The Impact of Self-assessment on Hydration

The Impact of Self-assessment on Wildland Firefighter and Surrogate Population Hydration

The studies objective is to assess the efficacy of hydration education and the use of a self-assessment worksheet vs. a no-intervention control on improving fluid intake and hydration status in underhydrated wildland firefighters (WLFFs) and their surrogates.

Part I allows to understand hydration status of the participants (screening phase), Part II confirms if participants indeed are deemed to be low fluid consumers, and Part III of this research is a clinical trial that will focus on the optimization of hydration by improving fluid intake (and as a result lowering urine concentration) allowing participants theoretically to improve exercise performance (acute) and optimize health on the long term.

Study Overview

• Status: Enrolling by invitation
• Conditions: Hydration Status
• Intervention / Treatment: Behavioral: Hydration education and self-assessment

Detailed Description

Enrollment will take place until enough people have been screened and be eligible to be enrolled in PART III of the study.

Aside from allowing the investigators to better understand the hydration status of participants in PART I, this part will help to determine potentially eligible participants that can be confirmed through PART II by collecting again a urine sample, and if again concentrated urine is confirmed the research team will take a 5 mL venous blood draw performed by a trained phlebotomist to confirm elevated a copeptin level. These confirmed participants can then be enrolled in PART III of the study when eligible.

PART I includes all participants:

Two urine samples and questionnaire at one day. Expected duration of 2-3 minutes per urine sample and 2-3 minutes for the participant demographics questionnaire which will also be used as a screener to identify eligibility for PART II and III.

PART II includes a smaller sample:

Collection of a urine sample and a blood sample at one follow up day for the duration of 10 minutes.

PART III, the intervention study (being a clinical trial):

Includes n=38 participants, that will invest a maximum of 2 hours and 15 minutes as part of the data collection over a period of 6 days, which includes:

• Education session (pre: INT, or post: CON) of 25 minutes.
• Consuming labelled water and providing a urine sample and bodyweight the day before the start of the study, 10-15 minutes.
• Participate in the study for 6 days (during normal work days) and bodyweight will be measured at day 2, 4 and 6 of the study, during all study days both INT and CON will provide a morning urine sample (and if possible an afternoon/evening sample after work), and during each days sensors will be attached to participants upper arm and gear, 5 minutes per day, 25-30 minutes total.
• The intervention group will track its use of the tools we have provided them with, while the other group will not perform any additional self-assessments during the study period, 10 minutes per day 25-50 minutes total.
• Final hydration strategy questionnaire for INT and CON, 5-10 minutes.

Allocation to INT or CON depends on the total number of participants at different locations that will be eligible. The investigators will try to match participants based on their sex, age and bodyweight, and then randomly assign these matched participants to the intervention or placebo.

• Study Type: Interventional
• Enrollment (Estimated): 38
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Arizona
    • Phoenix, Arizona, United States, 85054
      • ASU Health Futures Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

The study plans to include firefighters from the Tonto National Forest and the broader Phoenix Valley area, and if needed, other active populations that are similarly active to WLFFs. Participants with high urine concentration (≥1.020 USG) for both samples collected during Part I (screening phase), may be invited to provide an additional urine sample and a blood sample for copeptin analysis during a follow up day (Part II). Participants with elevated USG and copeptin are eligible to participate in the study.

Inclusion for PART I is that participants are part of a by the research selected wildland firefighter population (or surrogate population), no further exclusion criteria are followed for PART I. For Part II and Part III the following criteria apply:

Inclusion Criteria:

• Age 18-65 years
• Identifying as male, female or other

Exclusion Criteria:

• Thyroid medication
• Bariatric surgery
• Cardiovascular disease
• Renal disease
• Hepatic disease
• Bodyweight <110 lbs.
• Any injury that would not allow physical performance or activity
• Pregnant or lactating
• Diuretics
• Non-stable self-reported body weight for the last month (<10 lbs. fluctuation)

Investigators will not exclude participants reporting the use of dietary supplements as there is no evidence that the accuracy of self-assessment (specifically the accuracy of urine color assessment) to determine a low vs. high urine concentration is influenced by dietary supplement use, but participants will be questioned about their supplement, electrolyte and sport drink use.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Hydration education and hydration self-assessment; Participants will participate in a 25-minute hydration education session that also includes instruction about how the use the hydration self-assessment worksheets and materials.	Behavioral: Hydration education and self-assessment; Hydration education is a 25-minute session based on the theory of planned behavior, including the instructions how to use a worksheet for hydration self-assessment and materials.
No Intervention: No Hydration education and hydration self-assessment (business as usual); Participants do not participate in any education or self-assessment, other than applying their normal hydration strategies.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fluid turnover	Fluid turnover based on D2O analysis	Over a period of 4 days, in two 48-hour segments.
Urine concentration	Urine concentration (osmolality).	Afternoon sample day 1, morning sample day 2/4/6

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urine concentration	Urine concentration (USG ) for morning and when available afternoon/evening samples.	Afternoon sample day 1, morning (and potential afternoon) samples day 1/2/3/4/5/6.
Activity	Activity pattern using an activity tracker attached to the upper arm to allow comparing activity between INT and CON.	Throughout the study during working hours, which may vary between 8-16 hours per working day.
Hydration strategy	Retrospective hydration strategy (questionnaire) of INT and CON.	Day 6 of the data collection, covering the hydration strategy during the study period.
Heat stress	Direct experienced environmental heat, measured by a heat sensor mounted on helmet or gear.	Throughout the study during working hours, which may vary between 8-16 hours per working day.
INT: Self-reported hydration measures	Self-reported hydration measures in INT only (daily fluid intake in mL).	Study days 2/3/4/5/6.
INT: Self-reported hydration measures	Self-reported hydration measures in INT only (urine frequency, number of voids per 24-hour).	Study days 2/3/4/5/6.
INT: Self-reported hydration measures	Self-reported hydration measures in INT only (first morning urine volume in mL).	Study days 2/3/4/5/6.
INT: Self-reported hydration measures	Self-reported hydration measures in INT only (urine color, assessed on a scale from 1-7 ranging from light to dark).	Study days 2/3/4/5/6.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Demographics	Personal demographics, such as age, sex, race, ethnicity, work location, work status, short medical history, use of medication, use of dietary supplements, electrolyte and sports drinks, alcohol and tobacco use (questionnaire)	Measured at the start of the study during Part I (screening phase).
Environmental conditions	Environmental measurements using a local weather station to be able to report ambient temperature in degrees Celsius.	Throughout the study during working hours, which may vary between 8-16 hours per working day.
Environmental conditions	Environmental measurements using a local weather station to be able to report relative humidity (%).	Throughout the study during working hours, which may vary between 8-16 hours per working day.
Environmental conditions	Environmental measurements using a local weather station to be able to report solar radiation in watts per square meter (W/m2 = Wm-2).	Throughout the study during working hours, which may vary between 8-16 hours per working day.

Collaborators and Investigators

• Sponsor: Arizona State University
• Collaborators: Federal Emergency Management Agency

Publications and helpful links

General Publications

• Wardenaar FC, Thompsett D, Vento KA, Bacalzo D. A lavatory urine color (LUC) chart method can identify hypohydration in a physically active population. Eur J Nutr. 2021 Aug;60(5):2795-2805. doi: 10.1007/s00394-020-02460-5. Epub 2021 Jan 8.

Study record dates

Study Major Dates

• Study Start (Actual): April 22, 2025
• Primary Completion (Actual): February 12, 2026
• Study Completion (Estimated): December 30, 2026

Study Registration Dates

• First Submitted: April 17, 2025
• First Submitted That Met QC Criteria: April 30, 2025
• First Posted (Actual): May 2, 2025

Study Record Updates

• Last Update Posted (Actual): May 8, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Women; Healthy subjects; Education; Men; Self-assessment; Firefighters; Deuterium; Urine osmolality; Urine specific gravity; Labelled water (D20); Tactical operators
• Additional Relevant MeSH Terms: Endocrine System Diseases; Neoplasms by Site; Neoplasms; Genetic Diseases, Inborn; Endocrine Gland Neoplasms; Neoplastic Syndromes, Hereditary; Neoplasms, Multiple Primary; Multiple Endocrine Neoplasia; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Multiple Endocrine Neoplasia Type 1; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Self Evaluation
• Other Study ID Numbers: EMW-2022- FP-00082 (Other Grant/Funding Number: DHS: Federal Emergency Management Agency (FEMA))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No