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Introduction: Research investigating LAS and CAI has essentially focused on local adaptations. Recently, growing evidence is supporting the hypothesis neural plasticity occurs at both the spinal and cortical levels following (repeated) ligamentous ankle injury. These alterations might explain persisting dysfunctions, an increased injury risk, and the increased probability of developing CAI. This systematic review synthesizes the literature on brain plasticity following LAS and CAI. Methods: Studies eligible for this systematic review investigated the brain with direct outcomes measures in patients with LAS or CAI. The following electronic databases were used for the systematic search from their conception to 19/10/2021: Pubmed, Web of Science, Embase, Scopus, PEDro, The Cochrane Central Registry for Controlled Trials (CENTRAL) and SPORTDiscus. Three authors independently screened 1227 articles from 7 databases using a two-staged process to include 16 studies. The quality assessment tool for observationaland cross-sectional studies was used for the risk of bias assessment. The authors extracted and summarised relevant outcomes from each study in table 1. Results: Patients with LAS showed lower superior cerebellar peduncles (white matter microstructure) compared with healthy controls. CAI populations displayed an increased sensitivity of intermediate inhibitory neurons and a decreased sensitivity of excitatory neurons in the corticospinal pathway. They also found more variability in cortical activation in the superior parietal lobe, pre-and postcentral gyrus and the supplementary motor area with lower corticomotor excitability in several lower limb muscles in patients with CAI. Conclusion: Whilst these findings may support the hypothesis of brain plasticity in patients with ligamentous ankle injuries, all studies were retrospective in nature and most used different measurement methods which makes direct comparisons difficult and limits the strength of evidence of this review. Future research should focus on the understanding of the underlying neurophysiological mechanisms. Correspondence e-mail: alexandre.maricot@vub.be

INTRODUCTION: Mental fatigue, a psychobiological state that is induced when engaging in prolonged cognitive activity, affects both cognitive as well as physical performance. However, the significance and magnitude of these effects has recently been questioned. One of the underlying reasons could be the interindividual differences that are present in mental fatigue-effects. However, it’s not known yet whether these interindividual differences are trait or state-related, or which internal and/or external factors mediate these interindividual differences. The aim of this systematic review and meta-regression was to give an overview of interindividual differences in the effects of mental fatigue on physical performance, and possible internal factors influencing this effect. METHODS: Pubmed, Web of Science, SPORTDiscus and PsycINFO were searched for studies detailing the effect of mental fatigue on dynamic maximal whole body endurance performance. Studies needed to feature healthy participants with the inclusion of at least one internal factor in participants’ characteristics, and were required to include at least one manipulation check. The Cochrane crossover risk of bias tool was used to assess risk of bias. The meta-analysis and regression itself were conducted in R. RESULTS: 29 studies were selected for inclusion, with 24 studies eventually added to the overall random-effects meta-analysis (with 34 distinct effects) based on the successful induction of mental fatigue. This meta-analysis showed a small but significant effect of mental fatigue on endurance performance (g = - 0.31, 95% CI [-0.44; -0.17], t = -4.83, p < 0.001). The multiple meta-regression analysis (incorporating 11 effects) showed a significant influence of physical fitness level on mental fatigue-effects (estimate = 0.18, SE = 0.06, t = 2.84, p = 0.0296). However, this effect was only present when incorporated within the model together with sex ratio, mean age and body mass index. CONCLUSION: The present review confirms findings of the overall literature regarding the mediating influence of physical fitness level on the negative effects of mental fatigue on endurance performance. However, this influence is only apparent when different individual factors, such as sex, are taken into account. Moreover, multiple limitations still undermine these conclusions, from the overall underreporting of different participant characteristics to significant publication bias. An overall experimental study incorporating multiple different internal factors is therefore necessary to draw a definitive conclusion on this subject

The overall purpose of this dissertation was to contribute to clinical decision-making and functional performance testing across the sport injury spectrum. The three specific objectives encompassed: (1) establishing return to sport criteria following lateral ankle sprains, (2) mapping the reliability characteristics of the reactive balance test, (3) exploring electrophysiological brain changes induced by various types of fatigue when participants performed the Y-balance test and reactive balance test. The systematic review (Chapter 2) showed that currently no scientifically sound return to sport criteria following lateral ankle sprain injury can be determined. This was because not one original research study was performed on this topic. Therefore, we provided an overview of the relevant retrieved questionnaires, clinical assessment measures, functional and sport-specific performance tests within ankle sprain populations. Based upon this empirical research, return to sport variables were proposed. This chapter also encompasses rationales and considerations for return to sport decision-making following lateral ankle sprain injury. In Chapter 3, the reliability study is the first study to assess test-retest, intra- and inter-rater reliability of the reactive balance test within a recreationally trained population. Excellent intra- and inter-rater reliability for both outcomes (i.e. visuomotor response time and accuracy) were found. However, test-retest reliability showed good reliability for visuomotor response time and moderate reliability for accuracy. These results indicate that the reactive balance test is suited for performing analyses over time at the group level. The third study (Chapter 4) was designed to evaluate the impact of mental fatigue on electrophysiological brain measurements during Y-balance test and reactive balance test performance. Even though mental fatigue was successfully induced, it did not affect Y-balance test performance. However, an increase in prefrontal cortex theta activity was observed when performing the Y-balance test in a mentally fatigued state. Which means mental fatigue was successfully induced, and might suggest a lower availability of attentional resources and poorer decision-making. Regarding reactive balance test performance, only accuracy was compromised due to mental fatigue. No changes in visuomotor reaction time and electrophysiological brain outcome measures were found following the mental fatigue intervention. In Chapter 5, the results showed that acute physical fatigue impairs the accuracy of the reactive balance test, while Y-balance test performance and visuomotor response time of the reactive balance test remained unaffected. Nevertheless, the underlying changes at the peripheral and central physiological level completely differed from the previous study. During the execution of both tests, acute physical fatigue induced alterations in electrophysiological brain outcome measures in line with previous Wingate literature. Higher α power in the prefrontal cortex, motor cortex and posterior parietal cortex as well as higher β power in the prefrontal and posterior parietal cortex were observed during the execution of the Y-balance test in a fatigued state. Following acute physical fatigue, α and β power increments were found in the posterior parietal cortex and the prefrontal cortex during the execution of the reactive balance test, respectively. In summary, the research findings of this dissertation show that: (1) no scientifically sound return to sport criteria following lateral ankle sprain injury are currently available; (2) the reactive balance test has acceptable reliability characteristics and therefore is suited for performing analyses over time at the group level. (3) mental and acute physical fatigue do not impact YBT performance, even when underlying physiological and psychological changes are present; (4) the reactive balance test is capable of detecting fatigue changes at the group level culminating in decreased accuracy. When mentally fatigued, no changes at the electrophysiological brain level were measured. In a physically fatigued state the electrophysiological findings were partially in line with previous Wingate literature.

The overall purpose of this dissertation was to contribute to clinical decision-making and functional performance testing across the sport injury spectrum. The three specific objectives encompassed: (1) establishing return to sport criteria following lateral ankle sprains, (2) mapping the reliability characteristics of the reactive balance test, (3) exploring electrophysiological brain changes induced by various types of fatigue when participants performed the Y-balance test and reactive balance test. The systematic review (Chapter 2) showed that currently no scientifically sound return to sport criteria following lateral ankle sprain injury can be determined. This was because not one original research study was performed on this topic. Therefore, we provided an overview of the relevant retrieved questionnaires, clinical assessment measures, functional and sport-specific performance tests within ankle sprain populations. Based upon this empirical research, return to sport variables were proposed. This chapter also encompasses rationales and considerations for return to sport decision-making following lateral ankle sprain injury. In Chapter 3, the reliability study is the first study to assess test-retest, intra- and inter-rater reliability of the reactive balance test within a recreationally trained population. Excellent intra- and inter-rater reliability for both outcomes (i.e. visuomotor response time and accuracy) were found. However, test-retest reliability showed good reliability for visuomotor response time and moderate reliability for accuracy. These results indicate that the reactive balance test is suited for performing analyses over time at the group level. The third study (Chapter 4) was designed to evaluate the impact of mental fatigue on electrophysiological brain measurements during Y-balance test and reactive balance test performance. Even though mental fatigue was successfully induced, it did not affect Y-balance test performance. However, an increase in prefrontal cortex theta activity was observed when performing the Y-balance test in a mentally fatigued state. Which means mental fatigue was successfully induced, and might suggest a lower availability of attentional resources and poorer decision-making. Regarding reactive balance test performance, only accuracy was compromised due to mental fatigue. No changes in visuomotor reaction time and electrophysiological brain outcome measures were found following the mental fatigue intervention. In Chapter 5, the results showed that acute physical fatigue impairs the accuracy of the reactive balance test, while Y-balance test performance and visuomotor response time of the reactive balance test remained unaffected. Nevertheless, the underlying changes at the peripheral and central physiological level completely differed from the previous study. During the execution of both tests, acute physical fatigue induced alterations in electrophysiological brain outcome measures in line with previous Wingate literature. Higher α power in the prefrontal cortex, motor cortex and posterior parietal cortex as well as higher β power in the prefrontal and posterior parietal cortex were observed during the execution of the Y-balance test in a fatigued state. Following acute physical fatigue, α and β power increments were found in the posterior parietal cortex and the prefrontal cortex during the execution of the reactive balance test, respectively. In summary, the research findings of this dissertation show that: (1) no scientifically sound return to sport criteria following lateral ankle sprain injury are currently available; (2) the reactive balance test has acceptable reliability characteristics and therefore is suited for performing analyses over time at the group level. (3) mental and acute physical fatigue do not impact YBT performance, even when underlying physiological and psychological changes are present; (4) the reactive balance test is capable of detecting fatigue changes at the group level culminating in decreased accuracy. When mentally fatigued, no changes at the electrophysiological brain level were measured. In a physically fatigued state the electrophysiological findings were partially in line with previous Wingate literature.

Objective Over the course of the twenty-first century, work-related musculoskeletal disorders are still persisting among blue collar workers. At present, no epidemiological overview exists. Therefore, a systematic review and meta-analysis was performed on the epidemiology of work-related musculoskeletal disorders (WMSD) within Europe’s secondary industries. Methods Five databases were screened, yielding 34 studies for the qualitative analysis and 17 for the quantitative analysis. Twelve subgroups of WMSDs were obtained for the meta-analysis by means of predefined inclusion criteria: back (overall), upper back, lower back, neck, shoulder, neck/shoulder, elbow, wrist/hand, leg (overall), hip, knee, and ankle/feet. Results The most prevalent WMSDs were located at the back (overall), shoulder/neck, neck, shoulder, lower back and wrist WMSDs with mean 12-month prevalence values of 60, 54, 51, 50, 47, and 42%, respectively. The food industry was in the majority of subgroups the most prominent researched sector and was frequently associated with high prevalence values of WMSDs. Incidence ratios of upper limb WMSDs ranged between 0.04 and 0.26. Incidence ratios could not be calculated for other anatomical regions due to the lack of sufficient articles. Conclusion WMSDs are still highly present among blue collar workers. Relatively high prevalence values and low incidence ratios indicate a limited onset of WMSDs with however long-term complaints.

Additional file 1.

After lower extremity injury, only half of the injured athletes return to their pre-injury sports level. Even though functional performance tests are often used to make return to sport decisions, it is unknown whether functional performance is associated with return to performance after such injuries. The aim of this systematic review was to identify, critically appraise, and analyze studies that investigated the association of functional performance tests with return to performance after lower extremity injuries in athletes participating in high-impact sports. MEDLINE, Embase, Web of Science, and CINAHL were systematically searched for relevant studies. Articles were independently screened by two authors and data were obtained from each included study using a data extraction form. Two authors independently scored methodological quality using the Quality In Prognosis Studies tool. A qualitative best evidence synthesis was conducted. Eight studies reported the association of functional performance with return to performance after lower extremity injuries, involving 1,246 athletes after anterior or posterior cruciate ligament reconstruction. No studies were found on the association of functional performance with return to performance for lower extremity injuries other than after anterior or posterior cruciate ligament reconstruction. All included studies had a high risk of bias. Two studies found significant but small associations for selected hop tests after anterior cruciate ligament reconstruction. Low evidence of association between functional performance and return to performance was present after anterior cruciate ligament reconstruction for the triple hop for distance, the 6-meter timed hop, the side hop in female athletes, and for the combination of the single and crossover hop for distance. In athletes after posterior cruciate ligament reconstruction, the vertical jump showed a significant but small association with return to performance. There is no high-quality evidence that functional performance is associated with return to performance after lower extremity injuries in athletes practicing high-impact sports. Low quality evidence suggests small associations after anterior and posterior cruciate ligament reconstruction. No evidence exists for lower extremity injuries other than after anterior or posterior cruciate ligament reconstruction. Therefore, research on functional performance associated with return to performance is recommended in high-quality prospective cohort studies including athletes with any type of lower extremity injury.

BACKGROUND: Acute fatigue is hypothesized to alter lower extremity injury risk profiles by affecting intrinsic risk factors (i.e. single leg postural control, hamstring strength). However, no systematic overview exists that merges the insights into prospective lower extremity injury risk profiling with the effect of acute fatigue on functional test performance. OBJECTIVE: The objective of this review is to identify the influence of acute fatigue on prospectively determined modifiable intrinsic risk factors for lower extremity injuries. DESIGN: Systematic review. METHODS: PubMed (MEDLINE), Web of Science, PEDro, and Cochrane Library were searched until 29 May 2019. Studies were eligible when the study outcomes encompassed intrinsic modifiable risk factors for lower extremity injury, an acute fatigue intervention, and included healthy athletes or physically active people. Intrinsic modifiable risk factors were identified through recent systematic reviews and meta-analyses, and the referenced original research papers were used to determine outcome measures associated with increased injury risk. RESULTS: Forty-three studies reported acute fatigue effects on modifiable risk factors, with eight studies matching all criteria for data-extraction. Acute fatigue can decrease single leg postural control, decrease ankle joint position sense, decrease isokinetic strength of hamstring and quadriceps muscles and can affect isokinetic hamstring:quadriceps ratios. CONCLUSION: Acute fatigue affects prospective intrinsic modifiable risk factors for lower extremity injury, indicating an altered injury risk profile for lateral ankle sprain, patellofemoral pain syndrome and hamstring injuries. Future research should allow for individual fatiguability as a relevant outcome, and merge insights from athlete-centred injury risk profiling and fatigue.

INTRODUCTION:Evaluating the effectiveness of a lower-limb prosthetic device (LLPD) during daily activities is a crucial step in the iterativeprocess of redesigning and product development of new generation prostheses. To date, several different experimental protocols havebeen applied to evaluate a LLPD in laboratory and field conditions, which causes study heterogeneity. Therefore, the aim of this systematicreview was to formulate guidelines and recommendations in order to standardize the experimental methodology regarding the evaluationof a LLPD.METHODS: Two databases, PubMed and Web of Science, were screened and studies published between 1997 and 2019 evaluating aLLPD were included.RESULTS: Thirty-six articles were included. We identified forty-four outcome measures in four main categories: 54% were biomechanical,25% physiological, 14% physical performance and 7% psychological. Seven eligible tests were identified: the two- and six-minute walktest (80%), slope walking (14%), stair climbing (8%), dual tasks (6%), timed up & go (3%) and balance tests (3%).CONCLUSION: The main recommendation is to include functional tasks in a case-controlled (early stage) or crossover counterbalancedmatched group study design (later stage). Biomechanical, physiological, physical performance and psychological outcome measures arekey factors to investigate the human response to a LLPD in order to standardize experimental protocols.

INTRODUCTION: Sport performance is determined by a combination of physiological and cognitive capacity. Recently the importance of the brain/cognitive capacity in sport performance has been further substantiated by research demonstrating the negative effect of mental fatigue (MF) on sport-specific psychomotor skills [1]. Creatine supplementation improves strength, but can also improve cognitive functioning [2]. To further explore creatine’s role as a cognitive enhancer and unravel the mechanisms behind the MF-associated decrease in sport performance, the aim was to evaluate the role of phosphocreatine in the MF-associated impairments in cognitive performance and sport-specific psychomotor skills. METHODS: In 23°C and 35% relative humidity, 14 healthy subjects (4F 10M; mean ± SD; age:24 ± 3 y; mass:74 ± 13 kg; height:179 ± 9 cm) performed - counterbalanced, crossover and double blinded - a 7-min sport-specific visuomotor task before and after a 90-min mentally fatiguing task (i.e. Stroop task) in two differentconditions: after a 7-day creatine supplementation (CR; experimental; 20 g/day) and after a 7-day calcium lactate supplementation (PLAC; placebo), separated by a 5-week washout. In both conditions, a dynamic handgrip strength endurance task (12 maximal reps) and a 3-min Flanker task was performed before and after the mentally fatiguing task. Physiological and perceptual responses were measured throughout the protocol. Normality was checked, repeated measures ANOVAs were employed to observe interaction and/or main effects of condition and time. Follow up tests were performed where necessary (p7 min; e.g. 90-min soccer game) sport performance. From a mechanistic point of view the results suggest a possible role of brain-phosphocreatine in MF. References: 1. Russel et al.J Sci Med Sport,2018 2. McMorris et al.Psychopharmacology,2006

Objective. Differential learning is a motor learning method characterized by a high amount of variability during practice. The objective of this paper is twofold. First, a critical appraisal is performed of the theoretical rationale of the differential learning method. Second, a systematic review and meta-analysis of experimental results is made to compare the effectiveness of differential learning compared to other motor learning methods. Methods. Narrative review of the theoretical rationale of differential learning. Systematic review and meta-analysis of published randomized controlled trials where differential learning is compared to other motor learning methodologies. Results. The theoretical rationale of differential learning is reasonable, but at some points too metaphorically formulated. Especially the use of stochastic resonance as the mechanism behind differential learning is ambiguous and remains untested to this day. However, indirect evidence for a neurophysiological mechanism has been described and should be pursued further. Empirically, differential learning has been examined in a variety of contexts ranging from technical skills and performance outcomes in single sports movements to tactical sports contexts, fine motor skills, balance tasks and rehabilitation. The meta-analysis showed that differential learning performed better than traditional motor learning methods and that the effect was larger on the retention test than on the post-test. However, little to no evidence was found for the comparison to other variability-based motor learning techniques. Additionally, risk of bias was high or unclear on many items and publication bias was likely which limits strong confidence in the conclusions of the meta-analysis. Perspectives. Differential learning is a promising method to enhance motor learning but will require further research to test certain theoretical claims and to find factors that predict the individual and time-dependent optimal amount of practice variability.