Caffeine and Hypoxia During Exercise in Males and Females

NCT05764018 | Completed

• 1 other identifier: HypoCaff
• Study Type: interventional
• Target: 29
• Locations: 1 country
• Sites: 1

Brief Summary

Several high-altitude destinations recommend their visitors to avoid caffeine, theoretically due to the associated diuresis which could contribute to acute mountain sickness. There is however no direct evidence for this association. In fact, caffeine ingestion is known to improve exercise performance at sea level, and may therefore help mountaineers during expeditions. Sport science research is largely conducted in male participants, and the findings from these studies are assumed to apply to the female population. Given the known sex differences in body composition, hormones, and other physiological factors, this may not be appropriate. It is therefore important to conduct research in women, to allow for female-specific recommendations.

Conditions

Caffeine; Hypoxia

Keywords

Caffeine; Hypoxia; Female physiology; Exercise

Outcome Measures

Primary Outcomes (6)

• Peak oxygen uptake

  Peak oxygen consumption (VO2peak, ml/kg/min) will be quantified from the end of each maximal exercise test and compared between groups and conditions.

  Immediately prior to volitional exhaustion during the incremental exercise test

• Maximal aerobic power

  Maximal aerobic power (MAP, W) will be quantified based on the time at which participants reach volitional exhaustion during the incremental exercise tests. This value will then be compared between groups and conditions.

  At the instant of volitional exhaustion during the incremental exercise test

• Peak minute ventilation

  Peak minute ventilation (VEpeak, L/min) will be quantified from the end of each maximal exercise test and compared between groups and conditions.

  Immediately prior to volitional exhaustion during the incremental exercise test

• Peak heart rate

  Peak heart rate (HRpeak, bpm) will be quantified from the end of each maximal exercise test and compared between groups and conditions.

  Immediately prior to volitional exhaustion during the incremental exercise test

• Muscle oxygenation nadir

  The nadir in muscle oxygenation (TSIMmin, %) will be quantified from the end of each maximal exercise test and compared between groups and conditions.

  Immediately prior to volitional exhaustion during the incremental exercise test

• Peak blood lactate concentration

  Blood lactate concentration will be measured immediately after the incremental exercise test to exhaustion (\[BLapeak\], mmol/L).

  Immediately after volitional exhaustion during the incremental exercise test

Secondary Outcomes (9)

• Submaximal oxygen uptake

  From the onset of exercise to the end of the submaximal exercise period at 20 minutes.

• Submaximal minute ventilation

  From the onset of exercise to the end of the submaximal exercise period at 20 minutes.

• Submaximal substrate oxidation

  From the onset of exercise to the end of the submaximal exercise period at 20 minutes.

• Submaximal muscle oxygenation

  From the onset of exercise to the end of the submaximal exercise period at 20 minutes.

• Submaximal brain oxygenation

  From the onset of exercise to the end of the submaximal exercise period at 20 minutes.

Study Arms (4)

Normoxia-Placebo

PLACEBO COMPARATOR

Participants will be breathing room air, and ingest a flavoured drink containing only a trivial amount of maltodextrin.

Other: Placebo; Other: Normoxia

Normoxia-Caffeine

EXPERIMENTAL

Participants will be breathing room air, and ingest a flavoured drink containing a trivial amount of maltodextrin and 6 mg/kg body mass caffeine.

Dietary Supplement: Caffeine; Other: Normoxia

Hypoxia-Placebo

PLACEBO COMPARATOR

Participants will be breathing a 13% oxygen gas mixture, and ingest a flavoured drink containing only a trivial amount of maltodextrin.

Other: Hypoxia; Other: Placebo

Hypoxia-Caffeine

EXPERIMENTAL

Participants will be breathing a 13% oxygen gas mixture, and ingest a flavoured drink containing a trivial amount of maltodextrin and 6 mg/kg body mass caffeine.

Dietary Supplement: Caffeine; Other: Hypoxia

Interventions

Caffeine DIETARY_SUPPLEMENT

Negligible amount of maltodextrin in flavoured drink solution containing 6 mg/kg body mass caffeine provided 45 minutes before exercise

Hypoxia-Caffeine; Normoxia-Caffeine

Hypoxia OTHER

Participants will be breathing from a hypoxic gas mixture (13% O2) for the duration of the exercise bout. This will simulate an altitude of approximately 3500 m.

Also known as: Simulated altitude

Hypoxia-Caffeine; Hypoxia-Placebo

Placebo OTHER

Negligible amount of maltodextrin in flavoured drink solution provided 45 minutes before exercise.

Also known as: No caffeine

Hypoxia-Placebo; Normoxia-Placebo

Normoxia OTHER

Participants will be breathing from ambient air (\~21% O2) for the duration of the exercise bout. This will provide no hypoxic stimulus as the laboratory is located relatively near sea level (295 m)

Also known as: Sea level

Normoxia-Caffeine; Normoxia-Placebo

Eligibility Criteria

• Age: 18 Years - 30 Years
• Gender Eligibility Details: Participant eligibility is based on self-representation of gender identity. Self-identifying males and self-identifying females will be recruited for the study, and will form the two groups for comparison.
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Regularly physically active (at least 30 mins of structured exercise 5 times per week).
• Sea-level natives.

You may not qualify if:

• presence of any medical risk factors to exercise and/or exposure to altitude
• presence of any medical condition that would make the protocol unreasonably hazardous for the participant
• smokers
• exposure to altitude above 2000 m in the last 2 months

Sponsors & Collaborators

• Jozef Stefan Institute: lead

Study Sites (1)

University of Ljubljana

Ljubljana, 1000, Slovenia

Location

MeSH Terms

Conditions

Hypoxia; Motor Activity

Interventions

Caffeine; Sea Level Rise

Condition Hierarchy (Ancestors)

Signs and Symptoms, Respiratory; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Behavior

Intervention Hierarchy (Ancestors)

Xanthines; Alkaloids; Heterocyclic Compounds; Purinones; Purines; Heterocyclic Compounds, 2-Ring; Heterocyclic Compounds, Fused-Ring; Oceans and Seas; Geological Phenomena; Physical Phenomena; Climate Change; Climatic Processes; Ecological and Environmental Phenomena; Biological Phenomena; Water Movements

Study Officials

• Tadej Debevec, PhD

  University of Ljubljana

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: The participant will be blinded to both the supplement (placebo vs. caffeine) and the condition (normoxia vs. hypoxia). The investigator and the outcomes assessor will also be blinded to the supplement (placebo vs. caffeine), but both will be aware of condition (normoxia vs. hypoxia). Blinding success from the participants' perspectives will be assessed with an exit questionnaire.
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Model Details: Participants will perform four trials, to cover both levels of two factors; normoxia vs. hypoxia, and placebo vs. caffeine

Study Record Dates

• First Submitted: February 17, 2023
• First Posted: March 10, 2023
• Study Start: March 6, 2023
• Primary Completion: March 19, 2024
• Study Completion: March 19, 2024
• Last Updated: August 12, 2024

Record last verified: 2024-08

Data Sharing

• IPD Sharing: Will not share

Locations

SL (1)