How do I know if I'm overtraining?

The three stages sports science actually recognizes

The ECSS/ACSM consensus maps a continuum. Functional overreaching: short-term fatigue from a hard block that rebounds above baseline with a few days to two weeks of recovery — this is training working. Non-functional overreaching: fatigue that takes weeks to months to clear, with no performance bonus — you dug too deep. Overtraining syndrome: the severe end, taking months to years, diagnosed only by exclusion.

The line that matters for you is between the first and second stage — and that line is exactly what daily signals guard.

What to watch, concretely

The warning cluster:

• Resting HR 3–7 bpm above your normal for 3+ consecutive days with no obvious cause
• HRV below your 7-day baseline for multiple days, or day-to-day swings widening
• The same easy pace feeling harder (rising effort at constant speed)
• Sleep quality degrading; mood flat; motivation gone

Training isn't the only input

Work pressure, poor sleep, under-eating, and life stress feed the same fatigue pool as your mileage — the consensus statement is emphatic on this. Your morning signals capture that total load, which is exactly why they are more honest than your training log. The move when the cluster shows up is unsexy: a few genuinely easy days, early. Stage-1 fatigue recovers fast; stage 2 does not.