Research

Hormonal

A decreased testosterone-to-cortisol (T/C) ratio and elevated creatine kinase (CK) activity are biochemical markers indicating a catabolic state and muscle damage associated with overreaching.

Monitoring hormonal balance can help identify when you are overtrained. A drop in the testosterone-to-cortisol ratio and high creatine kinase levels indicate your body is in a catabolic (breaking down) state. If you have access to blood testing, these markers can guide your recovery needs. If not, focus on subjective feelings of fatigue and performance drops as proxies.

GoodSupportsMEDIUM confidence
The significant reduction in the T/C ratio and elevated CK activity following the 6-week overload training period suggests that the players were in a catabolic state with elevated levels of muscle damage when the MSFT performance was reduced.
Aaron J. Coutts et al. · International Journal of Sports Medicine · 2007

Why this rating

Consistent with previous literature cited, though limited by small sample size.

Source

Changes in Selected Biochemical, Muscular Strength, Power, and Endurance Measures during Deliberate Overreaching and Tapering in Rugby League Players

Aaron J. Coutts et al. · International Journal of Sports Medicine · 2007

DOI 10.1055/s-2006-924145

crossover · n=7Cited 281×
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DOI resolved against Crossref · corpus check 2026-06-10

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