On my 405CX, I can hold the "time" menu (top of the bezel) to switch the display to the time mode, without ending the workout or training. To go back to the training, just hold the "training" menu (right side of the bezel) to go back to the current workout or training.
A small warning, when switching the display to "time" mode, the watch can enter into a power saving mode after a few minutes that will end the workout or training. So do not wait too long before going back to your workout or training ...