Caffeine Increases Maximal Fat Oxidation During Exercise in Endurance-trained Men: is There a Diurnal Variation

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT04320446

Enrollment

Registered

2020-03-25

Start date

2019-06-01

Completion date

2019-11-30

Last updated

2020-03-25

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Athletic Performance, Energy Metabolism

Brief summary

Maximal fat oxidation during exercise (MFO) and the intensity of exercise that elicits MFO (Fatmax) has been recognized as potential determinants of endurance performance. The purpose of this study was to determine the possible interaction between the effects of diurnal variation (morning vs. afternoon) and caffeine ingestion on MFO, Fatmax and VO2 max in endurance-trained men. Specifically, the investigators sought to elucidate whether the stimulant actions of caffeine could reverse the decrements of MFO and Fatmax observed in the morning.

Detailed description

Body weight, height, body composition (DXA), exercise test (MFO and VO2max assessment) will be measured during the 4 evaluations. Participants were randomized into 4 exercise test conditions: 1. Exercise test in the morning with placebo intake 2. Exercise test in the evening with placebo intake 3. Exercise test in the morning with caffeine intake 4. Execrise test in the evening with caffeine intake

Interventions

BEHAVIORALTest in the morning

The exercise test was performed between 8 a.m and 11 a.m

BEHAVIORALTest in the afternoon

The exercise test was performed between 5 p.m. and 8 p.m.a

Study design

Allocation

RANDOMIZED

Intervention model

CROSSOVER

Primary purpose

OTHER

Masking

TRIPLE (Subject, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

MALE

Age

18 Years to 40 Years

Healthy volunteers

Yes

Inclusion criteria

* Having a body mass index (BMI) ranged from 18.5 to 28 kg/m2 * not suffering any specific disease which can be aggravated by physical exercise * having previous experience in endurance training (i.e. self-reporting at least 2 years of cycling or running training including more than 3 training sessions/week). * Participant must be capable and willing to provide consent, understand

Exclusion criteria

, instructions and protocols.

Design outcomes

Primary

Measure	Time frame	Description
MFO	Through study completion, an average of 1 month	Maximal fat oxidation during exercise

Secondary

Measure	Time frame	Description
FATmax	Through study completion, an average of 1 month	The intensity of exercise that elicits MFO
VO2max	Through study completion, an average of 1 month	Cardiorrespiratory fitness measured by maximal oxygen uptake

Countries

Spain

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 16, 2026