Effect of Glycerol Hyperhydration on Running Economy of Long-distance Runners

Iberoamerican Institute of Sports Science and Human Movement30 enrolled

Overview

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 Type

INTERVENTIONAL

Allocation

Purpose

TREATMENT

Masking

NONE

Enrollment

Conditions

Running Physical Conditioning, Human

Interventions

Outcomes

Primary Outcomes

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

Time frame: 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).

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

Secondary Outcomes

Body temperature

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

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.

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

Time frame: 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.

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.