Test-retest, intra- and inter-rater reliability of the reactive balance test in patients with chronic ankle instability

IntroductionThe Reactive Balance Test (RBT) could be a valuable addition to research on chronic ankle instability (CAI) and clinical practice, but before it can be used in clinical practice it needs to be reliable. It has already been proven reliable in healthy recreational athletes, but not yet in patients with CAI who have shown persistent deficits in dynamic balance. The study aimed to determine the test-retest, intra-, and inter-rater reliability of the RBT in patients with CAI, and the test-retest and inter-rater reliability of the newly developed RBT score sheet.MethodsWe used a repeated-measures, single-group design to administer the RBT to CAI patients on three occasions, scored by multiple raters. We included 27 participants with CAI. The study used multiple reliability measures, including Pearson r, intra-class correlations (ICC), standard error of measurement (SEM), standard error of prediction (SEP), minimal detectable change (MDC), and Bland–Altman plots, to evaluate the reliability of the RBT’s outcome measures (visuomotor response time and accuracy). It also assessed the test-retest and inter-rater reliability of the RBT score sheet using the same measures.ResultsThe ICC measures for test-retest reliability were similar for accuracy (0.609) and VMRT (0.594). Intra-rater reliability had high correlations and ICCs for accuracy (r = 0.816, ICC = 0.815) and VMRT (r = 0.802, ICC = 0.800). Inter-rater reliability had a higher ICC for VMRT (0.868) than for accuracy (0.690).ConclusionTest-retest reliability was moderate, intra-rater reliability was good, and inter-rater reliability showed moderate reliability for accuracy and good reliability for VMRT. Additionally, the RBT shows robust SEM and mean difference measures. The score sheet method also demonstrated moderate test-retest reliability, while inter-rater reliability was good to excellent. This suggests that the RBT can be a valuable tool in assessing and monitoring balance in patients with CAI

Incorporating methods and findings from neuroscience to better understand placebo and nocebo effects in sport

Placebo and nocebo effects are a factor in sports performance. However, the majority of published studies in sport science are descriptive and speculative regarding mechanisms. It is therefore not unreasonable for the sceptic to argue that placebo and nocebo effects in sport are illusory, and might be better explained by variations in phenomena such as motivation. It is likely that, in sport at least, placebo and nocebo effects will remain in this empirical grey area until researchers provide stronger mechanistic evidence. Recent research in neuroscience has identified a number of consistent, discrete and interacting neurobiological and physiological pathways associated with placebo and nocebo effects, with many studies reporting data of potential interest to sport scientists, for example relating to pain, fatigue and motor control. Findings suggest that placebos and nocebos result in activity of the opioid, endocannabinoid and dopamine neurotransmitter systems, brain regions including the motor cortex and striatum, and measureable effects on the autonomic nervous system. Many studies have demonstrated that placebo and nocebo effects associated with a treatment, for example an inert treatment presented as an analgesic or stimulant, exhibit mechanisms similar or identical to the verum or true treatment. Such findings suggest the possibility of a wide range of distinct placebo and nocebo mechanisms that might influence sports performance. In the present paper, we present some of the findings from neuroscience. Focussing on fatigue as an outcome and caffeine as vehicle, we propose three approaches that researchers in sport might incorporate in their studies in order to better elucidate mechanisms of placebo/nocebo effects on performance

From the midnight sun to the longest night: sleep in Antarctica

Sleep disturbances are the main health complaints from personnel deployed in Antarctica. The current paper presents a systematic review of research findings on sleep disturbances in Antarctica. The available sources were divided in three categories: results based on questionnaire surveys or sleep logs, studies using actigraphy, and data from polysomnography results. Other areas relevant to the issue were also examined. These included chronobiology, since the changes in photoperiod have been known to affect circadian rhythms; mood disturbances; exercise, sleep and hypoxia; countermeasure investigations in Antarctica; and other locations lacking a normal photoperiod

A caffeine-maltodextrin mouth rinse counters mental fatigue

Introduction: Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity that has negative implications on many aspects in daily life. Caffeine and carbohydrate ingestion have been shown to be able to reduce these negative effects of mental fatigue. Intake of these substances might however be less desirable in some situations (e.g., restricted caloric intake, Ramadan). Rinsing caffeine or glucose within the mouth has already been shown to improve exercise performance. Therefore, we sought to evaluate the effect of frequent caffeine-maltodextrin (CAF-MALT) mouth rinsing on mental fatigue induced by a prolonged cognitive task. Methods: Ten males (age 23?±?2 years, physical activity 7.3?±?4.3 h/week, low CAF users) performed two trials. Participants first completed a Flanker task (3 min), then performed a 90-min mentally fatiguing task (Stroop task), followed by another Flanker task. Before the start and after each 12.5% of the Stroop task (eight blocks), subjects received a CAF-MALT mouth rinse (MR: 0.3 g/25 ml CAF: 1.6g/25 ml MALT) or placebo (PLAC: 25 ml artificial saliva). Results: Self-reported mental fatigue was lower in MR (p?=?0.017) compared to PLAC. Normalized accuracy (accuracy first block?=?100%) was higher in the last block of the Stroop in MR (p?=?0.032) compared to PLAC. P2 amplitude in the dorsolateral prefrontal cortex (DLPFC) decreased over time only in PLAC (p?=?0.017). Conclusion: Frequent mouth rinsing during a prolonged and demanding cognitive task reduces mental fatigue compared to mouth rinsing with artificial saliva

The effects of acute dopamine reuptake inhibition on performance

Introduction: Acute bupropion (BUP; dopamine/noradrenaline reuptake inhibitor) administration significantly improved time trial performance and increased core temperature in the heat (30°C). Purpose: The present study was performed to examine the effect of a dopaminergic reuptake inhibitor on exercise capacity and thermoregulation during prolonged exercise in temperate and warm conditons. Methods: Eight healthy well-trained male cyclists participated in this study. Subjects ingested either a placebo (PLAC; lactose; 20mg) or Ritalin (RIT; methylphenidate (MPH); 20mg) one hour before the start of exercise in temperate (18°C) or warm (30°C) conditions and cycled for 60 min at 55% Wmax, immediately followed by a time trial (TT; pla18 and rit18; pla30 and rit30) to measure exercise performance. Results: Ritalin did not influence TT performance at 18oC (P=0.397). TT was completed 16% faster in rit30 (38.1±6.4min) than in pla30 (45.4±7.3min; p=0.049). Power output was higher in rit30, compared to pla30 (p<0.05). In the heat Tcore was significantly higher at rest (p=0.009), at the start of exercise and throughout rit30 (p<0.05). Throughout rit30 heart rates were significantly higher (p<0.05). Prolactin concentrations decreased after one hour cycling in 18°C (p=0,036) and at rest in 30°C (p=0,007) after RIT administration. Conclusions: These results show that RIT has a clear ergogenic effect that was not apparent in 18°C. The combination of a dopamine reuptake inhibitor and exercise in the heat clearly improved performance and appeared to increase metabolic heat production, suggesting an important role for dopamine in the fatigue process

Evaluating the real-world usability of BCI control systems with augmented reality: a user study protocol

Brain-computer interfaces (BCI) enable users to control devices through their brain activity. Motor imagery (MI), the neural activity resulting from an individual imagining performing a movement, is a common control paradigm. This study introduces a user-centric evaluation protocol for assessing the performance and user experience of an MI-based BCI control system utilizing augmented reality. Augmented reality is employed to enhance user interaction by displaying environment-aware actions, and guiding users on the necessary imagined movements for specific device commands. One of the major gaps in existing research is the lack of comprehensive evaluation methodologies, particularly in real-world conditions. To address this gap, our protocol combines quantitative and qualitative assessments across three phases. In the initial phase, the BCI prototype's technical robustness is validated. Subsequently, the second phase involves a performance assessment of the control system. The third phase introduces a comparative analysis between the prototype and an alternative approach, incorporating detailed user experience evaluations through questionnaires and comparisons with non-BCI control methods. Participants engage in various tasks, such as object sorting, picking and placing, and playing a board game using the BCI control system. The evaluation procedure is designed for versatility, intending applicability beyond the specific use case presented. Its adaptability enables easy customization to meet the specific user requirements of the investigated BCI control application. This user-centric evaluation protocol offers a comprehensive framework for iterative improvements to the BCI prototype, ensuring technical validation, performance assessment, and user experience evaluation in a systematic and user-focused manner

Effects of Mental Fatigue on Endurance Performance in the Heat

PURPOSE: Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity and has been observed to decrease time-trial (TT) endurance performance by ~3,5% in normal ambient temperatures. Recently it has been suggested that heat may augment the negative effect of mental fatigue on cognitive performance, raising the question whether it may also amplify the effect of mental fatigue on TT-performance. METHODS: In 30 °C and 30% relative humidity, ten endurance-trained male athletes (Age: 22 ± 3 y; Wmax: 332 ± 41 W) completed two experimental conditions: intervention (I; 45-min Stroop task) and control (C; 45-min documentary). Pre and post intervention/control, cognitive performance was followed up with a 5-min Flanker task. Thereafter subjects cycled for 45 min at a fixed pace equal to 60%-Wmax, immediately followed by a self-paced TT in which they had to produce a fixed amount of work (equal to cycling 15 min at 80%-Wmax) as fast as possible. RESULTS: Self-reported mental fatigue was significantly higher after I compared to C (P<0.05). Moreover electroencephalographic measures also indicated the occurrence of mental fatigue during the Stroop (P<0.05). TT-time did not differ between conditions (I: 906 ± 30 s, C: 916 ± 29 s). Throughout exercise, physiological (heart rate, blood lactate, core and skin temperature) and perceptual measures (perception of effort and thermal sensation) were not affected by mental fatigue. CONCLUSION: No negative effects of mild mental fatigue were observed on performance and the physiological and perceptual responses to endurance exercise in the heat. Most plausibly mild mental fatigue does not reduce endurance performance when the brain is already stressed by a hot environment

Repeated-sprints exercise in daylight fasting: carbohydrate mouth rinsing does not affect sprint and reaction time performance

To determine the effect of carbohydrate mouth rinsing (CHO-MR) on physical and cognitive performance during repeated-sprints (RS) after 3 days of intermittent fasting (abstaining from food and fluid 14 h per day). In a randomized and counter-balanced manner 15 active healthy males in a fasted state performed a RS-protocol [RSP; 2 sets (SET1 and SET2) of 5×5 s maximal sprints, with each sprint interspersed with 25 s rest and 3 min of recovery between SET1 and SET2] on an instrumented non-motorized treadmill with embedded force sensors under three conditions: i) Control (CON; no-MR), ii) Placebo-MR (PLA-MR; 0% maltodextrin) and iii) CHO-MR (10% maltodextrin). Participants rinsed their mouth with either 10 mL of PLA-MR or CHO-MR solution for 5 s before each sprint. Sprint kinetics were measured for each sprint and reaction time (RTI) tasks (simple and complex) were assessed pre-, during- and post-RSP. There was no statistical main effect of CHO-MR on mean power, mean speed, and vertical stiffness during the sprints between the PLA-MR and CON condition. Additionally, no statistical main effect for CHO-MR on accuracy, movement time and reaction time during the RTI tasks was seen. CHO-MR did not affect physical (RSP) or cognitive (RTI) performance in participants who had observed 3 days of intermittent fasting (abstaining from food and fluid 14 h per day)

Consensus recommendations on training and competing in the heat

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise–heat exposures over 1–2 weeks. In addition, athletes should initiate competition and training in an euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vests), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competitions are held in the heat

The Effects of Mental Fatigue on Physical Performance: A Systematic Review.

Background: Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. It has recently been suggested that mental fatigue can affect physical performance. Objective: Our objective was to evaluate the literature on impairment of physical performance due to mental fatigue and to create an overview of the potential factors underlying this effect. \ud Methods: Two electronic databases, PubMed and Web of Science (until 28 April 2016), were searched for studies designed to test whether mental fatigue influenced performance of a physical task or influenced physiological and/or perceptual responses during the physical task. Studies using short (<30 min) self-regulatory depletion tasks were excluded from the review. Results: A total of 11 articles were included, of which six were of strong and five of moderate quality. The general finding was a decline in endurance performance (decreased time to exhaustion and self-selected power output/velocity or increased completion time) associated with a higher than normal perceived exertion. Physiological variables traditionally associated with endurance performance (heart rate, blood lactate, oxygen uptake, cardiac output, maximal aerobic capacity) were unaffected by mental fatigue. Maximal strength, power, and anaerobic work were not affected by mental fatigue. Conclusion: The duration and intensity of the physical task appear to be important factors in the decrease in physical performance due to mental fatigue. The most important factor responsible for the negative impact of mental fatigue on endurance performance is a higher perceived exertion