Clinical Research Directory

Phosphatidylserine, Taurine, and Caffeine for Cognitive Fatigue in Professional Football Players

This randomized, double-blind, placebo-controlled, parallel-group trial will evaluate the effects of 14 days of taurine-caffeine supplementation with or without phosphatidylserine on neurocognitive fatigue resistance, visual search efficiency, and football-specific tactical decision-making in professional male football players. Sixty-two male outfield football players from two professional clubs will be randomized to placebo, taurine plus caffeine, or taurine plus caffeine plus phosphatidylserine. Laboratory and field-based outcomes will be assessed at baseline and after the supplementation period.

A Multi-Dimensional Comparative Study of Exercise Psychological Experience Under AI Fitness Companion and Human Coach Paradigms

This study conducted a comparative analysis of subjective exercise experiences between an AI-based fitness companion and traditional human coaching among 98 university students participating in a standardized 20-minute functional circuit training session. Participants were evaluated across three psychological dimensions: Emotional Resonance (ER), Interactive Dynamics (InD), and Embodied Presence (EP). The results indicated that human coaching elicited significantly higher levels of Emotional Resonance, whereas AI-based companions demonstrated superior performance in Interactive Dynamics. No significant differences were observed in Embodied Presence, suggesting that contemporary AI systems can provide spatial immersion and body-awareness comparable to human coaches. These findings indicate that AI and human coaches offer distinct psychological strengths, suggesting that AI should be viewed as a complementary, scalable tool for exercise guidance rather than a direct replacement for human emotional support.

Virtual Reality Training on Technical Skills, Training Load and Mental Fatigue in Football

Virtual reality (VR) technology has emerged as a promising supplementary training tool in football, yet no study has simultaneously examined its effects on technical skills, training load, and mental fatigue within a randomized controlled design. This study evaluated the effects of an 8-week Rezzil Index® VR training program on football-specific technical skills, training load (sRPE), and mental fatigue in licensed male football players. Twenty-four male football players (age: 18.82±0.85 years) were randomly assigned to a VR training group (n=12) or a control group (n=12). The VR group completed two supplementary sessions per week using the Rezzil Index® application (HTC Vive Pro and Oculus Quest 2) in addition to regular team training. Football-specific technical skills, mental fatigue (Modified Color-Word Stroop Test), and training load (session RPE) were assessed pre- and post-intervention. The VR group demonstrated statistically significant improvements in all technical skill measures (p\<0.05; d=0.91-1.69, large effects). Rezzil Index® VR training is an effective complementary method for improving football-specific technical skills.

Cognitive Reserve and Post-Fatigue Recovery in Older Adults

As people grow older, it is common to experience a drop in physical stamina and memory functions. This can make recovering from daily physical and mental fatigue more difficult, which directly impacts an individual's independent daily life and overall quality of life. "Cognitive reserve" is a term that describes the brain's built-in resilience. Built over a lifetime through education, work, and social activities, a higher cognitive reserve acts like a buffer, helping the brain adapt to stress and aging. While research shows that a high cognitive reserve protects against conditions like dementia, we still do not fully understand how it helps older adults bounce back from normal, everyday physical and mental exhaustion. The goal of this study is to investigate how cognitive reserve levels influence how individuals aged 65 and older perceive their recovery after experiencing physical and mental fatigue. What the Study Involves The researchers will evaluate participants aged 65 and older to measure their baseline cognitive reserve levels. The study will look closely at how these levels affect the participants': Ability to cope with daily physical and mental fatigue. Need for rest and rest patterns. Time and ability to return to normal daily activities. Overall perception of their mental and physical recovery. Expected Outcome By understanding this relationship, the study aims to fill a gap in medical literature and help healthcare providers design better, more personalized rehabilitation and lifestyle support programs to improve the quality of life for older adults.

Psychological Impacts of Exercise Snacks Versus Traditional Exercise: A Comparative Study

This study investigates the comparative psychological impacts of a high-frequency "Exercise Snacks" (ESG) protocol versus a traditional continuous exercise (TEG) regimen on healthy young adults. Utilizing a randomized controlled trial design over a 4-week longitudinal period, 180 participants were allocated into two groups of 90, with a standby recruitment protocol employed to ensure sample size stability. The intervention was standardized to equate total weekly exercise volume at 90 minutes. The TEG cohort performed 30-minute continuous cycling sessions three times per week, whereas the ESG cohort executed 15-minute distributed cycling sessions six times per week. To ensure physiological homogeneity and precision in workload prescription, individual baseline maximal aerobic capacity was assessed via incremental cardiopulmonary exercise testing. Based on these individual thresholds, exercise intensity for both cohorts was rigorously maintained at 40% of their respective maximal aerobic capacity throughout the intervention. Psychometric outcomes were evaluated within 24 hours of the intervention's conclusion, focusing on three dimensions: Perceived Stress, Decision Fatigue and Cognitive Load, and Physical Activity Enjoyment. By applying Lazarus and Folkman's Transactional Model of Stress and Coping, Sweller's Cognitive Load Theory, and Self-Determination Theory, this research examines how fragmented exercise protocols interact with daily workflow and self-regulatory resources. The findings provide critical insights into the real-world viability, behavioral resistance, and psychological divergence associated with high-frequency, fragmented exercise routines compared to conventional models.

Sleep, Mental Fatigue, and Performance in Students

This observational, prospective, within-subject study will examine how the volume and timing of physiotherapy and psychology classes and exams at LUDES Institute influence mental fatigue, sleepiness, motivation, executive function, and physical performance in university students. Approximately 30 students aged 18 years or older will complete repeated assessments at baseline (no formal academic activities), during a regular theoretical class, and, when feasible, during an exam session. At each time point, participants will undergo non-invasive measurements including self-reported mental fatigue (visual analogue scale), sleepiness (Karolinska Sleepiness Scale), motivation (Motivational States Scale), cognitive performance (Encephalapp Stroop task), and handgrip strength and endurance with perceived exertion ratings, alongside sleep diaries and wrist actigraphy. The primary endpoint is the pre-to post-session change in mental fatigue and cognitive performance, with secondary endpoints capturing sleep and circadian metrics, physical performance, motivation, and exam grades. Mixed-effects models will be used to test how class/exam duration, time of day, sleep quantity and quality, and chronotype relate to psychobiological responses, with the goal of informing evidence-based scheduling and workload policies in health-profession education.

Mental Fatigue Effects on Posture and Spinal Reflexes

This randomized crossover study investigates the effects of mental fatigue on postural control and spinal reflex excitability in healthy physically active adults aged 18-35 years. Participants will complete two experimental conditions: a mentally fatiguing Stroop task and a control condition involving passive documentary watching, separated by at least 48 hours. Postural control will be assessed using force plate measures of center of pressure displacement during bipedal and unipedal stance, with and without concurrent cognitive dual-tasking. In parallel, spinal reflex excitability will be evaluated using H-reflex recordings from the triceps surae muscles across sitting and standing postures. The primary aim is to determine whether mental fatigue increases postural sway, particularly in more challenging balance conditions such as single-leg stance. The secondary aim is to examine whether mental fatigue alters the normal modulation of spinal reflex excitability across progressively demanding postural tasks. Additional biomechanical and neuromuscular measures, including EMG activity and hip kinematics, will be recorded to provide insight into underlying control mechanisms. The study will include approximately 26 participants, with each serving as their own control. Data will contribute to understanding how cognitive fatigue influences balance control and spinal-level neuromuscular regulation.

The Effect of Mental Fatigue on Upper Extremity Functional Performance

Mental fatigue (MF) is known to impair cognitive performance and may negatively affect physical performance. While its effects on lower-extremity functional performance have been investigated, little is known about the influence of MF on upper-extremity physical performance tests commonly used in sports and rehabilitation settings. This randomized crossover study will investigate the effects of experimentally induced mental fatigue on upper-extremity physical performance in 16 healthy physically active adults. Participants will complete both a mental fatigue condition, involving a prolonged Stroop task, and a control condition consisting of watching an emotionally neutral documentary. Before and after each condition, participants will perform the Upper Quarter Y Balance Test, Reactive Upper Quarter Y Balance Test, Closed Kinetic Chain Upper Extremity Stability Test, and Seated Single-Arm Shot Put Test. Subjective mental fatigue, cognitive performance, motivation, and perceived exertion will also be assessed. The findings will improve understanding of whether mental fatigue influences upper-extremity physical performance test outcomes and may assist clinicians and researchers in interpreting these assessments in sports medicine and rehabilitation contexts.

tAN for First Responders

This study is designed as an open label, single arm, decentralized clinical study in which first responders will receive transcutaneous auricular neurostimulation (tAN), which targets the auricular branch of the vagus nerve (ABVN) via the mastoid and the auriculotemporal nerve (ATN) anterior to the tragus. Participants will be enrolled in the study over the course of eight weeks (56 days). Participants will respond to daily and weekly questionnaires regarding mood, stress, sleep, energy/fatigue, and burnout. Each week, participants will complete consolidated online questionnaires (intended to last no longer than 15 minutes) comprised of the Perceived Stress Short-Form (PSS-4), Well-Being Index (WHO-5), Mini-Z Burnout (5-item), PROMS Sleep Disturbance (PROMIS-SD), GAD-7 (every 2 weeks), and Perceived Stress (PSS-10; monthly). The PSS-10 will replace the PSS-4 on Days 0, 28, and 56. No tAN treatment will be delivered during the Baseline Period (days between Study Introduction and Day 0). Participants will complete the weekly set of questionnaires ("Weekly Questionnaires") on Day 0. Participants will be recommended to complete the daily set of questionnaires ("Daily Questionnaires ") on the other days of the Baseline Period. On Days 1 - 28, participants will self-administer one session of one to two hours of tAN therapy each day. Participants will be recommended to complete the daily tAN session post-shift prior to sleep. Weekly Questionnaires will be completed by participants on Study Days 0, 7, 14, 21, 28, 35, 42, 49, and 56. Participants will be recommended to complete Daily Questionnaires on all other study days, up to Day 28. Daily Questionnaires will not be required to be completed by participants. Daily tAN sessions and Daily Questionnaires will cease after Day 28. Participants will complete a Study Satisfaction Questionnaire with the Weekly Questionnaires on Day 56. Following Day 56, participants will schedule a Study Exit Interview with the Research Coordinator.

Impact of Astaxanthin on Cognition in Recreationally Active Females

The purpose of this study is to examine the protentional that the antioxidant Astaxanthin has on mitigating cognitive decline following mental fatigue.

The Restorative Role of Daytime Naps in Mentally Fatigued Endurance Athletes

This randomized, counterbalanced crossover study investigated whether a 30-minute daytime nap can mitigate the effects of experimentally induced mental fatigue in amateur master endurance athletes. Male athletes completed two home-based experimental sessions separated by one week: a mental fatigue condition, in which a 30-minute cognitively demanding task battery preceded the nap, and a control condition, in which participants took only the nap. Sleep parameters during the nap were monitored by wrist actigraphy, and perceived sleep quality was assessed after awakening. Subjective sleepiness, perceived mental fatigue, and cognitive performance were evaluated before the nap, immediately after the nap, and/or 30 minutes after the nap. The study examined whether mental fatigue influenced nap characteristics and whether the nap improved recovery-related outcomes. The main outcomes included actigraphy-derived nap parameters, perceived sleep quality, sleepiness assessed with the Karolinska Sleepiness Scale, perceived mental fatigue assessed using a visual analogue scale, and cognitive performance assessed with a Flanker task.

Ego-Tucking: Exploring the Psychological Mechanisms of the "Fo-xi" Phenomenon Among University Students

The objective of this cross-sectional study is to explore the multi-dimensional factors influencing the shift toward "Ego-Tucking" (Fo-xi) mindsets among the contemporary student population. By utilizing a comprehensive structured questionnaire, the research aims to quantify how individual experiences, family dynamics, and macro-social environments contribute to behavioral changes and psychological defense mechanisms in the face of intense academic and professional competition.

Benefits of Physical Activity During the School Day to Reduce Mental Fatigue and Optimize Cognitive and Psychosocial Processes in Secondary School Students

The main aim of the MENTALFIT project is to test the effectiveness of physically active teaching methodologies to reduce mental fatigue and optimize cognitive, emotional, and motivational processes in secondary school students. Specifically, the study aims to examine differences depending on the type of physically active strategy implemented (physically active learning, active breaks, and active recesses) on students' mental fatigue, cognitive function, group dynamics, and motivational processes. Furthermore, the project aims to compare whether learning and academic performance are similar in traditional classes versus classes employing a physically active teaching methodology. Finally, a secondary objective of the project is to create and validate new instruments to assess the different psychobiological and educational processes included in this project.

Effects of Vitamin B12 and Natural Orange Extract, and Their Combination on Physical and Mental Performance

The aim of this study was to determine the effects of a new formulation of vitamin B12, natural orange extract, and their combination on physical and mental performance.

Monitoring the Effect of Mental Fatigue on Physical Performance Using Wearable Sensors and Physiological Parameters

Mental fatigue (MF) negatively affects both cognitive and physical performance, increasing the risk of errors in high-stakes environments such as sports and surgery. Traditional methods to assess MF rely on subjective self-report scales, which are prone to bias, or on complex brain measurements (e.g. EEG) that are impractical outside laboratory settings. This study aims to develop a real-time, objective monitoring method for MF using wearable physiological sensors. The study will recruit healthy, trained runners (18-35 years old) who will complete both an MF-inducing cognitive task (Stroop test) and a control condition (watching a documentary) in a randomized, counterbalanced, crossover design. Heart rate variability, respiration rate, and pupil metrics will be continuously recorded using wearable devices. Machine learning models will be used to predict MF-level as well as the effect of MF on physical performance (5-km time trial on a treadmill) using the physiological data as input.

Evaluation of the Impact of a Nutritional Formulation on Cognitive Performance Following Stress Exposure.

The proposed project will evaluate the synergistic effects of a nutritional formulation, 'Think Tank' on cognitive performance following exposure to a psychological and physical stressor. Adopting a double-blind repeated measures cross-over design, middle-aged females (40-60 years) will be recruited to take part in a two-stage research study that will examine whether the formulation enhances cognitive performance and subjective well-being following the challenge of a stressor, compared to placebo. Cognitive assessments will examine the impact of the nutritional formulation on working memory, sustained attention, cognitive flexibility and inhibitory control. The study will also assess physiological (heart rate, blood pressure and cortisol) and subjective (well-being, anxiety, positive and negative mood, stress) markers of stress reactivity. The study will also explore levels sleep quality, mental and physical fatigue, effort, productivity, and perceived impact of the intervention.

Exploring Immunological Markers Associated With Mental Fatigue in Graves' Disease

Mental fatigue occurs in many diseases and the reasons are mostly unknown. The investigators hypothesize that remaining mental fatigue after restored hyperthyroidism in Graves' disease is an autoimmune complication. The aim of this study is to explore immunological markers possibly associated with mental fatigue in Graves' disease, which the investigators plan to validate in another study (ImmunoGraves wp 2). Using a cross-sectional study design, mental fatigue is scored using a questionnaire to find 60 patients with and 60 without mental fatigue 15-60 months after diagnosis of Graves disease. The patients and 60 thyroid healthy controls without mental fatigue are assessed for thyroid hormones, quality of life, anxiety and depression, self-evaluated stress, coping strategies, eye symptoms and background variables. SciLifeLab in Stockholm, the national facility for autoimmune profiling, has pre-set large arrays including 42000 human proteins. Serum and cerebrospinal fluid will be separately pooled and analysed for a subgroup of patients with or without mental fatigue and for a subgroup of the control group. Proteins that preferably bind to antibodies in sera and/or cerebrospinal fluid from Graves' patients with mental fatigue in comparison to non-mental fatigue patients, will be screened against the Human Protein Atlas and the Allen brain map to identify those proteins that are expressed in the brain. Antibodies at higher concentration in the mental fatigue pools compared to the group without mental fatigue will be selected for further analyses on an individual level in the whole cohort together with antibodies targeting g-protein coupled receptors, thyroid autoantibodies, cytokines and biomarkers indicating organic and structural nerve damage.

Music Intervention on Golfers Under Mental Fatigue

This study aims to evaluate the effects of music intervention on golf-specific skill performance under mental fatigue. It is a randomised, controlled, double-blind design. The study consists of three main phases: familiarisation with the experimental procedure, baseline testing, and the formal experiment. During the formal experiment, participants will be randomly assigned to one of the following three groups: (MF-Mu Group) Participants undergo a mental fatigue induction task followed by a music intervention; (MF-nMu Group) Participants undergo a mental fatigue induction task but do not receive a music intervention; (CON Group) Participants neither undergo a mental fatigue induction task nor receive a music intervention. The total intervention duration is 45 minutes, consisting of 30 minutes of mental fatigue induction and 15 minutes of music intervention. In conditions where mental fatigue induction or music intervention is not conducted, participants will remain in the same experimental environment and rest quietly for the same duration to control for external confounding factors and ensure experimental consistency. Immediately after the intervention, participants will complete golf skill testing, with the testing site located within a 2 minutes walking distance from the intervention area. Performance outcomes include driving performance, iron shot performance, chipping performance, and putting performance.

Validating Immunological Markers Associated With Mental Fatigue in Graves' Disease

Mental fatigue occurs in many diseases and the reasons are mostly unknown. The investigators hypothesize that remaining mental fatigue after restored euthyroidism in Graves' disease is an autoimmune complication. This is a confirmatory study of the biomarkers from ImmunoGraves WP1 in which immunological markers with possible association with mental fatigue in Graves' disease are explored. In ImmunoGraves WP2, 310 patients with Graves' disease are assessed for symptoms of mental fatigue, quality of life, anxiety and depression, self-evaluated stress, coping strategies, personality traits, eye symptoms and background variables. Participants are examined in hyperthyroidism at inclusion, within three weeks from diagnosis, and in euthyroidism after 15 months. Serum and cerebrospinal fluid (in a subsample of participants) is collected at both visits and will be evaluated for the immunological markers identified in WP1 as well as for thyroid hormones, thyroid autoantibodies and biomarkers indicating organic and structural nerve damage. Significant predictors for mental fatigue will be identified by logistic regression. To assess functional changes in the brain, magnetoencephalography will be performed in a subset of patients and in healthy controls at inclusion and after 15 to 18 months. Combined with magneto resonance imaging (MRI), magnetoencephalography gives information on neuronal activation during attention testing.