How does apathy impact exploration-exploitation decision-making in older patients with neurocognitive disorders?

Apathy is a pervasive clinical syndrome in neurocognitive disorders, characterized by a quantitative reduction in goal-directed behaviors. The brain structures involved in the physiopathology of apathy have also been connected to the brain structures involved in probabilistic reward learning in the exploration-exploitation dilemma. This dilemma in question involves the challenge of selecting between a familiar option with a more predictable outcome, and another option whose outcome is uncertain and may yield potentially greater rewards compared to the known option. The aim of this study was to combine experimental procedures and computational modeling to examine whether, in older adults with mild neurocognitive disorders, apathy affects performance in the exploration-exploitation dilemma. Through using a four-armed bandit reinforcement-learning task, we showed that apathetic older adults explored more and performed worse than non-apathetic subjects. Moreover, the mental flexibility assessed by the Trail-making test-B was negatively associated with the percentage of exploration. These results suggest that apathy is characterized by an increased explorative behavior and inefficient decision-making, possibly due to weak mental flexibility to switch toward the exploitation of the more rewarding options. Apathetic participants also took longer to make a choice and failed more often to respond in the allotted time, which could reflect the difficulties in action initiation and selection. In conclusion, the present results suggest that apathy in participants with neurocognitive disorders is associated with specific disturbances in the exploration-exploitation trade-off and sheds light on the disturbances in reward processing in patients with apathy.

Effect of a sex stereotype on cortical activity during a self-paced exercise: A motor-related cortical potential approach.

Recent research has shown that inducing a negative stereotype toward women does not always decrease the subsequent motor performance of women, but can increase it, especially during endurance tasks. The mechanisms involved are nonetheless still poorly understood. The main aim of the present study was to investigate the effect of a negative stereotype toward women on men's and women's performance during an endurance task, and to analyze the neuropsychological mechanisms involved through motor-related cortical potentials and motivation toward men/women. Thirty-four participants were assigned to a negative stereotype toward women condition and a nullified-stereotype condition and performed 80 self-paced intermittent isometric elbow contractions at a moderate perceived intensity. Results showed that women performed better when assigned to the negative stereotype toward women condition, they were more motivated to outperform men, and their MRCP amplitudes were higher in this same condition over the prefrontal cortex (i.e., FP1 and FP2). Concerning men, they also performed better when the negative stereotype toward women was induced. However, no effect emerged on motivation toward women and MRCP amplitudes. This study showed that inducing a negative stereotype during an endurance task led to a performance increase in women, which is contrary to the stereotype threat theory, strengthening the idea of a task-dependency effect when inducing a negative stereotype. This performance improvement observed in women may be caused by increased motivation to outperform men and a planning of the upcoming movement. Concerning men, more research is needed to clarify the mechanisms involved in such performance improvement.

Effects of muscular and mental fatigue on spatiotemporal gait parameters in dual task walking in young, non-frail and frail older adults.

BACKGROUND: Dual-task (DT) walking is of great interest in clinical evaluation to evaluate frailty or cognitive declines in older adults. Frail older adults are known to adopt different walking strategy to overcome fatigue. However, no studies evaluated the effect of muscular or mental fatigue on dual-task walking strategy and the difference between frail and non-frail older adults. AIMS: Evaluate the effect of mental and muscular fatigue on spatio-temporal parameters in dual-task walking in young, non-frail and frail older adults. METHODS: 59 participants divided into 20 young (Y) (24.9 ± 3 years old), 20 non-frail (NF) (75.8 ± 4.9 years old) and 19 frail older adults (F) (81 ± 4.7 years old) performed single-task (ST) walking, single-task cognitive (serial subtraction of 3), and dual-task (subtraction + walking) for 1 min at their fast pace. Gait speed, step length, step length variability, stance and swing phase time, single and double support time, cadence, gait speed variability were recorded in single- and dual-task walking. The dual-task effect (DTE) was calculated as ((DT - ST)/ST) × 100). Generalized linear mixed models (GLMM) were used to compare the effects of mental and muscular fatigue on gait and cognitive variables between the groups. RESULTS: The DTE walking parameters were worse in F compared to NF or Y but no significant effect of fatigue were highlighted except for swing time and single support time DTEs. CONCLUSIONS: The results were mitigated but a clear difference in dual-task spatio-temporal parameters was found between F and NF which brings hope into the capacity of DT to better reveal frailty.

Effects of individualized lower limb isokinetic strengthening in clinical rehabilitation of older post-stroke patients: A retrospective study.

OBJECTIVE: Muscle weakness in the lower limbs is a motor consequence of stroke that causes functional impairment. The aim of this study was to assess the effectiveness of an individualized isokinetic strengthening programme, using the moment-velocity profile, on functional recovery during post-stroke rehabilitation of older patients. A further objective was to describe the effects of the individualized isokinetic strengthening on muscular parameters. DESIGN: Retrospective study. PATIENTS: Older post-stroke patients. METHODS: Using the Barthel Index, functional abilities in basic daily tasks were assessed and retrospectively analysed for 88 patients in a post-stroke rehabilitation unit. Of these, 44 patients received conventional rehabilitation (conventional group) and 44 received individualized isokinetic strengthening in addition to conventional rehabilitation (isokinetic group). A 2-Group (isokinetic, conventional) × 2-Time (before, after intervention) repeated measures analysis of variance (ANOVA) was conducted. For muscular parameters, Student t-tests and Wilcoxon tests were performed. RESULTS: The Barthel Index score increased more in the isokinetic group (61.59 ± 26.34 to 88.18 ± 12.16) than in the conventional group (61.70 ± 26.5 to 76.93 ± 18.12). A significant Time × Group interaction was found (F(1,86) = 5.95, p = 0.02). In the isokinetic group all muscular parameters improved. CONCLUSION: This retrospective clinical study suggests that lower limb isokinetic strengthening, individualized using the moment-velocity profile, is clinically efficient for functional recovery during post-stroke rehabilitation of older patients. Intragroup effects of isokinetic strengthening also suggest benefits for muscular parameters.

Validation of 3D Knee Kinematics during Gait on Treadmill with an Instrumented Knee Brace.

To test a novel instrumented knee brace intended for use as a rehabilitation system, based on inertial measurement units (IMU) to monitor home-based exercises, the device was compared to the gold standard of motion analysis. The purpose was to validate a new calibration method through functional tasks and assessed the value of adding magnetometers for motion analysis. Thirteen healthy young adults performed a 60-second gait test at a comfortable walking speed on a treadmill. Knee kinematics were captured simultaneously, using the instrumented knee brace and an optoelectronic camera system (OCS). The intraclass correlation coefficient (ICC) showed excellent reliability for the three axes of rotation with and without magnetometers, with values ranging between 0.900 and 0.972. Pearson's r coefficient showed good to excellent correlation for the three axes, with the root mean square error (RMSE) under 3° with the IMUs and slightly higher with the magnetometers. The instrumented knee brace obtained certain clinical parameters, as did the OCS. The instrumented knee brace seems to be a valid tool to assess ambulatory knee kinematics, with an RMSE of <3°, which is sufficient for clinical interpretations. Indeed, this portable system can obtain certain clinical parameters just as well as the gold standard of motion analysis. However, the addition of magnetometers showed no significant advantage in terms of enhancing accuracy.

Effects of age, sex, frailty and falls on cognitive and motor performance during dual-task walking in older adults.

BACKGROUND: Dual-task (DT) walking is of great interest in clinical evaluation to evaluate the risk of falling or cognitive declines in older adults. However, it appears necessary to investigate deeply the confounding factors to better understand their impact on dual-task performance. OBJECTIVE: To evaluate the effect of age, sex, falls and frailty on cognitive and motor parameters in dual-task walking. SUBJECTS: 66 older participants (mean age = 75.5 ± 6.3; mean height = 165.8 ± 8.4 cm; mean weight = 68.4 ± 14 kgs) were split into groups based on their age, sex, fall and frailty status. METHODS: Participants performed single-task walking, single-task cognitive (serial subtraction of 3), and dual-task walking (subtraction + walking) for 1 min at their fast pace. Gait speed, step length, step length variability, stance and swing phase time, single and double support, cadence, step time variability and gait speed variability were recorded in single- and dual-task walking and used to calculate the dual-task effect (DTE) as ((DT - ST) / ST) ∗ 100). The cognitive score (DTEcog) was calculated as the number of correct responses minus errors. Generalized linear mixed models (GLMM) were used to compare the effects of falls, frailty, age and sex on gait and cognitive variables. RESULTS: The interaction frailty*sex and frailty*age were the major effect on the DTEs. Specifically, the DTE was higher in women than men and in the frail group compared to non-frail. CONCLUSIONS: The present findings provide a better understanding on the confounding factors explaining the behavior in DT that could be used to develop more effective dual-task clinical programs for community-living older adults.

A kinematic-geometric model based on ankles' depth trajectory in frontal plane for gait analysis using a single RGB-D camera.

The emergence of RGB-D cameras and the development of pose estimation algorithms offer opportunities in biomechanics. However, some challenges still remain when using them for gait analysis, including noise which leads to misidentification of gait events and inaccuracy. Therefore, we present a novel kinematic-geometric model for spatio-temporal gait analysis, based on ankles' trajectory in the frontal plane and distance-to-camera data (depth). Our approach consists of three main steps: identification of the gait pattern and modeling via parameterized curves, development of a fitting algorithm, and computation of locomotive indices. The proposed fitting algorithm applies on both ankles' depth data simultaneously, by minimizing through numerical optimization some geometric and biomechanical error functions. For validation, 15 subjects were asked to walk inside the walkway of the OptoGait, while the OptoGait and an RGB-D camera (Microsoft Azure Kinect) were both recording. Then, the spatio-temporal parameters of both feet were computed using the OptoGait and the proposed model. Validation results show that the proposed model yields good to excellent absolute statistical agreement (0.86 ≤ Rc ≤ 0.99). Our kinematic-geometric model offers several benefits: (1) It relies only on the ankles' depth trajectory both for gait events extraction and spatio-temporal parameters' calculation; (2) it is usable with any kind of RGB-D camera or even with 3D marker-based motion analysis systems in absence of toes' and heels' markers; and (3) it enables improving the results by denoising and smoothing the ankles' depth trajectory. Hence, the proposed kinematic-geometric model facilitates the development of portable markerless systems for accurate gait analysis.

Impact of a Wearable Activity Tracker on Disease Flares in Spondyloarthritis: A Randomized Controlled Trial.

OBJECTIVE: To evaluate the impact of a wearable activity tracker used to encourage physical activity, on disease flares in patients with spondyloarthritis (SpA). METHODS: This randomized controlled trial involved randomizing 108 patients with SpA into tracker and nontracker groups. The participants were then subjected to assessments of disease activity, performance (6-minute walk test), and quality of life (QOL; 36-item Short Form Health Survey) at the 12th, 24th, and 36th week. The primary outcome was the change in the frequency of flare episodes (categorized as no flare, flare in ≤ 3 days, and flare in > 3 days) between baseline and 12 weeks. RESULTS: The results of the study showed that at the 12th week, the mean change (∆) of the number of flares improved in both groups: -0.32 (95% CI -0.66 to 0.02) and -0.38 (95% CI -0.68 to -0.09) in the tracker and nontracker group, respectively. However, the between-group differences were insignificant (P = 0.87). Performance scores improved in both groups at the 12th, 24th, and 36th week (all P < 0.01). The different dimensions of QOL also improved at the 12th week (P < 0.01). Conversely, moderate flares (P < 0.01) and performance (P < 0.01) improved over time; however, the influence over time of a wearable activity tracker was not significant (P = 0.29 and P = 0.66, respectively). CONCLUSION: The use of a wearable activity tracker did not affect the number of flares, performance, or QOL of patients with SpA. Nevertheless, this study confirmed the benefits of physical activity on flares, disease activity, QOL, and physical performance in patients with SpA. (Move Your Spondyl "Better Live Its Rheumatism With the Physical Activity"; ClinicalTrials.gov: NCT03458026).

Apathetic patients with neurocognitive disorders are more fatigued and fatigable.

BACKGROUND: Apathy is common in neurocognitive disorders (NCD) and manifests as reduced goal-directed behaviors and activities. A decrease in everyday activities can also be due to fatigue, another common symptom in NCD. The aim of this study was to investigate if apathetic patients with NCD are more fatigued and more fatigable. METHOD: A self-report questionnaire and clinical functional tests assessed fatigue and fatigability in 30 apathetic vs 26 non-apathetic NCD participants. The Fatigue Severity Scale (FSS) was administered and a 15-s sustained maximal handgrip contraction and a 6-min walk test (6MWT) were performed. RESULTS: Apathetic subjects had higher FSS scores. A decrease in performance was observed in apathetic participants during the sustained maximal handgrip contraction but not the 6MWT. CONCLUSION: Higher self-reported fatigue and greater fatigability during the sustained maximal handgrip contraction test in apathetic subjects suggest the importance of assessing these symptoms in apathetic subjects to properly guide treatment. CLINICAL TRIAL REGISTRATION: NCT04573712.

Associations, overlaps and dissociations between apathy and fatigue.

Apathy and fatigue have a high prevalence in many pathological populations, but they are also present in healthy adults. The relationship between apathy and fatigue, which are both multidimensional, is still poorly understood. This study aims to describe the associations between the subdimensions of both apathy and fatigue and to investigate their overlaps and dissociations in healthy people. 729 participants (mean age = 30.8 ± 10.7 years) completed online self-assessment questionnaires. The Apathy Motivation Index and Dimensional Apathy Scale were used to assess apathy. The Multidimensional Fatigue Inventory was used to assess fatigue. The executive dimension of apathy showed the strongest correlations with mental fatigue and the two appeared to be underpinned by the same latent factor, according to exploratory factor analysis (EFA). The factor structure of EFA showed overlaps between behavioral apathy and both reduced motivation and activity in fatigue. Emotional and social dimensions of apathy were separately underpinned by a latent factor that comprised no items of fatigue. Apathy and fatigue have reduced activity and mental difficulties in common, whereas emotional and social disorders distinguish apathy from fatigue. This has important implications for assessing apathy and fatigue in the general population, and may be relevant for clinical practice.

The effect of different dual tasks conditions on gait kinematics and spatio-temporal walking parameters in older adults.

BACKGROUND: Dual-task (DT) walking has increasingly been investigated over the last decade because of its valuable role as a clinical marker of both cognitive impairment and fall risk in older adults based on cognitive and motor performance (DTEcog, DTEmotor). However, there is still a lack of information on what type of dual task to choose and which is the most adapted to the population of interest. RESEARCH QUESTION: To evaluate the effect of different dual-tasks (DT3, DT7, FLU, STROOP) on the spatiotemporal and kinematic parameters of hip, knee, and ankle joints. METHODS: Thirty-eight older adults were recruited (9 men, 29 women, mean age = 77.5 +/- 6.5 years, mean height = 163.6 +/- 8.6 cm, mean weight = 67.5 +/- 15.3 kg). They performed a single and dual-task walk with the 4 types of tasks during 1 min, equipped with an inertial system. Dual-task effect (DTE) on spatiotemporal and kinematic variables as well as cognitive score and speed were calculated. RESULTS: An alteration in most of the spatiotemporal parameters was observed in each DT condition (p < 0.05), especially in arithmetic tasks (DT3, DT7), while no DT effect was noticed on kinematic parameters (RMSE<3°) except on hip and knee angular velocities (RMSE>15°). Arithmetic tasks seemed to alter more spatiotemporal and kinematic parameters than the verbal fluency or STROOP test. However, DT7 appeared to be too difficult for the population of interest. SIGNIFICANCE: Arithmetic tasks seemed to be very pertinent as a clinical dual-task protocol for older adults. The use of an inertial system to retrieve kinematic variables is an improvement in these dual-task protocols.

How fiber dynamics of plantarflexor and dorsiflexor muscles based on EMG-driven approach can explain the metabolic cost at different gait speeds.

PURPOSE: The aim of this study was to investigate the fiber dynamics of plantarflexor and dorsiflexor muscles and their association with the net metabolic rate (NCw). METHODS: Metabolic, kinematic, kinetic, and electromyography measurements were made on seven young subjects while they walked on a force-plate instrumented treadmill at 1.00, 1.20, 1.40, 1.60, and 1.8 m/s for 1:30 min. The net metabolic rate was computed, and a one degree-of freedom EMG-driven approach was used to extract the force generation ability (Fability), and active force-length (fAL) and force-velocity (fV) multiplier of each muscle. A one-way (speeds) repeated measures ANOVA was performed for each muscle and a multiple linear regression model was used to explain NCw. RESULTS: Fability was significantly affected by gait speed for the GasMed and the SOL muscles. The decrease of Fability for the SOL and the GasMed was accompanied by a decrease in the force-velocity multiplier. The peak muscle force for the SOL increased for the lowest speed compared to the higher speed, and for the TibAnt increased at high speed compared to low speed. In addition, Fability fAL, and fV of the SOL predicted over 58% of NCw and FMax of the TibAnt accounts for 39.9% of the variance in NCw. CONCLUSION: The increase of NCw with gait speed over the preferred walking speed can be partially explained by the decreasing capacity of the SOL muscle to produce muscle force and more specifically by the force-velocity relationship and an increase in muscle force for the TibAnt.

Does the Effect of Stereotypes in Older People Depend Upon Task Intensity?

This study examined the effect of negative and positive stereotypes on the strength produced by older adults at different perceived effort intensities, reflecting different levels of task difficulty. Fifty older women were randomly assigned to a positive stereotype, a negative stereotype, or a control condition. Before (T1) and after (T2) the stereotype manipulation, they were asked to perform a voluntary isometric contraction at a level of muscular effort that corresponded to four perceived effort intensities ("easy," "moderate," hard" and "very hard"). Results showed that participants attained greater strength during the easy and hard tasks after exposure to both positive and negative stereotypes. At the moderate and very hard intensities, stereotype induction did not significantly change the strength from the baseline performance. While these results are not fully in line with the stereotype threat theory, they provide evidence that task difficulty could modulate the effect of aging stereotypes during physical tasks.

Metabolic cost and co-contraction during walking at different speeds in young and old adults.

BACKGROUND: The net metabolic cost of walking (NCw) and the co-activation of leg muscles are both higher in old adults (OG) than in young adults (YG). Nevertheless, the relation between the two remains unresolved, mainly due to the controversial co-activation measurement method used in previous studies. RESEARCH QUESTION: To compare ankle and knee co-contraction (CCI), calculated using an EMG-driven method, between the groups and to examine their relationship with NCw. METHODS: Nine young (YG = 25.2 +/- 3.3 years old) and nine older (OG = 68.7 +/5.9 years old) adults walked on a treadmill at five speeds (YG: 1; 1.2; 1.4; 1.6; 1.8 m/s; OG: 0.6; 0.8; 1; 1.2; 1.4 m/s) while electromyography (sEMG) and oxygen consumption were measured. CCI were calculated around the ankle and knee for different parts of the gait cycle (entire gait cycle 0-100 %, stance phase 0-60 %, swing phase 60-100 %). RESULTS: NCw was significantly higher (25 %, averaged over the walking speeds) in OG as were Knee_CCI, Knee_CCI_swing and Knee_CCI_stance. Multiple regression models in YG, OG and YG + OG highlighted Ankle_CCI as the main contributor in NCw (ß = 0.08-0.188, p < 0.05) with a positive relation between the two variables. SIGNIFICANCE: The present findings provide a better understanding of the association between muscle co-contraction and metabolic cost in older adults. It may help scientists and clinicians to further develop strategies aimed at neuromuscular rehabilitation as a means of improving mobility and independence among older adults.

6MWT on a new self-paced treadmill system compared with overground.

The 6-min walk test (6MWT) is a useful tool for clinicians and researchers to estimate gait performance and fatigue affecting functional mobility. A modified 6MWT administered on a treadmill (TM) can be an efficient, space-saving alternative to perform the 6MWT. The aim of this study was to investigate if a 6MWT on a self-paced (SP) TM produced similar results compared to an overground (OG) 6MWT among healthy participants with the hypothesis that users would demonstrate similar gait parameters. The second aim was to assess the reliability of SP TM sessions with the hypothesis that gait parameters would be reliable. Twelve healthy young adults performed one OG 6MWT and two SP TM 6MWTs, with the TM tests performed on two different testing days. The OG 6MWTs were conducted along a 20 m corridor with a portable optometric system. The SP TM 6MWTs were performed using a dual-belt instrumented TM with speed controlled by feedback from a LIDAR sensor. In the OG condition, participants walked 664.8 m ± 48.9 m when the standard method was used to calculate distance and 721.3 m ± 56.2 m with an average-speed-based estimation of distance, which corrects for U-turns. For the SP TM 6MWT, they covered 729.4 m ± 45.8 m in the first session and 727.4 m ± 56.0 m in the second session. Gait parameters showed good to excellent within- and between-day reliability on the adaptive TM. Gait parameters were similar between modalities. A significant difference in the 6MWT distance was found between modalities. This is attributable to the U-turns, because a comparison between TM 6MWT distance and the average-speed-based estimation of the distance for the OG modality showed no significant difference. However, this system produced similar spatiotemporal gait parameters among participants compared to OG.

Validity of a simple sit-to-stand method for assessing force-velocity profile in older adults.

BACKGROUND: Lower limb muscle strength is an important determinant of physical function in older adults. However, its measure in clinical settings is limited because of the requirement for large-scale and costly equipment. A new simple protocol based on sit-to-stand test (STS) is developed to measure force velocity (F-v) and power velocity (P-v) profile in the community-dwelling older adults. OBJECTIVE: The objective of this study was to assess the validity of this new methodology for measuring F-v and P-v profile compared to the gold standard isokinetic BIODEX. PARTICIPANTS: 46 older people aged 65-85 years (M = 73.7; SD = 7.7). METHODS: F-v and P-v profiles were assessed in participants on their dominant leg. The concurrent validity of STS was tested using Spearman's rank correlation coefficient and Passing Bablok: maximal power output Pmax, optimal velocity and force Vopt and Fopt, maximal force at null velocity F0, maximal unloaded velocity V0 and coefficient of F-v (SFV) and P-v equation (a_poly, b_poly). RESULTS: No proportional difference for F0 and b_poly and a low significant correlation for Pmax (r = 0.314), Sfv (r = 0.229), a_poly (r = 0.335) and b_poly (r = 0.226) whereas the other parameters were non correlated significantly. CONCLUSION: STS method is moderately reliable on force and power parameters whereas further improvements are needing for velocity parameters. However, its feasibility, portability and lower cost compared to other methods makes it very affordable in clinical context and will allow easy investigation of aging population.

Single-session training on an ascending treadmill slope: effects on gait parameters in persons with stroke. A pilot study.

OBJECTIVE: Treadmill training with an upward incline could improve gait parameters altered in persons with stroke, especially lower limb flexion. This study aimed to determine the effects of a treadmill single-session training with a 10% upward incline on biomechanical gait parameters in persons with stroke. METHODS: Fifteen persons with stroke-related hemiparesis performed a 20-min treadmill training session with a 10% ascending incline in this interventional pilot study. Spatiotemporal, kinematic and kinetic parameters were evaluated, overground, with a tridimensional optoelectronic system, before the session, immediately after and after a 20-min rest period. RESULTS: The single-session training on a treadmill with a 10% incline has significantly increased hip flexion peak on the paretic side (39.8°± 8.1 in baseline to 42.7°± 8.6 after the session, P < 0.001, large effect size) and knee flexion peak on the paretic side (39.9°± 11.6 in baseline to 43.1°± 11.7 after the session, P = 0.004, large effect size). Gait speed, other spatiotemporal gait parameters and propulsion on the paretic side were also significantly increased (P < 0.05, all large effects size). These short-term changes were maintained after the break. CONCLUSIONS: A treadmill single-session training with a 10% upward incline induces biomechanical changes in people with stroke. The environmental constraints of this training could explain these biomechanical adaptations, concerning especially paretic hip and knee flexion.

Effects of age, gender, frailty and falls on spatiotemporal gait parameters: a retrospective cohort study.

BACKGROUND: Many studies have explored spatial and temporal gait parameters in the elderly, and showed that frailty status, fall history, age, and gender may individually strongly influence these parameters. However, it appears necessary to investigate the confounding factors more deeply in order to better know the specific role of each of these factors impacting the evolution of gait with the increase of age. AIM: The aim of the present study was to determine the influence of frailty status, fall history, age and gender on spatiotemporal gait parameters. We hypothesized that frailty was the factor that most influence gait parameters. DESIGN: The present is a monocentric retrospective study. SETTING: This is a monocentric retrospective study performed at Nice University Hospital Center on older out-patients. POPULATION: Older adults were included in the study. This study explored for the first time how frailty status, age, gender and history of falls impact the multiple spatiotemporal parameters of gait using linear mixed models (LMM). RESULTS: 479 older adults (360 women and 119 men; 213 non-frail, 228 prefrail and 38 frail; aged from 65 to 94 years; 403 non-fallers and 73 fallers). Frailty status explained fully: 1) the gait speed; 2) the cadence; 3) the initial double contact (DS1); 4) the percentage of the single support phase; 5) the final double contact (DS2); and VI) the percentage of the swing phase of the gait cycle. CONCLUSIONS: The results of this study allowed a deeper understanding of the confounding factors since LMM highlighted the importance of frailty status for explaining all the spatiotemporal gait parameters. CLINICAL REHABILITATION IMPACT: These results showed that clinical intervention should focus on reducing frailty status to improve gait. It is also interesting to note that a history of falls explains none of the spatiotemporal gait parameters which suggests that it may be possible to improve gait in all frail subjects irrespective of their history of falls.

Relationship between personality and physical capacities in older adults: The mediating role of subjective age, aging attitudes and physical self-perceptions.

Walking speed and muscular strength are two main markers of health in adulthood. Previous studies have shown that personality traits may predict these two outcomes. However, little is known about the mechanisms underlying these relationships. Thus, the present study examined whether personality traits are associated with walking speed and muscular strength through the mediating role of subjective age (how young or old individuals experience themselves to be), attitudes toward aging and physical self-perceptions. Community-dwelling older women (N = 243; Mage = 73.0; SDage = 6.5) were recruited. For reasons of recruitment feasibility, participants were only older women. They were requested to complete a questionnaire measuring personality, subjective age, attitudes toward aging and physical self-perceptions. Following this, their walking speed and their muscular strength were investigated. Data were analyzed using structural equation modeling. In line with the literature, we extended the associations between extraversion, neuroticism, conscientiousness and walking speed and between conscientiousness, neuroticism, openness and muscular strength. Physical self-perceptions appear to be a robust mediator between personality traits and walking speed whereas attitudes toward aging and subjective age mediated the personality traits/muscular strength relationship. This study provides evidence, for the first time, that the associations between personality traits and physical capacities are different according to the physical capacities investigated. Based on these results, it could be interesting to adapt physical activity interventions to the psychological profile of older adults.

Self-rehabilitation combined with botulinum toxin to improve arm function in people with chronic stroke. A randomized controlled trial.

BACKGROUND: Botulinum toxin injection (BTI) reduces muscle hyperactivity, but its effect on active upper-limb function is limited. Intensive rehabilitation could optimize the effects; however, outpatient post-stroke rehabilitation is usually not intensive. One solution could be self-rehabilitation. OBJECTIVES: The aim of this randomized controlled trial was to determine the effect of a self-rehabilitation program combined with BTI on upper-limb function in individuals with chronic hemiparesis. METHODS: In total, 33 outpatients were randomly allocated to receive BTI+self-rehabilitation (R group: n=17) or BTI alone (C group: n=16). Outcomes evaluated just before the BTI and 4 weeks later included the Wolf Motor Function Test (WMFT time: primary outcome), Action Research Arm Test, fatigue and quality of life. RESULTS: Change in WMFT did not differ between groups at 4 weeks (WMFT time: -14% for R group, -4% for C group. WFMT score: +12% for R group, 0% in C group). WFMT time and score improved significantly in the R group only (-14%, P=0.01, and +12%, P=0.02). In addition, the proportion of patients with improved WMFT time and score was higher in the R than C group (R group: 71% improved score, 77% improved time; C group: 43% improved score, 50% improved time). Also, passive range of shoulder flexion (P=0.03) and wrist extension (P=0.01) improved only in the R group. No other variables changed significantly. Compliance was excellent; average daily training time was greater than that prescribed. CONCLUSIONS: The addition of a self-rehabilitation program to BTI did not significantly improve functional outcomes more than BTI alone; however, movement quality and speed improved only in the self-rehabilitation group. Participants in the self-rehabilitation group trained more than they were asked to, which suggests that they found the program worthwhile. These clinically relevant findings justify larger-scale studies of the effects of self-rehabilitation to enhance the effects of BTI. CLINICAL TRIAL: NCT02699762.