People in stressful situations often revert to what they have done before and cling to past practices as a way of coping.
Think of it as stress and regress.
How do you think this plays out when you are asking people to do new things after a training course?
If there is already significant stress in the workplace, trainees are unlikely to try new things, even if those new things are designed to alleviate the stress.
How can you help trainees deal with the current stress long enough to take on and benefit from the new behaviours, overcoming any additional stress this may at first cause?