WHY THIS HAPPENS
Functional overreaching crossing into non-functional overreaching — too much intensity, too little recovery
Sleep quality below 7 hours, or fragmented — destroys adaptation
Under-fuelling — chronic energy deficit drives RED-S symptoms in both men and women
Life stress stacking with training stress — the body doesn't distinguish between them
Iron deficiency (especially in women) — standard blood markers miss it
Zone drift — most training is actually zone 3 not zone 2, driving accumulated fatigue
Missing deload weeks — 3 weeks hard, 1 week easy is not optional