Armsträckning

Armsträckning, or arm extension, is the movement that lengthens the arm by straightening the elbow, increasing the angle between the upper arm and the forearm. In biomechanics, extension is the opposite of flexion; elbow extension is produced mainly by the triceps brachii and the small triceps accessory muscle, the anconeus, with the forearm moving away from the upper arm.

In a healthy elbow, full extension is close to 0 degrees, while flexion reaches about 140 to 150 degrees in many people. Some individuals can hyperextend the elbow slightly beyond 0 degrees. Clinicians often measure elbow extension and overall range of motion using a goniometer to assess functional capacity or recovery after injury or surgery.

Arm extension is involved in countless daily activities such as reaching, pushing, and throwing, and it is a common focus in sports training and rehabilitation. It also forms the basis of several resistance exercises targeting the triceps, such as overhead triceps extensions and various push-downs, where the elbow extends against resistance.

Limitations of elbow extension can arise from injuries (for example fractures or soft tissue damage), joint capsule tightness, or muscle imbalances. Loss of extension or painful limited extension is evaluated in clinical settings to guide treatment, which may include targeted stretching, gradual strengthening, and activity modification. Safety and progressive loading are important to avoid overstrain or aggravation of the joint and surrounding tissues. See also elbow extension, triceps brachii, and goniometry.