By setting a STRIDE different from 1, you change how frequently an action is calculated. In the case of actions such as PRINT, this just means how frequently you dump some quantity on the disk. Notice that variables are only computed when necessary. Thus, if a variable is only appearing as the argument of a PRINT statement with STRIDE=10, it will be computed every 10 steps.

In a similar fashion, the STRIDE keyword can be used in a bias potential so as to apply the bias potential every few steps. In this case, forces from this bias potential are scaled up by a factor equal to STRIDE.

This technique can allow your simulation to run faster if you need the apply a bias potential on some very expensive collective variable.

The technique is discussed in details here [21]