Research · 4 min read · 2026-10-15
When does tiredness become overtraining?
Planned tiredness makes you better. Tiredness that doesn't pass can become a problem. How to tell the difference.
Hard training should make you tired. That is part of how you get better. But when does tiredness become a problem? A joint statement from the European College of Sport Science and the American College of Sports Medicine describes the difference.
Three levels of tiredness
Short-term overreaching is planned. After a hard period, performance drops for a while, and after recovery it improves. The statement calls this functional overreaching.
When training and recovery are out of balance for longer, performance can stay down for weeks. This is called non-functional overreaching.
Overtraining syndrome is the most serious form, a long-lasting failure to adapt. Fatigue, falling performance and mood changes are typical. It can be very hard to tell apart from non-functional overreaching, and the diagnosis depends on ruling out other causes.
What else can look like overtraining
The statement stresses ruling out illness and infection, and factors such as eating too little, too little carbohydrate or protein, iron deficiency and allergies. Several of these can give the same symptoms.
What it means for you
Tiredness after a hard week is normal and passes with a few easier days. Tiredness that doesn't pass, runs that keep feeling harder at the same pace, poor sleep and low mood together are signs to ease off. If it lasts for weeks, talk to a doctor to rule out other causes.
It is much easier to prevent than to treat. Easy days, enough sleep and enough food do most of the work.
What the statement can't tell you
There is no single test for overtraining. The statement reviews hormones, performance tests, psychological tests and blood markers, and concludes that none of them is good enough to use on its own.
How we use it
PX7 Training compares how hard each session felt with what was expected. If several sessions in a row feel harder than they should, the next sessions are made easier.
Source
- Meeusen et al. (2013), Prevention, diagnosis, and treatment of the overtraining syndrome: joint consensus statement of the European College of Sport Science and the American College of Sports Medicine. Medicine & Science in Sports & Exercise.
Written by Jørgen Larsen for PX7 Training.