The invention relates to improved apparatus and methods for respiratory inductive plesthysmography. The invention includes apparatus for measuring changes in the circumference of a subject comprising of an energisable conducting wire having two ends, engagement means for engaging said ends to form a gapless conducting loop, the engagement means being in electrical communication with the conducting wire. The relationship between the elements of the apparatus provides a reduced level of noise associated with a measureable signal attributed to the changes in circumference. Signals generated in the apparatus may be processed and communicated through various means for analysis of respiratory effort. A method is disclosed for measuring respiratory effort with a gapless conducting wire energised with current.
