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Daily Heart Rate Variability (HRV) metrics, when averaged weekly, reveal parasympathetic hyperactivity (increased RMSSD and HF power) in endurance athletes experiencing functional overreaching (F-OR), whereas isolated single-day measurements fail to detect these autonomic changes.

If you are an endurance athlete suspecting overtraining, do not rely on a single daily HRV reading. Instead, record your Heart Rate Variability (specifically RMSSD) every morning upon waking. Calculate the weekly average of these values. A rising trend in your weekly average RMSSD during a heavy training block, accompanied by a drop in performance, is a strong indicator of parasympathetic hyperactivity and functional overreaching, signaling that you need a recovery taper.

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Using daily HRV recordings averaged over each week, this study detected a progressive increase in the parasympathetic modulation of HR in endurance athletes led to F-OR. It also revealed that due to a wide day-to-day variability, isolated, once per week HRV recordings may not detect training-induced autonomic modulations in F-OR athletes.
Yannick Le Meur et al. · Medicine & Science in Sports & Exercise · 2013

Source

Evidence of Parasympathetic Hyperactivity in Functionally Overreached Athletes

Yannick Le Meur et al. · Medicine & Science in Sports & Exercise · 2013

DOI 10.1249/mss.0b013e3182980125

rct · n=24Cited 224×
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DOI resolved against Crossref · corpus check 2026-06-10

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