Reliability and minimal detectable change of the MX3 hydration testing system

Area of Science:

• Sports Medicine
• Physiology
• Biotechnology

Background:

• Accurate hydration assessment is crucial but often limited by invasive or costly methods.
• Noninvasive, portable, and valid tools are needed for real-world hydration monitoring.
• Saliva osmolality is a potential biomarker for hydration status.

Purpose of the Study:

• To evaluate the within-day reliability and minimal detectable change (MDC) of the MX3 Hydration Testing System.
• To determine if the MX3 system provides a valid and practical method for measuring saliva osmolality.
• To assess the utility of the MX3 system for detecting hydration status changes outside laboratory settings.

Main Methods:

• Seventy-five adults provided two saliva samples within minutes for analysis using the MX3 system.
• Saliva osmolality was measured noninvasively using a portable testing device.
• Intraclass correlation coefficients (ICCs) and MDC were calculated to assess reliability.

Main Results:

• The MX3 system demonstrated moderate-to-good within-day test-retest reliability (ICC = 0.75).
• The minimal detectable change (MDC) at 90% confidence was 21.3 mOsm.
• Measurements showed equivalence between the two saliva samples, with a mean difference of -1.2 mOsm.

Conclusions:

• The MX3 Hydration Testing System is a practical and reliable tool for measuring saliva osmolality.
• The system is suitable for detecting moderate changes in hydration status (>20 mOsm) in non-laboratory environments.
• This noninvasive method offers a viable alternative for field-based hydration assessment.