Function doesn’t occur from a static position. A combination of joint motions creates “opposite” movement that helps us achieve the action we set out to do. It might seem like we don’t need these extra movements, but this opposite movement is a critical component of successful function.

The “opposite” movement lengthens and “loads” the muscles, getting them ready to complete the action and then transforming the energy into movement. We load to explode. To jump up, we go down. To throw forward, we reach back.

How Our Muscles Work During Load to Explode

Our muscles behave differently during different stages in the load to explode process. For example, the same muscles that lengthen during the “load” shorten during the “explode;” eccentric muscle activity decelerates the loading motions.

During this deceleration, our muscles store the loaded energy. The stored energy then transforms the eccentric into a concentric acceleration of the joints, producing the desired movement.

What’s the Difference Between Concentric and Eccentric Movement?

Concentric and eccentric movements are commonly understood as opposites. Concentric movement occurs when the muscle contracts and shortens, like when you do a bicep curl. During eccentric movements, the muscles lengthen. This usually happens when you’re returning a weight to its starting position, like lowering a biceps curl.

In certain movements, muscles lengthen in all three planes during the load phase, followed by a shortening in each of the three planes of motion during the explode phase.

Functional Movements Create Complex Muscle Actions in Multiple Joints at Once

During the loading movement, individual muscles may lengthen or shorten in one or two planes simultaneously; it’s extremely common for muscles that cross more than one joint to shorten at one joint while lengthening at another.

At Gray Institute®, this functional type of muscle contraction during a load to explode is called econcentric—eccentric and concentric at the same time. We describe the muscle function as an econcentric load transformed into an econcentric explode.

The Advantages to Econcentric Movement

Despite what conventional education may teach, these econcentric actions are common, and they offer a physiological and mechanical advantages.

A great example of the mechanical advantage is when the subtalar joint tries to supinate and invert to lock up the foot for propulsion. From the everted position, the tibialis posterior, soleus, and gastrocnemius create an explode. Lifting the arch against gravity requires a lot of force from the leg muscles, the same muscles are being lengthened by the ankle dorsiflexion. This lengthening in the sagittal plane creates the power to assist the shortening in the frontal and transverse planes.

Econcentrics at work, once again.

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Econcentrics Aren’t Limited to Multi-Joint Muscles

Econcentric movement can occur in many different places in the body, depending on the type of movement.

Let’s look at the gluteus maximus for an example. The gluteus maximus’ load and explode can be eccentric and concentric for some functional activities. For instance, if hip flexion is combined with abduction or external rotation, then the gluteus maximus lengthens in the sagittal plane and shortens in one of the other planes.

The movement you want to do dictates the combination of lengthening and shortening muscles. Our job as movement practitioners is to create movements and tasks that help our patients and clients achieve a better explode, starting with a better load.

Why Understanding Complex, Functional Movement Matters

As movement professionals, we need to understand how the body truly moves—in reality, not just theory—to truly empower our patients and clients to achieve their goals. For over 40 years, Gray Institute has led the movement industry in Applied Functional Science®. We equip passionate physical therapists, personal trainers, strength and conditioning coaches, and others with the tools they need to understand the truth of human movement and to give the people they work with the best possible outcome.

Enhance Your Movement Education With Gray Institute

If you’re ready to go deeper in your movement education, we discuss the topics covered in this article in-depth in our cornerstone course, 3D Movement Analysis and Performance System (3DMAPS®). To learn more about 3DMAPS, Applied Functional Science, or how we can help you reach your goals, please don’t hesitate to reach out.