Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT05703100 |
| Other study ID # |
2022-061 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
January 28, 2023 |
| Est. completion date |
May 11, 2023 |
Study information
| Verified date |
September 2023 |
| Source |
Technical University of Madrid |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
The goal of this clinical trial is to test whether changes in lactate kinetics during
exercise (due to glycogen depletion or hyperthermia) alter the pattern of fat oxidation
during a maximal incremental cycle ergometer test in healthy young active people. The main
questions it aims to answer are:
- Will a rightward shift in lactate kinetics, induced by a previous glycogen depletion,
produce a rightward shift in fat oxidation?
- Will a leftward shift in lactate kinetics due to an increase in ambient temperature
produce a leftward shift in fat oxidation?
Participants will perform three maximal incremental tests in three different conditions:
- one in the control condition;
- one with glycogen depletion;
- and one with ambient heat (the latter two in randomized, counterbalanced order).
Description:
Introduction Lactate has three major functions: it is an energy substrate, it is a
gluconeogenic precursor, and it is a signalling molecule (1). Among the signalling functions
is that of modulating skeletal muscle metabolism, as a regulator of fat oxidation at both the
autocrine and paracrine levels. At the autocrine level, lactate increases the levels of
Acetyl-coenzyme A (CoA) inside the mitochondria and, consequently, the levels of Malonyl-CoA.
The increase in Malonyl-CoA concentration inhibits Carnitine PalmitoylTransferase 1 (CPT1),
which is one of the transporters of fatty acids into the mitochondria (2). At the paracrine
level, an increase in blood lactate concentration reduces the release of fatty acids into the
blood by adipose tissue (3). This occurs because the G protein-coupled receptor present in
adipose tissue inhibits the release of fatty acids into the blood when the blood lactate
concentration increases (4). However, in vivo, only an inverse correlation between blood
lactate concentration and fatty acid oxidation has been demonstrated (5,6). Therefore, the
main objective of the study is to observe whether the pattern of fat oxidation during a
maximal incremental cycle ergometer trial is altered due to changes in lactate kinetics
during the given trial. For this purpose, three maximal trials will be performed with the
same loading protocol (intensity and progression of the same), but different physiological
conditions (normal vs. previous glycogen depletion vs. environmental hyperthermia).
Procedures Consent to participate (signature of informed consent) will be requested from all
volunteers who meet the inclusion criteria.
The tests that will be performed throughout this study will be the following:
1. At the first appointment, you will be asked about your medical history. Then, if
appropriate, an assessment of your body composition by dual X-ray absorptiometry (DEXA)
will be performed,
2. In the second appointment, spirometry, an electrocardiogram at rest, and finally, an
ergospirometric trial will be performed.
3. In the third, fourth, and fifth visits, three maximal exercise trials will be performed,
one each day. Of the three maximum ergospirometric trials that will be performed, one
will be in a hot environment -approximately 38º Celsius (ºC) ambient temperature- and
the other in a state of glycogen depletion. A glycogen depletion protocol and a
low-carbohydrate diet will be performed before the maximal ergospirometric trial in the
glycogen-depleted state, while the other two trials (simple maximal trial and
hot-environment maximal trial) will be performed after 24h of a high-carbohydrate diet.
4. The order of performance of each protocol will be randomized, provided that the glycogen
depletion protocol is performed at the visit prior to the maximal ergospirometric trial
under glycogen depletion. The depletion protocol consists of a 60-minute continuous
cycle ergometer effort at the power associated with 60% of the maximal oxygen uptake
(VO2) followed by six 30-second maximal efforts with four minutes of recovery. After
this glycogen depletion exercise protocol, the participant will follow a
low-carbohydrate diet (2% carbohydrate, 78% fat, and 20% protein), until the time of the
ergospirometric trial under glycogen depletion status.
