Skip to main content
OpenTrials
Completed

NCT Number: NCT06818253

Effect of Glycerol Hyperhydration on Running Economy of 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.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Running Behavior Motor Activity Physical Conditioning, Human

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Universidad de Guadalajara, Centro Universitario de Tonalá

Guadalajara, Jalisco, 45425, Mexico

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

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

Exclusion criteria

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

-

Treatment and study plan

The Effect of Glycerol Supplements

Dietary Supplement

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.

Primary outcomes

  1. Maximal oxygen consumption (VO₂peak) (ml/kg/min)

    Time frame: In the first evaluation session to be held in the first week of a total of 3 weeks of study duration

    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

  2. Running economy (CE)

    Time frame: In the first evaluation session to be held in the first week of a total of 3 weeks of study duration

    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).

Secondary outcomes

  1. Body temperature

    Time frame: 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.

    The temperature will be measured during the running economy evaluation with an infrared thermometer (Berrcom® JXB-178).

  2. Perception of exertion

    Time frame: It was applied during the evaluation of the stress tests to determine the Vo2peak and Running Economy.

    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

  3. Sweating rate.

    Time frame: 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.

    Fluctuations in body mass between the different sessions were evaluated.

Sponsors and collaborators

Lead sponsor

Iberoamerican Institute of Sports Science and Human Movement

Other

Collaborators

  • University of Guadalajara

Registry information

Official study title

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

Acronym: GHLDR

Important dates

Study start
2022
Primary completion
2023
Study completion
2024
First posted
Feb 10, 2025
Registry last updated
Feb 10, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.