Salivary IL-6/cortisol ratio and RSImod may serve as non-invasive indicators of non-functional overreaching in NCAA Division I American football athletes, with role-specific physiological signatures.
In a 15-week observational study of 39 NCAA Division I American football players, both starters and non-starters exhibited patterns consistent with non-functional overreaching (NFOR), but with distinct physiological signatures. Higher IL-6/cortisol ratios were associated with higher RSImod in starters, while in non-starters, higher IL-6/cortisol ratios were associated with poorer recovery despite lower external loads. Mid-season declines in countermovement jump performance coincided with biomarker changes suggestive of accumulated fatigue.
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Salivary IL-6/cortisol ratio and RSImod may serve as non-invasive indicators of non-functional overreaching in NCAA Division I American football athletes, with role-specific physiological signatures. The current body of evidence comprises 1 study. EvidenceHub rates the overall confidence at 32/100 (low).
The Claim
Salivary IL-6/cortisol ratio and RSImod may serve as non-invasive indicators of non-functional overreaching in NCAA Division I American football athletes, with role-specific physiological signatures.
This conclusion is most relevant to: 39 male NCAA Division I American football athletes (age 20.4 ± 1.75 years), including starters and non-starters..
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Multimodal indicators of non-functional overreaching in NCAA Division I American football athletes: evidence for role-specific physiological adaptation. (Frontiers in physiology, 2026) —
How It Works
The proposed biological pathway:
- ▸Accumulated training and competition stress leads to altered salivary biomarker ratios, particularly increased IL-6/cortisol ratio.
- ▸These biomarker changes are associated with reduced neuromuscular performance (e.g., lower RSImod) and poorer recovery (higher soreness, lower sleep quality).
- ▸Physiological responses differ by role: starters show better recovery with higher testosterone/cortisol, while non-starters show greater strain despite lower external loads.
- ▸Result: Both groups exhibit NFOR, but with role-specific physiological signatures, suggesting the need for tailored recovery strategies.
Who Might Benefit
Evidence fit by population:
- ▸39 male NCAA Division I American football athletes (age 20.4 ± 1.75 years), including starters and non-starters.
Recommended Dose
N/A
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Observational design; no control group, so causality cannot be established.
- ▸Small sample size (n=39) and single-site study may limit generalizability to other teams or sports.
Frequently Asked Questions
What is non-functional overreaching (NFOR) and how is it detected in this study?▼
NFOR is a state of accumulated training stress leading to performance decrements and prolonged fatigue. In this study, NFOR was inferred from patterns of salivary biomarkers (e.g., IL-6/cortisol ratio), neuromuscular performance (e.g., RSImod), and self-reported recovery metrics across a season.
How does the IL-6/cortisol ratio relate to recovery in football athletes?▼
Higher IL-6/cortisol ratios were associated with poorer recovery in non-starters (higher soreness, lower sleep quality) despite lower external loads, while in starters, higher IL-6/cortisol ratios were associated with higher RSImod, suggesting a different adaptive response.
Are there role-specific differences in physiological adaptation to training?▼
Yes, starters showed a positive association between testosterone/cortisol ratio and better recovery, while non-starters exhibited greater physiological strain (higher IL-6/cortisol) even with lower external loads, indicating that monitoring and recovery strategies should be tailored by playing role.
What practical implications do these findings have for coaches and sports scientists?▼
Salivary biomarker ratios, especially IL-6/cortisol, combined with neuromuscular measures like RSImod, could serve as non-invasive tools to monitor fatigue and guide individualized recovery interventions in American football athletes.
References
- 1.Aychman MM, Vinson K, Tasnim N, Perez J, Hodes GE, Basso JC. “Multimodal indicators of non-functional overreaching in NCAA Division I American football athletes: evidence for role-specific physiological adaptation..” Frontiers in physiology, 2026. PMID: 42553027 DOI: 10.3389/fphys.2026.1818629