Overtraining and overreaching
Evidence: moderate
A continuum from productive overreaching to overtraining syndrome, distinguished mainly by how long performance stays down. There is no single reliable biomarker, so it is usually confirmed only in hindsight.
Pushing training stress beyond what recovery can match runs along a continuum: functional overreaching, then non-functional overreaching, then overtraining syndrome, distinguished mainly by how long performance stays suppressed (Meeusen et al. 2013).
- Functional overreaching is a short dip of days to weeks that rebounds above baseline after recovery. It is the intended outcome of a hard training block.
- Non-functional overreaching is a stagnation or decrement lasting weeks to months, with eventual recovery but no gain.
- Overtraining syndrome is impairment for months with systemic symptoms, and is a diagnosis of exclusion: anaemia, infection, low energy availability, thyroid problems and depression must be ruled out first (Meeusen et al. 2013; Kreher & Schwartz 2012).
The hard problem is that the distinction can usually only be made retrospectively, by how long recovery actually takes. There is no single validated biomarker: resting heart rate, heart-rate variability, and the testosterone-to-cortisol ratio are all inconsistent, and none has a diagnostic threshold (Kreher & Schwartz 2012). Mood, tracked with a tool such as the Profile of Mood States, is among the more sensitive markers, especially a fall in “vigour”, but it is non-specific.
Prevalence figures are definition-dependent and self-reported, but a career experience of an overreaching or overtraining episode may reach around 60% in elite distance runners (Matos et al. 2011). The practical defence is not a gadget but spacing hard work, protecting sleep, and watching subjective wellness, which is more sensitive to accumulating load than most objective measures; see training monitoring.
Early warning signs
The useful signals are mostly subjective and show up before any test: performance stalling or sliding despite hard training, persistent heavy legs, disturbed sleep, low mood or irritability, loss of motivation, a higher-than-usual effort for easy paces, and frequent minor illness. None is diagnostic alone, but a cluster appearing together is the cue to insert rest before it tips into non-functional overreaching. The cheap, sensitive monitor is a short daily note on sleep, fatigue, soreness and mood (training monitoring); when several drift the wrong way at once, back off.