Biomechanical Assessment Methods Used in Chronic Stroke: A Scoping Review of Non-Linear Approaches.

Non-linear and dynamic systems analysis of human movement has recently become increasingly widespread with the intention of better reflecting how complexity affects the adaptability of motor systems, especially after a stroke. The main objective of this scoping review was to summarize the non-linear measures used in the analysis of kinetic, kinematic, and EMG data of human movement after stroke. PRISMA-ScR guidelines were followed, establishing the eligibility criteria, the population, the concept, and the contextual framework. The examined studies were published between 1 January 2013 and 12 April 2023, in English or Portuguese, and were indexed in the databases selected for this research: PubMed®, Web of Science®, Institute of Electrical and Electronics Engineers®, Science Direct® and Google Scholar®. In total, 14 of the 763 articles met the inclusion criteria. The non-linear measures identified included entropy (n = 11), fractal analysis (n = 1), the short-term local divergence exponent (n = 1), the maximum Floquet multiplier (n = 1), and the Lyapunov exponent (n = 1). These studies focused on different motor tasks: reaching to grasp (n = 2), reaching to point (n = 1), arm tracking (n = 2), elbow flexion (n = 5), elbow extension (n = 1), wrist and finger extension upward (lifting) (n = 1), knee extension (n = 1), and walking (n = 4). When studying the complexity of human movement in chronic post-stroke adults, entropy measures, particularly sample entropy, were preferred. Kinematic assessment was mainly performed using motion capture systems, with a focus on joint angles of the upper limbs.

Effect of experimentally induced muscle pain on neuromuscular control of force production.

PURPOSE: Neural and peripheral effects of induced muscle pain on explosive force production were investigated. METHODS: Nine participants performed two maximal, six explosive, and six electrical stimulations induced (twitches and octets) isometric knee extensions before and after (15 min of rest) receiving an intramuscular injection of hypertonic saline (pain inducer) or isotonic (placebo) infusions in two laboratory visits separated by 7 days. RESULTS: It was observed a reduction of peak torque production in maximal voluntary contraction in both conditions (9.3 and 3.3% for pain and placebo, respectively) and in the rate of torque development in placebo (7%). There was an increase in the rate of torque development for twitch and octets (10.5 and 15.8%, respectively) in the pain condition and peak torque for twitch (12%) in both conditions (as did the total rate of torque development for octets). CONCLUSION: Force production decreases and increases during voluntary and involuntary contractions, respectively, suggesting that acute pain impairs force production via central mechanisms.

Increased body movement equals better performance? Not always! Musical style determines motion degree perceived as optimal in music performance.

Musicians' body behaviour has a preponderant role in audience perception. We investigated how performers' motion is perceived depending on the musical style and musical expertise. To further explore the effect of visual input, stimuli were presented in audio-only, audio-visual and visual-only conditions. We used motion and audio recordings of expert saxophone players playing two contrasting excerpts (positively and negatively valenced). For each excerpt, stimuli represented five motion degrees with increasing quantity of motion (QoM) and distinct predominant gestures. In the experiment (online and in-person), 384 participants rated performance recordings for expressiveness, professionalism and overall quality. Results revealed that, for the positively valenced excerpt, ratings increased as a function of QoM, whilst for the negatively valenced, the recording with predominant flap motion was favoured. Musicianship did not have a significant effect in motion perception. Concerning multisensory integration, both musicians and non-musicians presented visual dominance in the positively valenced excerpt, whereas in the negatively valenced, musicians shifted to auditory dominance. Our findings demonstrate that musical style not only determines the way observers perceive musicians' movement as adequate, but also that it can promote changes in multisensory integration.

Effect of Randall foils on the rowing propulsive cycle.

Rowing performance depends on the design and building materials used for competition. Recently, attempting to improve rowing performance, the Randall foil has been attached to the top edge of a rowing Big blade, making it spoon shaped. The current study aimed to analyse the differences between Big blades with and without Randall foils in force-related variables. Nineteen rowers performed two bouts of 90 s at maximal effort tethered rowing and differences were found in cycle average peak force (4.33 ± 1.46 vs. 5.26 ± 1.57 N/kg), propulsive cycle average time (1.79 ± 0.38 vs. 1.52 ± 0.24 N/kg.s) and rate of force development (8.79 ± 4.75 vs. 12.07 ± 4.60 N/kg/s) for Big blades with and without foils (respectively). Differences were also observed between the middle (4.79 ± 1.21 vs. 4.08 ± 1.48 N/kg) and final phases (4.86 ± 1.45 vs. 4.04 ± 1.47 N/kg) of the rowing effort for the cycle average peak force of Big blades with and without Randall foils. Data suggest a positive effect of these foils on the force-time curve profile. Future studies should focus on testing its influence on free on-water rowing.

Post-activation performance enhancement does not occur following a large hand-paddles and parachute-resisted warm-up routine in collegiate swimmers.

Our aim was to investigate if using a warm-up routine that included parachute-resisted sprints with large hand-paddles improves 50 m freestyle performance in trained collegiate swimmers. Twelve swimmers (23.9 ± 2.2 years, 179 ± 7 cm, 77.1 ± 10.6 kg) participated in the study and completed two 50-m freestyle races, each preceded by a different warm-up routine, either control (CON) or experimental (EXP). The warm-up routines consisted of 500 m of swimming at self-selected speed, followed by four 10 s sprints with 1 min rest intervals. During EXP, sprints were performed using large hand-paddles and a swimming parachute, while during CON, sprints were performed freely. Performance and technique were assessed during the 50 m freestyle races. We found no significant differences in 25- and 50 m performance times (CON: 12.6 ± 0.8 vs. EXP: 12.5 ± 0.8 s, ES = 0.125; and CON: 26.8 ± 1.6 vs. EXP: 26.7 ± 1.7 s, ES = 0.06, respectively) between the two conditions. Mean stroke length (CON: 2.04 ± 0.21 vs. EXP: 2.02 ± 0.22 m·cycle-1, ES = 0.09), stroke frequency (CON: 55.4 ± 5.3 vs. EXP: 56.3 ± 5.2 cycles s-1, ES = 0.17), and propulsive time (CON: 0.62 ± 0.07 vs. EXP: 0.61 ± 0.06 s, ES = 0.15) were also not different between conditions. It is possible that the CON warm-up routine induced the priming effects that lead to PAPE, or that the EXP warm-up routine primed the athletes further but also induced greater fatigue, resulting in no significant effects on swimming performance. Our findings suggest that parachute-resisted sprints with hand-paddles during warm-up do not enhance 50 m freestyle swimming performance in trained collegiate swimmers. Coaches and practitioners should consider exploring different warm-up protocols to identify what works best for their athletes.

Acute Recovery after a Fatigue Protocol Using a Recovery Sports Legging: An Experimental Study.

Enhancing recovery is a fundamental component of high-performance sports training since it enables practitioners to potentiate physical performance and minimise the risk of injuries. Using a new sports legging embedded with an intelligent system for electrostimulation, localised heating and compression (completely embodied into the textile structures), we aimed to analyse acute recovery following a fatigue protocol. Surface electromyography- and torque-related variables were recorded on eight recreational athletes. A fatigue protocol conducted in an isokinetic dynamometer allowed us to examine isometric torque and consequent post-exercise acute recovery after using the sports legging. Regarding peak torque, no differences were found between post-fatigue and post-recovery assessments in any variable; however, pre-fatigue registered a 16% greater peak torque when compared with post-fatigue for localised heating and compression recovery methods. Our data are supported by recent meta-analyses indicating that individual recovery methods, such as localised heating, electrostimulation and compression, are not effective to recover from a fatiguing exercise. In fact, none of the recovery methods available through the sports legging tested was effective in acutely recovering the torque values produced isometrically.

Swimmers' Effective Actions during the Backstroke Start Technique.

The analysis of the external forces of swimming starts has revealed how swimmers propel themselves out of the block, but data should be properly interpreted to fully understand force-generation mechanisms. This study aimed to assess horizontal and vertical forces in the backstroke start based on swimmers' structural and propulsive actions. Firstly, a simulated structural force was estimated by two transient backstroke-start inter-segmental realistic body positions: a maximally tucked position and an extended one (just before the hands-off and the take-off, respectively). Secondly, 10 competitive backstroke swimmers performed four 15 m maximal backstroke starts with the external forces estimated. Thirdly, the simulated structural force was subtracted from raw horizontal and vertical force data, measured between hands-off and take-off instants, resulting in the propulsive forces. The application of the algorithm has evidenced that backstrokers' horizontal and vertical simulated-structural-force components contributed to ~40% of total force during start propulsion (~0.2-0.12 s before the take-off), followed by the propulsive horizontal force increment and a progressive vertical component reduction (~0.05 s) with ~20° take-off angle. Based on these findings, researchers and coaches can better guide swimmers as to the proper mechanical strategies to achieve effectiveness in the backstroke start, and to improve direct transfer of resistance training programs.

The kinematic profile of ventral swimming start: sex diversity.

It has been suggested that sex distinctions in physiology may affect the swimming performance of each sex differently. Yet, sex-based performance dependency has not been taken into consideration by most of the researchers evaluating swimming start. Therefore, the purpose of this research was to determine the effect of sex heterogeneity on the spatiotemporal characteristics of swimming start by investigating the determinants of its performance. A total of fifty-two international-level swimmers (thirty females and twenty-two males) performed three repetitions of the kick-start up to the 15-m mark. During trials, data were collected using video cameras and instrumented starting block. To search for evidence of differences between the two groups, the one-way ANOVA was conducted. Pearson's correlation coefficients were calculated between measurements widely used to describe overall starting performance and selected kinematical variables of swimming start. A sex effect was exposed for temporal variables describing all swimming start phases (p ≤ 0.015). Male swimmers, by spending less time during the push-off from the starting block (p = 0.002; η p 2 = 0.18), reaching higher take-off velocity (p < 0.001; η p 2 = 0.29), traveling longer distances during flight (p < 0.001; η p 2 = 0.40), and swimming faster in the water phase (p < 0.001; η p 2 = 0.40), took starting advantage over their female counterparts. Consequently, performance measures such as 5-m, 10-m, and 15-m start times indicated that male participants were faster than females (p < 0.001; η p 2 ≥ 0.40). Only in the group of male swimmers a significant correlation between variables describing overall starting performance (5-m, 10-m, and 15-m times), and variables commonly highlighted as starting performance determining factors (block phase duration, take-off horizontal velocity, and flight distance) was found. The current study shows that the spatiotemporal variables of swimming start, the relation between them as well as overall starting performance, vary by sex. Consequently, the requirement of sex factor and its heterogeneity effect should be included not only in detailed characteristics of separate variables but also in all approaches undertaken. Those findings seem to play a crucial role mainly in swimming start evaluations in post-pubertal age groups of swimmers.

Breaking Barriers: Artificial Intelligence Interpreting the Interplay between Mental Illness and Pain as Defined by the International Association for the Study of Pain.

Low back pain is one of the main causes of motor disabilities and psychological stress, with the painful process encompassing sensory and affective components. Noxious stimuli originate on the periphery; however, the stimuli are recombined in the brain and therefore processed differently due to the emotional environment. To better understand this process, our objective was to develop a mathematical representation of the International Association for the Study of Pain (IASP) model of pain, covering the multidimensional representation of this phenomenon. Data from the Oswestry disability index; the short form of the depression, anxiety, and stress scale; and pain catastrophizing daily questionnaires were collected through online completion, available from 8 June 2022, to 8 April 2023 (1021 cases). Using the information collected, an artificial neural network structure was trained (based on anomaly detection methods) to identify the patterns that emerge from the relationship between the variables. The developed model proved to be robust and able to show the patterns and the relationship between the variables, and it allowed for differentiating the groups with altered patterns in the context of low back pain. The distinct groups all behave according to the main finding that psychological and pain events are directly associated. We conclude that our proposal is effective as it is able to test and confirm the definition of the IASP for the study of pain. Here we show that the fiscal and mental dimensions of pain are directly associated, meaning that mental illness can be an enhancer of pain episodes and functionality.

Postural stability computerized evaluation in total knee arthroplasty.

PURPOSE: To evaluate the balance in patients with total knee arthroplasty (TKA) and knee osteoarthrosis (KOA), measured by postural stability computerized evaluation (PSCE), and to evaluate the effect of post-TKA patients' characteristics in their performance on PSCE. MATERIALS AND METHODS: An observational cross-sectional study was conducted in two sets of patients: (A) patients with KOA and primary TKA surgery scheduled and (B) patients who underwent primary TKA >9 months. Sociodemographic, radiographic, clinical and PSCE parameters (using the Biodex Balance System) were assessed. RESULTS: Post-TKA patients placed more load on the replaced knee than the contralateral osteoarthritic knee (p = 0.027). They had less imbalance on the balance tests performed with the eyes open, on stable (p = 0.032), and unstable platforms (p = 0.022). These patients also showed better postural stability in monopodalic stance, both standing on the TKA (p = 0.010) and contralateral knee (p = 0.017). Age, weight, pain on the operated knee, extension deficit on the operated knee, and Berg Balance Scale scores on post-TKA patients were significantly associated with their performance on PSCE tests. CONCLUSIONS: PSCE can be useful to quantify the balance of post-TKA and KOA patients.

Total knee arthroplasty is the definitive treatment for knee osteoarthrosis and it has several benefits, but its effect on balance is still unknown.Postural stability computerized evaluation is used to evaluate balance on vestibular diseases and it has been recently studied on musculoskeletal conditions.Postural stability computerized evaluation may be useful to evaluate patients' balance before and after total knee arthroplasty.

Severe infections in Portuguese patients with rheumatoid arthritis under biologic treatment - a multicenter, nationwide study (SIPPRA-B Study).

INTRODUCTION: Despite years of experience with biological disease modifying anti-rheumatic drugs (bDMARD) in rheumatoid arthritis (RA), little is known about differences in infectious risk among bDMARDs. The aim of this study was to assess the incidence and type of infections in RA patients on bDMARDs and to determine possible predictors. METHODS: A retrospective multicenter cohort study that included patients registered in the Rheumatic Diseases Portuguese Registry (Reuma.pt) with RA, and exposed to at least one bDMARD until April 2021. RA patients under bDMARD and with at least one episode of severe infection (SI), defined as infection that requires hospitalization, use of parenteral antibiotics or that resulted in death, were compared to patients with no report of SI. Demographic and clinical data at baseline and at the time of each SI were collected to establish comparisons between different groups of bDMARDs. Comparisons between different bDMARDs were assessed and logistic regression was performed to identify predictors of SI. RESULTS: We included 3394 patients, 2833 (83.5%) female, with a mean age at RA diagnosis of 45.5±13.7 years. SI was diagnosed in 142 of the 3394 patients evaluated (4.2%), totaling 151 episodes of SI. At baseline, patients with SI had a significantly higher proportion of prior orthopedic surgery, asthma, interstitial lung disease, chronic kidney disease and corticosteroid use, higher mean age and longer median disease duration at first bDMARD. Nine patients died (6.0%). Ninety-two SI (60.9%) occurred with the first bDMARD, the majority leading to discontinuation of the bDMARD within 6 months (n=75, 49.7%), while 65 (43.0%) restarted the same bDMARD and 11 (7.3%) switched to another bDMARD (6 of them to a different mechanism of action). In the multivariate analysis, we found that chronic kidney disease, asthma, infliximab, corticosteroid use, interstitial lung disease, previous orthopedic surgery, higher Health Assessment Questionnaire and DAS284V-ESR are independent predictors of SI. CONCLUSION: This study described the incidence and types of SI among Portuguese RA patients on biologics, identifying several predictors of SI, both globally and with different bDMARDs. Physicians should be aware of the real-word infectious risk in RA patients on bDMARDs when making treatment decisions.

Knee flexion of saxophone players anticipates tonal context of music.

Music performance requires high levels of motor control. Professional musicians use body movements not only to accomplish and help technical efficiency, but to shape expressive interpretation. Here, we recorded motion and audio data of twenty participants performing four musical fragments varying in the degree of technical difficulty to analyze how knee flexion is employed by expert saxophone players. Using a computational model of the auditory periphery, we extracted emergent acoustical properties of sound to inference critical cognitive patterns of music processing and relate them to motion data. Results showed that knee flexion is causally linked to tone expectations and correlated to rhythmical density, suggesting that this gesture is associated with expressive and facilitative purposes. Furthermore, when instructed to play immobile, participants tended to microflex (>1 Hz) more frequently compared to when playing expressively, possibly indicating a natural urge to move to the music. These results underline the robustness of body movement in musical performance, providing valuable insights for the understanding of communicative processes, and development of motor learning cues.

Swimming With the COSMED AquaTrainer and K5 Wearable Metabolic System in Breath-by-Breath Mode: Accuracy, Precision, and Repeatability.

PURPOSE: To compare ventilatory and cardiorespiratory responses between the COSMED AquaTrainer coupled with the K4b2 and K5 wearable metabolic systems in breath-by-breath mode over a wide range of swimming speeds. METHODS: Seventeen well-trained master swimmers performed 2 front-crawl 7 × 200-m incremental intermittent protocols (increments of 0.05 m·s-1 and 30-s rest intervals, with a visual pacer) with AquaTrainer coupled with either K4b2 or K5. RESULTS: Post hoc tests showed that swimming speed was similar (mean diff.: -0.01 to 0.01 m·s-1; P = .73-.97), repeatable (intraclass correlation coefficient: .88-.99; P < .001), highly accurate, and precise (agreement; bias: -0.01 to 0.01 m·s-1; limits: -0.1 to 0.1 m·s-1) between all conditions. Ventilatory and cardiorespiratory responses were highly comparable between all conditions, despite a "small" effect size for fraction of expired carbon dioxide at the sixth 200-m step (0.5%; ηp2=.12; P = .04) and carbon dioxide production at the fifth, sixth, and seventh 200-m steps (0.3-0.5 L·min-1; ηp2=.11-.17; P = .01-.05). We also observed high accuracy, which was greater for tidal volume (0.0-0.1 L), minute ventilation (-3.7 to 5.1 L·min-1), respiratory frequency (bias: -2.1 to 1.9 breaths·min-1), and oxygen uptake (0.0-0.2 L·min-1). Bland-Altman plots showed that the distribution inside the limits of agreement and their respective 95% CIs were consistent for all ventilatory and cardiorespiratory data. The repeatability (intraclass correlation coefficient) of tidal volume (.93-.97), minute ventilation (.82-.97), respiratory frequency (.68-.96), fraction of expired carbon dioxide (.85-.95), carbon dioxide production (.77-.95), fraction of expired oxygen (.78-.92), and oxygen uptake (.94-.98) data ranged from moderate to excellent (P < .001-.05). CONCLUSIONS: Swimming with the AquaTrainer coupled with K5 (breath-by-breath mode) yields accurate, precise, and repeatable ventilatory and cardiorespiratory responses when compared with K4b2 (previous gold standard). Swimming support staff, exercise and health professionals, and researchers can now relate differences between physiological capacities measured with the AquaTrainer while coupled with either of these 2 devices.

Is the use of the coefficient of variation a valid way to assess the swimming intra-cycle velocity fluctuation?

OBJECTIVES: Swimming intra-cycle velocity fluctuation has often been assessed using the coefficient of variation, which requires a mathematical assumption of a positive linear relationship between the velocity mean and standard deviation. As this assumption has never been tested, the current study aimed to investigate the within-participant relationship between the mean and standard deviation of the intra-cycle velocity. DESIGN: Cross-sectional study. METHODS: The intra-trial mean and standard deviation of one stroke cycle centre of mass velocity (vCMmean and vCMSD, respectively) were obtained from 80 front crawl trials (10 participants × eight swimming speeds) using whole-body three-dimensional motion analysis. The linear mixed-effect model and intra-class correlation analysis were used to test the linear relationship between vCMmean and vCMSD (n = 80) and the absolute agreement between vCMmean and vCMSD relative to those during the fastest trial (n = 70). RESULTS: Neither the linear regression model (95 % confidence interval range of the fixed effect of vCMmean: -0.003-0.031) nor the intra-class correlation coefficient (ICC = 0.07; p = 0.26) verified linear relationships between vCMmean and vCMSD, which violated the background assumption of coefficient of variation calculation. CONCLUSIONS: When investigating the intra-cycle velocity fluctuation, the coefficient of variation should not be used alone. Researchers and practitioners should always interpret/report the obtained results together with the mean and standard deviation to avoid misleading conclusions and feedback because the coefficient of variation obtained from one cycle velocity data is likely biased by mean velocity.

Influence of cognitive and motor tasks using smartphone during gait: EMG and gait performance analysis - Dual-task study.

Previous studies reported changes in spatiotemporal gait parameters during dual-task performance while walking using a smartphone compared to walking without a smartphone. However, studies that assess muscle activity while walking and simultaneously performing smartphone tasks are scarce. So, this study aimed to assess the effects of motor and cognitive tasks using a smartphone while simultaneously performing gait on muscle activity and gait spatiotemporal parameters in healthy young adults. Thirty young adults (22.83 ± 3.92 years) performed five tasks: walking without a smartphone (single-task, ST); typing on a smartphone keyboard in a sitting position (secondary motor single-task); performing a cognitive task on a smartphone in a sitting position (cognitive single-task); walking while typing on a smartphone keyboard (motor dual-task, mot-DT) and walking while performing a cognitive task on a smartphone (cognitive dual-task, cog-DT). Gait speed, stride length, stride width and cycle time were collected using an optical motion capture system coupled with two force plates. Muscle activity was recorded using surface electromyographic signals from bilateral biceps femoris, rectus femoris, tibialis anterior, gastrocnemius medialis, gastrocnemius lateralis, gluteus maximus and lumbar erector spinae. Results showed a decrease in stride length and gait speed from the single-task to cog-DT and mot-DT (p < 0.05). On the other hand, muscle activity increased in most muscles analyzed from single- to dual-task conditions (p < 0.05). In conclusion, performing a cognitive or motor task using a smartphone while walking promote a decline in spatiotemporal gait parameters performance and change muscle activity pattern compared to normal walking.

Physical Fitness Profile of High-Level Female Portuguese Handball Players.

We characterized the physical and physiological profiles of high-level female Portuguese handball players and examined the relationships between their anthropometric characteristics, general motor performance and cardiopulmonary fitness. Twenty-four high-level female handball players with an average age of 23.6 ± 5.5 years, height of 173.6 ± 5.1 cm and body mass of 72.6 ± 9.1 kg volunteered to participate. A Pearson correlation test was used to assess the relationship between variables. Direct relationships were observed between the players' height and arm span (r = 0.741), as well as between their squat jump and countermovement jump performances with regard to body mass (r = 0.448 and 0.496, respectively). The 9 m jump shot has a large relationship with the 7 m standing throw (r = 0.786) and between left hand dynamometry and body mass index (r = 0.595). The 30 m sprint has a relationship with the 7 m standing throw (r = -0.526) and the 9 m jump throw (r = -0.551). Oxygen uptake has a relationship with the players' height (r = -0.482) and time limit (r = 0.513), while the fitness index has a relation to the players' height (r = -0.488) and arm span (r = -0.422). Our results should be considered when using physical testing to plan optimal physical training regimens in elite team handball.

Assessment of calcinosis in Portuguese patients with systemic sclerosis - a multicenter study.

INTRODUCTION/OBJECTIVES: The study aims to define the clinical and subclinical calcinosis prevalence, the sensitivity of radiographed site and clinical method for its diagnosis, and the phenotype of Portuguese systemic sclerosis (SSc) patients with calcinosis. METHOD: A cross-sectional multicenter study was conducted with SSc patients fulfilling Leroy/Medsger 2001 or ACR/EULAR 2013 classification criteria, registered in the Reuma.pt. Calcinosis was assessed through clinical examination and radiographs of hands, elbows, knees, and feet. Independent parametric or non-parametric tests, multivariate logistic regression, and sensitivity calculation of radiographed site and clinical method for calcinosis detection were performed. RESULTS: We included 226 patients. Clinical calcinosis was described in 63 (28.1%) and radiological calcinosis in 91 (40.3%) patients, of which 37 (40.7%) were subclinical. The most sensitive location to detect calcinosis was the hand (74.7%). Sensitivity of the clinical method was 58.2%. Calcinosis patients were more often female (p = 0.008) and older (p < 0.001) and had more frequently longer disease duration (p < 0.001), limited SSc (p = 0.017), telangiectasia (p = 0.039), digital ulcers (p = 0.001), esophageal (p < 0.001) and intestinal (p = 0.003) involvements, osteoporosis (p = 0.028), and late capillaroscopic pattern (p < 0.001). In multivariate analysis, digital ulcers (OR 2.63, 95% CI 1.02-6.78, p = 0.045) predicted overall calcinosis, esophageal involvement (OR 3.52, 95% CI 1.28-9.67, p = 0.015) and osteoporosis (OR 4.1, 95% CI 1.2-14.2, p = 0.027) predicted hand calcinosis, and late capillaroscopic pattern (OR 7.6, 95% CI 1.7-34.9, p = 0.009) predicted knee calcinosis. Anti-nuclear antibody positivity was associated with less knee calcinosis (OR 0.021, 95% CI 0.001-0477, p = 0.015). CONCLUSIONS: Subclinical calcinosis high prevalence suggests that calcinosis is underdiagnosed and radiographic screening might be relevant. Multifactorial pathogenesis may explain calcinosis predictors' variability. Key Points • Prevalence of subclinical calcinosis in SSc patients is substantial. • Hand radiographs are more sensitive to detect calcinosis than other locations or clinical method. • Digital ulcers were associated with overall calcinosis, esophageal involvement and osteoporosis were associated with hand calcinosis, and late sclerodermic pattern in nailfold capillaroscopy was associated with knee calcinosis. • Anti-nuclear antibody positivity may be a protective factor for knee calcinosis.

Muscular and Prefrontal Cortex Activity during Dual-Task Performing in Young Adults.

Postural control depends on attentional resources besides automatic processes. The dual-task paradigm is a possible approach to analyzing the interference and performance between motor and/or cognitive tasks. Various studies showed that, when individuals simultaneously perform two tasks, the postural stability can decline during a dual-task compared with a single-task due to the attentional resources required performing the tasks. However, little is known about the cortical and muscular activity pattern during dual-task performance. Therefore, this study aims to analyze the muscular and prefrontal activity under dual-task performance in healthy young adults. Thirty-four healthy young adults (mean age ± SD = 22.74 ± 3.74 years) were recruited to perform a postural task (standing posture) and a dual-task (maintaining standing posture while performing a cognitive task). Lower-limb muscle activity was bilaterally collected from five muscles using surface electromyography (sEMG), and the co-contraction index (CCI) was also calculated for selected muscle pairings. The oxy- and deoxyhemoglobin concentrations (prefrontal cortex activity) were recorded using functional near-infrared spectroscopy (fNIRS). Data were compared between single- and dual-task performance. Prefrontal activity increased (p < 0.05), and muscle activity decreased in most analyzed muscles (p < 0.05), from the single-task to cognitive dual-task performing. The co-contraction index patterns changed from single- to dual-task conditions in most selected muscle pairs (p < 0.05). We conclude that the cognitive task negatively interfered with motor performance once the muscle activity decreased and the prefrontal cortex activity increased under a dual-task, suggesting that young adults prioritized cognitive task performance, and they allocated more attentional resources to the cognitive task over the motor performance. Understanding the neuromotor changes can help adopt a better clinical practice to prevent injuries. However, future studies are recommended to assess and monitor muscular and cortical activity during the dual-task performance to provide additional information about the cortical and muscular activity patterns in postural control while performing a dual-task.

"Selecting the right tool for the job" a narrative overview of experimental methods used to measure or estimate active and passive drag in competitive swimming.

Free-swimming performance depends strongly on the ability to develop propulsive force and minimise resistive drag. Therefore, estimating resistive drag (passive or active) may be important to understand how free-swimming performance can be improved. The purpose of this narrative overview was to describe and discuss experimental methods of measuring or estimating active and passive drag relevant to competitive swimming. Studies were identified using a mixed-model approach comprising a search of SCOPUS and Web of Science data bases, follow-up of relevant studies cited in manuscripts from the primary search, and additional studies identified by the co-authors based on their specific areas of fluid dynamics expertise. The utility and limitations of active and passive drag methods were critically discussed with reference to primary research domains in this field, 'swimmer morphology' and 'technique analysis'. This overview and the subsequent discussions provide implications for researchers when selecting an appropriate method to measure resistive forces (active or passive) relevant to improving performance in free-swimming.

The impact of visual display of human motion on observers' perception of music performance.

In investigating the influence of body movement in multimodal perception, human motion displays are frequently used as a means of visual standardization and control of external confounders. However, no principle is established regarding the selection of an adequate display for specific study purposes. The aim of this study was to evaluate the effects of adopting 4 visual displays (point-light, stick figure, body mass, skeleton) on the observers' perception of music performances in 2 expressive conditions (immobile, projected expressiveness). Two hundred eleven participants rated 8 audio-visual samples in expressiveness, match between movement and music, and overall evaluation. The results revealed significant isolated main effects of visual display and expressive condition on the observers' ratings (in both, p < 0.001), and interaction effects between the two factors (p < 0.001). Displays closer to a human form (mostly skeleton, sometimes body mass) exponentiated the evaluations of expressiveness and music-movement match in the projected expressiveness condition, and of overall evaluation in the immobile condition; the opposite trend occurred with the simplified motion display (stick figure). Projected expressiveness performances were higher rated than immobile performances. Although the expressive conditions remained distinguishable across displays, the more complex ones potentiated the attribution of subjective qualities. We underline the importance of considering the variable display as an influencing factor in perceptual studies.