Stretching is the way to get flexible, although you need to be careful as it can cause injury if performed incorrectly. When you stretch, your nerves send a signal to your brain, known as the ‘stretch reflex’. This causes the muscle to contract, preventing the muscle from stretching any further. It is thought that with training, you can change the point at which your brain tells the muscle to contact, allowing you to stretch further, and become more flexible. Other factors also affect your flexibility however, including your ligaments and tendons.