Associations between the resting EEG aperiodic slope and broad domains of cognitive ability.

Recent studies suggest that the EEG aperiodic exponent (often represented as a slope in log-log space) is sensitive to individual differences in momentary cognitive skills such as selective attention and information processing speed. However, findings are mixed, and most of the studies have focused on just a narrow range of cognitive domains. This study used an archival dataset to help clarify associations between resting aperiodic features and broad domains of cognitive ability, which vary in their demands on momentary processing. Undergraduates (N = 166) of age 18-52 years completed a resting EEG session as well as a standardized, individually administered assessment of cognitive ability that included measures of processing speed, working memory, and higher-order visuospatial and verbal skills. A subsample (n = 110) also completed a computerized reaction time task with three difficulty levels. Data reduction analyses revealed strong correlations between the aperiodic offset and slope across electrodes, and a single component accounted for ~60% of variance in slopes across the scalp, in both eyes-closed and eyes-open conditions. Structural equation models did not support relations between the slope and specific domains tapping momentary processes. However, secondary analyses indicated that the eyes-open slope was related to higher overall performance, as represented by a single general ability factor. A latent reaction time variable was significantly inversely related to both eyes-closed and eyes-open resting exponents, such that faster reaction times were associated with steeper slopes. These findings support and help clarify the relation of the resting EEG exponent to individual differences in cognitive skills.

Quantifying the effects of sleep on sensor-derived variables from upper limb accelerometry in people with and without upper limb impairment.

BACKGROUND: Despite the promise of wearable sensors for both rehabilitation research and clinical care, these technologies pose significant burden on data collectors and analysts. Investigations of factors that may influence the wearable sensor data processing pipeline are needed to support continued use of these technologies in rehabilitation research and integration into clinical care settings. The purpose of this study was to investigate the effect of one such factor, sleep, on sensor-derived variables from upper limb accelerometry in people with and without upper limb impairment and across a two-day wearing period. METHODS: This was a secondary analysis of data collected during a prospective, longitudinal cohort study (n = 127 individuals, 62 with upper limb impairment and 65 without). Participants wore a wearable sensor on each wrist for 48 h. Five upper limb sensor variables were calculated over the full wear period (sleep included) and with sleep time removed (sleep excluded): preferred time, non-preferred time, use ratio, non-preferred magnitude and its standard deviation. Linear mixed effects regression was used to quantify the effect of sleep on each sensor variable and determine if the effect differed between people with and without upper limb impairment and across a two-day wearing period. RESULTS: There were significant differences between sleep included and excluded for the variables preferred time (p < 0.001), non-preferred time (p < 0.001), and non-preferred magnitude standard deviation (p = 0.001). The effect of sleep was significantly different between people with and without upper limb impairment for one variable, non-preferred magnitude (p = 0.02). The effect of sleep was not substantially different across wearing days for any of the variables. CONCLUSIONS: Overall, the effects of sleep on sensor-derived variables of upper limb accelerometry are small, similar between people with and without upper limb impairment and across a two-day wearing period, and can likely be ignored in most contexts. Ignoring the effect of sleep would simplify the data processing pipeline, facilitating the use of wearable sensors in both research and clinical practice.

The effect of mobility-related anxiety on walking across the lifespan: a virtual reality simulation study.

Older adults who report a fear of falling are more likely to subsequently fall, yet, some gait anxiety-related alterations may protect balance. We examined the effect of age on walking in anxiety-inducing virtual reality (VR) settings. We predicted a high elevation-related postural threat would impair gait in older age, and differences in cognitive and physical function would relate to the observed effects. Altogether, 24 adults (age (y) = 49.2 (18.7), 13 women) walked on a 2.2-m walkway at self-selected and fast speeds at low (ground) and high (15 m) VR elevation. Self-reported cognitive and somatic anxiety and mental effort were greater at high elevations (all p < 0.001), but age- and speed-related effects were not observed. At high VR elevations, participants walked slower, took shorter steps, and reduced turning speed (all p < 0.001). Significant interactions with age in gait speed and step length showed that relatively older adults walked slower (ß = - 0.05, p = 0.024) and took shorter steps (ß = - 0.05, p = 0.001) at self-selected speeds at high compared to low elevation settings. The effect of Age on gait speed and step length disappeared between self-selected and fast speeds and at high elevation. At self-selected speeds, older adults took shorter and slower steps at high elevation without changing step width, suggesting that in threatening settings relatively older people change gait parameters to promote stability. At fast speeds, older adults walked like relatively younger adults (or young adults walked like older adults) supporting the notion that people opt to walk faster in a way that still protects balance and stability in threatening settings.

Are Abnormal Muscle Biomechanics and Patient-reported Outcomes Associated in Patients With Hip Dysplasia?

BACKGROUND: Developmental dysplasia of the hip (DDH) is a major risk factor for the early development of hip osteoarthritis. Recent studies have demonstrated how DDH alters hip muscle moment arms and elevates muscle-induced biomechanical variables such as joint reaction forces and acetabular edge loads. Understanding the link between abnormal biomechanics and patient-reported outcome measures (PROMs) is important for evidence-based clinical interventions that improve patient symptoms and functional outcomes. To our knowledge, there are no reports of the relationships between muscle-induced biomechanics and PROMs. QUESTIONS/PURPOSES: (1) Are there associations between PROMs and muscle-induced hip biomechanics during gait for patients with DDH and controls? (2) Are there associations among PROMs and separately among biomechanical variables? METHODS: Participants in this prospective cross-sectional comparative study included 20 female patients with DDH who had no prior surgery or osteoarthritis and 15 female individuals with no evidence of hip pathology (controls) (age: median 23 years [range 16 to 39 years]; BMI: median 22 kg/m 2 [range 17 to 27 kg/m 2 ]). Muscle-induced biomechanical variables for this cohort were reported and had been calculated from patient-specific musculoskeletal models, motion data, and MRI. Biomechanical variables included joint reaction forces, acetabular edge loads, hip center lateralization, and gluteus medius muscle moment arm lengths. PROMs included the Hip Disability and Osteoarthritis Outcome Score (HOOS), the WOMAC, International Hip Outcome Tool-12, National Institutes of Health Patient-Reported Outcome Measure Information System (PROMIS) Pain Interference and Physical Function subscales, and University of California Los Angeles activity scale. Associations between PROMs and biomechanical variables were tested using Spearman rank-order correlations and corrected for multiple comparisons using the Benjamini-Yekutieli method. For this study, associations between variables were considered to exist when correlations were statistically significant (p < 0.05) and were either strong (ρ ≥ 0.60) or moderate (ρ = 0.40 to 0.59). RESULTS: Acetabular edge load impulses (the cumulative acetabular edge load across the gait cycle), medially directed joint reaction forces, and hip center lateralization most commonly demonstrated moderate or strong associations with PROMs. The strongest associations were a negative correlation between acetabular edge load impulse on the superior acetabulum and the HOOS function in daily living subscale (ρ = -0.63; p = 0.001), followed by a negative correlation between hip center lateralization and the HOOS pain subscale (ρ = -0.6; p = 0.003), and a positive correlation between hip center lateralization and the PROMIS pain subscale (ρ = 0.62; p = 0.002). The University of California Los Angeles activity scale was the only PROM that did not demonstrate associations with any biomechanical variable. All PROMs, aside from the University of California Los Angeles activity scale, were associated with one another. Although most of the biomechanical variables were associated with one another, these relationships were not as consistent as those among PROMs. CONCLUSION: The associations with PROMs detected in the current study suggest that muscle-induced biomechanics may have wide-reaching effects not only on loads within the hip, but also on patients' perceptions of their health and function. As the treatment of DDH evolves, patient-specific joint preservation strategies may benefit from targeting the underlying causes of biomechanical outcomes associated with PROMs. LEVEL OF EVIDENCE: Level III, prognostic study.

Predicting later categories of upper limb activity from earlier clinical assessments following stroke: an exploratory analysis.

BACKGROUND: Accelerometers allow for direct measurement of upper limb (UL) activity. Recently, multi-dimensional categories of UL performance have been formed to provide a more complete measure of UL use in daily life. Prediction of motor outcomes after stroke have tremendous clinical utility and a next step is to explore what factors might predict someone's subsequent UL performance category. PURPOSE: To explore how different machine learning techniques can be used to understand how clinical measures and participant demographics captured early after stroke are associated with the subsequent UL performance categories. METHODS: This study analyzed data from two time points from a previous cohort (n = 54). Data used was participant characteristics and clinical measures from early after stroke and a previously established category of UL performance at a later post stroke time point. Different machine learning techniques (a single decision tree, bagged trees, and random forests) were used to build predictive models with different input variables. Model performance was quantified with the explanatory power (in-sample accuracy), predictive power (out-of-bag estimate of error), and variable importance. RESULTS: A total of seven models were built, including one single decision tree, three bagged trees, and three random forests. Measures of UL impairment and capacity were the most important predictors of the subsequent UL performance category, regardless of the machine learning algorithm used. Other non-motor clinical measures emerged as key predictors, while participant demographics predictors (with the exception of age) were generally less important across the models. Models built with the bagging algorithms outperformed the single decision tree for in-sample accuracy (26-30% better classification) but had only modest cross-validation accuracy (48-55% out of bag classification). CONCLUSIONS: UL clinical measures were the most important predictors of the subsequent UL performance category in this exploratory analysis regardless of the machine learning algorithm used. Interestingly, cognitive and affective measures emerged as important predictors when the number of input variables was expanded. These results reinforce that UL performance, in vivo, is not a simple product of body functions nor the capacity for movement, instead being a complex phenomenon dependent on many physiological and psychological factors. Utilizing machine learning, this exploratory analysis is a productive step toward the prediction of UL performance. Trial registration NA.

The ENIGMA Stroke Recovery Working Group: Big data neuroimaging to study brain-behavior relationships after stroke.

The goal of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Stroke Recovery working group is to understand brain and behavior relationships using well-powered meta- and mega-analytic approaches. ENIGMA Stroke Recovery has data from over 2,100 stroke patients collected across 39 research studies and 10 countries around the world, comprising the largest multisite retrospective stroke data collaboration to date. This article outlines the efforts taken by the ENIGMA Stroke Recovery working group to develop neuroinformatics protocols and methods to manage multisite stroke brain magnetic resonance imaging, behavioral and demographics data. Specifically, the processes for scalable data intake and preprocessing, multisite data harmonization, and large-scale stroke lesion analysis are described, and challenges unique to this type of big data collaboration in stroke research are discussed. Finally, future directions and limitations, as well as recommendations for improved data harmonization through prospective data collection and data management, are provided.

Efficacy of Corsi Block Tapping Task training for improving visuospatial skills: a non-randomized two-group study.

Even though impaired visuospatial abilities can negatively affect daily functioning, there are very few training programs that attempt to improve visuospatial abilities. The purpose of this study was to examine if a single training session with a computerized version of the Corsi Block Tapping Task could improve mental rotation skills. Fifty-three young adults were assigned to one of two groups: (1) control group (mean age = 21.4; 10 females), who had 20 min of rest after their baseline assessment, or (2) training group (mean age = 21.5; 17 females), who had 20 min of training on the Corsi Block Tapping Task after their baseline assessment. The primary outcome was reaction time on a computer-based mental rotation task, and it was assessed both before and after the rest or training. There was a significant interaction between time (pre vs. post) and group (control vs. training) on mental rotation performance (p = 0.04), with the training group performing on average 124 ms faster on accurate trials than the control group at post-test. This preliminary study suggested that improving mental rotation may be feasible through targeted cognitive training. Future studies will consider multiple sessions of Corsi Block Tapping Task training to maximize training benefits (i.e., dose-response), as well as longer term retention in cognitively intact and impaired individuals.

Accurate Prediction of Persistent Upper Extremity Impairment in Patients With Ischemic Stroke.

OBJECTIVE: To develop a simple and effective risk score for predicting which stroke patients will have persistent impairment of upper extremity motor function at 90 days. DESIGN: Post hoc analysis of clinical trial patients hospitalized with acute ischemic stroke who were followed for 90 days to determine functional outcome. SETTING: Patient were hospitalized at facilities across the United States. PARTICIPANTS: We created a harmonized cohort of individual patients (N=1653) from the NINDS tPA, ALIAS part 2, IMS-III, DEFUSE 3, and FAST-MAG trials. We split the cohort into balanced derivation and validation samples. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The primary outcome was persistent arm impairment, defined as a National Institutes of Health Stroke Scale (NIHSS) arm domain score of 2 to 4 at 90 days in patients who had a 24-hour NIHSS arm score of 1 or more. We used least absolute shrinkage and selection operator regression to determine the elements of the persistent upper extremity impairment (PUPPI) index, which we validated as a predictive tool. RESULTS: We included 1653 patients (827 derivation, 826 validation), of whom 803 (48.6%) had persistent arm impairment. The PUPPI index gives 1 point each for age 55 years or older and NIHSS values of worse arm (4), worse leg (>2), facial palsy (3), and total NIHSS (≥10). The optimal cutpoint for the PUPPI index was 3 or greater, at which the area under the curve was greater than 0.75 for the derivation and validation cohorts and when using NIHSS values from either 24 hours or in a subacute or discharge time window. Results were similar across different levels of stroke severity. CONCLUSION: The PUPPI index uses readily available information to accurately predict persistent upper extremity motor impairment at 90 days poststroke. The PUPPI index can be administered in minutes and could be used as inclusion criterion in recovery-related clinical trials or, with additional development, as a prognostic tool for patients, caregivers, and clinicians.

An extended challenge-based framework for practice design in sports coaching.

The challenge-point framework as a model for thinking about motor learning was first proposed in 2004. Although it has been well-cited, surprisingly this framework has not made its way into much of the applied sport science literature. One of the reasons for this omission is that the original framework had not been encapsulated into a paper accessible for sports practitioners. The framework had mostly a theoretical focus, providing a mechanistic summary of motor learning research. Our aims in this paper were to explain and elaborate on the challenge point framework to present an applied framework guiding practice design. We connect the framework to other theories that involve predictive coding, where information is attended when it disconfirms current predictions, providing a strong signal for learning. We also consider how two new dimensions (learners' motivation and practice specificity) need to be considered when designing practice settings. By moving around the different dimensions of functional difficulty, motivation, and specificity, coaches can optimize practice to achieve different learning goals. Specifically, we present three general "types" of practice: practice to learn, to transfer to competition, and to maintain current skills. Practical examples are given to illustrate how this framework can inform coach practice.

Red blood cell ATP release correlates with red blood cell hemolysis.

The precise matching of blood flow to skeletal muscle during exercise remains an important area of investigation. Release of adenosine triphosphate (ATP) from red blood cells (RBCs) is postulated as a mediator of peripheral vascular tone in response to shear stress, hypoxia, and mechanical deformation. We tested the following hypotheses: 1) RBCs of different densities contain different quantities of ATP; 2) hypoxia is a stimulus for ATP release from RBCs; and 3) hypoxic ATP release from RBCs is related to RBC lysis. Human blood was drawn from male and female volunteers (n = 11); the RBCs were isolated and washed. A Percoll gradient was used to separate RBCs based on cellular density. Density groups were then resuspended to 4% hematocrit and exposed to normoxia or hypoxia in a tonometer. Equilibrated samples were drawn and centrifuged; paired analyses of ATP (luminescence via a luciferase-catalyzed reaction) and hemolysis (Harboe spectrophotometric absorbance assay) were measured in the supernatant. ATP release was not different among low-density cells versus middle-density versus high-density cells. Similarly, hemoglobin (Hb) release was not different among the red blood cell subsets. No difference was found for either ATP release or Hb release following matched exposure to normoxic or hypoxic gas. The concentrations of ATP and Hb for all subsets combined were linearly correlated (r = 0.59, P ≤ 0.001). With simultaneous probing for Hb and ATP in the supernatant of each sample, we conclude that ATP release from RBCs can be explained by hemolysis and that hypoxia per se does not stimulate either ATP release or Hb release from RBCs.

Combining the AM-PAC "6-Clicks" and the Morse Fall Scale to Predict Individuals at Risk for Falls in an Inpatient Rehabilitation Hospital.

OBJECTIVE: To determine the effect of adding the Activity Measure for Post-Acute Care (AM-PAC) Inpatient '6-Clicks' Short Forms to the Morse Fall Scale (MFS) to assess fall risk. Falls that occur in a rehabilitation hospital result in increased morbidity and mortality, increased cost, and negatively affect reimbursement. Identifying individuals at high risk for falls would enable targeted fall prevention strategies and facilitate appropriate resource allocation to address this critical patient safety issue. DESIGN: We used a retrospective observational design and repeated k-fold cross-validation (10 repeats and 10 folds) of logistic regression models with falls regressed onto: MFS alone, AM-PAC basic mobility and applied cognitive scales alone, and MFS and AM-PAC combined. SETTING: Inpatient rehabilitation hospital. PARTICIPANTS: After exclusions, 2007 patients from an inpatient setting (N=2007; 131 experienced a fall). Primary diagnoses included 602 individuals with stroke (30%), 502 with brain injury (25%), 321 with spinal cord injury (16%), and 582 with other diagnoses (29%). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Experience of a fall during inpatient stay. RESULTS: The MFS at admission was associated with falls (area under the curve [AUC], 0.64). Above and beyond the MFS, AM-PAC applied cognitive and basic mobility at admission were also significantly associated with falls (combined model AUC, 0.70). Although MFS and applied cognition showed linear associations, there was evidence for a nonlinear association with AM-PAC basic mobility. CONCLUSIONS: The AM-PAC basic mobility and AM-PAC applied cognitive scales showed associations with falls above and beyond the MFS. More work is needed to validate model predictions in an independent sample with truly longitudinal data; prediction accuracy would also need to be substantially improved. However, the current data do suggest that the AM-PAC has the potential to reduce the burden of fall management by focusing resources on a smaller cohort of patients identified as having a high fall risk.

Nationality and sociocultural factors influence athlete development and sport outcomes: Perspectives from United States and Austrian youth alpine ski racing.

Geographical regions possess distinct sporting cultures that can influence athletic development from a young age. The United States (US) and Austria both produce elite alpine ski racers, yet have distinct sport structures (i.e., funding, skiing prominence). In this exploratory study, we investigated sport outcomes and psychological profiles in adolescent alpine ski racers attending skill development academies in the US (N= 169) and Austria (N= 209). Sport participation and psychological questionnaires (mental toughness, perfectionism, grit, coping, burnout) were administered to athletes. In Austria, athletes participated in fewer extracurricular sports, began competing and training younger, and accumulated less practice hours than athletes in the US. Athletes in the US reported greater burnout than athletes in Austria. Finally, in the US, women accumulated more practice hours and experienced more parental pressure than men, while men accumulated more practice hours in Austria. Austria's skiing-centric sport culture may encourage athletes to fully immerse into the sport, contributing to positive psychological outcomes. Reduced sport opportunities in the US beyond educational institutions may pressure athletes to practice more to ensure continued competitive skiing. Stressors for sport participation will be unique to gender in each country though, given their implicit gender stigmas for sport participation.

Longitudinal Structural MRI in Neurologically Healthy Adults.

BACKGROUND: Structural brain MRI measures are frequently examined in both healthy and clinical groups, so an understanding of how these measures vary over time is desirable. PURPOSE: To test the stability of structural brain MRI measures over time. POPULATION: In all, 112 healthy volunteers across four sites. STUDY TYPE: Retrospective analysis of prospectively acquired data. FIELD STRENGTH/SEQUENCE: 3 T, magnetization prepared - rapid gradient echo, and single-shell diffusion sequence. ASSESSMENT: Diffusion, cortical thickness, and volume data from the sensorimotor network were assessed for stability over time across 3 years. Two sites used a Siemens MRI scanner, two sites a Philips scanner. STATISTICAL TESTS: The stability of structural measures across timepoints was assessed using intraclass correlation coefficients (ICC) for absolute agreement, cutoff ≥0.80, indicating high reliability. Mixed-factorial analysis of variance (ANOVA) was used to examine between-site and between-scanner type differences in individuals over time. RESULTS: All cortical thickness and gray matter volume measures in the sensorimotor network, plus all diffusivity measures (fractional anisotropy plus mean, axial and radial diffusivities) for primary and premotor cortices, primary somatosensory thalamic connections, and the cortico-spinal tract met ICC. The majority of measures differed significantly between scanners, with a trend for sites using Siemens scanners to produce larger values for connectivity, cortical thickness, and volume measures than sites using Philips scanners. DATA CONCLUSION: Levels of reliability over time for all tested structural MRI measures were generally high, indicating that any differences between measurements over time likely reflect underlying biological differences rather than inherent methodological variability. LEVEL OF EVIDENCE: 4. TECHNICAL EFFICACY STAGE: 1.

The direction of postural threat alters balance control when standing at virtual elevation.

Anxiogenic settings lead to reduced postural sway while standing, but anxiety-related balance may be influenced by the location of postural threat in the environment. We predicted that the direction of threat would elicit a parallel controlled manifold relative to the standing surface, and an orthogonal uncontrolled manifold during standing. Altogether, 14 healthy participants (8 women, mean age = 27.5 years, SD = 8.2) wore a virtual reality (VR) headset and stood on a matched real-world walkway (2 m × 40 cm × 2 cm) for 30 s at ground level and simulated heights (elevated 15 m) in two positions: (1) parallel to walkway, lateral threat; and (2) perpendicular to walkway, anteroposterior threat. Inertial sensors measured postural sway acceleration (e.g., 95% ellipse, root mean square (RMS) of acceleration), and a wrist-worn monitor measured heart rate coefficient of variation (HR CV). Fully factorial linear-mixed effect regressions (LMER) determined the effects of height and position. HR CV moderately increased from low to high height (p = 0.050, g = 0.397). The Height × Position interaction approached significance for sway area (95% ellipse; ß = - 0.018, p = 0.062) and was significant for RMS (ß = - 0.022, p = 0.007). Post-hoc analyses revealed that sagittal plane sway accelerations and RMS increased from low to high elevation in parallel standing, but were limited when facing the threat during perpendicular standing. Postural response to threat varies depending on the direction of threat, suggesting that the control strategies used during standing are sensitive to the direction of threat.

Cardiopulmonary Demand of 16-kg Kettlebell Snatches in Simulated Girevoy Sport.

Chan, M, MacInnis, MJ, Koch, S, MacLeod, KE, Lohse, KR, Gallo, ME, Sheel, AW, and Koehle, MS. Cardiopulmonary demand of 16-kg kettlebell snatches in simulated Girevoy Sport. J Strength Cond Res 34(6): 1625-1633, 2020-Kettlebell lifting has become popular both as a strength and conditioning training tool and as a sport in and of itself: Girevoy Sport (GS). Although several kettlebell multimovement protocols have been analyzed, little research has attempted to quantify the aerobic stimulus of the individual events in GS, which could better inform kettlebell-related exercise prescription. The purpose of this study was to quantify the cardiopulmonary demand, assessed primarily by oxygen consumption (V[Combining Dot Above]O2) and heart rate (HR), of continuous high-intensity kettlebell snatches-under conditions relevant to GS-and to compare this demand with a more traditional graded rowing ergometer maximal exercise test. Ten male participants (age = 28.4 ± 4.6 years, height = 185 ± 7 cm, body mass = 95.1 ± 14.9 kg) completed (a) a graded-exercise test on a rowing ergometer to determine maximal oxygen consumption (V[Combining Dot Above]O2max) and maximal heart rate (HRmax) and (b) a graded-exercise test consisting of continuous 16-kg kettlebell snatches to determine peak oxygen consumption (V[Combining Dot Above]O2peak) and peak heart rate (HRpeak) during a simulated GS snatch event. Subjects achieved a V[Combining Dot Above]O2max of 45.7 ± 6.7 ml·kg·min and HRmax of 177 ± 8.3 b·min on the rowing ergometer. The kettlebell snatch test produced a V[Combining Dot Above]O2peak of 37.6 ± 4.4 ml·kg·min (82.7 ± 6.5% V[Combining Dot Above]O2max) and a HRpeak of 174 ± 10 b·min (98.0 ± 3.4% HRmax). These findings suggest that GS kettlebell snatches with 16-kg can provide an adequate aerobic stimulus to improve cardiorespiratory fitness in those with a V[Combining Dot Above]O2max of ≤51 ml·kg·min, according to aerobic training recommendations from the American College of Sports Medicine.

Predicting Motor Sequence Learning in People With Parkinson Disease.

BACKGROUND AND PURPOSE: Skill acquisition (ie, performance changes during practice) occurs in a nonlinear fashion. Despite this, motor learning is typically measured by comparing discrete timepoints. Thus, typical measures of motor learning do not detect skill acquisition characteristics that may be clinically meaningful. Reliable prediction of motor skill learning in people with Parkinson disease (PD) would allow therapists to more effectively individualize practice doses to fit specific patients' needs. The purposes of this study were to (a) characterize postural skill acquisition in people with PD, and identify factors (such as acquisition rate and practice dose to plateau) that predict learning, and (b) investigate whether levodopa medication (L-dopa) status during practice impacted learning. METHODS: Twenty-seven adults with PD practiced a postural motor task over 3 days, followed by 2 retention tests. Participants were randomized to practice either ON or OFF L-dopa. Data for repeating and random sequences were each analyzed using nonlinear curve-fitting and mixed-effects regressions. Learning was defined as pretest minus retention test performance. RESULTS: Participants with less physical impairment demonstrated less learning on the repeating and random sequence tasks compared with participants with more impairment. Participants who improved faster during practice demonstrated less learning on the repeating sequence task compared with participants who improved more slowly. Reaching plateau during practice was not related to learning. L-dopa did not impair learning. DISCUSSION AND CONCLUSIONS: Participants' skill acquisition characteristics were related to learning a postural motor task. Patient-specific factors, such as the rate of skill acquisition, level of physical function, and medication status, may influence how postural motor practice is delivered during balance rehabilitation.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A250).

On the Reporting of Experimental and Control Therapies in Stroke Rehabilitation Trials: A Systematic Review.

OBJECTIVE: To use the Centralized Open-Access Rehabilitation database for Stroke to explore reporting of both experimental and control interventions in randomized controlled trials for stroke rehabilitation (including upper and lower extremity therapies). DATA SOURCES: The Centralized Open-Access Rehabilitation database for Stroke was created from a search of MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Cumulative Index of Nursing and Allied Health from the earliest available date to May 31, 2014. STUDY SELECTION: A total of 2892 titles were reduced to 514 that were screened by full text. This screening left 215 randomized controlled trials in the database (489 independent groups representing 12,847 patients). DATA EXTRACTION: Using a mixture of qualitative and quantitative methods, we performed a text-based analysis of how the procedures of experimental and control therapies were described. Experimental and control groups were rated by 2 independent coders according to the Template for Intervention Description and Replication criteria. DATA SYNTHESIS: Linear mixed-effects regression with a random effect of study (groups nested within studies) showed that experimental groups had statistically more words in their procedures (mean, 271.8 words) than did control groups (mean, 154.8 words) (P<.001). Experimental groups had statistically more references in their procedures (mean, 1.60 references) than did control groups (mean, .82 references) (P<.001). Experimental groups also scored significantly higher on the total Template for Intervention Description and Replication checklist (mean score, 7.43 points) than did control groups (mean score, 5.23 points) (P<.001). CONCLUSIONS: Control treatments in stroke motor rehabilitation trials are underdescribed relative to experimental treatments. These poor descriptions are especially problematic for "conventional" therapy control groups. Poor reporting is a threat to the internal validity and generalizability of clinical trial results. We recommend authors use preregistered protocols and established reporting criteria to improve transparency.

An action-incongruent secondary task modulates prediction accuracy in experienced performers: evidence for motor simulation.

We provide behavioral evidence that the human motor system is involved in the perceptual decision processes of skilled performers, directly linking prediction accuracy to the (in)ability of the motor system to activate in a response-specific way. Experienced and non-experienced dart players were asked to predict, from temporally occluded video sequences, the landing position of a dart thrown previously by themselves (self) or another (other). This prediction task was performed while additionally performing (a) an action-incongruent secondary motor task (right arm force production), (b) a congruent secondary motor task (mimicking) or (c) an attention-matched task (tone-monitoring). Non-experienced dart players were not affected by any of the secondary task manipulations, relative to control conditions, yet prediction accuracy decreased for the experienced players when additionally performing the force-production, motor task. This interference effect was present for 'self' as well as 'other' decisions, reducing the accuracy of experienced participants to a novice level. The mimicking (congruent) secondary task condition did not interfere with (or facilitate) prediction accuracy for either group. We conclude that visual-motor experience moderates the process of decision making, such that a seemingly visual-cognitive prediction task relies on activation of the motor system for experienced performers. This fits with a motor simulation account of action prediction in sports and other tasks, and alerts to the specificity of these simulative processes.