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Concentric vs Eccentric: How Do They Affect Your Squats?

Jul 01, 2018

CoDark Iron Fitness Weightlifting Beltncentric vs Eccentric — how do they affect your squats?

Eccentric and Concentric are two words that people often mix up.

Both terms relate to the contractions of the muscle we use in bodybuilding and weightlifting.

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In general, the eccentric phase occurs when the muscle lengthens in a downward movement.

This happens in exercises where the muscle stretches under a load.

Types of Muscle Contractions

The concentric phase occurs when the muscle shortens in an upward movement.

Think of exercises where the muscle contracts under a load.

They are both types of isotonic contraction.

Isotonic contraction occurs when your muscles change length and produce the force necessary to move the joints in your body.

Related: Isotonic Vs. Isometric Contraction

 

Concentric vs Eccentric: Muscles Involved in Squatting

When broken down into its components, the squat motion is very complex.

Awareness of both the eccentric and concentric movements involved will help you recognize the multiple muscles that are strengthened.

Many large and small muscles of the lower body are involved during both the upward and downward phases of a squat.

Active muscles include the quadriceps, hamstrings, gluteus maximus, gastrocnemius and soleus muscles of the calf.

The posterior tibialis of the lower leg and foot and many smaller muscles in the foot and ankle also come into play.

Because so many muscles are involved in a single exercise that is functional for daily living, the squat is one of the best exercises for improving your quality of life.

Understanding the complex and coordinated muscle actions involved in squatting will help you maximize the benefits of your training and minimize the risk of injury.

Related: Benefits of Heavy Squats and The Other Effects They Have

 

Concentric vs Eccentric: Eccentric Phase of a Squat

An eccentric motion is when a muscle is lengthened during contraction.

When you squat, the eccentric movement happens during the downward phase of the squat motion as you slowly lower your body.

Hands Lowering Rope

During that phase, the muscles in the legs are lengthening to keep the pace of descent slow and controlled.

Think of lowering a bucket on a rope through a pulley.

If you let go of the rope, the bucket will fall to the ground.

But as the rope is slowly released to control the bucket’s fall, this is what your muscles are doing in the eccentric phase of a squat.

 

Concentric vs Eccentric: Concentric Phase of a Squat

Concentric Phase of a Squat

A concentric contraction is when the muscle length decreases to perform a movement.

In a squat, this would be the lifting phase of the squat as you rise to stand up.

Using the rope analogy again, a concentric movement would be similar to pulling a rope attached to a boulder.

As you work to pull the rope up, the boulder gets closer and closer, the same way a muscle shortens in a concentric contraction.

You cannot use as much weight during the concentric portion of the lift, but you can generate more force.

Related: Correct Posture for Squats

 

Concentric vs Eccentric: Muscle Actions

Isometric Squat

When you squat, your muscle actions occur in two phases.

During the concentric (shortening) phase, you generate enough force for your muscles to work against opposing forces and produce movement.

During the eccentric phase, there is still muscle tension, but at a lesser degree as your muscles lengthen.

Dark Iron Fitness Weightlifting BeltA third action, isometric contraction, occurs when muscle tension is present but the muscles do not change length.

Even though there is no movement, your muscles are still working and contracting.

Holding your squat position for a certain length of time is an example of isometric contraction.

When planning training workouts people focus on the concentric phase of an exercise.

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But in compound exercises like squats, which involve numerous joints and muscles, a huge part of the job is eccentric.

The muscles lengthen and act as brakes to slow the rate of movement and protect the body against injury.

Related: What Eccentric and Concentric Movements Are in a Squat?

 

Concentric vs Eccentric: Muscles Involved in Squats

Downward Phase Muscle Actions

Squatting

During the downward phase of a squat, gravity is a powerful downward force.

When you are lifting heavy, the force of gravity is magnified.

This will counteract the increased gravity and protect your joints:

  • the gluteus maximus and hamstring muscles work eccentrically from the hip,
  • your quadriceps work eccentrically at the knee,
  • your calf muscles, ankle flexors and posterior tibialis work eccentrically at the ankle.

As these muscles lengthen, they provide balanced tension.

Working together they control your speed and range of motion as you lower into your squat.

 

Upward Phase Muscle Actions

As you rise up from your squat, the muscles lengthened in the downward phase are activated concentrically.

They provide force for upward momentum as they fight against the force of gravity.

Their rate of activation will maintain ideal joint angles and prevent injury from a lateral or medial rotation of the lower extremities.

The gluteus maximus and hamstring muscles start from the pelvis.

Because of this, the abdominal and erector spinae muscles will produce an isometric counter-tension to stabilize the pelvis and the trunk of the body.

Related: Difference Between Eccentric and Concentric

 

Conclusion for Concentric vs Eccentric Squat

There are a few exceptions–jumping off a ledge is mainly eccentric, while a punch is mainly concentric.

But the majority of exercises use both concentric and eccentric actions.

So remember that when you lower down into your squat it’s eccentric, when you come back up it’s concentric.

Related: Benefits of Heavy Squats