As someone who has trained as far back as I can remember, there have been weeks where I may have over done its slightly. For example, trained every day, maybe even twice a day, maybe not eaten enough to allow for sufficient recovery, lack of sleep (Cadegiani, F, et al, 2020). To be honest, the list could go on.
SIGNS AND SYMPTOMS
If you're someone who trains often, then that feeling of heavy legs, getting out of breathe a lot quicker, fatigue, being REALLY hungry or a total loss of appetite, maybe increased injuries, reduced progress, etc. might be a familiar feeling and a sign to step of the gas a little or to consider looking at your current routine (that includes nutrition, sleep and stress) (Cadegiani, F, et al, 2020).
Rest days are vital for -
Mental breaks which can keep your focus
Maintain passion for training
Better quality sleep
Reduced risk of injury
Reduced risk of Depression
Allow for more heart rate variability (HRV)
Your lifestyle, which will always include that sleep, nutrition, stressors, work and family commitments, will determine your overall ability to commit to exercise and how your body can respond and adapt. Also knowing the signs and symptoms will play a huge role in managing your training.
A good training program will help to avoid overtraining. Good communication is key also. Knowing if you have work trips, heavier work loads, a very physical workout week, can help your training to adjust your week ahead of schedule too.
If you are mentally stressed, this can also reflect your body's ability to recover. So take this in to account.
Flavio A. Cadegiani, Claudio E. Kater, Matheus Gazola. (2019) Clinical and biochemical characteristics of high-intensity functional training (HIFT) and overtraining syndrome: findings from the EROS study (The EROS-HIFT). Journal of Sports Sciences 37:11, pages 1296-1307 [Accessed on - 21.03.2022]
Flavio Adsuara Cadegiani, Pedro Henrique Luiz da Silva, Tatiana Camargo Pereira Abrao, Claudio Elias Kater (2020) "Diagnosis of Overtraining Syndrome: Results of the Endocrine and Metabolic Responses on Overtraining Syndrome Study: EROS-DIAGNOSIS",Journal of Sports Medicine,vol. 2020,Article ID 3937819. Available at: https://doi.org/10.1155/2020/393781 [Accessed on 21.03.22]