After immobilisation of muscle in a shortened position there is a reduction of muscle fibre length due to a loss of serial sarcomeres. Experiments have been carried out to determine whether short, daily periods of stretch prevent sarcomere loss and the resultant loss of range of joint motion. It was found that periods of stretch as short as 1/2 h daily were sufficient not only to prevent loss of sarcomeres but actually to cause an increase in the number of sarcomeres in series. Range of joint motion was normal. Such short periods of stretch were also found to prevent much of the muscle atrophy normally associated with immobilisation in the shortened position.