View clinical trials related to Caffeine.
Filter by:Caffeine is the most commonly used stimulant drug with well documented effects on cerebral vascula-ture. Caffeine is known to non-specifically bind to adenosine receptors in the brain and to reduce resting blood flow while improving attention and cognitive function, which suggests that it may allow a more efficient dynamic blood flow regulation through neurovascular coupling. This study will use standardized dose of caffeine to test its effect on NVC responses in cerebral and retinal arterioles.
This study is a randomized, double-blind, placebo-controlled crossover trial examining the effects of caffeinated and non-caffeinated pre-workout supplements on resistance exercise performance. Resistance-trained adults will be randomly assigned to complete three study conditions (caffeinated pre-workout, non-caffeinated pre-workout, and placebo) in one of the six possible condition orders. During each condition, participants will report to the laboratory for ingestion of the assigned beverage and subsequent muscular performance testing. Major performance outcomes will be force production variables from a mechanized squat device and maximal strength and muscular endurance on the bench press and leg press exercises.
Several studies have shown the positive effect that caffeine has on athletic performance related variables. Nonetheless, most studies have been developed in males and have not studied the possible effects on biomechanics and related injuries. Moreover, the inclusion of personalized insoles could also affect biomechanical patterns and thus injury incidence that has shown to be higher when athletes are fatigued. Therefore, the aim of the present randomized controlled trial is to evaluate the effect of fatigue, caffeine supplementation and personalized insoles on biomechanics and athletic performance in female adult soccer players.
The purpose of this study is to investigate the impact of caffeine on myocardial oxygenation and other cardiovascular magnetic resonance parameters in healthy controls.
The purpose of this online research study is to determine whether or not a gradual caffeine reduction program developed at Johns Hopkins can help people reduce their caffeine use. The investigators will provide materials to help guide caffeine reduction and ask questions to track caffeine use over several weeks. The investigators will also assess how reducing caffeine may benefit common caffeine-related problems such as anxiety, sleep disturbances, and gastrointestinal distress. The study will also determine whether or not people like participating in this caffeine reduction program in an online format.
Disruption of the normal gastrointestinal (GI) motility is a well-known consequence of major surgery. The pathophysiology behind this phenomenon is not fully understood but involves the autonomic nervous system as well as a systemic stress response to surgery. A number of factors interfere with GI motor activity, such as the direct manipulation of intestines during surgery and the use of opioid analgesia. Post-operative ileus (POI) refers to a delay in regaining GI motility beyond the anticipated normal duration of time. Signs and symptoms include nausea, vomiting, abdominal distention, the absence of flatus or stool in the preceding 24 hours, and/or an inability to tolerate oral intake. The incidence of POI in abdominal surgery is estimated to be approximately 10%-30%. Beyond increased patient discomfort and distress, the development of POI is associated with increased healthcare costs. Coffee is a popular beverage: two thirds of Canadians are coffee drinkers, averaging approximately 3.2 cups per day. Coffee is composed of hundreds of chemicals, many with demonstrated pharmacologic effects. The most well-known of these compounds is caffeine, known to exert a stimulatory effect on the cardiovascular and nervous system. A recent systematic review of 7 randomized controlled trials (N=606 colorectal and gynecology surgical patients) determined that the consumption of coffee reduced the time of several measures of GI recovery, such as time to tolerance of food, without any increased rate of complications or adverse events although overall, the evidence was graded as low to moderate certainty, and further confirmatory studies are needed. In this trial, patients aged 18 years or higher who undergo laparoscopic or open abdominal surgery, with an estimated length of stay > 24 hours will be randomized to receive approximately one cup of either coffee, decaffeinated coffee, or warm water, three times daily. This trial will be conducted under the IMPACTS (Innovative, Multicentre, Patient-centred Approach to Clinical Trials in Surgery) program umbrella and will follow IMPACTS methodology. For the Vanguard trial, the aim is to determine the feasibility of conducting a definitive trial. Future outcomes of interest include: time to first flatus, time to first bowel movement, placement of an NG tube, length of stay in hospital, 30-day mortality, and 30-day postoperative complications.
The effect of caffeine on appetite and body weight is controversial. Mostly epidemiological studies exist that show either a negative effect (reduction of appetite and body weight) or no effect. In this trial we are going to study the results of the consumption of 5mgr/kgr body weight of caffeine on appetite, food consumption and hormones ghrelin, asprosin, leptin and pancreatic polypeptide in relation to gene polymorphisms that affect caffeine metabolism and body weight. Seventy subjects will participate in a cross sectional study consisting of two trials (with or without the consumption of caffeine) in order to study the aforementioned parameters. Differences of total calories consumption between fast metabolizers of caffeine and the rest of the participants is the primary outcome.
The mechanism of methylxanthines is thought to increase chemoreceptor responsiveness to CO2 in central nervous system. Besides, effect of methylxanthines on diaphragmatic contractility has also been found in experimental studies. A study of premature newborns has showed caffeine increase diaphragmatic activity and tidal volume. But, there is limited data about caffeine direct effect on diaphragma. Objective: The investigators aimed to show the direct effect of caffeine on diphragmatic contractility. Method: The babies under 32 weeks with respiratory support, are being enrolled in this study if caffeine treatment is decided to receive. Evaluation of muscle contraction is being made by ultrasound before and 30 minutes after caffeine loading dose. Right and left sides of diaphragm thickness are being measured by two clinicians on B mode ultrasound by anterior subcostal view. The velocity before and after caffeine administration will be calculated, dividing excursion frequency (parameter) for inspiratory time. Movement of the diaphragm at inspiratory and expiratory phases are also observed on M mode and the difference between the two phases are measured.
The purpose of this investigation was to examine the acute effects of consuming two different fitness drink formulas on the physiological response at rest and to exercise in healthy men and women.
Sleep deprivation (SD) has a powerful degrading effect on cognitive performance, particularly psychomotor vigilance (PV) and reaction time. Caffeine is well known to be an effective countermeasure to the effects of SD. However, individuals differ in both their response to SD and to the administration of caffeine. This has made it difficult to provide individualized recommendations regarding the use of caffeine to sustain alertness when needed. For the past two decades, the Army's Biotechnology HPC Institute (BHSAI), in collaboration with the Walter Reed Army Institute of Research, have been developing statistical models to predict individual performance during prolonged SD. Recently, this resulted in the publication of the 2B-Alert app, a computer algorithm based on large datasets that can learn an individual's response to SD by combining actigraphic sleep data with simultaneously acquired PV performance data. The 2B-Alert algorithm can predict an individual's sleep need and performance after ~2 weeks of training the model. Recently, the model has been extended to incorporate individualized responses to caffeine. This was recently validated in a retrospective study published by BHSAI in 2019. The present study is designed to test the predictive capacity of the 2B-Alert app in real time. During Phase 1 a total of 21 healthy participants will wear an actigraph & complete multiple daily PV tests on a personal cell phone. After 2 weeks, these individuals will attend Phase 2 involving an in-laboratory stay & SD. Participants will have an 8-hour period of sleep in the laboratory, followed by 62 hours of continuous wakefulness. During these 62 hours, participants will complete PV and mood testing every 3 hours. The 2B-Alert app will be used to predict individual caffeine need to sustain performance at near-baseline levels based on the statistical model. At 44 hours SD, participants will undergo a 6-hour "alertness window" where they may receive individualized doses of caffeine based on the recommendations of the model. After 62 hours of SD, Phase 3 begins, involving a night of monitored recovery sleep and additional sessions of PV and mood testing until release from the study at 6 pm on the final day. It is hypothesized that the 2B-Alert app will be effective at providing caffeine dosing recommendations that return PV and mood performance to normal levels during the alertness window.