase flexibility as opposed to prolonged, static stretching. Studies have shown that individuals who focus on slow, eccentric hamstring curls increase flexibility twice as much as those who focused on static hamstring stretches. But you must work through the entire range of motion you have available and work into the feeling of a stretch at the end of the eccentric phase. Overtime not only will the muscle lengthen, but you will also have increase strength at your end ranges which leads nicely into our next benefit of eccentric strengthening: injury reduction.

Injury Reduction

Many injuries in sport are known as “deceleration injuries” and occur when trying to slow down a movement and change direction. This is true of non-contact ACL injuries commonly occurring during cutting and landing or the fact that many arm injuries in baseball and other overhead sports occur after the ball is released when the body is slowing down the arm. Working eccentrically in the gym helps to prepare you to better absorb these loads safely. Additionally, eccentric strengthening has also shown to enhance the durability of other connective tissues throughout the joints, not just the muscles and tendons which again leads to reduced injury on the field.

One thing to keep in mind…

Eccentric exercises also lead to increased muscle soreness (Delayed Onset Muscle Soreness) compared to concentric focused lifting. As discussed previously, during the eccentric phase there is greater force production leading to greater microscopic muscle damage. Keep this in mind if training in-season, but understand that during off-season training, this type of muscle soreness is highly desirable. It only means you’re getting stronger!

If you’re not focusing on eccentric strengthening as part of your fitness routine, you don’t really have a good, comprehensive fitness routine! Start slowly down the eccentric phases of all your strength training exercises immediately! Good luck!

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