Aging effects of haptic input on postural control under a dual-task paradigm.

Postural control relies on three principal sensory systems: vision, vestibular and proprioceptive; that are affected by aging. When performing a cognitive task concomitantly with a motor task, those sensory impairments lead to even greater deleterious effects on balance. We aimed to study the effects of a sensory aid (a light touch) on a dual task paradigm and sought to understand the different responses on balance due to aging. Fifty healthy and highly physical active women were divided in two groups: young (N = 25, 24.2 ± 4.0 years) and older adults (N = 25, 67.3 ± 4.2 years). In a random and balanced order, all participants performed five tasks: Stroop test while seated (Seated); Stroop test while standing quiet (ST); Standing quiet (BL); Standing quiet with a haptic input (LT); and Stroop test with a haptic input while standing quiet (SL). In the Stroop test, older women committed more errors (50 vs 11 errors, p < 0.001) and had higher reaction time (1.001 ± 0.191 vs 0.699 ± 0.081 s, p < 0.001). The haptic input (LT) reduced all body sway parameters, in both groups, regardless the condition. This means that postural control under a dual task paradigm (ST) deleterious effect can be mitigated by a haptic input.

Eccentric Strength Assessment of Hamstring Muscles with New Technologies: a Systematic Review of Current Methods and Clinical Implications.

BACKGROUND: Given the severe economic and performance implications of hamstring injuries, there are different attempts to identify their risk factors for subsequently developing injury prevention strategies to reduce the risk of these injuries. One of the strategies reported in the scientific literature is the application of interventions with eccentric exercises. To verify the effectiveness of these interventions, different eccentric strength measurements have been used with low-cost devices as alternatives to the widespread used isokinetic dynamometers and the technically limited handheld dynamometers. Therefore, the purpose of the present systematic review was to summarize the findings of the scientific literature related to the evaluation of eccentric strength of hamstring muscles with these new technologies. METHODS: Systematic searches through the PubMed, Scopus, and Web of Science databases, from inception up to April 2020, were conducted for peer reviewed articles written in English, reporting eccentric strength of hamstrings assessed by devices, different to isokinetic and handheld dynamometers, in athletes. RESULTS: Seventeen studies were finally included in the review with 4 different devices used and 18 parameters identified. The pooled sample consisted of 2893 participants (97% male and 3% female: 22 ± 4 years). The parameters most used were peak force (highest and average), peak torque (average and highest), and between-limb imbalance (left-to-right limb ratio). There is inconsistency regarding the association between eccentric hamstrings strength and both injury risk and athletic performance. There is no standardized definition or standardization of the calculation of the used parameters. CONCLUSIONS: The current evidence is insufficient to recommend a practical guide for sports professionals to use these new technologies in their daily routine, due to the need for standardized definitions and calculations. Furthermore, more studies with female athletes are warranted. Despite these limitations, the eccentric strength of hamstring muscles assessed by different devices may be recommended for monitoring the neuromuscular status of athletes.

Perception of impact is affected by stimulus intensity.

Perception of external loads may be a central topic to understand adjustments to the mechanical demands during movement. Nevertheless, the association between the perceived and the real load received is still controversial. This study aimed to correlate vertical ground reaction force (vGRF) to the perception of impact in different regimens of stimulus application. Ten physically active men performed drop jumps from four different heights (0.20, 0.40, 0.60 and 0.80 m). A force plate measured the vGRF, while perception of impact was evaluated through Borg's Ratings of Perceived Exertion. Higher values of maximum vGRF (Fy_max) and impulse of the first 50 ms (I_50), and reduced time to reach Fy_max indicate increased external forces as drop jump height raised. Perception of impact increased gradually with increasing jump height for I_50. Fy_max and I_50 showed moderate to strong correlations to perceived load for 70% and 90% of participants, respectively. Higher and different intensity of stimulus facilitated the perception of impact, presenting moderate to strong correlations to kinetic parameters related to external load during landing from drop jump. Perception of higher impacts could be used as a surrogate to monitor 'real' impacts and possibly also for managing impact-related injury risk.

Overall indexes of coordination in front crawl swimming.

The aim of this study was to propose a group of parameters able to quantify not only arm coordination but also inter limb coordination. These include the well know index of coordination with the relative duration of the stroke phases and two new parameters: the Index of synchronization (Ids) between arms and legs actions; and the Index of inter limb coordination (IdIC) calculated as the relative foot position during successive arm stroke phases. These parameters were compared between experts and amateur swimmers in a maximal front crawl sprint. The influence of arm stroke in leg kick parameters was also assessed, comparing the full stroke condition with a condition without arms actions. Sixty-five per cent of expert swimmers used synchronized limb actions while 95% of amateur swimmers used non-synchronized limb motions. These synchronized expert swimmers also converged towards a specific coordination pattern between foot position and arm stroke phases. In the condition without arms, both groups changed kick rate and amplitude. The present study reveals the interdependency of arms and legs actions and the importance of coordination and synchronization between limbs. Therefore, the proposed group of overall indexes of coordination provides a more complete marker for the analysis of swimming technique.

A High-Intensity Exercise Intervention Improves Older Women Lumbar Spine and Distal Tibia Bone Microstructure and Function: A 20-Week Randomized Controlled Trial.

Introduction: The effects of ageing on bone can be mitigated with different types of physical training, such as power training. However, stimuli that combine increasing external and internal loads concomitantly may improve bone quality. The goal of this study was to assess the efficacy of a combined power and plyometric training on lumbar spine and distal tibia microstructure and function. Methods: 38 sedentary elderly women between 60 and 70 years were randomly allocated in experimental (N = 21) and control group (N = 17). The effects of the 20-week protocol on lumbar spine microstructure and tibia microstructure and function were assessed by trabecular bone score (TBS), high resolution peripheral quantitative computed tomography (HR-pQCT) and microfinite element analysis. Results: when compared to the effects found in the control group, the experimental group showed significant improvements in lumbar spine TBS (Hedges' g = 0.77); and in distal tibia trabecular thickness (g = 0.82) and trabecular bone mineral density (g=0.63). Conclusion: our findings underscore the effectiveness of the proposed intervention, suggesting it as a new strategy to slow down and even reverse the structural and functional losses in the skeletal system due to ageing.

Sleep quality monitoring in individual sports athletes: parameters and definitions by systematic review.

In the present review, we identify which instruments and parameters are used for sleep quality monitoring in individual sport athletes and which definitions were used for sleep quality parameters in this literature field. Systematic searches for articles reporting the qualitative markers related to sleep in team sport athletes were conducted in PubMed, Scopus and Web of Science online databases. The systematic review followed the Preferred Reporting Items for Systematic Reviews. The initial search returned 3316 articles. After the removal of duplicate articles, eligibility assessment, 75 studies were included in this systematic review. Our main findings were that the most widely used measurement instruments were Actigraphy (25%), Rating Likert Scales (16%) and Sleep Diary (13%). On sleep quality parameters (Sleep duration = 14%; Wake after sleep onset = 14%; Sleep Quality = 12%; Sleep Effciency = 11% and Sleep Latency = 9%), the main point is that there are different definitions for the same parameters in many cases reported in the literature. We conclude that the most widely used instruments for monitoring sleep quality were Actigraphy, Likert scales and Sleep diary. Moreover, the definitions of sleep parameters are inconsistent in the literature, hindering the understanding of the sleep-sport performance relationship.

Muscle stretching changes neuromuscular function involved in ankle stability.

It has been postulated that the mechanical and neurophysiological effects induced by stretching decrease maximal muscle strength and power. Additionally, the reduction in neural input and muscle stiffness can affect the joint stabilization process. However, there is no evidence available to support this hypothesis. Thus, the aim of this study is to analyze the influence of static stretching on dynamic joint stability. Twenty physically active female university students (22.8 ± 5.3 years; 58 ± 8.8 kg; 1.62 ± 0.07 m) performed a series of static-passive stretching exercises for the peroneus longus and brevis muscles (four repetitions of 30 s). Before and after the stretches, electromyography was performed on both muscles during simulated ankle sprain. Mathematical algorithms calculate the latency and the electromyography activity (RMS). After stretching, the latency increased from 66ms to 73 ms (p = 0.003) for the peroneus brevis muscle and from 70 ms to 79 ms (p = 0.001) for the peroneus longus muscle. The RMS, calculated 100 ms after the simulation, decreased in the peroneus brevis muscle, from 25.05 to 18.16 (p = 0.001), and in the peroneus longus muscle, from 22.84 to 15.61 (p = 0.001). Muscle stretching changed the motor responses of both muscles. The increase in latency and the decrease in RMS indicate that static stretching influences the neuromuscular function involved in the joint stabilization process.

The effect of aquatic and treadmill exercise in individuals with chronic stroke / Efeito do treinamento aeróbio em piscina e em esteira em hemiparéticos crônicos / El efecto del ejercicio en piscina y en cinta de correr en pacientes hemiparéticos crónicos

ABSTRACT We compared the effect of gait training on treadmill versus deep water on balance and gait in 12 ischemic stroke chronic survivors randomly sorted to the Pool or Treadmill Groups. Berg Scale (BBS) and timed up and go test (TUG) were applied before and after the interventions. Just one person applied all tests and she was blinded for the aims of the study. Surface EMG of the paretic and non-paretic (NP) side muscles were recorded during walking on a treadmill. Three 100-ms epochs were extracted from the EMG related to gait phases: weight acceptance; propulsion; and pre-strike. For each epoch, we calculated the RMS of the EMG signal. Participants did gait training for 9 weeks (3 times/week, 40 minutes/session). The Pool group did the deep-water walking with a swimming belt. The Treadmill group walked on the treadmill at the maximum speed they could stand. The Manova group compared the effect of training, group, side, muscles, and gait phase into the EMG. Anova was used to test the effect of training, group side, and gait phase into BBS, TUG and EMG variables. Pool and Treadmill had increased balance and agility. The highest EMG RMS occurred at the paretic side, for the Treadmill and after training. The mm. tibialis anterior, gastrocnemius lateralis, vastus lateralis, and biceps femoris presented the highest RMS for the NP side; while for mm. rectus femoris and semitendinosus, the paretic side presented the highest RMS. Thus, the both types of exercise lead to similar functional adaptations with different muscular activations during walking.

RESUMO Comparamos o efeito do treinamento de marcha em esteira versus piscina no equilíbrio e na marcha em 12 sobreviventes crônicos de AVC isquêmico separados aleatoriamente nos grupos piscina ou esteira. A escala de Berg (EEB) e timed up and go test (TUG) foram aplicados antes e após as intervenções. A EMG de superfície dos músculos do lado parético e não parético foi registrada na caminhada em esteira. Três janelas de 100 ms foram extraídas da EMG relacionada às fases da marcha: aceitação de peso; propulsão; e pré-contato do pé. Para cada fase, calculou-se o RMS do sinal EMG. Os participantes treinaram 9 semanas (3 vezes/semana, 40 minutos/sessão). O grupo piscina fez marcha na água com cinto de natação. O grupo esteira fez treinamento de marcha na na velocidade máxima confortável. A Manova comparou o efeito do treinamento, grupo, lado, músculos e fase da marcha na EMG. A Anova testou o efeito do treinamento, lado do grupo e fase da marcha nas variáveis BBS, TUG e EMG. Os grupos piscina e esteira aumentaram o equilíbrio e a agilidade. O maior EMG RMS ocorreu no lado parético, no grupo esteira e após o treinamento. Os músculos: tibial anterior, gastrocnêmio lateral, vasto lateral e bíceps femoral apresentaram o maior RMS para o lado não parético; enquanto para os músculos reto femoral e semitendíneo, o lado parético apresentou o maior RMS. Assim, os dois tipos de exercício levaram a adaptações funcionais semelhantes com diferentes ativações musculares durante a caminhada.

RESUMEN Se comparó el efecto del entrenamiento de la marcha en cinta de correr y en piscina en el equilibrio y la marcha de 12 sobrevivientes crónicos de accidente cerebrovascular isquémico, quienes fueron clasificados aleatoriamente en los grupos piscina o cinta de correr. Se aplicaron la Escala de Equilibrio de Berg (BBS) y la Timed up and go test (TUG) antes y después de las intervenciones. Solo una persona aplicó todas las pruebas con evaluación ciega para los objetivos del estudio. Se registró la EMG de superficie de los músculos laterales paréticos y no paréticos durante la caminata en la cinta. Se extrajeron tres momentos de 100 ms de la EMG relacionadas con las etapas de la marcha: aceptación de peso; propulsión; y precontacto del pie. Para cada momento, se calculó el RMS de la señal EMG. Los participantes realizaron entrenamientos de marcha durante 9 semanas (3 veces/semana, 40 minutos/sesión). El grupo piscina caminó con un cinturón de natación. El grupo cinta de correr caminó en la cinta a la velocidad máxima confortable. Utilizando la Manova se comparó el efecto del entrenamiento, el grupo, los músculos laterales y la fase de la marcha en la EMG. Con la ANOVA se probó el efecto del entrenamiento, el lado grupal y la fase de marcha en las variables BBS, TUG y EMG. El equilibrio y la agilidad aumentaron en ambos grupos. El EMG RMS más alto ocurrió en el lado parético del grupo cinta de correr y después del entrenamiento. Los músculos tibial anterior, gastrocnemio lateral, vasto lateral y bíceps femoral presentaron el RMS más alto en el lado no parético; mientras que en los músculos recto femoral y semitendinoso, el lado parético presentó el RMS más alto. Por lo tanto, los dos tipos de ejercicio conducen a adaptaciones funcionales similares con diferentes activaciones musculares durante la marcha.

Creatine supplementation can improve impact control in high-intensity interval training.

OBJECTIVES: This study aimed to investigate the effects of creatine (Cr) supplementation on biomechanical parameters related to shock attenuation during a session of high-intensity interval training (HIIT). METHODS: A single-blinded, placebo-controlled, crossover design was adopted to test eight male elite soccer players during HIIT sessions under two conditions: after placebo supplementation and after Cr supplementation. HIIT test sessions consisted of an intermittent test (five bouts of running) with a constant load applied until exhaustion was reached. The vertical component of ground reaction force and electromyography data were recorded by Gaitway and Lynx-EMG Systems, respectively. Heart rate, rated perceived exertion (Borg's Scale) and lactate concentration information were also obtained. RESULTS: Cr supplementation did not affect heart rate, rated perceived exertion, and lactate concentration. Decreased values of magnitude of the first peak of the vertical component of ground reaction force (17.2-24.2%) and impulse of the first 50 ms (Imp50; 34.3%) were observed for Cr, but higher values of time to reach the first peak were detected for Cr compared with placebo. Significant modifications in muscle activation were also observed, mainly in the pre-activation phase, and changes were observed in intermediary bouts. CONCLUSIONS: Cr supplementation has the potential to influence biomechanical parameters related to impact control during a single session of HIIT based on running. In particular, the findings of the current study indicate possible improvements in shock attenuation and a safer practice of HIIT under Cr supplementation.

Immediate effects of a distal gait modification during stair descent in individuals with patellofemoral pain.

Background: Knee pain during stair managing is a common complaint among individuals with PFP and can negatively affect their activities of daily living. Gait modification programs can be used to decrease patellofemoral pain. Immediate effects of a stair descent distal gait modification session that intended to emphasize forefoot landing during stair descent are described in this study. Objectives: To analyze the immediate effects of a distal gait modification session on lower extremity movements and intensity of pain in women with patellofemoral pain during stair descent. Method: Nonrandomized controlled trial. Sixteen women with patellofemoral pain were allocated into two groups: (1) Gait Modification Group (n = 8); and 2) Control Group (n = 8). The intensity of pain (visual analog scale) and kinematics of knee, ankle, and forefoot (multi-segmental foot model) during stair descent were assessed before and after the intervention. Results: After the gait modification session, there was an increase of forefoot eversion and ankle plantarflexion as well as a decrease of knee flexion. An immediate decrease in patellofemoral pain intensity during stair descent was also observed. Conclusion: The distal gait modification session changed the lower extremity kinetic chain strategy of movement, increasing foot and ankle movement contribution and decreasing knee contribution to the task. An immediate decrease in patellofemoral pain intensity during stair descent was also observed. To emphasize forefoot landing may be a useful intervention to immediately relieve pain in patients with patellofemoral pain during stair descent. Clinical studies are needed to verify the gait modification session effects in medium and long terms.

Interpretation of propulsive force in tethered swimming through principal component analysis / Interpretação da força propulsora no nado estacionário através da análise do componente principal / Interpretación de la fuerza propulsora en el nado estacionario a través del análisis del componente principal

ABSTRACT Introduction: Propulsive force in swimming, represented through impulse, is related to performance. However, since the as different biomechanical parameters contribute to impulse generation, coaches have a difficult task when seeking for performance improvement. Objective: Identify the main components involved in impulse generation in the front crawl stroke. Methods: Fourteen swimmers underwent a 10-second all-out fully tethered swimming test. The following parameters were obtained from the force-time curve: minimum force, peak force, mean force, time to peak force, rate of force development and stroke duration. This stage was followed by a principal component analysis. Results: The principal component analysis showed that component 1, predominantly kinetic, was composed of peak force, mean force and rate of force development, and accounted for 49.25% of total impulse variation, while component 2, predominantly temporal, composed of minimum force, stroke duration, and time to peak force, represented 26.43%. Conclusion: Kinetic parameters (peak force, mean force, and rate of force development) are more closely associated with impulse augmentation and, hypothetically, with non-tethered swimming performance. Level of Evidence II; Diagnostic studies - Investigating a diagnostic test.

RESUMO Introdução: A força propulsora na natação, representada através do impulso, está relacionada ao desempenho. Entretanto, já que diferentes parâmetros biomecânicos contribuem para a geração do impulso, os treinadores têm uma difícil tarefa ao buscarem a melhora do desempenho. Objetivos: Identificar os principais componentes envolvidos na geração do impulso na braçada do nado crawl. Métodos: Catorze nadadores foram submetidos ao teste de nado estacionário, totalmente all-out, com duração de 10 segundos. Os parâmetros de força mínima, força máxima, força média, tempo para força máxima, taxa de desenvolvimento da força e a duração da braçada foram obtidos a partir da curva força-tempo e, depois, foi realizada uma análise do componente principal. Resultados: A análise do componente principal revelou que o componente 1, predominantemente cinético, era composto pelos parâmetros de força máxima, força média e taxa de desenvolvimento da força e contava com 49,25% da variação total do impulso, enquanto que o componente 2, predominantemente temporal, composto pelos parâmetros de força mínima, duração da braçada e tempo para força máxima, representava 26,43%. Conclusão: Os parâmetros cinéticos (força máxima, força média e taxa de desenvolvimento de força) estão mais associados ao aumento do impulso e, hipoteticamente, ao desempenho no nado não estacionário. Nível de Evidência II; Estudos diagnósticos - Investigação de um exame para diagnóstico.

RESUMEN Introducción: La fuerza propulsora en la natación, representada a través del impulso, está relacionada al desempeño. Entretanto, ya que diferentes parámetros biomecánicos contribuyen para la generación del impulso, los entrenadores tienen una difícil tarea al buscar la mejora del desempeño. Objetivos: Identificar los principales componentes involucrados en la generación del impulso en la brazada del nado crawl. Métodos: Catorce nadadores fueron sometidos al test de nado estacionario, totalmente all-out, con duración de 10 segundos. Los parámetros de fuerza mínima, fuerza máxima, fuerza promedio, tiempo para fuerza máxima, tasa de desarrollo de la fuerza y la duración de la brazada fueron obtenidos a partir de la curva fuerza-tiempo y, después, fue realizado un análisis del componente principal. Resultados: El análisis del componente principal reveló que el componente 1, predominantemente cinético, era compuesto por los parámetros de fuerza máxima, fuerza promedio y tasa de desarrollo de la fuerza y contaba con 49,25% de la variación total del impulso, mientras que el componente 2, predominantemente temporal, compuesto por los parámetros de fuerza mínima, duración de la brazada y tiempo para fuerza máxima, representaba 26,43%. Conclusión: Los parámetros cinéticos (fuerza máxima, fuerza promedio y tasa de desarrollo de fuerza) están más asociados al aumento del impulso e, hipotéticamente, al desempeño en el nado no estacionario. Nivel de Evidencia II; Estudios diagnósticos - Investigación de un examen para diagnóstico.

Moderate intensity is a better stimulus to induce quadripecs femoris power in elderly adults / Intensidade moderada é o estímulo mais adequado para induzir potência de quadriceps em idosos / Intensidad moderada es el más adecuado para inducir potencia de quadriceps en ancianos

ABSTRACT Introduction: The best strategy for improving knee extensor power, a major functional capacity indicator in older adults, is power training. Nonetheless, the training intensity required to induce optimal gains is yet to be found. Objective: Our purpose was to compare knee extensor peak power responses between low, moderate, and high intensity load conditions (30%, 50% and 70% of 1RM). Methods: Thirteen sedentary elderly women performed six knee extensions in each load condition, calculating knee extensor mechanical work/power output and knee extension peak angular velocity. Results: No difference in peak power was found between the high (207.0 ± 68.1 W) and moderate (206.1 ± 71.6 W) load conditions (p = 0.994), and both had higher values (p ≤0.004) than the low intensity condition (135.6 ± 56.3 W). Conclusion: Moderate load at 50% of 1RM appears to be the preferred strategy for inducing knee extensor power output because in contrast with the high intensity condition, the moderate load yielded higher angular peak velocity, which is also a functional indicator. Level of Evidence ll; Therapeutic studies - Investigating treatment results.

RESUMO Introdução: A melhor estratégia para melhorar a potência dos extensores do joelho, principal indicador da capacidade funcional em idosos, é o treinamento de força. No entanto, a intensidade do treinamento exigida para induzir a maiores benefícios ainda não é conhecida. Objetivo: Nosso objetivo consistiu em comparar as respostas de potência máxima dos extensores do joelho entre as condições de carga baixa, moderada e de alta intensidade (30%, 50% e 70% de uma repetição máxima). Métodos: Treze mulheres idosas sedentárias realizaram seis extensões de joelho em cada condição de carga, sendo calculado o trabalho mecânico/débito de força e a velocidade angular máxima (ou pico) dos extensores do joelho. Resultados: Não houve diferença significativa na potência máxima entre as condições de carga alta ((207,0 ± 68,1 W) e moderada (206,1 ± 71,6 W) (p = 0,994), e ambas apresentaram valores maiores (p ≤ 0,004) do que a condição de baixa intensidade (135,6 ± 56,3 W). Conclusão: A carga moderada a 50% de 1RM parece ser a estratégia preferida para induzir o débito de força dos extensores do joelho, uma vez que quando comparada com a condição de alta intensidade, a carga moderada apresentou um pico de velocidade angular maior, o que também é um indicador funcional. Nível de Evidência II; Estudos terapêuticos - Investigação dos resultados do tratamento.

RESUMEN Introducción: La mejor estrategia para mejorar la potencia de los extensores de la rodilla, principal indicador de la capacidad funcional en personas de la tercera edad, es el entrenamiento de fuerza. Sin embargo, la intensidad del entrenamiento exigida para inducir a mayores beneficios aún no es conocida. Objetivo: Nuestro objetivo consistió en comparar las respuestas de potencia máxima de los extensores de la rodilla entre las condiciones de carga baja, moderada y de alta intensidad (30%, 50% y 70% de una repetición máxima). Métodos: Trece mujeres de la tercera edad sedentarias realizaron seis extensiones de rodilla en cada condición de carga, siendo calculado el trabajo mecánico/débito de fuerza y la velocidad angular máxima (o pico) de los extensores de la rodilla. Resultados: No hubo diferencia significativa en la potencia máxima entre las condiciones de carga alta ((207,0 ± 68,1 W) y moderada (206,1 ± 71,6 W) (p = 0,994), y ambas presentaron valores mayores (p ≤ 0,004) que la condición de baja intensidad (135,6 ± 56,3 W). Conclusión: La carga moderada a 50% de 1RM parece ser la estrategia preferida para inducir el débito de fuerza de los extensores de la rodilla, dado que cuando comparada con la condición de alta intensidad, la carga moderada presentó un pico de velocidad angular mayor, lo que también es un indicador funcional. Nivel de Evidencia II; Estudios terapéuticos - Investigación de los resultados del tratamiento.

CrossFit Overview: Systematic Review and Meta-analysis.

BACKGROUND: CrossFit is recognized as one of the fastest growing high-intensity functional training modes in the world. However, scientific data regarding the practice of CrossFit is sparse. Therefore, the objective of this study is to analyze the findings of scientific literature related to CrossFit via systematic review and meta-analysis. METHODS: Systematic searches of the PubMed, Web of Science, Scopus, Bireme/MedLine, and SciELO online databases were conducted for articles reporting the effects of CrossFit training. The systematic review followed the PRISMA guidelines. The Oxford Levels of Evidence was used for all included articles, and only studies that investigated the effects of CrossFit as a training program were included in the meta-analysis. For the meta-analysis, effect sizes (ESs) with 95% confidence interval (CI) were calculated and heterogeneity was assessed using a random-effects model. RESULTS: Thirty-one articles were included in the systematic review and four were included in the meta-analysis. However, only two studies had a high level of evidence at low risk of bias. Scientific literature related to CrossFit has reported on body composition, psycho-physiological parameters, musculoskeletal injury risk, life and health aspects, and psycho-social behavior. In the meta-analysis, significant results were not found for any variables. CONCLUSIONS: The current scientific literature related to CrossFit has few studies with high level of evidence at low risk of bias. However, preliminary data has suggested that CrossFit practice is associated with higher levels of sense of community, satisfaction, and motivation.

Correction: 16 Weeks of Progressive Barefoot Running Training Changes Impact Force and Muscle Activation in Habitual Shod Runners.

[This corrects the article DOI: 10.1371/journal.pone.0167234.].

The countermovement jump to monitor neuromuscular status: A meta-analysis.

OBJECTIVES: The primary objective of this meta-analysis was to compare countermovement jump (CMJ) performance in studies that reported the highest value as opposed to average value for the purposes of monitoring neuromuscular status (i.e., fatigue and supercompensation). The secondary aim was to determine the sensitivity of the dependent variables. DESIGN: Systematic review with meta-analysis. METHODS: The meta-analysis was conducted on the highest or average of a number of CMJ variables. Multiple literature searches were undertaken in Pubmed, Scopus, and Web of Science to identify articles utilizing CMJ to monitor training status. Effect sizes (ES) with 95% confidence interval (95% CI) were calculated using the mean and standard deviation of the pre- and post-testing data. The coefficient of variation (CV) with 95% CI was also calculated to assess the level of instability of each variable. Heterogeneity was assessed using a random-effects model. RESULTS: 151 articles were included providing a total of 531 ESs for the meta-analyses; 85.4% of articles used highest CMJ height, 13.2% used average and 1.3% used both when reporting changes in CMJ performance. Based on the meta-analysis, average CMJ height was more sensitive than highest CMJ height in detecting CMJ fatigue and supercompensation. Furthermore, other CMJ variables such as peak power, mean power, peak velocity, peak force, mean impulse, and power were sensitive in tracking the supercompensation effects of training. CONCLUSIONS: The average CMJ height was more sensitive than highest CMJ height in monitoring neuromuscular status; however, further investigation is needed to determine the sensitivity of other CMJ performance variables.

16 Weeks of Progressive Barefoot Running Training Changes Impact Force and Muscle Activation in Habitual Shod Runners.

Short-term effects of barefoot and simulated barefoot running have been widely discussed in recent years. Consequences of adopting barefoot running for a long period, including as a training approach, still remain unknown. The present study evaluated the influence of 16 weeks of progressive barefoot running training on impact force and muscle activation in habitual shod runners. Six habitual shod runners (3 men and 3 women, 29.5 ± 7.3 years) were tested barefoot (BF) and shod (SH), before and after 16 weeks of progressive barefoot running training. Tests consisted of running on instrumented treadmill at 9 km/h, for 10 minutes in each experimental condition. Nine data acquisitions (10 s) of vertical ground reaction force (VGRF) and electromyographic (EMG) signal were conducted in each experimental condition for each test. BF training was effective to alter VGRF and EMG parameters of running in habitual shod runners, regardless of footwear condition (SH or BF). The magnitude of first peak of VGRF (Fy1) and the impulse of the first 50 ms decreased after training for BF and SH (p<0.01). The activation reduced from PRE to POST training for four muscles in BF running (p<0.001), whereas only muscle gastrocnemius lateralis decreased significantly its activation (p<0.01) in SH running. A 16-week progressive barefoot running training seems to be an effective training strategy to reduce impact force, improve shock attenuation and to decrease muscle activation intensity, not only in BF running, but also in SH running, although BF condition seems to be more influenced by BF training.

KINESIO TAPING NÃO ALTERA A RELAÇÃO EMG ENTRE VASTO LATERAL E VASTO MEDIAL DURANTE MEIO-AGACHAMENTO / KINESIO TAPING DON'T CHANGE EMG RELATION BETWEEN VASTUS LATERALIS - MEDIALIS IN HALF SQUAT / KINESIO TAPING NO ALTERA LA RELACIÓN EMG ENTRE VASTO LATERAL Y VASTO MEDIAL DURANTE MEDIO AGACHAMIENTO

RESUMO Introdução: Kinesio Taping é uma técnica realizada com aplicação de fitas elásticas sobre a pele, que se propõe a produzir determinados efeitos com fins de prevenção e tratamento das lesões musculoesqueléticas. No entanto, os meios pelos quais tais efeitos ocorrem continuam sendo investigados e discutidos, principalmente no que diz respeito à utilização no campo da reabilitação e do esporte. Objetivo: Analisar a relação da atividade eletromiográfica encontrada nos músculos vasto lateral (VL) e vasto medial (VM) em duas condições: sem aplicação de Kinesio Taping (GnKT) e com aplicação de Kinesio Taping (GKT) em uma população saudável, com experiência em treinamento de força. Métodos: Dezoito sujeitos do sexo masculino (idade: 28,1 ± 6,9 anos; massa corporal: 85,5 ± 8,3 kg; estatura: 179,5 ± 6,9 cm; comprimento de membro inferior: 97,0 ± 4,2 cm) realizaram o exercício de meio-agachamento livre, com velocidade controlada, sem e com aplicação de Kinesio Taping. A relação foi verificada pela proporção de magnitude de ativação (VM/VL), utilizando-se os valores de root mean square (RMS). A sequência para realização dos exercícios nas condições mencionadas foi randomizada e balanceada. Resultados: Os valores encontrados para a razão VM/VL na situação GnKT foram de 83,96 ± 5,79% para VM e 84,13 ± 7,16% para VL. Já na situação GKT, 84,55 ± 16,97% para VM e 80,53 ± 9,20% para VL. Não foram observadas diferenças significativas nos valores de RMS para a relação VM/VL submetidos a aplicação de Kinesio Taping. Conclusão: A aplicação de Kinesio Taping não demonstrou influenciar a relação da atividade eletromiográfica entre os músculos vasto lateral e vasto medial durante a execução do exercício de meio-agachamento.

ABSTRACT Introduction: Kinesio Taping is a technique carried out with application of elastic tapes on the skin, which is intended to produce certain effects on prevention and treatment of musculoskeletal injuries. However, the means by which these effects occur are still being investigated and discussed, particularly with regard to rehabilitation and sport. Objective: To analyze the relationship of the electromyographic activity found in the vastus lateralis (VL) and vastus medialis (VM) muscles on two conditions: without the application of Kinesio Taping (GnKT) and with the application of Kinesio Taping (GKT) in a healthy population with experience in strength training. Methods: Eighteen male subjects (age: 28.1 ± 6.9 years, body mass: 85.5 ± 8.3 kg, height: 179.5 ± 6.9 cm, length of lower limb: 97.0 ± 4.2 cm) performed the exercise of free half-squat with controlled speed with and without applying Kinesio Taping. The relationship was verified by the ratio of activation magnitude (VM/VL) using the root mean square (RMS). The sequence for the exercises under such conditions was randomized and balanced. Results: The values for the ratio VM/VL in the GnKT situation were 83.96 ± 5.79% for VM and 84.13 ± 7.16% for VL. In the GKT situation, 84.55 ± 16.97% for VM and 80.53 ± 9.20% for VL. No significant differences were observed in RMS values for the VM/VL ratio when the Kinesio Taping was applied. Conclusion: The application of Kinesio Taping did not affect the electromyographic ratio between the vastus lateralis and vastus medialis muscles during the half-squat exercise.

RESUMEN Introducción: Kinesio Taping es una técnica realizada con aplicación de cintas elásticas sobre la piel, que se propone producir determinados efectos con fines de prevención y tratamiento de las lesiones musculoesqueléticas. Sin embargo, los medios por los que tales efectos ocurren continúan siendo investigados e discutidos, principalmente en lo que refiere al uso en el campo de la rehabilitación y del deporte. Objetivo: Analizar la relación de la actividad electromiográfica encontrada en los músculos vasto lateral (VL) y vasto medial (VM) en dos condiciones: sin aplicación de Kinesio Taping (GnKT) y con aplicación de Kinesio Taping (GKT) en una población saludable, con experiencia en entrenamiento de fuerza. Métodos: Dieciocho sujetos del sexo masculino (edad: 28,1 ± 6,9 años; masa corporal: 85,5 ± 8,3 kg; estatura: 179,5 ± 6,9 cm; longitud de miembro inferior: 97,0 ± 4,2 cm) realizaron el ejercicio de medio agachamiento libre, con velocidad controlada, sin y con aplicación de Kinesio Taping. La relación fue verificada por la proporción de magnitud de activación (VM/VL), utilizándose los valores de root mean square (RMS). La secuencia para realización de los ejercicios en las condiciones mencionadas fue aleatorizada y balanceada. Resultados: Los valores encontrados para la razón VM/VL en la situación GnKT fueron de 83,96 ± 5,79% para VM y 84,13 ± 7,16% para VL. Ya en la situación GKT, 84,55 ± 16,97% para VM y 80,53 ± 9,20% para VL. No fueron observadas diferencias significativas en los valores de RMS para la relación VM/VL sometidos a la aplicación de Kinesio Taping. Conclusión: La aplicación de Kinesio Taping no demostró influenciar la relación de la actividad electromiográfica entre los músculos vasto lateral y vasto medial durante la ejecución del ejercicio de medio agachamiento.

ADHERENCE TO SIX MONTHS OF INSTRUCTED MINIMALIST AND BAREFOOT RUNNING TRAINING / ADESÃO A SEIS MESES DE TREINAMENTO INSTRUÍDO DE CORRIDA MINIMALISTA E DESCALÇA / ADHESIÓN A SEIS MESES DE ENTRENAMIENTO INSTRUIDO DE CARRERA MINIMALISTA Y DESCALZA

ABSTRACT Introduction: The interest in minimalist and barefoot running is growing continuously. However, there is no data on how many runners drop out during this process. Objective: To describe the adhesion and dropout rates of a six-month instructed training program based on barefoot and minimalist footwear running. Methods: Thirty-four recreational runners participated in the study: 20 runners started the race training barefoot, while 14 runners were involved in training with minimalist footwear. Adhesion to intervention programs was evaluated through training spreadsheets and recording attendance at training sessions, while dropouts were evaluated at the end of training. A questionnaire was sent to participants who dropped out of the training, to obtain information related on why they had abandoned it. Results: Considering all participants (n=34), 41.2% of the runners completed six months with reduced plantar protection; 70% of all dropouts occurred in barefoot training; the main reasons for leaving the training were injury/pain (40%) and lack of time/suitable place for training (40%); and the majority of dropouts (50%) occurred in the first month of training. Barefoot training (n=20) showed 70% dropouts, 57.1% of them due to lack of time/suitable place for training; and 71.4% of the dropouts occurred in the first month of the intervention. The training with minimalist footwear (n=14) had fewer dropouts (42.9%) than the barefoot training, all of them due to injury/pain; 50% of them occurred in the third month of intervention. Conclusion: Dropouts usually occur at the beginning of training. Training involving barefoot running has more dropouts than training with minimalist footwear. Intervention programs lasting six months based on minimalist footwear/barefoot seems to have similar adhesion to other supervised exercise programs. The main reasons for dropping out are injury/pain and lack of time/suitable place to run.

RESUMO Introdução: O interesse acerca da corrida minimalista e descalça cresce continuamente. Contudo, não há dados sobre a evasão de corredores nesse processo. Objetivo: Descrever a adesão e a evasão de um programa de seis meses de treinamento instruído baseado na corrida descalça e em calçados minimalistas. Métodos: Trinta e quarto corredores recreacionais participaram do estudo: 20 corredores iniciaram o treinamento de corrida com os pés descalços, enquanto 14 se envolveram no treinamento com calçado minimalista. A adesão aos programas de intervenção foi verificada por intermédio de planilhas de treinamento e controle de presença nas sessões de treino, enquanto a evasão foi avaliada ao término do treinamento. Um questionário foi enviado aos participantes que saíram do treinamento, obtendo-se informações relacionadas ao abandono das intervenções. Resultados: Considerando-se todos os participantes (n = 34), 41,2% dos corredores finalizaram os seis meses de treinamento com proteção plantar reduzida; 70% das evasões ocorreram no treinamento descalço; as principais razões para abandonar o treinamento foram lesão/dor (40%) e ausência de tempo/local apropriado para o treinamento (40%) e a maioria das desistências (50%) ocorreu no primeiro mês de treinamento. O treinamento descalço (n = 20) apresentou 70% de evasão, sendo 57,1% devido à ausência de tempo/local apropriado para o treinamento; 71,4% da evasão ocorreu no primeiro mês de intervenção. O treinamento de corrida com calçado minimalista (n = 14) apresentou menor evasão (42,9%) que o treinamento descalço, sendo todas devido à lesão ou dor; 50% delas ocorreram no terceiro mês de intervenção. Conclusão: A evasão em geral ocorre no início do treinamento. A corrida descalça apresenta mais evasão do que a corrida com calçado minimalista. Os programas de intervenção que duram seis meses, baseados em calçado minimalista/pés descalços parecem ter adesão similar à de outros programas dirigidos de exercício. Os principais motivos para o abandono são lesão e dor e falta de tempo/local adequado para correr.

RESUMEN Introducción: El interés en la carrera minimalista y descalza crece continuamente. Sin embargo, no hay datos sobre la evasión de practicantes durante el proceso. Objetivo: Describir la adhesión y evasión de un programa de seis meses de entrenamiento instruido de carrera descalza y con calzado minimalista. Métodos: Treinta y cuatro corredores recreativos participaron en el estudio: 20 corredores comenzaron el entrenamiento en pies descalzos, mientras 14 hicieron el entrenamiento con el calzado minimalista. La adhesión a los programas de intervención se verificó a través de hojas de cálculo y control de la presencia en las sesiones de entrenamiento, mientras la evasión se evaluó al final del entrenamiento. Se envió un cuestionario a los participantes que abandonaron el entrenamiento para la obtención de información relacionada con el abandono de las intervenciones. Resultados: De todos los participantes (n = 34), el 41,2% de los corredores han completado seis meses de entrenamiento con protección plantar reducida; 70% de evasión se produjo en el entrenamiento descalzo; las principales razones para abandonar el entrenamiento fueron: lesión/dolor (40%) y la falta de tiempo/lugar adecuado para el entrenamiento (40%); la mayoría de abandonos (50%) ocurrieron en el primer mes de entrenamiento. El entrenamiento descalzo (n = 20) mostró 70% de evasión, con 57,1% debido a la falta de tiempo/lugar adecuado para entrenamiento; 71,4% de la evasión se produjo en el primer mes de la intervención. La carrera con el calzado minimalista (n = 14) mostró evasión más baja (42,9%) que el entrenamiento descalzo, todos los casos debiéndose a lesión o dolor; 50% de ellos se produjo en el tercer mes de la intervención. Conclusión: El abandono por lo general ocurre al comienzo del entrenamiento. La carrera descalza presenta más evasión que la carrera con calzado minimalista. Los programas de intervención con duración de seis meses y en base a carrera minimalista/descalza parecen que tienen evasión similar a otros programas de ejercicios supervisados. Las principales razones para el abandono son las lesiones y el dolor y la falta de tiempo y/o lugar adecuado para la carrera.

Parâmetros biomecânicos da marcha em crianças com pé torto congênito unilateral e bilateral / Biomechanical gait parameters in children with unilateral and bilateral clubfoot

Resumo Uma variedade de disfunções congênitas pediátricas demonstra que deformidades do pé interferem na capacidade de locomoção. No entanto, há em muitas vezes incertezas sobre os seus reais efeitos mecânicos. O pé torto congênito é um exemplo de uma disfunção pouco conhecida no que diz respeito as suas influências na locomoção de crianças. Desta forma, uma melhor compreensão da marcha destas crianças pode auxiliar no melhor no direcionamento de futuras ações na tentativa de minimizar ou corrigir tais possíveis desequilíbrios. O objetivo da pesquisa foi analisar parâmetros cinéticos e cinemáticos da marcha de crianças com pé torto congênito unilateral e bilateral submetidas a tratamento cirúrgico. Artigo Científico Original Observacional. O protocolo consistiu da investigação da marcha em velocidade auto-selecionada, com identificação de parâmetros em forças de reação do solo vertical e antero-posterior, além de parâmetros angulares do tornozelo e do joelho. Testes estatísticos não-paramétricos foram utilizados na análise dos resultados. As crianças com pé torto mostraram maiores desequilíbrios nos parâmetros investigados, com ênfase para as diferenças entre o grupo de pé torto unilateral e controle. Nesta comparação, no início da fase de apoio, foram encontradas maior primeiro pico da força vertical e alterações angulares do joelho e tornozelo; no médio apoio, foram observados aumento da flexão do joelho e dorsiflexão do tornozelo, além de menor magnitude da força vertical; na fase de propulsão foram encontrados menores valores na força antero-posterior e no segundo pico da força vertical, além de menor flexão plantar. Crianças com pé torto unilateral apresentam maiores desequilíbrios em parâmetros biomecânicos da marcha em comparação com crianças acometidas bilateralmente. As alterações encontradas nos parâmetros da marcha no presente estudo podem contribuir nas compreensões dos desequilíbrios e fornecer informações para entender os movimentos dos membros inferiores durante a marcha em crianças pé torto.(AU)

Abstract A variety of congenital pediatric disorders have demonstrated that foot deformities interfere in locomotion ability. However, there are uncertainties about the mechanical effects of this deformity. Quantitative gait analysis allows the measurement and assessment of walking biomechanics, which facilitates the recommendation of treatment alternatives. The purpose of this investigation was to analyze gait parameters in unilateral and bilateral clubfoot children after operative therapy. Observational Original Scientific Article. The protocol consisted of self-selected speed gait investigation with parameter identification in vertical and antero-posterior ground reaction forces and ankle and knee angles. Non-parametric statistics tests were used in analysis of the results. Children with clubfoot showed larger imbalances in parameters with an emphasis towards the greatest differences occurring between unilateral clubfoot group and controls. For initial stance phase, we found higher first vertical force peak and knee and ankle angular alterations. For midstance, we observed more knee flexion and ankle dorsiflexion, and less vertical force. For propulsion phase, there were smaller values in antero-posterior force, second vertical force peak and plantarflexion. Unilateral clubfoot presents more imbalances in gait biomechanical parameters compared with bilateral clubfoot children. The alterations in gait parameters in this study help to understand the imbalances and provide information to understand the lower extremity movements during gait in clubfoot children.(AU)

Does "transition shoe" promote an intermediate biomechanical condition compared to running in conventional shoe and in reduced protection condition?

This study evaluated if running in a "transition shoe" commercially available results in intermediate mechanical load upon lower extremities compared to conventional shoe and minimalist shoe/barefoot. Kinematic and kinetic parameters while running in different shoe conditions were compared. Fourteen runners (12 men, 2 women; age=28.4±7.3 years), inexperienced in minimalist shoes and barefoot running, ran on an instrumented treadmill within four experimental conditions (conventional shoe - CS, transition shoe - TrS, minimalist shoe - MS, and barefoot - BF). Running was performed at 9km/h for 10min in each experimental condition. Vertical ground reaction force (VGRF) and two-dimensional kinematic variables of lower limbs (both legs) were recorded. Nine data acquisitions (10s) were conducted for each footwear condition. Transition shoe lead to significant changes in VGRF variables related to impact control, while kinematic parameters were little affected. The TrS had smaller first peak of VGRF (Fy1) than CS (p≤0.001) and higher than MS (p=0.050) and BF (p≤0.001). Time to first peak of VGRF (tFy1) of TrS was smaller than CS (p≤0.001) and higher than MS (p≤0.001) and BF (p≤0.001). The TrS and MS induced to lesser knee flexion (p<0.001) and greater dorsiflexion (p<0.001) than CS and BF. Thus, results suggest the transition shoe (TrS) tested seem to promote an intermediate mechanical load condition only for VGRF parameters, presenting values of impact forces between those found for conventional shoe and minimalist shoe/barefoot. Such knowledge could be useful for the transition process from conventional running shoe to minimalist shoe/barefoot.