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Isabel de Almeida Paz, Francesca Chaida Sonda, Matias Fröhlich, João Luiz Quagliotti Durigan, and Marco Aurélio Vaz

Context: Pulsed current and kilohertz frequency alternating current are 2 types of neuromuscular electrical stimulation (NMES) currents often used by clinicians during rehabilitation. However, the low methodological quality and the different NMES parameters and protocols used in several studies might explain their inconclusive results in terms of their effects in the evoked torque and the discomfort level. In addition, the neuromuscular efficiency (ie, the NMES current type that evokes the highest torque with the lowest current intensity) has not been established yet. Therefore, our objective was to compare the evoked torque, current intensity, neuromuscular efficiency (evoked torque/current intensity ratio), and discomfort between pulsed current and kilohertz frequency alternating current in healthy people. Design: A double-blind, randomized crossover trial. Methods: Thirty healthy men (23.2 [4.5] y) participated in the study. Each participant was randomized to 4 current settings: 2 kilohertz frequency alternating currents with 2.5 kHz of carrier frequency and similar pulse duration (0.4 ms) and burst frequency (100 Hz) but with different burst duty cycles (20% and 50%) and burst durations (2 and 5 ms); and 2 pulsed currents with similar pulse frequency (100 Hz) and different pulse duration (2 and 0.4 ms). The evoked torque, current intensity at the maximal tolerated intensity, neuromuscular efficiency, and discomfort level were evaluated. Results: Both pulsed currents generated higher evoked torque than the kilohertz frequency alternating currents, despite the similar between-currents discomfort levels. The 2 ms pulsed current showed lower current intensity and higher neuromuscular efficiency compared with both alternated currents and with the 0.4 ms pulsed current. Conclusions: The higher evoked torque, higher neuromuscular efficiency, and similar discomfort of the 2 ms pulsed current compared with 2.5-kHz frequency alternating current suggests this current as the best choice for clinicians to use in NMES-based protocols.

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Landon B. Lempke, Matthew C. Hoch, Jarrod A. Call, Julianne D. Schmidt, and Robert C. Lynall

Context: Aberrant movement patterns among individuals with concussion history have been reported during sport-related movement. However, the acute postconcussion kinematic and kinetic biomechanical movement patterns during a rapid acceleration–deceleration task have not been profiled and leaves their progressive trajectory unknown. Our study aimed to examine single-leg hop stabilization kinematics and kinetics between concussed and healthy-matched controls acutely (≤7 d) and when asymptomatic (≤72 h of symptom resolution). Design: Prospective, cohort laboratory study. Methods: Ten concussed (60% male; 19.2 [0.9] y; 178.7 [14.0] cm; 71.3 [18.0] kg) and 10 matched controls (60% male; 19.5 [1.2] y; 176.1 [12.6] cm; 71.0 [17.0] kg) completed the single-leg hop stabilization task under single and dual task (subtracting by 6’s or 7’s) at both time points. Participants stood on a 30-cm tall box set 50% of their height behind force plates while in an athletic stance. A synchronized light was illuminated randomly, queuing participants to initiate the movement as rapidly as possible. Participants then jumped forward, landed on their nondominant leg, and were instructed to reach and maintain stabilization as fast as possible upon ground contact. We used 2 (group) × 2 (time) mixed-model analyses of variance to compare single-leg hop stabilization outcomes separately during single and dual task. Results: We observed a significant main group effect for single-task ankle plantarflexion moment, with greater normalized torque (mean difference = 0.03 N·m/body weight; P = .048, g = 1.18) for concussed individuals across time points. A significant interaction effect for single-task reaction time indicated that concussed individuals had slower performance acutely relative to asymptomatic (mean difference = 0.09 s; P = .015, g = 0.64), while control group performance was stable. No other main or interaction effects for single-leg hop stabilization task metrics were present during single and dual task (P ≥ .051). Conclusions: Greater ankle plantarflexion torque coupled with slower reaction time may indicate stiff, conservative single-leg hop stabilization performance acutely following concussion. Our findings shed preliminary light on the recovery trajectories of biomechanical alterations following concussion and provide specific kinematic and kinetic focal points for future research.

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Fernanda Metzen, João Breno Ribeiro-Alvares, Klauber Dalcero Pompeo, Francesca Chaida Sonda, Rodrigo Silva Santos, and Marco Aurélio Vaz

Développé à la seconde is a classic ballet movement that requires the maintenance of a high hip joint range of motion (ROM) and muscle strength. However, the contribution of these hip joint biomechanical parameters to this movement’s esthetic performance is unclear. Therefore, this study evaluated hip joint biomechanical characteristics of 21 experienced ballet dancers (15–29 y old) and verified the relationship between these variables with the développé à la seconde static and dynamic performance. Correlations between age, ballet practice time, gluteus maximus and gluteus medius thicknesses, ROM, and muscle strength with absolute and relative static and dynamic performances were verified. Flexors, extensors, and internal rotators peak strength and external rotation ROM were highly correlated with absolute and relative static performances (0.5–0.7). Flexors and extensors strength and external and internal rotation ROM showed the highest correlations with the développé dynamic performance (0.49–0.67). Flexor strength and flexor and internal rotation ROM predicted 26% to 41% of this movement’s static and dynamic performances. Thus, from a biomechanical perspective, clinical assessment of hip strength and ROM may be used to predict the quality of the ballet dancers’ performance of the développé à la seconde and guide classical ballet training.

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Jurate Pozeriene, Arūnas Emeljanovas, Vida Ostaseviciene, Kestutis Skucas, Kristina Bradauskiene, Renatas Mizeras, Ausrine Packeviciute, Kristina Venckuniene, Vaida Pokvytyte, Diana Reklaitiene, and Kwok Ng

Despite the recognized benefits of physical activity (PA) for children and adolescents with disabilities (CAWD), collective information on this is lacking in Lithuania. The purpose of this study was to investigate the current “state of the nation” PA levels of CAWD, based on the 10 indicators from the Active Healthy Kids Global Alliance Global Matrix 4.0 methodology. Scientific articles, practical reports, and published theses related to the 10 indicators from the Global Matrix 4.0 on CAWD age 6–19 years were reviewed, and data were converted to grades from A to F. (A) Strengths, Weaknesses, Opportunities, and Threats analysis was carried out to interpret the grades by four experts. Data on organized sport participation (F), school (D), community & environment (D), and government (C) were available. Data on other indicators are largely missing yet are needed for policymakers and researchers to be aware of the current state of PA among CAWD.

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José Francisco López-Gil, Susana Aznar, Blanca Roman-Viñas, Javier Brazo-Sayavera, Rocío Izquierdo-Gómez, Sabina Barrios-Fernández, Olga Rodríguez Ferrán, and Salome Aubert

This report aims to provide a better understanding of physical activity (PA) and related factors among Spanish children and adolescents living with disabilities. The 10 indicators used for the Global Matrix on Para Report Cards of children and adolescents living with disabilities were evaluated based on the best available data in Spain. An analysis of strengths, weaknesses, opportunities, and threats based on data provision was drafted by three experts and critically reviewed by the authorship team to provide a national perspective for each evaluated indicator. Government was the indicator with the highest grade (C+), followed by Sedentary Behaviors (C−), School (D), Overall PA (D−), and Community & Environment (F). The remaining indicators received an incomplete grade. There were low levels of PA in Spanish children and adolescents living with disabilities. Yet, opportunities to improve the current surveillance of PA among this population exist.

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Joseph E. Manzi, Jonathan S. Yu, Suleiman Y. Sudah, Mark Wishman, Theodore Quan, Alexander Koo, Kyle N. Kunze, Michelle Kew, James B. Carr II, Michael Fu, and Joshua S. Dines

Context: Ball velocity for baseball pitchers is influenced by a multitude of factors along the kinetic chain. While a vast amount of data currently exist exploring lower-extremity kinematic and strength factors in baseball pitchers, no previous study has systematically reviewed the available literature. Objective: The aim of this systematic review was to perform a comprehensive assessment of the available literature investigating the association between lower-extremity kinematic and strength parameters and pitch velocity in adult pitchers. Evidence Acquisition: Cross-sectional studies that investigated the association between lower-body kinematic and strength factors and ball velocity in adult pitchers were selected. A methodological index for nonrandomized studies checklist was used to evaluate the quality of all included studies. Evidence Synthesis: Seventeen studies met the inclusion criteria comprising a total of 909 pitchers (65%, professional, 33% college, and 3% recreational). The most studied elements were hip strength and stride length. The mean methodological index for nonrandomized studies score was 11.75 of 16 (range = 10–14). Pitch velocity was found to be influenced by several lower-body kinematic and strength factors including the following: (1) hip range of motion and strength of muscles around the hip and pelvis, (2) alterations in stride length, (3) alterations in lead knee flexion/extension, and (4) several pelvic and trunk spatial relationships throughout the throwing phase. Conclusions: Based on this review, we conclude that hip strength is a well-established predictor of increased pitch velocity in adult pitchers. Further studies in adult pitchers are needed to elucidate the effect of stride length on pitch velocity given mixed results across multiple studies. This study can provide a basis for trainers and coaches to consider the importance of lower-extremity muscle strengthening as a means by which adult pitchers can improve pitching performance.

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Yeshayahu Hutzler, Sharon Barak, Salomé Aubert, Kelly Arbour-Nicitopoulos, Riki Tesler, Cindy Sit, Diego Augusto Santos Silva, Piritta Asunta, Jurate Pozeriene, José Francisco López-Gil, and Kwok Ng

The purpose was to synthesize information gathered from the interpretation and conclusion sections of the Global Matrix of Para Report Cards on the physical activity of children and adolescents with disabilities. The synthesis was based on the strengths, weaknesses, opportunities, and threats framework. The procedure consisted of three stages: (a) the application of the International Classification of Functioning, Disability and Health as the theoretical framework; (b) identifying and aligning Global Matrix indicators and benchmarks with the International Classification of Functioning, Disability and Health components through a Delphi approach; and (c) using content analysis to identify themes from specific report cards. Outcomes reveal that further attention toward including children and adolescents with disabilities in fitness assessments is needed as well as adapted assessment methods. Program availability, equipment and facilities, and professional training emerged as strengths but need further development to overcome weaknesses. Paralympic inspiration was an opportunity, whereas extreme weather conditions presented potential threats to physical activity participation among children and adolescents with disabilities.

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Kishor Lakshminarayanan, Rakshit Shah, Yifei Yao, and Deepa Madathil

Previous studies have demonstrated that both visual and proprioceptive feedback play vital roles in mental practice of movements. Tactile sensation has been shown to improve with peripheral sensory stimulation via imperceptible vibratory noise by stimulating the sensorimotor cortex. With both proprioception and tactile sensation sharing the same population of posterior parietal neurons encoding within high-level spatial representations, the effect of imperceptible vibratory noise on motor imagery-based brain–computer interface is unknown. The objective of this study was to investigate the effects of this sensory stimulation via imperceptible vibratory noise applied to the index fingertip in improving motor imagery–based brain–computer interface performance. Fifteen healthy adults (nine males and six females) were studied. Each subject performed three motor imagery tasks, namely drinking, grabbing, and flexion–extension of the wrist, with and without sensory stimulation while being presented a rich immersive visual scenario through a virtual reality headset. Results showed that vibratory noise increased event-related desynchronization during motor imagery compared with no vibration. Furthermore, the task classification percentage was higher with vibration when the tasks were discriminated using a machine learning algorithm. In conclusion, subthreshold random frequency vibration affected motor imagery–related event-related desynchronization and improved task classification performance.

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Jozef J.M. Suskens, Gustaaf Reurink, Johannes L. Tol, Gino M.M.J. Kerkhoffs, Edwin A. Goedhart, Huub Maas, and Jaap H. van Dieën

This study assessed activity distribution among the hamstring muscles during the Nordic hamstring exercise (NHE). The objective was to compare muscle activity between and within muscles during the NHE to add insights in its underlying protective mechanism. Through multichannel electromyography, we measured muscle activity in male basketball players during the NHE. Electromyography was assessed at 15 locations: 5 for biceps femoris long head, 4 for semitendinosus, and 6 for semimembranosus. For each percent of the eccentric phase of the NHE, muscle activity was calculated for each electrode location within each hamstring muscle individually. To quantify whole muscle head activity, means and variances across electrodes within each muscle were calculated. Thirty-five noninjured participants were included (mean age, 18 [2] y; mass, 87 [12] kg; height, 192 [9] cm). Heterogeneous muscle activity was found between 38% and 62% and over the whole eccentric contraction phase within the semitendinosus and the semimembranosus, respectively. Muscle activity of the semitendinosus was significantly higher than that of the biceps femoris long head. During the NHE, the relative contribution of the semitendinosus is the highest among hamstring muscles. Its strong contribution may compensate for the biceps femoris long head, the most commonly injured hamstring muscle head.

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Jesús Díaz-García, Bart Roelands, Jelle Habay, Inmaculada González-Ponce, Miguel Ángel López-Gajardo, Tomás García-Calvo, and Jeroen Van Cutsem

This study aimed to assess, for the first time, how self-reported sleep, mental toughness, and reaction time are impacted by a professional padel tournament. In addition, we evaluated whether sex, age, and/or ranking play a role in this possible effect of a tournament on these variables. Twenty-three professional players (15 men, M age = 24 ± 6 years; eight women, M age = 21 ± 5 years) were evaluated on two occasions: (a) baseline, in a noncompetitive week and (b) postmeasure, the morning after an individual was eliminated from the tournament. The Pittsburgh Sleep Quality Index, the Mental Toughness Questionnaire, and the psychomotor vigilance task were used to evaluate the dependent variables. Wilcoxon tests or paired samples t tests were employed to assess the effect of participating in the tournament. To test correlations between variables, Pearson correlation coefficients (quantitative variables) or chi-square distributions (qualitative variables) were employed. Results showed that self-reported sleep (p < .01), mental toughness (p = .01), and reaction time (p = .04) were significantly impaired by the tournament. Exploring moderating variables, results showed that mental toughness did not correlate with sleep impairments (p > .05). In contrast, a nearly significant correlation between sleep impairments and higher reaction times was found (p = .066). No significant effects of age, sex, and ranking were observed. In conclusion, participating in a padel competition impairs the self-reported sleep, mental toughness, and reaction time of professional padel players. A trend toward a significant correlation between the competition-related impairment in sleep and reaction time was observed, whereas age, ranking, and sex were not found to be moderators of any of these impairments.