The silent illness.

Wednesday. You feel completely normal. Good energy, no soreness, motivated to train.

But Rudder flags something: HRV has been declining for 3 consecutive days without a training load explanation. RHR is 4 bpm above your baseline for the second day in a row. Respiratory rate ticked up slightly.

None of them connect the dots: HRV + RHR + respiratory rate declining together WITHOUT recent hard training = illness pattern.

Illness suspicion: “possible” (escalating to “likely” if temperature joins).

Checks training load: no hard sessions in 3 days. This isn’t fatigue — there’s no training explanation for the decline.

Recommendation: MODIFY to easy day. “Your HRV is declining without a training load explanation. The last time this pattern happened — November 14 — you got sick 2 days later. Easy day. Hydrate. Sleep early.”

Thursday: still feel okay but a bit tired. Friday: sore throat, headache, full cold.

But because you rested Wednesday and Thursday, you’re back training Monday. Your training partner who pushed through is out for 2 weeks.

HRV managed to indicate sicknesses before I actually feel them. HRV will drop, I’ll feel fine… Third day I’m dying and finally realized why my HRV had dropped.

HRV suppression without training load change predicted illness onset 1–3 days before symptoms (Hamlin et al., 2019).