Which types of muscles do isometric concentrations?

Isometric training, often called a static hold, involves contracting a muscle without changing its length or joint angle.

- Primary movers: the large, superficial muscles that do all the hard work and get pumped up at the gym—for example, your biceps at the front of your upper arm or your quadriceps, or thighs

- Core (stabilizing/postural/abdominals) muscles: your lower back muscle (specifically those along your spine), abdominals, chest, and other back muscles such as latissimus dorsi

- Joint muscles. There are numerous muscles throughout your entire body that move or hold different joints as needed—your shoulders’ and knees’ rotator cuff (RC) is one example