From 1 July 2025, the Department of Creative Industries, Tourism and Sport (CITS) replaces the Department of Local Government, Sport and Cultural Industries (DLGSC).
Intro
Hydration testing is often proposed as a way to monitor athletes’ weight loss and protect their health. But if the tests don’t reflect real fluid loss, or give different results each time, they become misleading and unusable.
Accuracy means: Does the test reflect the true amount of fluid or weight lost?
Reliability means: Will the result be the same each time we test?
If hydration tests are inaccurate or inconsistent, they cannot be used to monitor, assess, or regulate rapid weight loss practices.
How well do hydration markers reflect actual weight loss?
✅ Fingerprick blood was the best, but still only explained 22% of the weight lost.
❌ Other markers like urine and tear fluid explained even less.
Can hydration markers give the same result across trials?
✅ Fingerprick blood was again the best, but agreement was 61% across two identical trials.
❌ Other methods were even less consistent.
👉 Conclusion: Biomarkers are not reliable enough to track weight loss over time.
⚠️ Hydration testing should not be used to assess or manage rapid weight loss before competition.
👉Even though it can appear objective, hydration testing is not accurate or reliable enough to be useful in this context.
Doherty CS, Fortington LV, Barley OR. Blood, Sweat, and Tears: Implications for Hydration Testing in Combat Sports-Investigating Body Mass Loss and Biomarker Changes. Scand J Med Sci Sports. 2024, 34(8):e14701. doi: 10.1111/sms.14701.