Joint extension in exercise is when you increase the angle in a joint between two bones. This is opposite of joint flexion.
For example in a glute bridge as you lift your glutes off the ground, you are increasing the angle of your hip joint.
The muscles that help you extend at a joint are extensor muscles.
One way to remember adduction definition is to imagine a line passing through the center of your body. When you move a part of your body towards this line, you are adducting, you are adding to this imaginary line.
Imagine that your hands are stretched out to the side. There are infinite ways you can bring your hands toward the mid-line of your body. You can lower your arms to your side which is called frontal plane adduction. You can also bring your hands toward the mid-line of your body like seals clapping. This is called transverse plane adduction.
The normal flexion definition for joints is reducing the joint angle by moving two bones close to each other. For example you move your forearm toward your arm and narrow the spacing in the elbow joint.
It would help you if you thought about flexion as reducing the joint spacing in harmony with the natural structural design of the joint. Many of the exercise motions do not consider this simple criteria. It makes no sense and yet is common. You’ll see example of this later.
Contraction of the muscles are muscles is part of this motion. When we say flex your biceps, we really mean flex your elbow joint and contract your biceps. Again for health and performance reasons, it is important to think of flexion in relationship to your joints and not muscles.
Your awareness of joint movements helps you move in harmony with them, keep them healthy to improve your performance and retain your freedom and mobility. You don’t have to suffer from many forms of joint pains that could be both prevented and treated through moving well. Moving well is not common and takes practice.
Fundamental joint movements are listed below. These are the building blocks of complex movements you perform daily.
External or lateral rotation