BACKGROUND:The importance of 24-h movement behaviour, including sleep, physical activity (PA) and sedentary behaviour (SB), has gained prominence due to its significant impact on the health and development of children, including those with cerebral palsy (CP). The 24-h activity checklist for CP, a tool developed in the Netherlands to monitor the activity in CP paediatric population, requires translation and cultural adaptation to Portuguese for use in Brazil and Portugal. METHODS:This cross-sectional methodological study involved translating and culturally adapting the 24-h activity checklist for CP into Brazilian Portuguese (BP) and European Portuguese (EP) languages. The process included forward translation, synthesis and backward translation, expert panel evaluation and pretesting. Brazilian and Portuguese experts appraised content validity, assessed by the individual item (I-CVI) and scale level content validity index scores (S-CVI/Ave). Sixty parents of children with CP participated in the test-retest analysis, reported with the Intraclass Correlation Coefficients (ICCs). RESULTS:I-CVI scores were higher than 0.78 for both versions. S-CVI/Ave scores were considered excellent for BP (0.91) and EP version (1.0). Expert's appraisal results in the inclusion of a question about sleep-related time indicators and the split of sleep, PA, and screen time questions for weekdays and weekends. Brazilian and Portuguese parents of children with CP reported understanding on instructions, questions, and answer options. The ICC values range from 0.81 to 0.99 and 0.6 to 0.98, for BP and EP, respectively. CONCLUSIONS:The BP and EP versions of 24-h activity checklist for CP demonstrated good content validity and test-retest reliability, supporting its use in Brazil and Portugal. This tool can contribute to improving communication between families and healthcare professionals to monitor and develop tailored interventions for healthy movement behaviours in children with CP.

This study aimed to investigate if there are differences in neck strength between dental students in their fourth and fifth years, with and without neck pain. Neck muscle strength was assessed in flexion, extension, and lateral flexion to both sides using a handheld dynamometer while participants performed maximum voluntary isometric contractions with a make test procedure. Differences between groups were evaluated through a one-way analysis of variance followed by Tukey’s post hoc comparison. Forty-three students (twenty-one fourth-year and twenty-two fifth-year students) participated in the study. Fifth-year students with neck pain (P5) (n = 14) showed less strength (p = 0.018) compared to the no-pain group (NP) (n = 15) in neck flexion and lateral flexion for both sides (p < 0.001). The fourth-year symptomatic students (P4) (n = 14) showed reduced right lateral flexion strength compared to the NP group (p = 0.035). No significant differences were observed in neck extension across all groups (p = 0.085). Our research indicates a progressive decline in neck muscle strength in flexion and lateral flexion among students with neck pain over their training years. Our findings suggest that this may be linked to the increasing mechanical demands of clinical practice during training, potentially affecting muscle balance and cervical function. This pain could be associated with changes in motor behavior and reduced cervical muscle strength.

BACKGROUND AND AIMS:Besides muscle damage, eccentric contractions also impose significant mechanical loads on peripheral nerves. However, the impact of eccentric contractions on peripheral nerve properties remains unclear. We aimed to reveal the immediate (i.e., <2 h and short-term (i.e., <10 days) effects of eccentric contractions on functional, structural, morphological, physiological and biomechanical properties of peripheral nerves. METHODS:Four electronic databases (PubMed, Science Direct, PEDro and Cochrane) were searched for animal and human studies which evaluated the immediate and/or short-term impact of eccentric contractions of upper or lower limb muscles on outcomes related functional, structural, morphological, physiological and biomechanical properties of peripheral nerves. RESULTS:From a total of 2415 articles, two human and two animal studies met the selection criteria. Several signs of nerve damage following eccentric exercises were observed, such as reductions in myelin sheath thickness, nerve fibre diameter, sensory and motor nerve conduction velocity, and protein zero levels, alongside increased levels of macrophage-related protein and tropomyosin receptor kinase C. No significant changes were identified in growth-associated protein 43. It is worth noting that some variables exhibited differences in their time course between human and animal studies. Animal studies revealed that the effects were more pronounced when eccentric contractions were performed at higher velocities. CONCLUSION:Current evidence is suggestive that eccentric contractions has the potential to alter the peripheral nerves structural, morphological, functional and physiological properties, which are indicative of nerve damage. SYSTEMATIC REVIEW REGISTRATION:CRD42021285767.

INTRODUCTION:The single leg bridge test (SLBT) has been suggested as a clinical test to examine function, screen injury risk, and monitor the effectiveness of rehabilitation programes targeting the hamstring. This study aimed to determine the inter-day reliability and repeatability of both SLBT performance, semitendinosus (ST), and biceps femoris long head (BFlh) surface electromyography (sEMG) responses and characterise the BFlh and ST electrical activity during the SLBT performed until exhaustion in healthy individuals. METHODS:Twelve physically active young men without previous hamstring injury were tested for the number of repetitions attained, and sEMG signal median frequency and amplitude in both ST and BFlh of each lower limb, randomly in two sessions, with a seven-day interval between sessions. RESULTS:High reliability [ICC = 0.85] was found for the number of SLBT repetitions attained. Reliability of sEMG outcomes showed better results for ST (ICC = 0.62-0.91) than for BFlh (ICC = 0.39-0.81), and a high to very-high repeatability was found for both ST (ICC = 0.91-0.84) and BFlh (ICC = 0.91-0.85). sEMG median frequency decreased and amplitude increased for both BFlh (p ≤ 0.001) and ST (p ≤ 0.039) at the end of SLBT, suggesting localised fatigue. CONCLUSIONS:The SLBT performed by healthy individuals until exhaustion proved to be reliable and to induce fatigue in both BFlh and ST, where the sEMG median frequency and amplitude can be measured on different days with acceptable reliability and high repeatability, suggesting its potential future use in both practical and clinical settings.

The purpose of this study was to examine the impact of a sensorimotor training program on maximum ankle dorsiflexion (ankle DF), coordination, dynamic balance and postural control, and lower-limb muscle power, in competitive junior surfers, and its relation to parameters of sensorimotor control required to perform aerial maneuvers. Twelve junior competitive surfers followed a 7-week sensorimotor training program, being assessed pre- and post-program with the knee-to-wall test (KW), Y-Balance test—lower quarter (YBT-LQ), and the countermovement jump test (CMJ). Post-training assessment revealed positive effects on the KW (ankle DF) distance, which increased approximately 2 cm (p < 0.001) for both ankles, and all scores for the YTB-LQ (coordination, dynamic balance, and postural control) variables increased, being significant (p < 0.005) for some reach distances (YBT-LQ—Anterior Left, YBT-LQ—Postero-medial Left, and YTB-LQ Anterior Right). YBT-LQ Anterior Reach Asymmetry also improved by decreasing 1.62 cm (p < 0.001) and the CMJ height (lower limb muscle power) increased 2.89 cm (p < 0.001). The training program proved to effectively enhance parameters of physical performance for this sample, including ankle DF, coordination, dynamic balance, postural control, and lower limb muscle power. This tailored-made task approach can help to optimize surfing performance capabilities and contribute to reducing the risk of injuries while performing aerials.

Aim This study aimed to assess the prevalence, anatomical distribution, and contributing biological and psychosocial factors of work-related musculoskeletal disorders (WMSDs) among dental students. Subject and methods We used the Nordic Musculoskeletal Questionnaire (NMQ) to determine the prevalence and anatomical distribution of WMSDs, integrating biological and psychosocial variables, including stress, anxiety, and quality of life levels measured by the Perceived Stress Scale (PSS), Generalized Anxiety Disorder Assessment (GAD-7), and World Health Organization Quality of Life-Brief Form (WHOQOL-Bref), respectively. We used chi-square tests to analyze differences between the prevalences of independent groups, and binary logistic regression models to identify potential predictors among sociodemographic and psychosocial characteristics. Results A total of 239 students were contacted to participate and 123 answered the questionnaire, setting the response rate at 51.5%. We excluded 18 for being over 30 years old and 25 for having diagnosed and ongoing musculoskeletal injuries, leaving 80 participants. They were 77.5% women and 22.5% men with 22.69 ± 1.63 years, 1.67 ± 0.08 m, 60.44 ± 10.94 kg and a body mass index (BMI) of 21.46 ± 2.61 kg/m 2 . A total of 91.3% of the participants reported symptoms in at least one body region in the past year. The neck and lower back (63.8%) were the most frequently affected areas, followed by 40% in the shoulders and 31% in the wrists/hands. Over the period of a week, 23.8% experienced symptoms in the lower back, 21.3% in the cervical region, and 15% in both shoulders and wrists/hands. Additionally, male students are 90% more likely to develop WMSDs in the shoulders, and students with anxiety are 49% more prone to refer WMSDs in lower back region. Conclusion High WMSDs rates were observed in dental students in neck, low back, and shoulders. Male students and those with increased levels of anxiety were more likely to develop WMSDs. Further investigation focused on the motor-behavior adaptations and psychosocial determinants underpinning these findings is fundamental to fully understand them, allowing the development and implementation of strategies to prevent and manage WMSDs in dental students.

Background: Kinematic gait assessment is essential to the gait rehabilitation program after stroke. Portable devices composed of inertial sensors are an alternative for this evaluation. However, knowledge regarding the psychometric properties of these devices is needed to understand their accuracy, especially in evaluation of individuals with movement disorders (e.g., people post stroke). This systematic review aims to analyze the psychometric properties of portable devices that use inertial sensors to assess kinematic gait parameters in people post stroke. We will also investigate which portable device assesses alterations in lower limb angular movements during gait. Methods: We will search for studies in English without publication date restriction, that evaluated psychometric properties of portable devices that use inertial sensors to assess kinematic gait parameters in people after stroke. Searches will be performed in the following electronic databases: Cochrane Central Registry of Controlled Trials (CENTRAL), Medline/PubMed, EMBASE Ovid, CINAHL EBSCO, PsycINFO Ovid, IEEE Xplore Digital Library (IEEE), and Physiotherapy Evidence Database (PEDro). Gray literature will also be searched, including published and unpublished studies (dissertations and theses). The Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) risk of bias tool will be used to assess the quality of studies that analyzed reliability and measurement error of devices. Expected results: This will be the first review assessing the risk of bias in studies that analyzed psychometric properties of portable devices that use inertial sensors to assess kinematic gait parameters in people post stroke. Then, we hope to elucidate this topic and help the decision-making of clinicians regarding the feasibility of these devices. Finally, we also hope to provide an overview of the characteristics of portable devices that assessed changes in angular lower limb movements during gait in this population. Registration: The protocol was registered in Open Science Framework on May 11th 2023 (https://doi.org/10.17605/OSF.IO/7M6DA).

Changes in postural control associated with clinical practice or specific conditions such as the presence of neck pain remain unexplored in dental students. Therefore, this study aimed to explore the time-course changes in postural control complexity among dental students enrolled in clinical practice, comparing those with and without neck pain. We used an online Nordic Musculoskeletal Questionnaire for group allocation and center of pressure (CoP) oscillations with a tri-axial Bertec force plate. Baseline data were acquired from dental students with neck pain (NP) (n = 21) and asymptomatic in a control group (n = 23), before starting their clinical practice, and assessments were repeated after their first semester. CoP fluctuations were determined through the calculation of sample entropy. Both groups had similar postural control at baseline, but asymptomatic students exhibited more irregular CoP AP (p = 0.013) and ML (p = 0.015) oscillations, while students with neck pain showed a more rigid pattern (p = 0.004) in the AP direction at the endpoint. Our results showed that dental students’ postural control complexity decreased during the first semester of clinical practice. Over time, asymptomatic students exhibited more random postural control patterns, while students with neck pain demonstrated more rigid postural control during upright stance, indicating that postural control complexity differs between students with and without neck pain when exposed to clinical training.

Introdução: É amplamente reconhecido que as contrações musculares excêntricas quando repetidas com volume e intensidade consideráveis podem induzir dano ao músculo esquelético. No entanto, há pouco conhecimento sobre o impacto das contrações excêntricas em estruturas não musculares como o nervo periférico. Objetivos: Revelar os efeitos imediatos (isto é, <2 horas) e a curto prazo (isto é, <10 dias) das contrações musculares excêntricas nas propriedades estruturais, biomecânicas, fisiológicas e funcionais dos nervos periféricos, tanto de estudos em animais quanto em humanos. Material e Métodos: Quatro bases de dados (ou seja, Pubmed, Science Direct, PEDro e Cochrane) foram utilizadas para a pesquisa de estudos que envolvessem contrações excêntricas dos músculos dos membros superiores ou inferiores e resultados relacionados aos efeitos imediatos e/ou a curto prazo destas na estrutura, propriedades fisiológicas, biomecânicas e funcionais dos nervos periféricos. A qualidade metodológica dos estudos humanos foi avaliada com recurso à escala Risk Of Bias in Non-randomised Studies of Interventions (ROBINS-I) e SYRCLE’s Risk of Bias tool para estudos em animais. Resultados: De um total de 2415 artigos, 2 estudos em humanos e 2 em animais cumpriram os critérios de inclusão. A avaliação do risco de viés para os estudos em animais foi divergente para todos os itens em relação ao viés de seleção. Os estudos em humanos revelaram uma qualidade metodológica geral baixa a moderada. Foram encontradas alterações sugestivas de lesão do nervo periférico associada ao exercício. Observou-se redução na espessura da bainha de mielina e diâmetro da fibra (Kouzaki et al., 2016), diminuição da velocidade de condução nervosa sensorial e motora (Ochi et al., 2021). O nível de proteína zero reduziu, enquanto a concentração de macrófagos e tropomiosina quinase C aumentaram (Lee et al., 2014). Diferenças temporais foram encontradas entre estudos em humanos e animais. Além disso, nos estudos em animais, os efeitos foram de maior magnitude quando as contrações excêntricas eram realizadas a uma maior velocidade. Conclusões: As contrações excêntricas aparentemente alteram as propriedades estruturais, morfológicas, funcionais e fisiológicas dos nervos periféricos, o que provavelmente pode ser interpretado como dano neural.

BACKGROUND:Wearable technologies using inertial sensors are an alternative for gait assessment. However, their psychometric properties in evaluating post-stroke patients are still being determined. This systematic review aimed to evaluate the psychometric properties of wearable technologies used to assess post-stroke gait and analyze their reliability and measurement error. The review also investigated which wearable technologies have been used to assess angular changes in post-stroke gait. METHODS:The present review included studies in English with no publication date restrictions that evaluated the psychometric properties (e.g., validity, reliability, responsiveness, and measurement error) of wearable technologies used to assess post-stroke gait. Searches were conducted from February to March 2023 in the following databases: Cochrane Central Registry of Controlled Trials (CENTRAL), Medline/PubMed, EMBASE Ovid, CINAHL EBSCO, PsycINFO Ovid, IEEE Xplore Digital Library (IEEE), and Physiotherapy Evidence Database (PEDro); the gray literature was also verified. The Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) risk-of-bias tool was used to assess the quality of the studies that analyzed reliability and measurement error. RESULTS:Forty-two studies investigating validity (37 studies), reliability (16 studies), and measurement error (6 studies) of wearable technologies were included. Devices presented good reliability in measuring gait speed and step count; however, the quality of the evidence supporting this was low. The evidence of measurement error in step counts was indeterminate. Moreover, only two studies obtained angular results using wearable technology. SIGNIFICANCE:Wearable technologies have demonstrated reliability in analyzing gait parameters (gait speed and step count) among post-stroke patients. However, higher-quality studies should be conducted to improve the quality of evidence and to address the measurement error assessment. Also, few studies used wearable technology to analyze angular changes during post-stroke gait.

Neck pain can induce specific motor responses and alterations in muscle strength. Therefore, this study aimed to investigate and compare the progression of cervical muscle strength within and between students with and without neck pain over the course of their first semester of clinical training. We used an online Nordic Musculoskeletal Questionnaire for group allocation, and neck strength in flexion, extension, and lateral flexion on both sides was measured using the KForce Bubble Pro hand-held dynamometer. Forty-four students were divided into neck pain (n = 21) and asymptomatic (n = 23) groups. Both groups increased neck strength by the end of the semester in flexion, extension, and left and right lateral flexion (p < 0.001). Students experiencing neck pain showed a significantly lesser degree of improvement (p = 0.036) in right lateral flexion. The agonist/antagonist ratios revealed an enhanced role of neck extensors across both groups. Dental students showed overall increased cervical strength in their first semester of clinical training. Those with neck pain exhibited a diminished rate of strength gain in right lateral flexion when compared with students without pain by the semester’s end, suggesting different neuromuscular adjustments to clinical practice in students experiencing pain, which may lead to functional impairments in later training stages.

Cervical pain has been linked to increased motor unit activity, potentially associated with the initiation and progression of chronic neck pain. Therefore, this study aimed to compare the time-course changes in cervical superficial muscle activation patterns among dental students with and without neck pain throughout their initial semester of clinical training. We used an online Nordic Musculoskeletal Questionnaire for group allocation between neck pain (NP) (n = 21) and control group (CG) (n = 23). Surface electromyography (sEMG) of the sternocleidomastoid and upper bilateral trapezius was recorded before starting their clinical practice and after their first semester while performing a cranio-cervical flexion test (CCFT) in five increasing levels between 22 mmHg and 30 mmHg. After the first semester, both the CG (p < 0.001) and NP (p = 0.038) groups showed decreased sternocleidomastoid activation. The NP group exhibited a concomitant increase in upper trapezius coactivation (p < 0.001), whereas the muscle activation pattern in asymptomatic students remained unchanged (p = 0.980). During the first semester of clinical training, dental students exhibited decreased superficial flexor activity, but those with neck pain had increased co-contraction of the upper trapezius, likely to stabilize the painful segment. This altered activation pattern could be associated with further dysfunction and symptoms, potentially contributing to chronicity.

Objectives:This study aimed to determine the prevalence of work-related musculoskeletal disorders (WMSDs) in dental students and analyze the potential associated risk factors.Methods:This review was registered in PROSPERO with the number CRD42022349864. We performed a meta-analysis calculating event rates with relative 95% confidence intervals for each body region. Two investigators systematically searched Cochrane, Pubmed, Scopus, and EBSCO databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).Results:Sixteen studies, with 3761 dental students, were included. The highest 7-day prevalence was in the lower back (27.2%; 95% CI 20-35), neck (27%; 95% CI 19.1-35.8), and upper back (24.2%; 95% CI 17.2-32). Yearly occurrence was mainly in the neck (51%; 95% CI 41-61), followed by shoulders (45.3%; 95% CI 37.6-53.1) and lower back (42%; 95% CI 34.1-50.2) and a fraction of these reported that symptoms in lower-back (15.2%; 95% CI 12.1-18.5), neck (13.9%; 95% CI 10.6-17.5) and shoulders (12.2%; 95% CI 8.7-16.3) affected work or normal activities. Associated contributing factors include female sex, poor posture habits, inadequate ergonomics knowledge, sedentary lifestyle, high physical activity levels, poor quality of life, and smoking. In contrast, engaging in physical exercise has positively impacted mitigating the risk of musculoskeletal disorders.Conclusions:WMSDs have a high prevalence among dental students, particularly in the cervicothoracic, lumbar, and shoulder regions, having a significant impact since training years. Further research with a multidimensional approach with psychosocial and physical assessments is recommended to understand this issue thoroughly.

Purpose was to analyse parameters of high-level surfing aerial manoeuvres, supporting specific training and injury prevention. Using video analysis of aerials completed by top-5 male surfers in 19 events during 2018 and 2019 seasons of the World Championship Tour, were selected (n=97): Frontside Air, Frontside Air Reverse 360, Backside Air and Backside Air Reverse 360. This is an observational mixed method research. Has a qualitative performance analysis, carried out through phase analysis, considering key features from body actions and principles of movement. For the quantitative analysis was measured the aerial height, the BoS width, and flexion angles of front knee and front ankle. Qualitative analysis references were: rotation of the head and trunk, triple-flexion of the lower limbs (retraction) and more pronounced in the follow-through; head, trunk, and arms flexion from the take-off (retraction) to the peak of the flight (action) causing the anterosuperior CoM displacement; widening of the BoS for frontside aerials (action). Quantitative analysis allowed to identify the mean of aerial height (169.60±52.85cm), of base of support (BoS) width (79.17±13.72cm), and flexion angles of front knee (113.78±19.90º) and front ankle (32.74±14.51º) during landing. Descriptive analysis may contribute to the development of specific training programs for teaching and learning, aiming to improve performance of aerial manoeuvres. El objetivo fue analizar parámetros de maniobras aéreas de surf de alto nivel, apoyando el entrenamiento específico y la prevención de lesiones. Utilizando análisis de video de maniobras aéreas completadas por surfistas masculinos de top-5 en 19 eventos durante las temporadas 2018 y 2019 del World Championship Tour, se seleccionaron (n=97): Frontside Air, Frontside Air Reverse 360, Backside Air y Backside Air Reverse 360. Se trata de una investigación observacional de método mixto. Tiene un análisis de desempeño cualitativo, realizado a través de la análisis en fases, considerando características clave de las acciones corporales y principios de movimiento. Para el análisis cuantitativo se midió la altura del aéreo, el ancho del BoS y los ángulos de flexión de la rodilla y del tobillo delanteros. Las referencias en el análisis cualitativo fueron: rotación de cabeza y tronco, triple flexión de miembros inferiores (preparación) y más pronunciada en la recuperación; flexión de cabeza, tronco y brazos desde el despegue (preparación) hasta el pico del vuelo (principal) provocando el desplazamiento anterosuperior del CoM; ampliación de la BoS para aéreos frontales (principal). El análisis cuantitivo permitió identificar lá média de la altura del aéreo (169,60±52,85cm), del ancho de la base de sustentación (BoS) (79,17±13,72cm), y de los ángulos de flexión de la rodilla (113,78±19,90º) y del tobillo (32,74±14,51º) delanteros durante el aterrizaje. El análisis descriptivo puede contribuir al desarrollo de programas de formación específicos para la enseñanza y el aprendizaje, con el objetivo de mejorar el rendimiento de las maniobras aéreas. O objetivo foi analisar parâmetros de manobras aéreas de surf de alto nível, dando suporte ao treino específico e à prevenção de lesões. Através da análise de vídeo de manobras aéreas concluídas por surfistas masculinos do top-5, em 19 eventos durante as temporadas 2018 e 2019 do World Championship Tour, foram selecionados (n=97): Frontside Air, Frontside Air Reverse 360, Backside Air e Backside Air Reverse 360. Este é um estudo observacional com um método misto. Temos uma análise qualitativa do desempenho, realizada através da análise por, considerando as principais características das ações corporais e dos princípios do movimento. Para a análise quantitativa foi medida a altura do aéreo, a largura do BoS e os ângulos de flexão do joelho e do tornozelo dianteiros. As referências da análise qualitativa foram: a rotação de cabeça e tronco, tripla flexão dos membros inferiores (preparação) e mais acentuada na finalização; flexão da cabeça, tronco e braços desde a descolagem (preparação) até o pico do voo (ação principal) causando o deslocamento anterosuperior do CoM; alargamento da BoS para aéreos frontais (ação principal). A análise quantitativa permitiu identificar a média da altura do aéreo (169,60±52,85cm), da largura da base de sustentação (BoS) (79,17±13,72cm) e dos ângulos de flexão do joelho (113,78±19,90º) e tornozelo (32,74±14,51º) dianteiros durante a aterragem. A análise descritiva pode contribuir para o desenvolvimento de programas de treino específicos para ensino e aprendizagem, visando melhorar o desempenho das manobras aéreas.

BACKGROUND:The effect of 10 × 30 m repeated sprints on passive and active stiffness of semitendinosus (ST) and biceps femoris long head (BFlh), and knee flexor maximal voluntary isometric contraction (MVIC) and rate of force development (RFD), and whether athletes with previous hamstring injury have a different response, is unknown. HYPOTHESIS:Repeated sprints would (1) increase BFlh stiffness and decrease ST stiffness and knee flexors MVIC and RFD in healthy participants; and (2) greater magnitude of response would be seen in athletes with previous hamstring injury. STUDY DESIGN:Case series (experiment I) and case control (experiment II) study designs. LEVEL OF EVIDENCE:Level 3. METHODS:Healthy nonathletes attended 2 replicated sessions (experiment I, n = 18), while soccer players with (n = 38) and without (n = 67) previous hamstring injury attended 1 testing session (experiment II). RESULTS:In both experiments, the knee flexors MVIC and RFD decreased after the sprints (P < 0.05). In experiment I, the ST and BFlh passive stiffness reduced after the sprints (P < 0.02), while a small BFlh active stiffness increase was noted (P = 0.02); however, no correlation was observed between the 2 testing sessions for the postsprint muscle stiffness responses (r = -0.07-0.44; P > 0.07). In experiment II, only an ST passive stiffness reduction was observed after the sprints (P < 0.01). No differences were noted between injured and noninjured lower limbs for any variable (P > 0.10). CONCLUSION:Repeated sprints are likely to decrease the knee flexor's maximal and rapid strength, and to alter the hamstring stiffness in the nonathlete population. Previous hamstring injury does not apparently affect the footballer's hamstring functional and mechanical responses to repeated sprints. CLINICAL RELEVANCE:The responses of hamstring stiffness and knee flexor strength to repeated sprints are unlikely to be associated with hamstring injury.

Irish dance is growing in popularity, evolving to a more athletic and demanding dance style. The aim of this study is to conduct a systematic review, previously registered with PROSPERO, to identify the prevalence, incidence, and the injury pattern among Irish dancers and analyse the associated risk factors. Six online databases and two dance-specific science publications were searched systematically. Studies were included if the patterns of injuries among Irish dancers were evaluated or the factors associated with injury were analysed, published in English or Portuguese, in peer-reviewed scientific journals. Four reviewers assessed the quality and level of evidence using the Downs and Black criteria and a modified Oxford Centre of Evidence-Based Medicine 2009 model, respectively. Eleven articles were included, eight of Level 3c (cross-sectional) and three of Level 3b (prospective). Mean DB percentage score was 63% ± 7.2%. Prevalence ranged from 72.2% to 92.6%, affecting mostly the foot/ankle complex. Only two articles reported incidence, which ranged from 3.4 to 10.6 injuries/1000 h danced depending on injury definition. Psychological factors, elite level, and insufficient/poor sleep were associated with musculoskeletal injury. Injury prevalence and incidence is high in Irish dancers, with the foot and ankle being more affected. Due to heterogeneity in injury definitions, methods, and populations, along with the need for improvement in studies quality, recommendations were made for future research.

It has been found that fractal-like patterns are present in the temporal structure of the variability of healthy biological rhythms, while pathology and disease lead to their deterioration. Interestingly, it has recently been suggested that these patterns in biological rhythms are related with each other, reflecting overall health or lack of it, due to their interaction. However, the underlying neurophysiological mechanisms responsible for such dependency remain unknown. In addition, this relationship between different elements needs to be first verified before we even pursue understanding their interaction. This study aimed to investigate the relationship between two elements of the neuromuscular system, gait and muscle activity variability patterns in older adults. Twenty-one older adults walked at their preferred walking speed on a treadmill. Inter-stride intervals were obtained through an accelerometer placed on the lateral malleoli to assess the temporal structure of variability of stride-to-stride fluctuations. Inter muscle peak intervals were obtained through the electromyographic signal of the gastrocnemius to assess the temporal structure of the variability of the simultaneous muscle activity. The temporal structure of variability from both signals was evaluated through the detrended fluctuation analysis, while their magnitude of variability was evaluated using the coefficient of variation. The Pearson's Correlation coefficient was used to identify the relationship between the two dependent variables. A significant strong positive correlation was found between the temporal structure of gait and muscle activity patterns. This result suggests that there is an interdependency between biological rhythms that compose the human neuromuscular system.

Ocean acidification is considered to affect fish behaviour through the disruption of GABAergic neurotransmission in controlled laboratory conditions, but less is known of the GABAergic role on fish behavioural performance in the wild. Most coral reef fishes engage in complex cleaning interactions, where they benefit from ectoparasite removal and stress relief. Here, we tested whether potential ocean acidification impairment of wild cleaning interactions, between the cleaner fish Labroides dimidiatus and its clients, can be explained by the GABAAR model. We used, the GABAA receptor agonist (muscimol) and antagonist (gabazine) for the first time in the wild and tested their effects on cleaning behaviour in Moorea Island (French Polynesia) to address natural interactions and recovery capacity. After exposure to expected ocean acidification conditions, the proportion of time spent advertising cleaning services, a measure of motivation to interact, dropped significantly relative to controls. Furthermore, the GABAergic antagonist gabazine recovered most CO2-induced behavioural alterations to control levels, consistent with the GABAAR model of altered Cl− flux in ocean acidification-exposed fish. However, muscimol treatment only produced the same behavioural alterations found with CO2 exposure in time spent advertising cleaning. Our results support the evidence that ocean acidification alters some components of cleaning behaviour through GABAA receptor modulation with potential cascading effects on coral reef health and structure.

Background: Incorporating variability within gait rehabilitation offers a promising approach to restore functional capacity. However, it's success requires adequate synchronization, a parameter that lacks report in most of the literature regarding cued gait training.Research question: How changes to synchronization performance during fractal-like and isochronous cueing impacts gait variability measures?Methods: We asked twelve young male participants to walk in synchronization to two different temporally structure cueing (isochronous [ISO] and fractal [FRC]). We have also manipulated the cueing's tempo by increasing and decreasing it by 5% to manipulate synchronization, resulting in six conditions (stimuli [ISO,FRC] x tempo [SLOW, NORMAL, FAST]). The normal condition was set from an uncued trial through the participant's self-paced stride time. Synchronization performance (ASYNC) and gait variability (fractal scaling and coefficient of variation) were calculated from stride time data ( -ISIs,CV-ISIs). Repeated measures analysis of variance or Aligned Rank Transform were conducted to determine significant differences between metronome tempo and stimuli for the dependent variablesResults: Our results showed a FAST tempo decreases synchronization performance (ASYNC) and leads to lower -ISIs, for both ISO and FRC stimuli. This indicates that when an individual exhibits poor synchronization during cued gait training, his/her gait variability patterns will not follow the temporal structure of the presented metronome. Specifically, if the individual poorly synchronizes to the cues, the gait patterns become more random, a condition typically observed in older adults and neurological patients, which runs contrary to the hypothesis when using fractal-like metronomes. Significance: This study provides supporting evidence that measuring synchronization performance in cued training is fundamental for a proper clinical interpretation of its effects. This is particularly relevant for the recent and ongoing clinical research using fractal-like metronomes since the expected gait patterns are dependent on the synchronization performance. Randomized control trials must incorporate synchronization performance related measures.