I have done a little research on chakras and a friend of mine can I think sense them, I have needed my sacral chakra unblocked for quite some time, but I am getting better at meditating on it, I am unsure of my other chakras though how can you tell how active or under active they are?
I'm not sure about anyone else but, I believe your body tells you how open your chakras are. For example: i'll work on opening my 3rd eye chakra with meditation and music. When its opened too much I get headaches. The green Heart chakra seems to open quite a bit as well. I feel lots of compassion towards people and sense a bit of heartache when I let those feelings in too much. Just listen to what your body is feeling and telling you and you'll know when those chakras are open or closed. Hope this helps.
I have seen tests that people take to indicate there chakra activity, how accurate they are, I'm not sure. Some people find it difficult to tell how open it is while others are at ease with it. For some, the only actual indicator is that they are good with different things associated with the chakra point, therefore they assume it is functioning.
There is alot of differing info out there on chakras. The first book that seemed legitamite to me, i read cover to cover and practiced the excercices enough that i still remember how to do them even years later. And dont ask me to tell you the name of the book cause i dont remember. Ive read so many books that i stopped keeping track a long time ago. Point being. I dont use chakras very often because as a general rule i forget to close them after opening them for a specific purpose and that has caused alot of unneccisary turmoil in my life. Powerful tool. If you can master it.