An intra vaginal device (10) including an elongated hollow body (1 1) with side wall portions (15, 16 and 24). Secured to each wall portion (15 and 24) is a sensor (19), while secured to the wall portion (16) is a sensor (20). The sensors (19) simply measure forces directly applied by the bi-lateral contraction of the pubococcygeus, while the sensor (20) provides an indication of the puborectalis contraction forces.