Japan’s Teijin Fibers Limited has taken the idea of ‘changing clothes’ to the extreme in developing a new self-regulating fibre, provisionally named the "M.R.T. Fibre" that visibly changes its structure. The M.R.T. fibre, which has been developed for in the "Nike Sphere React" sportswear range, has reversible transformation properties, whereby the fibre stretches when moisture is absorbed and shrinks when it dries out.

In order to produce this, Teijin developed a new polymer - a polyester ester polymer - that absorbs and discharges moisture quickly, so that it ‘breathes with the athlete’. The idea behind the technology is that as the wearer sweats the M.R.T. fibre opens up instinctively, becoming more breathable to permit increased airflow across the skin. The fabric reacts to the body's moisture, and can double its breathability. This creates a cooler personal atmosphere between the body and the fabric and is said to give the athlete freedom to perform more comfortably. It then returns to its original size as the body cools.