A stretchy elastic loop used to add resistance to strength exercises is called a resistance band.
Resistance bands create opposing force when they are stretched, so muscles must work to control the movement. They can be used for exercises such as rows, presses, squats, leg abductions, and assisted pull-ups. Because they are light and portable, they are popular for home workouts, travel, rehabilitation, and general strength training.
Bands come in several forms, including flat therapy bands, continuous loop bands, tube bands with handles, figure-eight bands, and ankle-cuff systems. Colours often indicate resistance levels, but the colour code is not universal; one brand's red band may not match another brand's red band.
Many resistance bands originated from surgical tubing used in rehabilitation during the early 20th century. Unlike free weights, bands usually become harder to stretch as the range of motion increases, so the resistance changes throughout an exercise. Users should inspect bands for cracks or worn sections because a damaged band can snap.