A method for determining a target rotational speed below an application rotational speed of a washing drum of a laundry treatment device having a drive and a vibrating system, wherein a dependence of a mechanical effect on items to be washed located in the washing drum on the respective nominal speed of the washing drum is used to ascertain the target rotational speed at which the mechanical effect is at the greatest. The mechanical effect at a respective target rotational speed is ascertained by measuring vibrating system movements of the vibrating system which exhibit greater frequency than the respective target rotational speed. The rotational speed at which the maximum vibrating system movement was measured is selected for carrying out the washing care procedure. The advantage of such a method is that the washing mechanics can be increased, thus improving the cleaning efficiency.