<qa>  What do TTFields do?Electric fields can also cause muscles to twitch and if strong enough may heat tissues. TTFields are alternating electric fields of low intensity. This means that they change their direction repetitively many times a second. Since they change direction very rapidly 150 thousand times a second, they do not cause muscles to twitch, nor do they have any effects on other electrically activated tissues in the body brain, nerves and heart. Since the intensities of TTFields in the body are very low, they do not cause heating. 