the Science of Isometrics

Using isometrics is one of the best ways you can help improve the mechanical execution of an exercise. They’re particularly valuable in rehabilitation or beginner settings as they provide people with an understanding of their position during the movement (proprioception) as well as controlled load through targeted joints. In this case, effective distribution of load through the ankle, knee, and hip is critical, as it helps recruit specific muscles we are looking to rebuild after a patellar tendon reattachment.

Isometric training involves static muscle contractions without any visible movement at the joints. The muscle length remains constant during these exercises, and the joint angle doesn’t change. Instead of the traditional range of motion seen in dynamic exercises like squats or bicep curls, isometric exercises focus on maintaining a fixed position against an immovable force.

The plank is a classic isometric exercise where the individual holds a push-up position with arms extended and the body straight. The muscles in the core, arms, and legs engage to keep the body stable against gravity’s attempt at sinking your midsection to the floor.

But isometric training is far more useful than just increasing stability. It will get you strong, jacked, and keep your joints happy forever.

Unlike dynamic exercises, where you are moving against force, isometric exercises involve exerting force against an immovable object or resisting force applied by external resistance. This produces high tension levels, which is what you need for muscle growth.

You technically don’t need the muscles to change length during your isometric training set. In fact, it might even be advantageous to utilize isometrics when a muscle is in a shortened position. Research has shown this can help promote hypertrophy. (1)

During isometric contractions, motor units are recruited, generating tension within the muscle fibers. This tension increases muscle activation, stimulating muscle fibers to adapt and grow over time. While isometric training is often associated with improving static strength and joint stability, research indicates that it can also play a crucial role in hypertrophy. (2)

The key to growing from isometrics is similar to dynamic strength training. You need to train with enough intensity so high levels of motor unit recruitment occur along with sufficient tension imposed on muscle fibers.

You’re only as strong as your weakest muscles. If you consistently fail your squat in the hole, it’s worth doing isometrics in that position. The same principle applies if you can’t lock out your bench press. Developing isometric strength in that position will be crucial for strengthening the whole exercise. Isometric training also allows you to engage your muscle fibers better and generate more force.

This also translates to improved athletic performance. Many sports, like rock climbing, martial arts, and gymnastics, involve isometrics, where you must hold muscle contractions for extended durations.