The band looks the same as it did last week, but the last few centimetres of the movement feel much harder. Before calling that a loss of strength, check where you started. The resistance of an elastic band changes as it stretches, so a different setup can change the exercise. Laboratory measurements published in the Journal of Physical Therapy Science compared band tension at different percentages of elongation. Those measurements describe the products tested, not a universal colour code.
Colour is useful only within the manufacturer’s own product system. A blue band from another range is not a reliable match. Note the exact band and follow its instructions, including permitted uses and stretch limits.
Make the setup repeatable
For a movement taught by your trainer, record the hand position, starting distance and intended range. A quick note such as “same band, same grip marks, same starting stance” is more informative than recording only the number of repetitions.
Do not add arbitrary extra stretch to make an exercise harder. A secure, manufacturer-approved anchor and an appropriate movement matter before progression. If you are unsure about the arrangement, ask a qualified trainer to check it.
Compare two sets only when their setups are meaningfully similar. In an illustrative example, stepping farther from an anchor between sessions changes the starting tension. Completing fewer repetitions may reflect that changed resistance rather than a decline in ability.
Watch the return as well as the pull
A controlled return is part of the repetition. If the band pulls you out of position or you cannot bring it back without losing control, stop and reassess the exercise rather than letting it snap back.
Keep the band’s path clear of your face and other people, and follow its inspection and replacement guidance. Stop for pain or an unexpected problem. A general article cannot select a suitable resistance for an injury or rehabilitation programme.
Progress can mean performing the same movement with more consistent control. When a trainer recommends changing resistance, record that change explicitly. The aim is a useful account of what you did, not a bigger repetition number produced by quietly shortening the movement.