The bladder meridian is the yang to complement the kidney’s yin and as such it presents the same characteristics as the kidney’s meridian (see Treating the kidney meridian through yoga practice if you want to know more). It controls the willpower of the individual and their determination, much like its yin counterpart. Specifically, it is responsible for protecting the individual from negative ‘energies’, like our own personal shield it runs along the back of the body from head to little toes. A depleted immune system and recurrent illnesses can be signs that the shield isn’t doing its job properly. You can test it by looking at the flexibility of your lower back and hamstrings. If the meridian has been depleted, you will see excellent flexibility but not strength. On the other hand, if it’s full or too high, it will be poor.