The Difference Between Isometric, Concentric, & Eccentric Strength
Isometric, Concentric, and Eccentric are terms tossed around the weight room almost daily, and in almost every program you come across, you may see these terms and whether you know it or not, every movement in the weight room utilizes those three terms; so what are they?
Isometrics are movements where the muscle length does not change. Some examples can include a plank, a paused squat or bench, or a hold on a lunge.
At Ironworks we at times will program a short pause on a squat, have a pin press movement where you push and hold a bar into one of the racks, or holds on a glute bridge; these are all examples of isometrics being used in our training.
Isometric exercises are great for allowing athletes to feel movements, brace the core, and feel different points in the range of motion in training. Additionally, it allows athletes to feel more connection through each movement (mind muscle connection).
Isometrics are also great for injury rehabilitation because they allow athletes/clients to train certain points of the range of motion and also allow for each specific angle to be trained in a safe manner.
An eccentric movement is when the muscle is lengthening or when the muscle is elongated.
A very easy movement to imagine is the RDL (pictured above) when the weight is being lowered the hamstrings are being lengthened or eccentrically loaded.
To emphasize the lengthening of this movement, in some programming at Ironworks you will see us program a Tempo, typically 3 seconds on the down portion or the eccentric portion of the lift. Adding the tempo to the eccentric portion of the lift will increase the time under tension of the muscle group increasing hypertrophy and activation of the muscle fibers.
One of the downfalls of eccentric tempos is the demand that is placed on the muscle fibers and central nervous system, leaving some athletes needing more time to recover after training sessions.
A concentric movement is exactly the opposite of the eccentric movement; the shortening of the muscle group.
From the example above of the RDL, think of the up portion of the lift where you are raising the bar.
The concentric portion of the lifts emphasizes strength & power; this is when the muscle is producing force, think of when you lock out on a deadlift on dynamic effort day, the speed you develop to move the bar to lock out is during the concentric phase of the lift.
The concentric movements in training create less stress on the body and muscle groups therefore needing less time to recover.
Remember, when training our isometric focussed movements and eccentric focussed movements are going to create far more stress on the body and will need more time to recover.
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