It feels as though my muscles are always in a strained/constricted state so it doesnt take much for everything to get out of whack. I have to be so careful about straining them even in the slightest way because if I do I will get knots and spasms and as a result will get headaches at the base of the skull and back pain. So for me I cannot push the envelope in lifting, pushing, pulling etc, I don't feel like this would be a problem if my muscles weren't stiff and inflexable in the first place. So.........for me the headaches at the base of the skull are a result of overstraining the muscles. If I remember right I think malic acid helped with the muscles stiffness in the past.......think i will try it again.