Effects of Acute Glycerol Ingestion on Performance, Metabolic and Biochemical Markers in International Athletes

This clinical study evaluates the acute effect of glycerol ingestion on performance (power output), weight, urine specific gravity, biochemical (antioxidants and lactate) and metabolic (indirect calorimetry) markers in international athletes in hot conditions. The investigators hypothesized that acute glycerol ingestion can prevent performance loss (power generated at submaximal intensity) in hot conditions. To justify this hypothesis, the investigators will measure the aforementioned markers, which could establish a cause-effect relationship between acute glycerol intake and decreased performance loss in hot conditions.

Study Overview

• Status: Completed
• Conditions: Antioxidative Stress; Lactate Blood Increase; Performance Enhancing Product Use; Change, Body Weight; Change, Body Temperature; Thermal Sensation Disorders
• Intervention / Treatment: Other: PLACEBO; Dietary supplement: GLYCEROL

Detailed Description

All participants will be informed about the procedures and provide signed informed consent. The study will be conducted according to the guidelines of the Helsinki Declaration for Human Research and the protocol was approved by the Ethics Committee/Institutional Review Catholic University of Murcia (Code: CE091802).

Study design

This is a randomized crossover study. There are 3 types of intervention: water intake of 26 mL/kg/weight at 16°C (CON), 26 mL/kg/weight + placebo at 28°C (PLA) and intake of 1.2 g glycerol + 26 mL/kg/weight at 28°C (GLY). In addition, athletes will be instructed to take a individualized diet in relation to macronutrients (verified by dietary record) and they will follow their adjusted training schedule so that there would be no effect on the tests. Participants in both groups will be instructed not to consume supplements 3 weeks prior to the start of the study.

Procedures

Participants will visit the laboratory on five occasions. Visit 1 consists of a medical examination and a blood draw to determine health status. At visit 2, after a dinner the night before and a standard breakfast, an incremental test will be performed to determine the exercise zones in the rectangular test. At visits 3, 4 and 5, a record of the diet (individually set) will be performed regarding the former 7 days, followed by a rectangular treadmill test.

Visit 1:

Health status blood test: A general blood test will be performed. The blood will be drawn through a vein. (Fasting) Medical examination: A medical history of family and personal history, an electrocardiogram (ECG) at rest and a medical examination (auscultation, blood pressure, etc.) will be carried out to certify that the person is healthy and is not at risk to participate in the study. (Fasting)

Visits 2:

Incremental test with final ramp test will be performed on a cycle ergometer using a metabolic cart (Metalyzer 3B. Leipzig, Germany) to determine maximal fat oxidation zone (FatMax), ventilatory thresholds 1 (VT1) and 2 (VT2) and maximal oxygen consumption (VO2max). Participants will begin cycling at 35W for 2 min, increasing then by 35W every 2 min until RER>1.05, initializing then the final ramp (+35W·min-1) until exhaustion.

Visits 3:

The rectangular test will be performed on a treadmill using the speed values obtained in the incremental test (15 sets x 2 min at 95% with 2:30 recovery at 85% of maximum speed between sets). Cardiorespiratory variables (VO2, VCO2, VO2R, VE/VO2, VE/VCO2, VE/VCO2, respiratory coefficient, respiratory frequency, carbohydrate oxidation (CHO), fat oxidation (FAT), running economy and energy expenditure) will be determined in the 1st, 5th, 10th and 15th series.

For power measurement, each participant will wear the Stryd power meter, which is an inertial sensor (9.1 g) mounted on the foot, firmly attached to the shoe and according to the manufacturer's recommendations. The device stores at a sampling rate of 1 Hz the following variables: estimated power (PO), pace, cadence, leg sprint stiffness (LSS), form power, form power ratio, ground contact time (GCT), vertical oscillation, stride length. These variables will then be determined in the 1st, 5th, 10th and 15th series of the rectangular test. According to information from the Stryd team, the device is operational out of the box and should not require any calibration, accepting a measurement error of 3 percent. Participants will fill in their height and body mass prior to use, which is required for PO estimation. The firmware version that will be used is 2.1.16 (released in August 2020).

For lactate and antioxidant measurements, a Lactate Pro 2 meter and eBQC lab will be used on finger capillary blood at rest, after the 5th, 10th and after completion of the rectangular test.

For body temperature, the investigators will use an infrared thermographic camera (FLIR) to measure heat distribution (head, trunk, lower and upper limbs in both anterior and posterior aspects of the body).

Urine Samples Urine will be collected from the intake of water or water + glycerol or water + placebo until the start of the rectangular test and up to one hour after the rectangular test. The volume of urine excreted pre and post rectangular test will be recorded and the urine specific gravity will be analyzed.

• Study Type: Interventional
• Enrollment (Actual): 4
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Spain
  • Murcia
    • La Ñora, Murcia, Spain, 30830
      • Research Center for High Performance Sport. Catholic University of Murcia

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 25 years to 35 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• Be an international athlete with the Spanish national athletics team.

Exclusion Criteria:

• Are smokers or regular alcohol drinkers,
• Have a metabolic, cardiorespiratory or digestive pathology or anomaly,
• Have an injury in the prior 6 months
• Are supplementing or medicating in the prior 2 weeks
• Have non-normal values in the blood analysis parameters.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: CONTROL; In this phase of the study, the rectangular test will be performed in conditions of 16°C and 25-30% humidity, intaking 26 mL/kg/body weight of water one and a half hours before the test.
Placebo Comparator: PLACEBO (PLA); In this intervention, subjects will perform the rectangular test at 28°C and 25-30% humidity, ingesting 26 mL/kg/body weight of water and placebo one and a half hours before the test.	Other: PLACEBO; Athletes will perform the rectangular test at a temperature of 28°C and ingested 26 mL/kg body weight + placebo one and half hours before the test.
Experimental: GLYCEROL (GLY); In this intervention, subjects will perform the rectangular test at 28°C and 25-30% humidity, ingesting 1.2 g + 26 mL/kg/body weight of water one and a half hours before the test.	Dietary supplement: GLYCEROL; Athletes will perform the rectangular test at a temperature of 28°C and ingested 26 mL/kg body weight + 1.2 g of glycerol one and half hours before the test.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Body weight	Record body weight before and after the rectangular test	Throughout study completion, an average of 3 weeks
Urine specific gravity	Record urine specific gravity by means a digital refractometer (Atago) before and after the rectangular test	Throughout study completion, an average of 3 weeks
Power output	Record the power produced by means the stryd sensor (shoe) in the 1st, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Body temperature	Record body temperature by thermography of the head, trunk, and lower limbs, anterior and posterior in rest, after 5th and 10th series, and after completion of the rectangular test	Throughout study completion, an average of 3 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Lactate	Record lactate in rest, after 5th and 10th series, and after completion of the rectangular test	Throughout study completion, an average of 3 weeks
Measurement of fast- and slow-acting antioxidants (Q1 and Q2) and total antioxidant capacity by a portable analyzer eBQC0101	Record the antioxidant markers in rest, after 5th and 10th series, and after completion of the rectangular test	Throughout study completion, an average of 3 weeks
Heart rate	Record the heart rat in rest,1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
VO2	Record the oxygen uptake (L/min) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
CO2	Record the carbon dioxide exhalation (L/min) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
RER	Record respiratory exchange ratio in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
VE	Record ventilation (L/min) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
FAT ox	Record fat oxidation (g/h) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
HC ox	Record carbohydrate oxidation (g/h) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
FR	Record respiratory frequency (breaths/min) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
EE	Record energy expenditure (kcal/h) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
V'E/V'O2	Record ventilatory equivalents for oxygen (L/min) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
V'E/V'CO2	Record ventilatory equivalents for carbon dioxide (L/min) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
VO2/R	Record oxygen consumption relative to weight (mL/min/kg) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Cadence	Record cadence (steps per minute) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Leg spring stiffness	Record leg spring stiffness (kN/m) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Form power ratio	Record form power ratio in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Form power	Record form power (W) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Ground contact time	Record ground contact time (ms) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
Vertical oscillation	Record vertical oscillation (cm) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks
PO/R	Record power output relative to weight (W/kg) in 1th, 5th, 10th and 15th series of the rectangular test	Throughout study completion, an average of 3 weeks

Collaborators and Investigators

• Sponsor: Francisco Javier Martínez Noguera
• Investigators: Study Chair: Francisco Javier Martínez Noguera, PhD, Research Center for High Performance Sport. Catholic University of Murcia

Publications and helpful links

Helpful Links

• Research Center for High Performance Sport. Catholic University of Murcia

Study record dates

Study Major Dates

• Study Start (Actual): February 10, 2022
• Primary Completion (Actual): February 25, 2022
• Study Completion (Actual): February 25, 2022

Study Registration Dates

• First Submitted: February 24, 2022
• First Submitted That Met QC Criteria: March 15, 2022
• First Posted (Actual): March 25, 2022

Study Record Updates

• Last Update Posted (Actual): March 25, 2022
• Last Update Submitted That Met QC Criteria: March 15, 2022
• Last Verified: March 1, 2022

More Information

Terms related to this study

• Keywords: Hydration; Performance; Metabolism; Thermography; Power; Oxygen uptake; Endurance Sport; Ergogenic Aids; Hyperhydration
• Additional Relevant MeSH Terms: Metabolic Diseases; Nervous System Diseases; Neurologic Manifestations; Body Weight; Body Weight Changes; Sensation Disorders; Body Temperature Changes; Somatosensory Disorders; Hyperlactatemia; Physiological Effects of Drugs; Protective Agents; Cryoprotective Agents; Glycerol
• Other Study ID Numbers: CE102102

Drug and device information, study documents

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