Method for thermal treatment of a running yarn (14) on a multi-workstation twisting machine, each station having a device (1) for thermal treatment of the yarn, and a delivery system (2, 3) preceding or following such device (1). The yarn (14) passes through the device (1) substantially without tension, and after passing the downstream delivery system (3), is wound. The yarn (14) is loaded with a defined force by position-variable means (24, 25, 27). Position changes of such means caused by a change in the yarn tension under disruptive influences during the thermal treatment of the yarn (14) are used as a control variable for controlling at least one of the delivery systems (2, 3).