An isometric contraction occurs when a muscle creates force without any movement at the joint. The muscle works hard but its length stays the same and the limb stays still. Isometrics can be used in almost any movement by targeting specific joint angles, and they are most often performed in three main ways. Before we get into the top five reasons to use them, it is important to understand what each type is.
The Three Kinds of Isometrics
1. Yielding Isometrics
Also called isometric holds, these can be done with body weight such as a dead hang or a squat hold. They can also be performed with load where the athlete maintains the weight at a specific location. The example shown is a back extension isometric on our GHD Machine. The athlete holds their chest parallel to the ground by using the lower back and posterior chain to keep the torso level. If they create more force than needed they will rise above parallel and if they create less force they will fall below it.
2. Overcoming Isometrics
An overcoming isometric is a maximal contraction against an immovable object, usually held for three to fifteen seconds. This lets athletes train maximal intent safely and increase force output. It also allows you to attack specific joint angles or sticking points such as mid shin, knee, or mid thigh in the deadlift. The example shown is the isometric mid thigh pull, one of the most common overcoming isometrics used by sport scientists and strength coaches for force testing. Here it is performed with a barbell and ISO Cups.
3. Functional Isometrics
Combines a short range of motion with an isometric hold by trapping the bar between two sets of pins. The athlete lifts a few inches until the bar meets the top pins and then drives hard into that fixed position. This method blends controlled movement with high force production and lets you train through a specific segment of the lift. Coaches use functional ISO's to improve sticking points, sharpen technique, and build strength in the exact ranges where athletes struggle. They can be applied to squats, benches, and deadlifts using standard spotter arms or our ISO Teeth on our spotter arms. Anthony Cockrill from SMU Volleyball S&C has a great post on this topic, linked here.
