Effect of Glycerol Hyperhydration on Running Economy of Long-distance Runners (GHLDR)

Effects of Glycerol Hyperhydration on Running Economy in Long-Distance Runners

The aim of this study was to evaluate the effects of hyperhydration with glycerol on running economy (RE) in trained runners. The main questions sought to be answered are:

1. Does hyperhydration with glycerol improve running economy?
2. Are there beneficial effects on physical performance?

The researchers will conduct a clinical trial with 30 runners (15 men, 15 women) in three sessions. In the first session, VO2peak was determined and running speeds were established for sessions 2 and 3. In the second session, participants performed a stress test. In the second session, participants performed a running test in the euhydrated state under fluid restriction, and in the third session, with glycerol supplementation (22 ml/kg sports drink + 1.2 g/kg glycerol). Variables such as caloric cost unit (CCU), oxygen cost unit (OCU), heart rate (HR), body temperature (BT) and perceived exertion (RPE) were evaluated.

Study Overview

• Status: Completed
• Conditions: Running; Physical Conditioning, Human
• Intervention / Treatment: Dietary supplement: The Effect of Glycerol Supplements

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Mexico
  • Jalisco
    • Guadalajara, Jalisco, Mexico, 45425
      • Universidad de Guadalajara, Centro Universitario de Tonalá

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

1. Competitive runners with a minimum record of 4.2 min/km.
2. Age between 18 and 35 years old
3. Apparently healthy athletes
4. Signature of informed consent form

Exclusion Criteria:

1. Presence of comorbidities that could alter the study variables (such as arterial hypertension, hyperthyroidism or heart disease).
2. Consumption of medications or stimulants (such as caffeine or diuretics) 48 hours before the tests.

3. Pregnancy.

   -

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Arm glycerol supplementation; This arm participated in a crossover design allowed minimizing interindividual variability by using each participant as their own control, evaluating the conditions of (1) hyperhydration with glycerol and (2) water restriction. The main variables evaluated were maximal oxygen consumption (VO₂max), running economy (CE), calculated using the oxygen cost unit (OCU) and caloric cost unit (CCU), as well as body temperature, perception of exertion and sweating rate.

Dietary supplement: The Effect of Glycerol Supplements; The main factor that distinguishes this intervention is first of all the dosage of the dietary supplement and the effects on the variables to be analyzed related to physical performance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximal oxygen consumption (VO₂peak) (ml/kg/min)	Session 1: VO2peak measurements through an incremental treadmill test with 2 km/h speed increments every 3 minutes, maintaining a constant 1% incline. The test started at 6 km/h for all participants and continued until volitional exhaustion	In the first evaluation session to be held in the first week of a total of 3 weeks of study duration
Running economy (CE)	Test under Hydration Restriction (No-GLY): As a mandatory requirement, participants reported to the laboratory in a euhydrated state (USG: 1.018-1.024) prior to the start of the test, following the criteria outlined in previous research [31]. They ran for 15 minutes on a treadmill at a speed equivalent to 65%-70% of their VO2peak from the first session. During the test, running economy variables such as the caloric cost unit (CCU), oxygen cost unit (OCU), body temperature (BT), rating of perceived exertion (RPE) via the Borg scale, and hydration status were measured. Running Economy Calculation: i) The caloric cost unit (CCU) was calculated via the following equation [25]: CCU =((VO2 x δ x 1000)/(V x MC)) x 100 where VO2 is the oxygen consumption rate (L/min); δ is the kcal/L of oxygen based on the respiratory exchange ratio (RER); V is the speed (m/min); and MC is the body mass (kg).	In the first evaluation session to be held in the first week of a total of 3 weeks of study duration

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body temperature	The temperature will be measured during the running economy evaluation with an infrared thermometer (Berrcom® JXB-178).	Body temperature was measured during sessions 2 (No Gly) and 3 (Gly) at the following times: at minute 0 (prior to the start of each test) and at minutes 5, 10 and 15 during a treadmill test.
Perception of exertion	The Borg effort perception scale, with a range of scores from 6 to 20, was used during the three sessions, recording the perception of effort in each minute of the test according to the following classification: 6-7: Very very very light; 8-9: Very light; 10-11: Light; 12-13: Regular; 14-15: Heavy; 16-17: Very heavy; 18-19-20: Very very heavy	It was applied during the evaluation of the stress tests to determine the Vo2peak and Running Economy.
Sweating rate.	Fluctuations in body mass between the different sessions were evaluated.	In sessions 1 and 2, urine specific gravity (USG) was assessed, which was one of the key criteria for determining whether subjects could continue in the study without being eliminated.

Collaborators and Investigators

• Sponsor: Iberoamerican Institute of Sports Science and Human Movement
• Collaborators: University of Guadalajara

Publications and helpful links

General Publications

• Jolicoeur Desroches A, Naulleau C, Deshayes TA, Parent-Roberge H, Pancrate T, Goulet EDB. Effect of Glycerol-Induced Hyperhydration on a 5-kilometer Running Time-Trial Performance in the Heat in Recreationally Active Individuals. Nutrients. 2023 Jan 24;15(3):599. doi: 10.3390/nu15030599.

Study record dates

Study Major Dates

• Study Start (Actual): November 10, 2022
• Primary Completion (Actual): October 13, 2023
• Study Completion (Actual): January 13, 2024

Study Registration Dates

• First Submitted: January 25, 2025
• First Submitted That Met QC Criteria: February 4, 2025
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: February 4, 2025
• Last Verified: January 1, 2025

More Information

Terms related to this study

• Keywords: thermoregulation; Glycerol; athletic performance; running; sports nutritional sciences
• Additional Relevant MeSH Terms: Metabolic Diseases; Chemically-Induced Disorders; Water-Electrolyte Imbalance; Poisoning; Water Intoxication; Physiological Effects of Drugs; Protective Agents; Cryoprotective Agents; Glycerol
• Other Study ID Numbers: IICDEM-ID-001-2022

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
• product manufactured in and exported from the U.S.: No