This can be a very real challenge to have, especially when you first start working with a new client and you haven’t developed that client/trainer relationship yet. Not knowing how your client ticks could make it difficult to differentiate between an overtrained person and someone who is simply training hard.
Overtraining is defined as excessive frequency, volume, or intensity of training over an extended period of time, resulting in fatigue (which is also due to a lack of proper rest or recovery). It can cause significant performance decreases in clients of all training levels. If you have your client on a realistic, properly designed program and you suspect him or her of being overtrained – or, more likely, of ‘overreaching’ – it could potentially be due to their lack of self-care (sleep, nutrition, hydration, etc.) outside of the time spent with you.