Green resistance bands are medium resistance. These bands are less stretchy and have more tension than yellow bands. Green bands are used for muscle groups that need slightly more tension, such as the biceps or triceps.
Red resistance bands are medium to heavy resistance. They have a higher level of tension than green or yellow bands and are harder to stretch. Red bands are suitable for muscle groups that are larger, such as the legs, chest and back, or for individuals who have been building muscle strength.
Blue resistance bands are heavy resistance. These are much more stiff than red, green or yellow and do not provide as much stretch. Blue bands are for those who are very strong, or for larger muscle groups, such as the legs, chest and back. These are also the bands to use when working out with someone else – when two people pull against a band.
Black resistance bands have the most resistance. These are the hardest bands to stretch and pull. Like blue bands, black bands are used for the large muscle groups, such as the legs, or when working with others. Some sets of bands come in all black and the level of resistance is not based on color in these sets.