Clinical Trial Details
— Status: Not yet recruiting
Administrative data
| NCT number |
NCT05355493 |
| Other study ID # |
NIRS_EX |
| Secondary ID |
|
| Status |
Not yet recruiting |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
May 1, 2022 |
| Est. completion date |
February 29, 2024 |
Study information
| Verified date |
April 2022 |
| Source |
Vrije Universiteit Brussel |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
The experiment will consist of 3 consecutive trials performed in a sound-insulated climate
chamber (20°C and 40% RH) at the VUB. Participants will be asked to return 3 successive
weeks. Trained staff (pre-doctoral researchers and trained master students) will be present
during the experimental trials. The first visit will be a familiarization trial in which they
will complete all procedures as if it was an experimental trial, except for the
interventional 60min Stroop task. Instead of the 60-min Stroop task the participants' maximal
cognitive capacity will be determined.
The participant wil come in, perform a cognitive performance test, will then perform the
intervention/control procedure, which will be followed by an additional conduction of the
same cognitive performance test as before the intervention/control, as well as a physical
performance test (time to exhaustion cycling test). The intervention will consist of a 60 min
Stroop task, while the control trial will consist of watching a documentary of the same
duration. Multiple different questionnaires (e.g. to assess the mentally fatigued state of
participants) will be assessed throughout the experimental/control trial. The aim of this
study will be to research if mental fatigue influences prefrontal cortex oxygenation during a
time to exhaustion cycling test. Marcora et al. (2009) already showed a decrease in cycling
performance during the exact same protocol.
Description:
The investigators use a randomized, blinded, placebo controlled, counter-balanced, cross-over
design. The real purpose of the study will be hold back from the participants by recruiting
participants who are unaware of the possible negative effects of mental fatigue. We will
inform the participants in a way that explains the study as an investigation about the
influence of different cognitive tasks on a subsequent cycling. the investigators will strive
equal expectations for all the participants in both the experimental and the control trial
concerning the influence of the cognitive task on the cognitive and cycling task. At the end
of the last trial the investigators will ask a standardized question to follow up on their
thoughts about the objective of the study.
The experiment will consist of 3 consecutive trials performed in a sound-insulated climate
chamber (20°C and 40% RH) at the VUB. Participants will be asked to return 3 successive
weeks. Trained staff (pre-doctoral researchers and trained master students) will be present
during the experimental trials. During the first visit, subjects will read and sign the
informed consent and get a thorough explanation of what is expected from them, afterwards
they will have the possibility to ask questions. After signing, participants complete a
familiarization trial in which they will complete all procedures as if it was an experimental
trial, except for the 60min cognitive task. Instead of the 60-min cognitive task the
participants' maximal cognitive capacity will be determined. Therefore, a Stroop task divided
in blocks of 96 stimuli will be used. After each block, the accuracy (ACC) will be
calculated. When the ACC is higher than 85%, the difficulty of the Stroop task will be
increased by decreasing the stimulus presentation time (SPT). If the ACC is lower than 85%,
this block will be considered as an 'error' and the subject must re-do the block without
changing the SPT. The first block will have a SPT of 1500 ms and will have the main objective
to get familiar with the task. When the required accuracy is achieved, the SPT will decrease
in the following order: 1100, 900, 800, 700, 650, 600, 550 ms… to determine the individual
cognitive load. Before the start of each block, the subjects will be able to take a break if
they like. When the subject makes three errors in a row, or five errors during the whole
trial, the trial is considered as completed and will be ended. The SPT of the last,
successfully completed block will be considered as the maximum capacity of that individual
and will be used to individualize the difficulty of the 60-min Stroop task. There will be a
continuous feedback of the performance to motivate the subjects, as this has been pointed out
by Kurzban et al. to be important for task-engagement.
The next two trials will be performed in a counterbalanced randomized order, a mental fatigue
trial (MF) and a control trial (CON). Randomization will be assured by using a web-based
computer program (www.randomization.com) to determine treatment order (MF or CON trial; see
intervention for details). All trials will be separated by at least 5 days to ensure full
recovery.
After arrival at the laboratory for the experimental trials, participants will be asked to go
to the toilet, after which they enter the climatic chamber which has reached 20°C and 40%RH.
Participants will have to fill in 2 questionnaires (~3min) to estimate mood and motivation.
NIRS equipment will be applied. The NIRS-optode pair will be applied prefrontally. NIRS
measurement will start to verify hemodynamic changes during the absorption period.
Physiological measures (HR, SaO2, BP, Hb, Respiratory Rate (RR), Glucose, NIRS, ventilation
(VE), Blood lactate (BL) will be recorded.
Go/NoGo. As a manipulation check, the Go/NoGo paradigm task will be used to assess cognitive
performance as suggested by Guo et al. (2018) and Kato et al. (2009). Participants are to
react to different stimuli displayed on a computer screen positioned about 1 meter from the
subject, preceded by a screen with general instructions. Two different stimuli were present
at the same time: a Go or NoGo stimulus, and a left or right stimulus (meaning that four
combinations are possible: GoRight, GoLeft, NoGoRight and NoGoLeft). If a Go-stimulus is
presented, participants are instructed to react to the left or right stimuli with the
corresponding arrows. However, if a NoGo stimulus is presented, participants are instructed
to refrain from reacting to the either the left or right stimuli. This proposed paradigm
measures attention, response inhibition and working memory, executive functions who are all
consistently negatively impacted by MF. Stimuli will be presented for 500 ms, with a varying
interstimulus time between 1100 and 1700 ms. Outcomes for Go trials include reaction time and
accuracy while the outcome for NoGo trials is only accuracy. The ratio of Go/NoGo trials will
be 80 to 20% respectively. Since the trials concern seven different interstimulus times, 1
cycle of trials consists of 56 Go and 14 NoGo trials. Moreover, to consistently detect large
ERP's, research has suggested that between 30 and 40 stimuli should be present. Therefore, to
be able to investigate ERP's in NoGo trials, at least 3 cycles are necessary to complete,
leading to a tot task duration of about 6,5 min (taken into account a mean trial duration of
1900 ms).
Mental fatigue task:
A modified Stroop task, based on their performance during max test (familiarization session)
of approximately 60 min, partitioned in 6 blocks of 336 stimuli, will be used as the mentally
fatiguing task. In this task, four colored words ("rood", "blauw", "groen" and "geel") will
be presented one at a time on a computer screen. The participants will be required to
indicate the color of the word, ignoring the meaning of the word itself. If, however, the ink
color is red, the button to be pressed will be the button linked to the real meaning of the
word, not the ink color. The word presented and its ink color will be randomly selected by
the computer (100% incongruent), with all incongruent word-color combinations being equally
common (meaning, in each block 84 words will be presented in the color red, yellow, green and
blue). Each word will be presented on screen in 34 point font for 1000 ms with an
inter-stimulus interval based on their performance on the max test. Subjects will be
instructed to respond as quickly and accurately as possible. To assess performance accuracy
(ACC) and reaction time (RT) will be collected and averaged every block. Each of the 6 blocks
will be separated by a 30-s period during which stimuli will keep presenting themselves, but
where the researchers will assess the mental fatigue visual analog scale (M-VAS). Subjects
will be asked to draw a line with their dominant hand on the M-VAS and to continue answering
using their non-dominant hand for the four different stimuli. Stroop Task results from these
30-s periods will not be taken into account so that participants can fill in the M-VAS scale
and reset there focus on the Stroop Task. During each block, NIRS, HR, RR and SaO2 data will
be assessed and averaged.
Control task:
In the control task subjects will have to watch a documentary during 60 min on the same
computer screen as that used for the experimental trial. In order to avoid under- and
over-arousal the subjects will have the opportunity to choose between several episodes (One
Planet, Frozen Worlds, Jungles, Costal Seas, From Desserts to Grasslands, The High Seas,
Fresh Water and Forests) of the Netflix documentary "Our Planet, 2019" as proposed by the
research team. During the control task physiological and psychological measures will be
assessed at the same time points as during the mental fatigue trial.
Time to exhaustion cycling test (TTE):
After completing the MF- or control task. Participants will be asked to take place on the
(propositioned) cycle ergometer (Lode Excalibur Sport, Groningen, The Netherlands). After 2
minutes of passive sitting on the ergometer a 2-minute NIRS-baseline will be measured. When
all baseline measures have been collected, participants will perform a 3-min warm-up at 40%
of peak power output followed by a rectangular workload at a power output corresponding to
their predetermined respiratory compensation point (±80% peak power output). Pedal frequency
was freely chosen between 60 and 100 RPM and was recorded every minute. TTE was measured from
the start of the rectangular workload until the pedal frequency was less than 60 RPM for more
than 5 s despite standardized verbal encouragement provided by a research assistant blind to
treatment allocation. This TTE task was chosen, based on a previous study of Marcora et al.
(2009), who found that mental fatigue impairs physical performance. A researcher will sit
behind the subject to ensure compliance with treatment. Subjects will be equipped with a
heart rate monitor to continuously follow up heart rate (HR). Subjective psychological
assessment will take place with a M-VAS-scale, the National Aeronautics and Space
Administration Task Load Index (NASA-TLX), the success motivation and intrinsic motivation
scales developed and validated by Matthews et al., Karolinska Sleepiness Scale (KSS) and
visual analog scale for boredom (B-VAS).
