Originating in the early 20th century, the bands were originally made from surgical tubing and the exercises conducted for muscle rehabilitation, and resistance band training is now used widely as part of general fitness and
strength training. Their flexibility in use and light weight are a significant advantage for many users. Typically, the bands are color-coded to show different levels of resistance and users need to select an appropriate level. Code colors vary between brands. Also, available are loop bands, as well as (a common option for many purchasers). Some types allow handles to be clipped on the band or loop. Resistance bands are simple to use, and their light weight allows people to easily carry them if travelling and continue with routine sessions for strength training. Although there are many different forms of exercises for the bands, the resistance of the band as well as the number of repetitions are the main variables used to lower or increase the intensity of the workout. In 2014, researchers found that the Bench Press and the resistance band Push-up, at similar stress levels, produced similar strength gains.{{cite web == Types of resistance bands ==