The Power of Isometrics in Performance and Rehab

undefeatedptandper
Sep 14, 2025
2 min read

By Dr. Carmen Jansante, PT, DPT, CSCS

When we think about strength training, we usually picture moving up and down — squats, presses, curls, and other dynamic exercises. But one of the most underutilized tools in both performance and rehabilitation is the isometric contraction.

What Is an Isometric?

An isometric is when we hold a muscle in a sustained position with contraction, without moving through a range of motion. For example, if you dropped into the bottom of a squat and just held that position for a set amount of time, that’s an isometric.

Isometrics don’t take the muscle or tendon through a full lengthening. The tendon, which connects muscle to bone, stays under tension but without the sliding or stretching that comes with concentric (shortening) or eccentric (lengthening) movements.

This makes isometrics a unique and powerful way to train.

Using Isometrics for Performance

One of the best ways to use isometrics is for central nervous system (CNS) activation right before high-power movements.

For example, before a pitcher throws or before an athlete lifts explosively, we can prime the body with isometrics. A great example is a push press isometric:

Set a barbell under safety stoppers in the rack so it can’t be fully extended overhead.
Drive the barbell against the stoppers for 5–10 seconds.
Start submaximal (around 50%) and progress up.

Because the resistance can’t be moved, your body recruits a massive effort and the nervous system ramps up quickly. Afterward, the body is primed to generate more power and force, improving performance without creating unnecessary fatigue.

Using Isometrics in Rehab

Isometrics are also incredibly effective in rehabilitation. When someone has a muscle strain, partial tear, or tendon irritation, moving through full ranges can cause more damage.

Take a hamstring injury as an example: performing full-length hamstring curls (all the way up and down) may overload the tissue. Instead, we use isometric holds in mid-range.

Start with short holds (5 seconds) to build tolerance.
Progress to longer holds (20–40 seconds).
Perform 3–5 repetitions, often around 30 seconds each.

This allows the tendon and muscle to be safely loaded without overstretching. It stimulates healing and strength while protecting the injured tissue.

Why Tendons and Ligaments Benefit

Muscles and tendons adapt differently.

Muscles are pliable and stretchable.
Tendons are stiffer and respond best to sustained tension.

When we use isometrics, tendons take on a large portion of the load. This stimulates collagen production, improves tendon stiffness, and reduces pain — making isometrics one of the best tools for tendon health.

Ligaments, which connect bone to bone, also benefit indirectly. For example, think about the UCL (Tommy John ligament) in the elbow. By performing isometric exercises for the elbow, we strengthen the tendons and muscles that support the ligament, ultimately improving its durability and resilience.

Bringing It All Together

At Undefeated Physical Therapy and Performance, we program isometrics into both our arm care programs for athletes and rehab plans for patients. They are a valuable complement to concentric and eccentric exercises and provide unique benefits for the nervous system, muscles, tendons, and ligaments.

If you’re looking to enhance your performance, recover from injury, or protect your joints long-term, don’t overlook the power of isometrics.

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