The Use of Home-Based Nonimmersive Virtual Reality to Encourage Physical and Cognitive Exercise in People With Mild Cognitive Impairment: A Feasibility Study.

Individuals with mild cognitive impairment are at risk of cognitive and physical decline. Virtual reality (VR) exercise may provide beneficial physical and cognitive exercise. The objectives of this study were to assess the feasibility and safety of home-based VR exercise and to provide pilot data for physical and cognitive efficacy. Eleven individuals with mild cognitive impairment (seven males/four females, average 78 years old, and average 3 years since diagnosis) performed a 30-min home-based VR exercise program 5 days a week for 6 weeks. The VR platform was successfully installed in participants' homes, and all participants were able to learn the VR program and progress. Participants completed 99% of the prescribed exercise. There were no major adverse events. Most participants enjoyed the VR program and reported physical benefits; fewer reported cognitive benefits. No physical or cognitive outcome measures showed change after 6 weeks. Home-based VR exercise is safe and feasible in individuals with mild cognitive impairment.

How do we define and measure sarcopenia? A meta-analysis of observational studies.

OBJECTIVE: this study aimed to investigate how sarcopenia has been defined and measured in the literature reporting its prevalence, and how different definitions and measurement tools can affect prevalence estimates. DESIGN: systematic review and meta-analysis. SETTING AND PARTICIPANTS: community-dwelling older people. METHODS: meta-analysis of data collected from observational studies. We performed an electronic search in five databases to identify studies reporting the prevalence of sarcopenia. We used descriptive statistics to present data pertaining sarcopenia definition and measurement tools, and the quality-effects model for meta-analysis of pooled prevalence. RESULTS: we found seven different operational definitions for sarcopenia and a variety of tools applied to assess the sarcopenic markers; muscle mass, muscle strength and physical performance. The prevalence of sarcopenia varied between the definitions with general estimates ranging from 5% based on the European Working Group on Sarcopenia in Older People (EWGSOP1) criterion to 17% with the International Working Group on Sarcopenia. According to the tool used to assess muscle mass, strength and physical performance, prevalence values also varied within definitions extending from 1 to 7%, 1 to 12% and 0 to 22%, respectively. CONCLUSION AND IMPLICATIONS: the criteria used to define sarcopenia, as well as the measurement tools applied to assess sarcopenic markers have influence in the prevalence of sarcopenia. The establishment of a unique definition for sarcopenia, the use of methods that guarantee an accurate evaluation of muscle mass and the standardisation of measurement tools are necessary to allow a proper diagnosis and comparison of sarcopenia prevalence among populations.

The influence of knee extensor fatigue on lower extremity muscle activity during chair rise in young and older adults.

PURPOSE: The purpose of this investigation was to evaluate alterations in muscular effort and temporal characteristics of their activity during the sit-to-stand (STS) due to isolated fatiguing of the knee extensors, as indicated by declines in torque output. METHODS: Surface electromyography of the lower extremity was recorded in healthy young (n = 11) and older (n = 11) adults as they ascended from a seated position, before and after dynamic knee extension exercise. RESULTS: Knee extensor fatigue caused significant increases in soleus, gastrocnemius, and gluteus maximus relative effort (%MVC) in both age groups during the STS task. Rectus femoris %MVCs in both young and older adults significantly increased to similar extents throughout the STS movement, whereas vastus lateralis amplitudes only increased in preparation for seat-off. Muscle temporal characteristics appeared to generally be invariant with fatigue, except for earlier activation onset for the ankle musculature in older adult participants. CONCLUSIONS: These findings demonstrate that isolated knee extension fatiguing exercise caused compensatory changes in muscle activation patterns and increased reliance of non-fatigued muscles at the ankle and hip as well as increased activity of synergist muscles during the STS. Moreover, this occurred to similar extents in older adults who had lower knee extensor strengths and greater quadriceps %MVCs in comparison to their younger counterparts, regardless of fatigue condition.

The role of thigh muscular efforts in limiting sit-to-stand capacity in healthy young and older adults.

Aging is associated with an unavoidable decline in muscle mass, known as sarcopenia, leading to neuromuscular declines, muscle weakness, and subsequent disability. One particular measure utilized by rehabilitative professionals in evaluating functional declines in older persons is sit-to-stand (STS) capacity. The purpose of this investigation was to determine the role of activation intensity requirements of the thigh musculature in limiting a multi-joint STS endurance task. To do so, surface EMG signals of the quadriceps femoris (QF) and hamstrings (biceps femoris; BF) and their co-activation ratios (H:Q) were collected in young (18-35 years; n = 12) and older (60-75 years; n = 12) adult participants who repeatedly stood from a seated position until exhaustion. QF %MVIC was the sole predictor of total STS task times, as those who required the highest quadriceps efforts had the shortest task times. Moreover, older adult participants had significantly higher starting QF %MVIC as well as shorter task times. Interestingly, the H:Q ratio was not a significant predictor of STS capacities, nor did it differ between age groups or with fatigue. Results indicate that strengthening of the quadriceps to elevate or maintain strength reserves may improve an older adult's ability to perform multi-joint tasks repetitively throughout the day.

Virtual reality exercise improves mobility after stroke: an inpatient randomized controlled trial.

BACKGROUND AND PURPOSE: Exercise using virtual reality (VR) has improved balance in adults with traumatic brain injury and community-dwelling older adults. Rigorous randomized studies regarding its efficacy, safety, and applicability with individuals after stroke are lacking. The purpose of this study was to determine whether an adjunct VR therapy improves balance, mobility, and gait in stroke rehabilitation inpatients. METHODS: A blinded randomized controlled trial studying 59 stroke survivors on an inpatient stroke rehabilitation unit was performed. The treatment group (n=30) received standard stroke rehabilitation therapy plus a program of VR exercises that challenged balance (eg, soccer goaltending, snowboarding) performed while standing. The control group (n=29) received standard stroke rehabilitation therapy plus exposure to identical VR environments but whose games did not challenge balance (performed in sitting). VR training consisted of 10 to 12 thirty-minute daily sessions for a 3-week period. Objective outcome measures of balance and mobility were assessed before, immediately after, and 1 month after training. RESULTS: Confidence intervals and effect sizes favored the treatment group on the Timed Up and Go and the Two-Minute Walk Test, with both groups meeting minimal clinical important differences after training. More individuals in the treatment group than in the control group showed reduced impairment in the lower extremity as measured by the Chedoke McMaster Leg domain (P=0.04) immediately after training. CONCLUSIONS: This VR exercise intervention for inpatient stroke rehabilitation improved mobility-related outcomes. Future studies could include nonambulatory participants as well as the implementation strategies for the clinical use of VR. CLINICAL TRIAL REGISTRATION URL: http://www.ANZCTR.org.au/. Unique identifier: ACTRN12613000710729.

The influence of age and surface compliance on changes in postural control and attention due to ankle neuromuscular fatigue.

The reduction in the quality and integration of sensory information with aging could increase the alterations in postural control associated with muscle fatigue observed in younger adults. This study aimed to compare changes in postural control and attentional demands due to ankle muscle fatigue, with intact and reduced proprioceptive information at the ankle, between young and older adults. Eleven young (24 ± 4 years) and 13 older (65 ± 4 years) men stood quietly on a force platform (blindfolded) under four experimental conditions (combinations of firm (FS)/compliant (CS) surfaces and single/dual tasks), before and immediately after a fatiguing exercise. The fatiguing exercise, performed on a dynamometer, consisted of maintaining an isometric contraction of the plantarflexors at 50 % of maximum until exhaustion. Both COP sway area and COP sway velocity were greater on the CS compared to FS and increased with fatigue for both groups in all conditions. COP sway area showed a greater increase with fatigue in older adults when standing on the CS. Reaction time (secondary task) increased significantly after fatigue, but only for older adults when standing on the CS. The effects of fatigue on postural control are more important when proprioceptive information at the ankle is altered. In particular, older adults had more difficulty and may have needed more attention to stand quietly, compared with young adults.

Attentional focus influences postural control and reaction time performances only during challenging dual-task conditions in healthy young adults.

The dual-task paradigm has previously been used to investigate the attentional demands associated with postural control. Previous studies have identified both the focus of attention and the difficulty of a postural task as potential factors influencing dual-task performance. The aim of this study was to examine how the instructed focus of attention influences dual-task performance during quiet standing tasks of various levels of difficulty. Thirteen young adults participated in two testing sessions consisting of standing as still as possible on a force platform in different postural conditions, while simultaneously performing a simple reaction time (RT) task. Postural task difficulty was manipulated by various combinations of three bases of support (feet together, tandem and single leg) and two visual conditions (eyes opened and closed). Participants were instructed to focus on either their balance or their RT performance, depending on the testing session. When comparing postural control with respect to session focus, anterior-posterior sway velocity decreased with the addition of the simple RT task when the focus was on balance, but only during the more difficult dual-task conditions. In contrast, sway area and medial-lateral sway velocity did not change between the two instructed focus sessions. Participants responded faster in all dual-task conditions when focusing on RT performance than on balance. The modified attention allocation index indicated that participants' ability to modulate their allocation of attentional resources to respond positively to instruction was more pronounced in the most challenging postural condition. The present findings could have important implications for the interpretation of dual-task performance in both clinical and research settings.

Effect of trunk extensor fatigue on the postural balance of elderly and young adults during unipodal task.

Muscle fatigue can influence the various mechanisms that regulate balance. Few studies have investigated the effects of trunk extensor muscle fatigue on postural control. The purpose of this study was to evaluate the impact of trunk extensor fatigue during a one-leg balance test in young and elderly adults, as well as to determine the time necessary to recover posture control after fatigue. A total of 36 subjects (18 elderly and 18 young adults) participated in the study. Subjects were tested on a force platform to assess the postural control parameters associated with center of pressure (COP) movements, before and after a fatiguing trunk extension-flexion exercise on a roman chair carried out to exhaustion. Post-fatigue effects and postural control recovery were investigated at different times in minutes (MIN): immediately post-fatigue (postIME), after 5 (rec5MIN), 10 (rec10MIN), and 20 min (rec20MIN). Elderly subjects had greater sway (P < 0.05) than young adults in all COP parameters. In both groups, there was an increase in postIME sway compared with pre-fatigue values for all COP parameters. However, the differences were significant only for the COP velocity parameter, with more pronounced effects in young adults that did not return to pre-fatigue values at the end of rec20MIN. The present study demonstrated a significant effect of trunk extensor muscle fatigue on postural control, which was more evident in young adults than in the elderly.

Sex differences concerning the effects of ankle muscle fatigue on static postural control and spinal proprioceptive input at the ankle.

Aims: The main aim of this study was to determine sex differences in postural control changes with ankle muscle fatigue during a standing forward leaning (FL) task under different vision conditions. The secondary aim was to examine sex differences in the effect of fatigue on soleus (SOL) H-reflex amplitude, a measure of motoneuron excitability with activation of Ia afferents. Methods: Fifteen healthy young adult males (mean age: 28.0 years) and 16 healthy young adult females (mean age: 26.1 years) were asked to perform four consecutive FL tasks [30 s; two with eyes open (EO) and two with eyes closed (EC)] before, and immediately following a fatiguing exercise consisting of alternating ankle plantarflexion (6 s) and dorsiflexion (2 s) maximal isometric contractions, and at 5 and 10 min of recovery. Center of pressure (COP) sway variables (mean position, standard deviation, ellipse area, average velocity, and frequency), an ankle co-contraction index, and a ratio of SOL H-reflex to the maximum amplitude of the compound muscle action potential (M-max) were obtained during the FL tasks. A rating of perceived fatigue (RPF) was also documented at the different time points. Results: Time to task failure (reduction of 50% in maximal voluntary isometric contraction torque of ankle plantar flexors) and the increase in RPF value were not significantly different between males and females. Both sex groups showed similar and significant increases (p < 0.05) in mean COP sway velocity with no significant changes in co-contraction indices. No significant effects of fatigue and related interactions were found for SOL H/M-max ratio. Discussion: The absence of a significant sex difference in postural control change (sway and co-contraction) with fatigue could be explained by similar perceived (RPF) and performance fatigability (exercise duration) between males and females in the present study. Fatigue did not lead to significant changes in SOL spinal motoneuron excitability with activation of Ia afferents.

A physiotherapist's perception of their own behavior compared to the perception of their behavior by persons with TBI within the context of telerehabilitation: A self-determination theory perspective.

BACKGROUND: According to Self-Determination Theory, the fulfillment of basic psychological needs of autonomy, competence, and relatedness plays an important role in one's motivation, engagement, and well-being. How a therapist is perceived to support or thwart these needs can impact adherence to treatment, thus influencing the effectiveness of therapeutic interventions. OBJECTIVES: This alternating single-subject design explores how the physiotherapist self-reports interpersonal behaviors, how the person living with a disability (PwD) perceives the physiotherapist's supportive/thwarting interpersonal behaviors, and how the two align in the context of telerehabilitation. METHODS: Five PwD and their physiotherapist completed two telerehabilitation exercise programs. The PwD completed the Interpersonal Behavior Questionnaire (IBQ) to examine how they perceived the physiotherapist interpersonal behaviors. The physiotherapist completed the Interpersonal Behavior Questionnaire-Self (IBQ-Self) to document how they self-reported these same behaviors. Descriptive statistics were used to document self-reports and perceptions of behaviors. RESULTS: Each PwD perceived the physiotherapist as being more supportive than thwarting. The supportive/thwarting behaviors varied across relationships. Greater alignment of the perceptions of therapist and the PwD was observed at the end of the programme when compared to baseline. CONCLUSION: Assessing how therapist support/thwart psychological needs and how these behaviors are perceived by PwD is recommended as it may influence the therapist's behavior and the PwD's adherence to future telerehabilitation exercise programs.

The Impact of Two Telerehabilitation Supervision Schedules on Physical Activity, Mobility, and Balance Among People with Moderate to Severe Traumatic Brain Injury: A Mixed-Method Single-Subject Design.

Background: Many individuals who experience a moderate or severe traumatic brain injury (TBI) have long-term deficits in physical activity, balance, and mobility requiring specialized care. New delivery models are being investigated for interventions to address challenges caused by living in remote communities, difficulties with transportation, and/or physical distancing requirements. Determining the effectiveness of telerehabilitation is critical given the current movement toward remote health care delivery. Objective: We investigated the effectiveness of two teletherapy supervision schedules used to deliver a home-based, intensive exercise programme on 1) physical activity, mobility, balance, participation, and 2) concerns with falling, and satisfaction with life. Methods: A mixed methods approach with alternating single subject design (SSD) and interviews was used. Five individuals who experienced a moderate or severe TBI completed two intensive home-based telerehabilitation programmes. Programmes differed only by supervision schedule - daily or weekly. Impacts on objective and patient-reported outcomes were measured. Results: Four individuals demonstrated clinically significant improvements in physical activity level, balance, and mobility. One individual experienced less concerns with falling after both schedules, while two other individuals showed a trend in that direction after the weekly remote supervision. Important functional gains (i.e., improved balance and decreased fatigue) were also perceived and reported by family partners regardless of supervision schedule. Conclusion: Although the study has limitations, the findings indicate that exercise programmes delivered via telerehabilitation can improve balance and mobility as well as positively affect concerns with falling and physical activity levels for this population. No clear differences were seen between the two telerehabilitation supervision schedules.

Historique : de nombreuses personnes qui sont victimes d'un traumatisme crânien (TC) modéré ou grave ont des déficits à long terme en matière d'activité physique, d'équilibre et de mobilité et doivent recevoir des soins spécialisés. De nouveaux modèles de prestation sont en cours d'étude afin que les interventions relèvent les problèmes liés à la vie en région éloignée, au transport ou à la distanciation physique. Il est essentiel de déterminer l'efficacité de la téléréadaptation en raison du mouvement actuel vers la prestation des soins à distance. Objectif : examiner l'efficacité de deux horaires de supervision de la téléthérapie utilisés pour fournir un programme d'exercice intensif à domicile sur 1) l'activité physique, la mobilité, l'équilibre et la participation et 2) les craintes de chutes et la satisfaction de vivre. Méthodologie : méthodologie mixte faisant appel à une alternance entre la méthodologie individuelle et les entrevues. Cinq personnes qui avaient été victimes d'un TC modéré ou grave ont suivi deux programmes intensifs de téléréadaptation à domicile. Les programmes différaient seulement en fonction de l'horaire de supervision, qui était quotidien ou hebdomadaire. Les chercheurs ont mesuré les répercussions sur les résultats cliniques objectifs et déclarés par les patients. Résultats : quatre personnes ont démontré des améliorations cliniquement significatives au taux d'activité physique, à l'équilibre et à la mobilité. Une personne craignait moins les chutes après les deux programmes tandis que les deux autres ressentaient une tendance dans cette direction après la supervision hebdomadaire à distance. Des gains fonctionnels importants (amélioration de l'équilibre et diminution de la fatigue) étaient également perçus et déclarés par les partenaires familiaux, quel que soit l'horaire de supervision. Conclusion : même si l'étude comporte des limites, les observations indiquent que les programmes d'exercices donnés en téléréadaptation peuvent améliorer l'équilibre et la mobilité et avoir des effets positifs sur les craintes de tomber et les taux d'activité physique dans cette population. Il n'y avait pas de différences évidentes entre les deux horaires de supervision de la téléréadaptation.

Remotely Supervised Exercise Programmes to Improve Balance, Mobility, and Activity Among People with Moderate to Severe Traumatic Brain Injury: Description and Feasibility.

Purpose: Further investigation into the feasibility of using videoconferencing and activity tracking devices to provide high-intensity home-based exercise programmes for people with a moderate or severe traumatic brain injury (TBI) is needed to inform clinical implementation and patient adoption. This study aimed to (1) determine if home-based telerehabilitation exercise programmes were feasible for people with a moderate or severe TBI and (2) better understand the lived experience of people with a TBI and their family partners with this programme. Methods: A mixed-methods approach consisting of measures of feasibility and semi-structured interviews was used. Five participants with moderate to severe TBI and their family partners completed two high-intensity home-based exercise programmes delivered remotely by a physiotherapist (i.e., daily and weekly). Results: Telerehabilitation services in home-based settings were feasible for this population. Adherence and engagement were high. Dyads were satisfied with the use of technology to deliver physiotherapy sessions. Conclusion: Telerehabilitation provides a delivery option that allows people with TBI to spend energy on therapy rather than on travelling. A pre-programme training on key components, such as the use of technology, safety precautions, and communication methods, likely improved the overall feasibility. Further research is needed to better understand the effectiveness of such a programme on balance, mobility, and physical activity levels.

Objectif : des recherches plus approfondies s'imposent sur la faisabilité d'utiliser les visioconférences et les dispositifs de suivi des activités pour fournir des programmes d'exercices à domicile à haute intensité aux personnes atteintes d'un traumatisme crânien (TC) modéré à grave qui éclaireront la mise en œuvre clinique et l'adoption par le patient. Cette étude visait à 1) déterminer s'il était faisable d'offrir des programmes d'exercices en téléréadaptation à domicile pour les personnes atteintes d'un TC modéré à grave et 2) mieux comprendre l'expérience vécue des personnes atteintes d'un TC et de leurs partenaires familiaux au sein de ce programme. Méthodologie : les chercheurs ont utilisé une approche mixte composée de mesures de faisabilité et d'entrevues semi-structurées. Cinq participants atteints d'un TC modéré à grave et leurs partenaires familiaux ont effectué deux programmes d'exercices à domicile à haute intensité donnés à distance par un physiothérapeute (quotidiennement et hebdomadairement). Résultats : les services de téléréadaptation à domicile étaient faisables pour cette population. L'adhésion et la participation étaient élevées. Les dyades étaient satisfaites par l'utilisation de la technologie pour la prestation des séances de physiothérapie. Conclusion : la téléréadaptation fournit un mode de prestation qui permet aux personnes atteintes d'un TC à consacrer leur énergie au traitement plutôt qu'aux déplacements. Une formation avant le programme portant sur les principaux éléments, tels que le recours à la technologie, les mesures de précaution et les modes de communication, améliorait probablement la faisabilité globale. D'autres recherches seront réalisées pour mieux comprendre l'efficacité de ce programme sur l'équilibre, la mobilité et les taux d'activité physique.

Donating One's Body to HIV Cure Research Through Canadian Medical Assistance in Dying: A Case Study.

BACKGROUND: Finding a cure for HIV is challenged by persisting reservoirs, the mapping of which necessitates invasive procedures. Inviting people with HIV (PWHIV) at the end of life to donate body specimens post-mortem through research autopsies is a novel approach, raising ethical concerns. OBJECTIVE: This case study aims to explore the motivations, barriers, and facilitators of a terminally-ill Canadian PWHIV who requested medical assistance in dying (MAID) and expressed interest in donating his body for HIV cure research. CASE PRESENTATION: An in-depth 3-hour and semi-structured interview was conducted with the participant. The interview transcription was thematically coded to identify motivations and perceived barriers and facilitators to participate in end-of-life HIV cure research. Our analysis identified six themes. Two themes expressed motivations: Collaboration in progress in health and science, seeing cure research as collaboration with professionals; and Opportunity to learn more, mostly about science and health. One theme expressed a barrier: Losing interest in or identification with long-term care research matters, especially those related to the management of long-term care. Three themes expressed by facilitators: Receiving information from professionals one trusts and knows, especially clinical and research teams; Perceiving research procedures as simple, useful, and embedded in care, perceiving clinical, educational, and interpersonal benefits that surpass costs of participation; and Perceiving research as one last way to contribute, that is, feeling useful or give back. CONCLUSION: Several circumstances facilitated the patient's participation: being a single man, having time to participate, having no strong religious belief, and valuing clear, direct communication. His motivations to participate in HIV cure research were altruistic, and also an experience of working with clinical and research teams. Finally, this perspective highlights HIV cure research participant candidates' need for education about research procedures.

Effects of fatiguing isometric and isokinetic ankle exercises on postural control while standing on firm and compliant surfaces.

BACKGROUND: Fatiguing exercises used across studies to induce alterations in postural control are diverse and may explain the different findings reported. This study aimed to compare the effects of two types of fatiguing plantarflexion exercises on postural control on a firm and a compliant surface. Ten healthy young men (29 ± 4 years) were asked to stand as steadily as possible for 30 s, blindfolded with feet together, on a firm and a compliant surface before and immediately after an isometric and an isokinetic fatiguing exercise. RESULTS: Maximal force reduction due to fatigue was found significant but similar between exercises. No significant difference was found between the fatiguing exercises on all Center of Pressure (CoP) parameters. Both fatiguing exercises induced increases in CoP excursion area, CoP variability and CoP velocity in both planes (antero-posterior, mediolateral) on the compliant surface. On the firm surface, both fatiguing exercises only induced increases in CoP variability and CoP velocity in the fatigued plane (antero-posterior). CONCLUSIONS: Isometric and isokinetic fatiguing exercises, when producing a similar level of force reduction, induce similar decreases in postural control. The effects of fatigue on postural control in healthy young men are more pronounced when standing on a compliant surface, i.e. when proprioceptive information at the ankle is altered.

Sex differences in central and peripheral fatigue induced by sustained isometric ankle plantar flexion.

The main aim of this study was to determine sex differences in central and peripheral fatigue produced by a sustained isometric exercise of ankle plantar flexors in healthy young adults. Ten males and fourteen females performed a sustained isometric ankle exercise until task failure. Maximal voluntary isometric contraction (MVIC) torque (plantarflexion), voluntary activation level (using the twitch interpolation technique), and resting twitch contractile properties [twitch peak torque (ST), twitch half relaxation time, and low frequency fatigue (LFF) ratio] were measured before, immediately after, and throughout a recovery period (1, 2, 5, and 10 min) following the exercise protocol in order to characterize neuromuscular fatigue. Fatigue had effects (p≤ 0.05) on all dependent variables (reduction in MVIC, VA and twitch torque and slowing of relaxation time). However, no significant differences in performance fatigability markers (MVIC torque decline and time to fatigue) and only minor differences in the variables reflecting central and peripheral fatigue mechanisms were found between males and females. A regression analysis did suggest a somewhat greater role of central fatigue in males compared with females. Females also showed a slightly greater and more prolonged decline in ST and LFF after exercise compared with males. The presence of only minor differences in central and peripheral fatigue mechanisms between males and females in the present study could be explained by the lack of important sex differences in performance fatigability, which could be due to lesser sex differences in the relative area of type I muscle fibers and in contractile function (muscle strength) of ankle plantar flexors as compared with other muscle groups.

Sex differences in the effect of muscle fatigue on static postural control under different vision and task conditions.

The main aim of this study was to compare the effects of ankle plantar flexors fatigue on postural control between healthy young adult males and females. The secondary aim was to determine the effects of vision on the fatigue-induced postural changes. Ten healthy young males and nine females were asked to perform quiet standing (QS) and standing forward lean (FL) tasks with eyes open (EO) and closed (EC) before and immediately following exercise, and throughout a 15-min recovery period. A sustained isometric exercise of ankle plantar flexors was performed until participants were no longer able to maintain a target torque of 50% of maximal voluntary isometric contraction (MVIC). Mean anteroposterior (AP) and mediolateral (ML) positions of the center of pressure (COP), mean COP sway velocity, and 95% ellipse area of COP sway were measured. Ankle plantar flexors fatigue had significant effects on all dependent variables, except for sway area. A fatigue X sex interaction was found for sway velocity with the most challenging task condition (FL-EC), where males showed a significant increase in sway velocity up to 15 min following exercise, whereas females did not. Fatigue X vision interactions for AP position were also found, with the withdrawal of vision leading to a greater backward shift during recovery for both the QS (5 to 15 min) and FL (5 to 10 min) tasks. Our findings suggest the use of different postural control strategies with ankle fatigue between males and females, and also a contribution of vision to compensate for fatigue-induced instability that is not dependent on task difficulty.

Willingness of Older Canadians with HIV to Participate in HIV Cure Research Near and After the End of Life: A Mixed-Method Study.

HIV cure research requires interrogating latent HIV reservoirs in deep tissues, which necessitates autopsies to avoid risks to participants. An HIV autopsy biobank would facilitate this research, but such research raises ethical issues and requires participant engagement. This study explores the willingness to participate in HIV cure research at the end of life. Participants include Canadians with HIV [people with HIV (PWHIV)] aged 55 years or older. Following a mixed-method study design, all participants completed a phone or online survey, and a subset of participants participated in in-depth phone or videoconference interviews. We produced descriptive statistics of quantitative data and a thematic analysis of qualitative data. Barriers and facilitators were categorized under domains of the Theoretical Domains Framework. From April 2020 to August 2021, 37 participants completed the survey (mean age = 69.9 years old; mean duration of HIV infection = 28.5 years), including 15 interviewed participants. About three quarters of participants indicated being willing to participate in hypothetical medical studies toward the end of life (n = 30; 81.1%), in HIV biobanking (n = 30; 81.1%), and in a research autopsy (n = 28; 75.7%) to advance HIV cure research, mainly for altruistic benefits. The main perceived risks had to do with physical pain and confidentiality. Barriers and facilitators were distributed across five domains: social/professional role and identity, environmental context and resources, social influences, beliefs about consequences, and capabilities. Participants wanted more information about study objectives and procedures, possible accommodations with their last will, and rationale for studies or financial interests funding studies. Our results indicate that older PWHIV would be willing to participate in HIV cure research toward the end of life, HIV biobanking, and research autopsy. However, a dialogue should be initiated to inform participants thoroughly about HIV cure studies, address concerns, and accommodate their needs and preferences. Additional work is required, likely through increased community engagement, to address educational needs.

Rating of perceived exertion (RPE) in studies of fatigue-induced postural control alterations in healthy adults: Scoping review of quantitative evidence.

BACKGROUND: Amongst the literature researching the effects of exercise-induced fatigue on postural control in healthy adults, many studies have used the Borg scales to document the rating of perceived exertion (RPE) and have shown a broad range of RPE values. Our main aim was to map fatigue-induced RPE values in included publications. Secondary aims were to summarize the preference and purpose for the use of Borg scales within the included publications and to explore the potential associations between fatigue-induced RPE values and postural control changes. METHODS: Five databases (Ovid Medline, PubMed, CINAHL, Scopus, and SPORTDiscus) were systematically searched for synthesizing data among the publications that reported RPE values on the Borg RPE- and Category-Ratio (CR) 10 scales and also found fatigue effects on postural control in healthy adults. Spearman's rank correlations were conducted to assess potential associations between fatigue-induced RPE values and maximal postural control changes across the included publications (group data). RESULTS: 45 of 51 studies included in this review reported maximal RPE values following exercise and ranged from 10.4-20 (6-20 Borg RPE) or 0.9-10 (CR10) indicating "very light" or "very weak" to "maximal" exertions. The 6-20 Borg and CR10 scales were mainly used to assess cardiovascular and muscular exertion, respectively. The scales were used mostly to estimate fatigue levels (n = 45), and to a lesser extent to produce a specific exercise intensity (n = 5) and as the criterion for exercise termination (n = 1). In general, there was no significant association between RPE and postural control changes across studies. CONCLUSION: The broad range of RPE values and weak correlations may suggest that various fatigue levels can lead to postural control changes. However, one should be careful in comparing the extent of fatigue from RPE values and its potential effect on postural control in the light of many confounding factors.

Multiscale codependence analysis: an integrated approach to analyze relationships across scales.

The spatial and temporal organization of ecological processes and features and the scales at which they occur are central topics to landscape ecology and metapopulation dynamics, and increasingly regarded as a cornerstone paradigm for understanding ecological processes. Hence, there is need for computational approaches which allow the identification of the proper spatial or temporal scales of ecological processes and the explicit integration of that information in models. For that purpose, we propose a new method (multiscale codependence analysis, MCA) to test the statistical significance of the correlations between two variables at particular spatial or temporal scales. Validation of the method (using Monte Carlo simulations) included the study of type I error rate, under five statistical significance thresholds, and of type II error rate and statistical power. The method was found to be valid, in terms of type I error rate, and to have sufficient statistical power to be useful in practice. MCA has assumptions that are met in a wide range of circumstances. When applied to model the river habitat of juvenile Atlantic salmon, MCA revealed that variables describing substrate composition of the river bed were the most influential predictors of parr abundance at 0.4-4.1 km scales whereas mean channel depth was more influential at 200-300 m scales. When properly assessed, the spatial structuring observed in nature may be used purposefully to refine our understanding of natural processes and enhance model representativeness.

The effect of sex and chronic low back pain on back muscle reflex responses.

Different back muscle reflex assessment protocols have shown abnormally longer reflex latency responses of back muscles in chronic low back pain (CLBP). However, many confounding variables are difficult to control, such as the load magnitude and the preactivation of trunk muscles. The aims of this study were to evaluate, in 30 subjects with CLBP and 30 healthy controls, the activation levels of back muscles during pre-loading and their reflex responses to sudden loading. After subjected to six practice perturbations, 20 sudden and unexpected forward perturbations of the trunk were applied in 30 CLBP subjects (14 women) and 31 controls (17 women), while attempting to minimize the confounding effect of preactivation level and perturbation amplitude. Reflex latency and amplitudes were computed from the surface EMG signals of four back muscles (bilaterally at L5, L3, L1, T10 vertebral levels). EMG was also collected from abdominal muscles. Subjects with CLBP significantly increased the preactivation of back muscles (abdominal preactivation the same) relative to controls while no sex effect was observed. While adjusting statistically for these differences, reflex amplitude was significantly higher in subjects with CLBP and men, compared to healthy controls and women, respectively. Interestingly, contrary to most of the literature available, no between-group effects were detected for reflex latency, which could potentially be explained by an appropriate control of confounding variables, but this remains to be clarified in future research.