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Introduction: Higher cortical activity has been observed in people with multiple sclerosis (pwMS) during walking and dual-tasking. However, further studies in overground walking and considering pre-frontal cortex (PFC) sub-areas are necessary., Objectives: To investigate PFC activity during a cognitive-motor dual-task (DT) and its single component tasks, in combination with behavioral outcomes in pwMS., Methods: Fifteen pwMS (EDSS 3.5 [2-5.5], 42 ± 11 years) and 16 healthy controls (HC, 45.2 ± 13.2 years) performed 3 conditions: single motor-walking (SWT), single cognitive - subtracting sevens (SCT), and a DT. Meters walked and the number of correct answers were obtained from which, respectively, the motor (mDTC) and cognitive (cDTC) DT costs were calculated. A functional Near-Infrared Spectroscopy covering the frontopolar and dorsolateral PFC (DLPFC) areas was used to concentration of relative oxyhemoglobin (ΔHbO2) and deoxyhemoglobin (ΔHHb) in the PFC. A repeated 2-way ANOVA (group × conditions) was used to compare ΔHbO2/ΔHHb and behavioral outcomes., Results: PwMS walked shorter distances ( P  < .002) and answered fewer correct numbers ( P  < .03) than HC in all conditions, while cDTC and mDTC were similar between groups. PwMS presented higher ΔHbO2 in the frontopolar area than HC in the SWT ( P  < .001). HC increased ΔHbO2 in frontopolar during the SCT ( P  < .029) and DT ( P  < .037) compared with the SWT., Conclusion: Higher frontopolar activity in pwMS compared to HC in the SWT suggests reduced gait automaticity. Furthermore, it seems that only HC increased neural activity in the frontopolar in the SCT and DT, which might suggest a limit of cognitive resources to respond to DT in pwMS., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Distance walking fatigability (DWF) in people with multiple sclerosis (pwMS) is defined as a decrease in the distance walking over time. However, declines in gait quality (i.e., gait quality fatigability- GQF) may occur independently or alongside DWF., Objective: i) to investigate how walking fatigability manifests and its prevalence in pwMS; ii) to describe the temporal pattern of the changes of specific gait characteristics during the 6-minute walking test (6MWT) METHODS: Eighty-eight pwMS (EDSS 4[0-6.5], 49[21-70] years) and 47 healthy controls (HC- 46[25-60] years) performed the 6MWT wearing inertial measurement units. Gait characteristics (stride length, sensor-based gait speed, cadence, double support, step duration, stance phase, step duration asymmetry, step duration variability, foot-strike, toe-off, and leg circumduction) and walking distance were recorded in 1-minute intervals. A fatigability index was calculated by comparing the last and first minute of the 6MWT to identify abnormal worsening based on cutoff scores. The manifestation of walking fatigability was counted. The temporal pattern of worsening of gait characteristics during the 6MWT was examined in pwMS exceeding the cutoff values, compared to pwMS without abnormal changes and HC, using a two-way ANOVA (group vs. minutes) RESULTS: Thirty-five pwMS presented both DWF and GQF, 2 presented isolated DWF, 27 presented isolated GQF, and 24 presented non-walking fatigability. PwMS having GQF presented worsening in gait characteristics (cadence, step duration, step duration variability, or toe-off angle) from minute 2 onwards of the 6MWT, while HCs and pwMS without abnormal changes stabilized gait from minute 2 towards the end of the 6MWT., Conclusion: Walking fatigability in pwMS manifests not only as a decrease in walking distance but also as changes in gait quality. Understanding changes in gait characteristics during walking can help tailor rehabilitation interventions., Competing Interests: Declaration of competing interest The Author (s) declare (s) that there is no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Due to improvement in movement performance, post-activation performance enhancement (PAPE) may open new possibilities to improve gait performance. However, no study has attempted to translate this phenomenon into walking. Therefore, the study aimed to test whether acute stretching followed by a conditioning exercise can improve subsequent gait performance in healthy adults., Research Question: Can an exercise protocol subsequently improve gait performance?, Methods: Sixteen individuals walked four 10-m trials (in each period) before and after 7 min of an exercise protocol composed of stretching (focusing on the lower limb) and a conditioning exercise (standing calf-raise wearing a vest of 20 kg). Gait spatialtemporal parameters and muscle activity of tibialis anterior and gastrocnemius medialis and lateralis muscles were obtained by a 3D-motion system and wireless electromyography, respectively. Before and after the exercise protocol, kinematic and muscle activity parameters were compared by a one-way ANOVA and the Wilcoxon signed-rank test, respectively., Results: After the exercise protocol, the participants walked with a faster step velocity ( p  < 0.018) and with a lower step duration ( p  < 0.025). Also, higher peak muscle activity ( p  < 0.008) and low-frequency ( p  < 0.034) activation of the anterior tibial muscle after the exercise protocol were observed., Significance: In conclusion, the protocol improves the stability and the muscles' efficiency during gait, contributing to a new approach to enhancing gait rehabilitation programs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (© 2024 Santinelli, Prieto Silveira-Ciola, Moreno, Kuroda and Barbieri.)

Background: Gait characteristics and their changes during the 6-minute walking test (6MWT) in people with multiple sclerosis (pwMS) have been described in the literature, which one may refer to as walking fatigability in the body function level of the International Classification of Functioning, Disability, and Health. However, whether these metrics are reliable is unknown., Objective: To investigate the between-day reliability of the gait characteristics and their changes in pwMS and healthy controls (HCs)., Methods: Forty-nine pwMS (EDSS 4.82 ± 1.22 and 54.7 ± 9.36 years) and 23 HCs (50.6 ± 6.1 years) performed the 6MWT, as fast as possible but safely while wearing Inertial Measurement Units. Gait characteristics were measured in the pace, rhythm, variability, asymmetry, kinematics, coordination, and postural control domains and were obtained in intervals of 1 minute during the 6MWT. In addition, gait characteristics change in the last minute compared with the first minute were calculated for all gait variables using a fatigability index (ie, distance walking index). The intraclass correlation coefficient (ICC), Bland-Altman Plots, and Standard error of measurement were applied to investigate reliability., Results: Reliability of gait characteristics, minute-by-minute, and for their changes (ie, using the fatigability index) ranged from poor to excellent (pwMS: ICC 0.46-0.96; HC: ICC 0.09-0.97 and pwMS: ICC 0-0.72; HC: ICC 0-0.77, respectively)., Conclusion: Besides coordination, at least 1 variable of each gait domain showed an ICC of moderate or good reliability for gait characteristics changes in both pwMS and HC. These metrics can be incorporated into future clinical trials and research on walking fatigability. Clinical Trial Registration: NCT05412043., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

People with Parkinson's disease (pwPD) have reduced adaptability to postural control during prolonged standing compared to neurologically healthy individuals (control). Objective. The study aimed to characterize postural changes during prolonged standing and their effect on postural control in pwPD compared to control. We recorded the body sway of the second lumbar vertebra of 23 pwPD and 23 control while they performed prolonged standing (15 min). The number and amplitude of the body sway patterns (shifts, fidgets, and drifts), the root mean square, velocity, and frequency of the body sway were analyzed. The number of shifts in the anterior-posterior (AP) and medial-lateral (ML) directions was greater for the pwPD than the control. In addition, the amplitudes of shifts in the AP direction and fidgets in the AP and ML directions were greater for the pwPD than the control. Our results show that: (1) A larger number of shifts of body sway suggest references positions are frequently changing; (2) Fidgets is a pumping mechanism and can be sensory-demand action to restore mechanoreceptors activity on the foot sole; and (3) No drift changes may suggest there is no slow migration of reference position. We conclude that pwPD exhibits different behavior than healthy ones during prolonged standing, suggesting that prolonged standing could distinguish individuals with Parkinson's disease., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier B.V.)

The imbalance in the concentration of metallic nanoparticles has been demonstrated to play an important role in multiple sclerosis (MS), which may impact cognition. Biomarkers are needed to provide insights into the pathogenesis and diagnosis of MS. They can be used to gain a better understanding of cognitive decline in people with MS (pwMS). In this study, we investigated the relationship between the blood concentration of metallic nanoparticles (blood nanoparticles) and cognitive performance in pwMS. First, four mL blood samples, clinical characteristics, and cognitive performance were obtained from 21 pwMS. All participants had relapse-remitting MS, with a score of ≤4.5 points in the expanded disability status scale. They were relapse-free in the three previous months from the day of collection and had no orthopedic, muscular, cardiac, and cerebellar diseases. We quantified the following metallic nanoparticles: aluminum, chromium, copper, iron, magnesium, nickel, zinc, and total concentration. Cognitive performance was measured by mini-mental state examination (MMSE) and the symbol digit modalities test (SDMT). Pearson's and Spearman's correlation coefficients and stepwise linear regression were calculated to assess the relationship between cognitive performance and blood nanoparticles. We found that better performance in SDMT and MMSE was related to higher total blood nanoparticles (r = 0.40; p < 0.05). Also, better performance in cognitive processing speed and attention (SDMT) and mental state (MMSE) were related to higher blood iron (r = 0.44; p < 0.03) and zinc concentrations (r = 0.41; p < 0.05), respectively. The other metallic nanoparticles (aluminum, chromium, copper, magnesium, and nickel) did not show a significant relationship with the cognitive parameters ( p > 0.05). Linear regression estimated a significant association between blood iron concentration and SDMT performance. In conclusion, blood nanoparticles are related to cognitive performance in pwMS. Our findings suggest that the blood concentration of metallic nanoparticles, particularly the iron concentration, is a promising biomarker for monitoring cognitive impairment in pwMS.

Background: Gait asymmetry and deficits in gait initiation (GI) are among the most disabling symptoms in people with Parkinson's disease (PwPD). Understanding if PwPD with reduced asymmetry during GI have higher asymmetry in cortical activity may provide support for an adaptive mechanism to improve GI, particularly in the presence of an obstacle., Objective: This study quantified the asymmetry of anticipatory postural adjustments (APAs), stepping parameters and cortical activity during GI, and tested if the presence of an obstacle regulates asymmetry in PwPD., Methods: Sixteen PwPD and 16 control group (CG) performed 20-trials in two conditions: unobstructed and obstructed GI with right and left limbs. We measured, through symmetry index, (i) motor parameters: APAs and stepping, and (ii) cortical activity: the PSD of the frontal, sensorimotor and occipital areas during APA, STEP-I (moment of heel-off of the leading foot in the GI until the heel contact of the same foot); and STEP-II (moment of the heel-off of the trailing foot in the GI until the heel contact of the same foot) phases., Results: Parkinson's disease showed higher asymmetry in cortical activity during APA, STEP-I and STEP-II phases and step velocity (STEP-II phase) during unobstructed GI than CG. However, unexpectedly, PwPD reduced the level of asymmetry of anterior-posterior displacement ( p < 0.01) and medial-lateral velocity ( p < 0.05) of the APAs. Also, when an obstacle was in place, PwPD showed higher APAs asymmetry (medial-lateral velocity: p < 0.002), with reduced and increased asymmetry of the cortical activity during APA and STEP-I phases, respectively., Conclusion: Parkinson's disease were not motor asymmetric during GI, indicating that higher cortical activity asymmetry can be interpreted as an adaptive behavior to reduce motor asymmetry. In addition, the presence of obstacle did not regulate motor asymmetry during GI in PwPD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Faria, Simieli, Rietdyk, Penedo, Santinelli and Barbieri.)

The effects of a cooling strategy following repeated high-intensity running (RHIR) on soccer kicking performance in a hot environment (>30ºC) were investigated in youth soccer players. Fifteen academy under-17 players participated. In Experiment 1, players completed an all-out RHIR protocol (10×30 m, with 30s intervals). In Experiment 2 (cross-over design), participants performed this running protocol under two conditions: (1) following RHIR 5 minutes of cooling where ice packs were applied to the quadriceps/hamstrings, (2) a control condition involving passive resting. Perceptual measures [ratings of perceived exertion (RPE), pain and recovery], thigh temperature and kick-derived video three-dimensional kinematics (lower limb) and performance (ball speed and two-dimensional placement indices) were collected at baseline, post-exercise and intervention. In Experiment 1, RHIR led to small-to-large impairments ( p  < 0.03;d = -0.42--1.83) across perceptual, kinematic and performance measures. In experiment 2, RPE ( p  < 0.01; Kendall's W = 0.30) and mean radial error ( p  = 0.057; η 2  = 0.234) increased only post-control. Significant small declines in ball speed were also observed post-control ( p  < 0.05; d = 0.35). Post-intervention foot centre-of-mass velocity was moderately faster in the cooling compared to control condition ( p  = 0.04; d = 0.60). In youth soccer players, a short cooling period was beneficial in counteracting declines in kicking performance, in particular ball placement, following intense running activity in the heat.

The contribution of cortical activity (e.g. EEG recordings) in various brain regions to motor control during goal-directed manipulative tasks using lower limbs remains unexplored. Therefore, the aim of the current study was to determine the magnitude of associations between EEG-derived brain activity and soccer kicking parameters. Twenty-four under-17 players performed an instep kicking task (18 m from the goal) aiming to hit 1 × 1 m targets allocated in the goalpost upper corners in the presence of a goalkeeper. Using a portable 64-channel EEG system, brain oscillations in delta, theta, alpha, beta and gamma frequency bands were determined at the frontal, motor, parietal and occipital regions separately for three phases of the kicks: preparatory, approach and immediately prior to ball contact. Movement kinematic measures included segmental linear and relative velocities, angular joint displacement and velocities. Mean radial error and ball velocity were assumed as outcome indicators. A significant influence of frontal theta power immediately prior to ball contact was observed in the variance of ball velocity ( R 2  = 35%, P  = 0.01) while the expression of occipital alpha component recorded during the preparatory phase contributed to the mean radial error ( R 2  = 20%, P  = 0.049). Ankle eversion angle at impact moment likely mediated the association between frontal theta power and subsequent ball velocity (β = 0.151, P  = 0.06). The present analysis showed that the brain signalling at cortical level may be determinant in movement control, ball velocity and accuracy when performing kick attempts from the edge of penalty area. Trial registration number #RBR-8prx2m-Brazilian Registry of Clinical Trials ReBec., Supplementary Information: The online version contains supplementary material available at 10.1007/s11571-022-09786-2., Competing Interests: Conflict of interestThe authors state no potential conflicts of interest in relation to the content of the present study., (© The Author(s), under exclusive licence to Springer Nature B.V. 2022.)

Purpose: The current study examined the possible relationships between one-off single night sleep metrics and subsequent kicking performance in a youth soccer context., Methods: Twenty-eight under-17 academy players (15.9 ± 0.8 years-old) completed a kick testing protocol consisting in 20 attempts, 18 m from the goal and against a goalkeeper. Four digital video cameras (240 Hz) allowed to determine 3-D approach run, lower limb and ball velocities. Two additional cameras (60 Hz) were used to calculate 2-D mean radial error, bivariate variable error and accuracy. Over 24 h prior to testing, players were monitored by wrist actigraphy to determine their sleep indices. Self-reported sleep quality, sleepiness and chronotype scale scores (Horne and Östberg morningness-eveningness questionnaire) were also collected immediately before kicking experiment., Results: Multiple linear regressions indicated that wake up time and chronotype contributed to 40% of mean radial error. Self-reported sleep quality influenced respectively on 19% and 24% of accuracy and bivariate variable error variances. Taken together self-reported sleep quality and wake up time explained 33% of accuracy (all p < 0.05). Indicators of kicking velocity were non-significantly correlated with sleep ( r = -0.30-0.29; p > 0.05)., Conclusion: One-off sleep measures showed some sensitivity to acutely detect inter-individual oscillations in kicking performance. Low perceived sleep quality, later wake up time and a chronotype toward evening preference seem either related to immediately subsequent worst ability of ball placement when kicking. Monitoring sleep-wake transition and perceived sleep quality may be important to help prevent acute performance declines in targeting the goal during kick attempts from the edge of penalty area.

Background: It has been suggested that the protein Brain-derived Neurotrophic Factor (BDNF) plays a neuroprotective role in people with multiple sclerosis (pwMS). Also, BDNF seems to play a role in cognition performance. In the same line, gait in pwMS requires a higher cognitive resource, mainly during complex walking. Thus, maybe BDNF could be related to gait in pwMS., Objective: To investigate the relationship between BDNF and gait spatial-temporal parameters during unobstructed and obstructed conditions and the Timed Up and Go (TUG) in pwMS and healthy controls (HC)., Methods: The study included 20 pwMS (11F/9M, 33.1±7.5 years, Expanded Disability Status Scale- EDSS 2.2±1.2) and 18 HC (13F/5M, 35.5±5.9 years). Both groups performed 20 gait attempts in two conditions: unobstructed walking (10 trials) and avoiding an obstacle. The obstacle was 15 cm in height and made of foam material. The BDNF serum concentration was collected with participants in fasting and completed before the clinical, gait, and mobility assessments. Clinical variables included the Symbol Digit Modality Test (SDMT), the Fatigue Severity Scale (FSS), and the International Physical Activity Questionnaire (IPAQ- short version). Associations between BDNF and spatial-temporal gait parameters, clinical variables, and TUG were determined by Pearson/Spearman correlations with Bonferroni's correction being applied (p<0.0013). Gait was compared by a two-way, repeated-measures ANOVA (group and condition) to characterize our cohort., Results: Reduced BDNF was observed for pwMS (41.66±4.45 ng/ml) in comparison with HC (61.67±7.07, p<0.001). However, although some correlations presented a moderate correlation between BDNF with gait variables, the correlations didn't reach a significant p-value after Bonferroni's correction. Lastly, pwMS presented shorter step length and slower step velocity for both gait conditions, with more evidence for obstacle conditions. Only pwMS changed gait behavior from unobstructed walking to obstacle avoidance conditions (i.e., reduced step length and velocity and increased step duration)., Conclusion: BDNF is not related to either clinical (i.e., EDSS, SDMT, FSS, or IPAQ) or gait parameters in pwMS and HC, even in a condition involving higher cognitive demand. These results may suggest that BDNF does not play a role in these parameters' performance., Competing Interests: Declaration of Competing Interest The Authors declare that there is no financial/personal interest which could impact in this manuscript., (Copyright © 2022. Published by Elsevier B.V.)

Background: Postural impairment is one of the most debilitating symptoms in people with Parkinson's disease (PD), which show faster and more variable oscillation during quiet stance than neurologically healthy individuals. Despite the center of pressure parameters can characterize PD's body sway, they are limited to uncover underlying mechanisms of postural stability and instability., Research Question: Do a multiple domain analysis, including postural adaptability and rambling and trembling components, explain underlying postural stability and instability mechanisms in people with PD?, Method: Twenty-four individuals (12 people with PD and 12 neurologically healthy peers) performed three 60-s trials of upright quiet standing on a force platform. Traditional and non-linear parameters (Detrended Fluctuation Analysis- DFA and Multiscale Entropy- MSE) and rambling and trembling trajectories were calculated for anterior-posterior (AP) and medial-lateral (ML) directions., Results: PDG's postural control was worse compared to CG, displaying longer displacement, higher velocity, and RMS. Univariate analyses revealed largely longer displacement and RMS only for the AP direction and largely higher velocity for both AP and ML directions. Also, PD individuals showed lower AP complexity, higher AP and ML DFA, and increased AP and ML displacement, velocity, and RMS of rambling and trembling components compared to neurologically healthy individuals., Significance: Based upon these results, people with PD have a lower capacity to adapt posture and impaired both rambling and trembling components compared to neurologically healthy individuals. These findings provide new insights to explain the larger, faster, and more variable sway in people with PD., Competing Interests: Conflict of interest The authors declare that there is no conflict of interest., (Copyright © 2022 Elsevier B.V. All rights reserved.)

COVID-19 in Brazil is threatening, and it has forced the government to adopt partial lockdown as a strategy to stop the spread of the virus in the first wave of pandemic (March 2020). These preventive measures during the COVID-19 pandemic may affect the motor and non-motor symptoms in people with Parkinson's disease (PD) and Multiple sclerosis (MS). Thus, the purpose of this study was to investigate the perception during the first wave of COVID-19 pandemic lockdown on motor and non-motor symptoms, and also measure physical activity level, quality of life, and sleep quality in Brazilian people with PD and MS. One hundred and fifty-three participants (PD-97 and MS-56) answered an online survey to identify the perception of motor and non-motor symptoms, and characterize the physical activity level, and quality of life and sleep in these neurological Brazillian population. During the beginning of pandemic lockdown in Brazil, our results indicated that 69% of people with PD and 55% of people with MS reported worse on motor aspects and lower amount of physical activity performed. Also, 75.2% (PD) and 92.9% (MS) of our cohort were considered inactive or sedentary. Based on the perception and behavior of the population studied, people with PD and MS should be encouraged to perform more physical activity in order to reduce the effects of isolation in motor and non-motor aspects of the diseases. Teleinterventions, such as home-based exercise, should be included in the new routine of people with PD and MS to reduce the impacts of lockdown and to maintain quality of life at a good level., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Simieli, Santinelli, Costa, Kuroda, Oliveira, Penedo, Pilon, Silveira, Assis, Tardelli, Okamoto and Barbieri.)

Background: Our understanding of how balance control responds to levodopa over the course of a single day in people with Parkinson's disease (PD) is limited with the majority of studies focused on isolated comparisons of ON vs. OFF levodopa medication., Objective: To evaluate the temporal dynamics of postural control following the first levodopa dose of the day during a challenging standing task in a group of people with PD., Methods: Changes in postural control were evaluated by monitoring cortical activity (covering frontal, motor, parietal and occipital areas), body sway parameters (force platform), and lower limb muscle activity (tibialis anterior and gastrocnemius medialis) in 15 individuals with PD during a semi-tandem standing task. Participants were assessed during two 60 second trials every 30 minutes (ON-30 ON-60 etc.) for 3 hours after the first matinal dose (ON-180)., Results: Compared to when tested OFF-medication, cortical activity was increased across all four regions from ON-60 to ON-120 with early increases in alpha and beta band activity observed at ON-30. Levodopa was associated with increased gastrocnemius medialis activity (ON-30 to ON-120) and ankle co-contraction (ON-60 to ON-120). Changes in body sway outcomes (particularly in the anterior-posterior direction) were evident from ON-60 to ON-120., Conclusions: Our results reveal a 60-minute window within which postural control outcomes may be obtained that are different compared to OFF-state and remain stable (from 60-minutes to 120-minutes after levodopa intake). Identifying a window of opportunity for measurement when individuals are optimally medicated is important for observations in a clinical and research setting., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study had the purpose of analyzing dominant and non-dominant limb performances (frequency of use and accuracy) during match-play technical actions with ball possession (receiving, passing, and shooting a ball) in professional futsal and also check for the possible influence of playing position and the quality of opponent. We have analyzed data pertaining to eight matches of the FIFA Futsal World Cup Thailand 2012™ in which 76 male professional senior futsal players participated (44 right-footed and 32 left-footed). In total, we coded 5,856 actions (2,550 ball receptions, 3,076 passes, and 230 shoots). Our main findings were that (a) players used the dominant limb more frequently than the non-dominant limb for all actions considered [ p < 0.001; effect size (ES) medium-to-large]; (b) accuracy was generally greater when using the dominant limb, regardless of the quality of opponent ( p < 0.01; ES large); and (c) in shooting actions, pivots showed similar accuracy between dominant and non-dominant limbs ( p = 0.51; ES small). The study suggested that when completing technical actions with the ball in futsal, high-level players depended to a greater extent on the use of their dominant lower limb during official matches. Excepting a similarity detected between limbs on shooting performance of pivots, players from all positional roles generally showed a higher accuracy rate in receiving, passing, and shooting a ball when using their dominant limb as compared to their non-dominant one during match-play and the limb usage and accuracy seemed to be independent of the quality of opponents., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Palucci Vieira, Kalva-Filho, Santinelli, Clemente, Cunha, Schimidt and Barbieri.)

Background: People with Multiple Sclerosis (PwMS) present higher cortical activity during walking. However, the cortical activity during gait while avoiding an obstacle is still not clear., Objective: To investigate cortical activity and gait spatial-temporal parameters in PwMS during two different gait tasks (i.e., unobstructed and obstacle avoidance)., Method: Fifteen PwMS and 15 healthy controls (CG) were recruited. Participants performed ten trials in each gait condition, wearing a 64-electrode cap electroencephalogram (EEG) at 1024 Hz. Kinematic data were obtained through 10 Vicon® cameras at 200 Hz. EEG was analyzed through four cortical areas (frontal, motor, parietal, and occipital cortex areas) and five frequency bands (delta, theta, alpha, beta, and gamma) obtained through the power spectral density. In addition, spatial-temporal gait parameters (e.g., step length and velocity) were measured. Two-way ANOVA (group x gait condition) and MANOVA (group x gait condition) were used to compare gait and EEG parameters, respectively. One-way ANOVA was used to compare groups in the crossing phase of the obstacle avoidance condition., Results: PwMS presented lower step length and velocity, and higher cortical activity in frontal (beta and gamma) and parietal (gamma) cortical areas in both gait conditions compared to CG. Moreover, PwMS presented increased cortical activation (frontal and parietal) and decreased step length and velocity in obstacle avoidance compared with unobstructed gait. In addition, PwMS required more cortical resources (frontal and parietal) than CG to accomplish both gait conditions. During the obstacle avoidance task, it was further observed that PwMS positioned their feet closer to the obstacle, before and after the task, compared to CG., Conclusion: PwMS demand higher cortical resources to accomplish gait tasks, mainly when it is necessary to negotiate an obstacle in the pathway. This higher cortical activity may be a compensatory mechanism to deal with damage in subcortical structures caused by multiple sclerosis., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The aim of this study was to investigate the effects of ankle and hip muscle fatigue on motor adjustments (experiment 1) and symmetry (experiment 2) of postural control during a quiet standing task. Twenty-three young adults performed a bipedal postural task on separate force platforms, before and after a bilateral ankle and hip muscle fatigue protocol (randomized). Ankle and hip muscles were fatigued separately using a standing calf raise protocol (ankle fatigue) on a step and flexion and extension of the hip (hip fatigue) sitting on a chair, at a controlled movement frequency (0.5Hz), respectively. In both experiments, force, center of pressure, and electromyography parameters were measured. The symmetry index was used in experiment 2 to analyze the postural asymmetry in the parameters. Our main findings showed that muscle fatigue impaired postural stability, regardless of the fatigued muscle region (i.e., ankle or hip). In addition, young adults used an ankle motor strategy (experiment 1) before and after both the ankle and hip muscle fatigue protocols. Moreover, we found increased asymmetry between the lower limbs (experiment 2) during the quiet standing task after muscle fatigue. Thus, we can conclude that the postural motor strategy is not muscle fatigue joint-dependent and a fatigue task increases postural asymmetry, regardless of the fatigued region (hip or ankle). These findings could be applied in sports training and rehabilitation programs with the objective of reducing the fatigue effects on asymmetry and improving balance., Competing Interests: The authors have declared that no competing interests exist.

Background: Impaired movement stability is a common symptom of Parkinson's disease (PD) that leads to falls and mishandled objects. Decline in synergistic stabilization of movement in PD patients has been observed in manual and postural tasks. However, locomotor synergies have not been quantified in PD patients., Research Question: The purpose of this work was to quantify the strength of the synergy stabilizing the step length while crossing an obstacle in PD patients. We hypothesized that (1) the distances of the front and rear feet relative to the obstacle would display compensatory across-trial co-variance that stabilizes step length in PD patients and age-matched controls, and (2) the step-length stabilization would be weaker in PD patients., Methods: Thirteen PD patients and eleven healthy age-matched controls walked up to and stepped over a 15 cm high obstacle fifteen times.We measured the distances of the rear and front foot toes from the obstacle during the crossing step. We used the uncontrolled manifold method to parse the across-trial variance in toe distances into a component that maintains the step length and a component that changes the step length. These variance components yielded the synergy index that quantified the stability of step length., Results: Step length was stabilized in PD patients as well as controls. However, the synergy index was 53% lower in the PD patients (p < 0.01). Thus, both our hypotheses were supported., Significance: This is the first study reporting impaired locomotor synergies in PD patients. Most PD patients in our sample were early stage (10 out of 13 patients were Hoehn-Yahr ≤ 2). Therefore, this result motivates further studies to establish step-length synergy during adaptive locomotor tasks as a biomarker for early detection of locomotor impairments in PD patients., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Studies on short-term upright quiet standing tasks have presented contradictory findings about postural control in people with Parkinson's disease (pwPD). Prolonged trial durations might better depict body sway and discriminate pwPD and controls., Objective: The aim of this study was to investigate postural control in pwPD during a prolonged standing task., Methods: A total of 26 pwPD and 25 neurologically healthy individuals performed 3 quiet standing trials (60 s) before completing a constrained prolonged standing task for 15 minutes. Motion capture was used to record body sway (Vicon, 100 Hz). To investigate the body sway behavior during the 15 minutes of standing, the analysis was divided into three 5-minute-long phases: early, middle, and late. The following body sway parameters were calculated for the anterior-posterior (AP) and medial-lateral (ML) directions: velocity, root-mean-square, and detrended fluctuations analysis (DFA). The body sway area was also calculated. Two-way ANOVAs (group and phases) and 1-way ANOVA (group) were used to compare these parameters for the prolonged standing and quiet standing, respectively., Results: pwPD presented smaller sway area ( P < .001), less complexity (DFA; AP: P < .009; ML: P < .01), and faster velocity (AP: P < .002; ML: P < .001) of body sway compared with the control group during the prolonged standing task. Although the groups swayed similarly (no difference for sway area) during quiet standing, they presented differences in sway area during the prolonged standing task ( P < .001)., Conclusions: Prolonged standing task reduced adaptability of the postural control system in pwPD. In addition, the prolonged standing task may better analyze the adaptability of the postural control system in pwPD.

Background: Multiple Sclerosis (MS) is a neurodegenerative and inflammatory disease that impacts both visual and postural control. It is currently unknown how the integration between visual and postural control is affected in people with MS (PwMS). It has been shown in healthy individuals that saccadic eye movements can decrease body sway as result as the integration of eye and postural movements., Objective: Investigate the effect of saccadic eye movement on postural control in PwMS and compare with neurologically healthy people., Methods: Thirteen mildly affected PwMS (1.53 ± 1.03 on Expanded Disability Status Scale - EDSS) and 12 healthy neurologically people participated in this study. Postural control was assessed on a force platform under two eye movement conditions: fixation on a central target and saccadic eye movement. The dependent variables assessed were the displacement, velocity, root-mean-square (RMS) and area of postural center of pressure and the number, duration, variability, fixations errors and eye response time. A mobile eye tracker was used to record eye movement. Two-way ANOVA (group and eye movement) for postural variables was performed. For the eye variables, one-way ANOVA with factor to group was performed. The p-value was maintained at 0.05 for all statistical analysis and the effect sizes were based on Cohen's d., Results: No group or interaction effects (group*eye movement) were found for postural and eye variables. However, the saccadic eye movement attenuated the postural displacement in anteroposterior (AP) direction (p < 0.001, Cohen's d = 4.677), RMS AP (p < 0.001, Cohen's d = 4.399) and area (p < 0.013, Cohen's d = 2.163) in comparison with the central fixation condition in both groups. The Cohen's d showed a large effect between groups for fixation errors (d = 0.741)., Conclusion: Both groups presented similar postural control performance in both eye movement conditions. Moreover, PwMS could attenuate body sway similarly to the control group, showing that the central integration of dynamic eye movements and postural control is preserved in mildly affected PwMS., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study investigated changes in postural control complexity in people with multiple sclerosis (PwMS) before and after a fatigue protocol. Thirteen minimally affected PwMS (1.53 ± 1.03- Expanded Disability Status Scale) and 12 non-MS controls. Postural test included quiet stance on a force platform under two visual conditions (saccades and fixation) before and after a fatigue protocol. Postural complexity was assessed through the multiscale entropy. A three-way ANOVA showed a main effect of fatigue in the medial-lateral direction ( p <0.007), with fatigue protocol reducing postural complexity in both groups. No differences were found between groups or visual conditions. Minimally affected PwMS demonstrated similar postural complexity compared with non-MS controls under both visual tasks and showed similar decrements in postural complexity as a result of fatigue.

The color of an obstacle may enable a more detailed view of the environment to facilitate obstacle avoidance. However, people with Parkinson's disease (PD) present visual contrast and color detection dysfunction, which could affect obstacle avoidance according to obstacle color. Thus, the aim of this study was to investigate the influence of obstacle color on locomotor and gaze behavior during obstacle avoidance in people with PD and neurologically healthy older individuals. Thirteen people with PD and eleven matched-control group individuals, with normal visual acuity (20/20 on the Snellen chart), performed 20 trials (5 trials for each obstacle color condition) of the obstacle avoidance task with the following obstacle colors: white, black, red, and blue. Participants were positioned at the beginning of a walkway with their eyes closed and, after the start command, opened their eyes, started walking at their preferred velocity, and crossed the obstacle. Spatial-temporal parameters and fixations on the obstacle (gaze behavior) were measured using a three-dimensional camera system and mobile eye-tracker, respectively. Our main findings were the absence of significant color interaction on locomotor and gaze behaviors, the absence of significant main effect of color on gaze behavior, and an effect of obstacle color on locomotor behavior, specifically in the placement of the heel from the obstacle after crossing and toe-clearance for both trailing and leading limbs, which indicates that obstacle color can play a role in obstacle avoidance during walking. However, there was no consistent obstacle color that influenced the locomotor behavior. Therefore, the conclusion of this study is that obstacle color seems to affect locomotor behavior, but not gaze behavior, during walking with obstacle avoidance in people with PD and neurologically healthy individuals. However, no particular obstacle color causes a consistent effect on locomotor behavior.