This paper considers the application of flexibility sensors and wearable technologies on smart textiles to enhance the functionality of clothing and protective textiles for the benefit of people, especially older people. By introducing flexibility sensors based strain sensors, we can find its potential of the flexibility science in developed clothing and protective textiles. It has promising application on smart textile products and services appropriate to the needs and aspirations of active users. It shows us how the appropriate design of flexibility sensors has the potential to promote independence and wellbeing, and may enable participation in healthy exercise in the everyday lives of the active ageing.