The effects of fatigability on shooting skill performance in goalball penalty shots

This study evaluated the influence of acute fatigue on shooting skill performance in goalball penalty shots. Eleven sub-elite male players were evaluated in an official court using a two-dimensional procedure (60 Hz) to compute the mean radial error, bivariate variable error and accuracy, and three-dimensional kinematics (240 Hz) to measure ball velocity. Rating of perceived exertion, blood lactate concentration and knee extension isometric maximal voluntary contractions were assessed at rest and immediately after the completion of an incremental test specific to goalball. Although significant differences were observed for rating of perceived exertion (pre: M = .36 AU, SD = .67; post: M = 9.27 AU, SD = .79), blood lactate concentration (M = 1.33 mM, SD = .51; M = 9.04 mM, SD = 2.25) and peak force (M = 597.85 N, SD = 132.35; M = 513.37 N, SD =107.00) at the end of the incremental test, no differences were identified in the pre and post moments for mean radial error (M = .10 m, SD = 1.01; M =.37 m, SD = 2.19), bivariate variable error (M = 3.56 m, SD = .70; M = 3.25 m, SD = .70), accuracy (M = 3.68 m, SD = .74; M = 3.78 m, SD = 1.13) and ball velocity (M = 18.53 m.s-1, SD = 1.53; M =18.46 m.s-1, SD = 1.65). We concluded that even though significant levels of fatigability can be attributed to the incremental test specific to goalball, shooting skill performance in goalball penalty shots does not appear to be affected. However, further investigations are needed so that goalball coaches can develop strategies that contribute to improve performance in this technical action. Such improvements are decisive for the outcome of a match

A prototype for dynamic knee extension: construction, force characterization and electromyographic responses

BACKGROUND: In the dynamic knee extension (DKE), a metal bar is positioned parallel to the bicycle frame, replacing the pedal and allowing consecutive extensions instead of a pedaling movement. In this exercise model, the knee joint returns to its initial position passively, allowing studies about the role of anterior thigh muscles during locomotion or balance. However, the DKE ergometer is not commercially available. AIM: To describe the construction, responses, and applicability of a prototype ergometer for DKE. METHOD: In the first experiment, six participants underwent a progressive effort to volitional exhaustion. The electromyography signals of the Vastus Lateralis and Biceps Femoris were monitored. In the second experiment, the twitch interpolation technique was used to test the fatigue status of seven participants after a high-intensity exercise. RESULTS: The force signal has three phases: I: knee extension moment; II: crank draws the metal rod back; III: rapid compression of the load cell by the leg. In addition, Vastus Lateralis activation was higher than Biceps Femorisin all stages (p<0.02). The TI was sensitive to assess the peripheral characteristics of the high-intensity effort. CONCLUSION: The construction of a DKE ergometer is plausible, increasing the possibilities of research into motor behavior

Assimetrias laterais no movimento de chute e rendimento no futebol e no futsal

Para proficiência no futebol e no futsal é necessário que o atleta apresente similar rendimento entre os membros contralaterais. No entanto, poucos atletas atingem este nível de comportamento. O objetivo deste estudo foi revisar na literatura as assimetrias laterais presentes no chute no futebol e no futsal e quais seus efeitos no rendimento. O estudo utilizou uma revisão sistemática para responder aos questionamentos. Os resultados evidenciaram as assimetrias entre os membros contralaterais com relação à habilidade de chutar, sendo necessário treinamento adequado e igualitário entre os lados para desenvolver similarmente os membros. Emais, a similaridade deve ser no nível mais alto, ou seja, no nível de execução do membro dominante. Ainda, no treinamento deve-se dar maior ênfase aos aspectos cinemáticos do chute do que aos aspectos relacionados à força, tanto do membro dechute como do membro de suporte. Conclui-se que as assimetrias entre os lados nos chutes existem e prejudicam o rendimento do atleta durante o jogo, mas essa questão ainda não foi solucionada, necessitando de mais estudos com relação ao treinamento e às diferenças entre os lados

Effects of experimentally induced fatigue on healthy older adults' gait:A systematic review

INTRODUCTION: While fatigue is ubiquitous in old age and visibly interferes with mobility, studies have not yet examined the effects of self-reported fatigue on healthy older adults' gait. As a model that simulates this daily phenomenon, we systematically reviewed eleven studies that compared the effects of experimentally induced muscle and mental performance fatigability on gait kinematics, variability, kinetics, and muscle activity in healthy older adults. METHODS: We searched for studies in databases (PubMed and Web of Science) using Fatigue, Gait, and Clinical conditions as the main terms and extracted the data only from studies that experimentally induced fatigue by sustained muscle or mental activities in healthy older adults. RESULTS: Eleven studies were included. After muscle performance fatigability, six of nine studies observed increases in stride length, width, gait velocity (Effect Size [ES] range: 0.30 to 1.22), inter-stride trunk acceleration variability (ES: 2.06), and ankle muscle coactivation during gait (ES: 0.59, n = 1 study). After sustained mental activity, the coefficient of variation of stride outcomes increased (ES: 0.59 to 0.67, n = 1 study) during dual-task but not single-task walking. CONCLUSION: Muscle performance fatigability affects spatial and temporal features of gait and, mainly, inter-stride trunk acceleration variability. In contrast, sustained mental activity tends only to affect step variability during dual tasking. A critical and immediate step for future studies is to determine the effects of self-reported fatigue on gait biomechanics and variability in healthy older adults to verify the viability of experimentally induced fatigue as a model for the study of gait adaptability in old age

Efecto del ejercicio físico en la amplitud del movimiento articular de las extremidades inferiores de individuos con la enfermedad de Parkinson

The aim of this study was to investigate the effect of eight months of a multimodal program of physical exercise on articular range of motion of the lower limb of patients with Parkinson disease (PD), considering gender and disease stage. Seventeen individuals with PD participated in this study. Participants were assessed before of multimodal program of the physical exercise and after four and eight months of physical exercise. In these periods were evaluated the clinical aspects and articular range of motion of the lower limb. For statistical analysis, patients were distributed according to gender and disease stage. A MANOVA considering exercise, gender and stage of disease, with repeated measures for the first factor, was performed. The clinical results showed regression of disease progression, indicating cognitive decline for women. The articular range of motion improved after four and eight months of physical exercise, especially for the hip and ankle, independent of gender and stage of PD. It was concluded that the multimodal exercise program of the eight months was effective in improving articular range of motion in patients with PD. The benefits of exercise for this physical capacity were independent of gender and severity of PD.El objetivo de este estudio fue verificar el efecto de ocho meses de un programa multimodal de ejercicio físico en la amplitud de movimiento articular de la extremidad inferior de pacientes con enfermedad de Parkinson (EP), considerando género y la etapa de la enfermedad. El estudio incluyó a 17 sujetos con EP idiopática. Los participantes fueron evaluados antes del período de ejecución del programa multimodal de ejercicio físico y tras cuatro y ocho meses de ejercicio físico. Se evaluaron aspectos clínicos y la amplitud de movimiento de las articulaciones de las extremidades inferiores. Para el análisis estadístico, los pacientes fueron agrupados de acuerdo con el género y etapa de la enfermedad, mediante la realización de un MANOVA con factor para ejercicio físico, género y estadio de la enfermedad, con medidas repetidas para el primer factor. Los resultados clínicos mostraron regresión de la progresión de la EP, y el deterioro cognitivo en las mujeres. La amplitud de movimiento articular mejoró tras cuatro y ocho meses de ejercicio físico, especialmente para la cadera y el tobillo, independientemente de su género y etapa de la enfermedad de Parkinson. Se concluyó que el programa multimodal de ejercicio físico de los ocho meses fue eficaz en mejorar la amplitud de movimiento articular en pacientes con EP, y los beneficios independiente del género y la gravedad de la EP.O objetivo deste estudo foi verificar o efeito de oito meses de um programa multimodal de exercício físico na amplitude de movimento articular do membro inferior de pacientes com doença de Parkinson (DP), considerando gênero e estágio da doença. Participaram deste estudo 17 indivíduos com DP idiopática. Os participantes foram avaliados antes do período da execução do programa multimodal de exercício físico e após quatro e oito meses de exercício físico. Foram avaliados aspectos clínicos e a amplitude de movimento das articulações do membro inferior. Para análise estatística, os pacientes foram agrupados de acordo com gênero e estágio da doença, sendo realizada uma MANOVA com fator para exercício físico, gênero e estágio da doença, com medidas repetidas para o primeiro fator. Os resultados clínicos indicaram regressão da progressão da DP, com declínio cognitivo para as mulheres. A amplitude de movimento articular melhorou após quatro e oito meses de exercício físico, principalmente para o quadril e tornozelo, independente de gênero e estágio da doença de Parkinson. Conclui-se que o programa multimodal de exercício físico de oito meses foi eficiente em melhorar a amplitude de movimento articular de pacientes com DP, sendo os benefícios independentes do gênero e da severidade da DP

Being physically active minimizes the effects of leg muscle fatigue on obstacle negotiation in people with Parkinson's disease

It is challenging for people with Parkinson's disease (PwPD) to adjust their gait to perturbations, including fatigue. Obstacle negotiation increases the risk of tripping and falling in PD. Being physically active can improve gait control and the ability to negotiate obstacles while walking under fatigue state. We thus determined the effects of Parkinson's disease, fatigue, and level of physical activity on gait during the approach to and crossing an obstacle during gait. Forty participants were stratified to people with Parkinson's disease active and inactive, and control individuals active and inactive. Participants walked on an 8 m walkway and stepped over an obstacle placed at the middle (4 m). They performed three trials before and after repeated sit-to-stand (rSTS)-induced fatigue state. Maximum voluntary force was assessed before and after rSTS. We measured the length, width, duration, and velocity of the approach (stride before obstacle) and crossing (step over the obstacle) phases and the leading and trailing placements and clearance during crossing phase. Fatigue trait was determined by multidimensional fatigue inventory. Before rSTS, people with Parkinson's disease inactive vs. other subgroups approached the obstacle using 18-28% shorter, wider and slower steps and crossed the obstacle slower (all p < 0.04). After rSTS, people with Parkinson's disease inactive increased (23-34%) stride length and velocity and decreased (-21%) the step width (p < 0.01). People with Parkinson's disease approached the obstacle similarly to control individuals. Physical activity minimizes Parkinson's disease-typical gait impairments during obstacle negotiation and affords a protective effect against fatigue-effects on obstacle negotiation

Effects of leg muscle fatigue on gait in patients with Parkinson's disease and controls with high and low levels of daily physical activity

Patients with Parkinson's disease (PD) are more susceptible to muscle fatigue, which can damage their gait. Physical activity can improve muscle condition, which is an important aspect during walking. The aim of this study was to analyze the effects of lower limb muscle fatigue on gait in patients with PD and healthy individuals, grouped according to physical activity level. Twenty Patients with PD (PD group) and 20 matched individuals (control group) were distributed according to physical activity level into four subgroups of ten individuals (active and inactive). Participants performed three walking trials before and after lower limb muscle fatigue, induced by a repeated sit-to-stand task on a chair. Kinematic (stride length, width, duration, velocity and percentage of time in double support) and kinetic (propulsive and breaking anterior-posterior and medio-lateral impulse) gait parameters were analyzed. In both groups, participants increased stride length and velocity and decreased stride duration and braking vertical impulse after lower limb muscle fatigue. The PD groups presented higher step width and percentage of double time support than the control groups before muscle fatigue. The control groups increased step width and decreased percentage of time in double support, while the PD groups did not change these parameters. For physical activity level, active individuals presented longer stride length, greater stride velocity, higher braking and propulsive anterior-posterior impulse and shorter step width than inactive individuals. Groups sought more balance and safety after lower limb muscle fatigue. Physical activity level does not appear to modify the effects of lower limb muscle fatigue during unobstructed walking in individuals with PD or controls

Age-specific modulation of intermuscular beta coherence during gait before and after experimentally induced fatigue

We examined the effects of age on intermuscular beta-band (15-35 Hz) coherence during treadmill walking before and after experimentally induced fatigue. Older (n = 12) and younger (n = 12) adults walked on a treadmill at 1.2 m/s for 3 min before and after repetitive sit-to-stand, rSTS, to induce muscle fatigability. We measured stride outcomes and coherence from 100 steps in the dominant leg for the synergistic (biceps femoris (BF)-semitendinosus, rectus femoris (RF)-vastus lateralis (VL), gastrocnemius lateralis (GL)-Soleus (SL), tibialis anterior (TA)-peroneus longus (PL)) and for the antagonistic (RF-BF and TA-GL) muscle pairs at late swing and early stance. Older vs. younger adults had 43-62% lower GL-SL, RF-VL coherence in swing and TA-PL and RF-VL coherence in stance. After rSTS, RF-BF coherence in late swing decreased by similar to 20% and TA-PL increased by 16% independent of age (p = 0.02). Also, GL-SL coherence decreased by similar to 23% and increased by similar to 23% in younger and older, respectively. Age affects the oscillatory coupling between synergistic muscle pairs, delivered presumably via corticospinal tracts, during treadmill walking. Muscle fatigability elicits age-specific changes in the common fluctuations in muscle activity, which could be interpreted as a compensation for muscle fatigability to maintain gait performance

Older Compared With Younger Adults Performed 467 Fewer Sit-to-Stand Trials, Accompanied by Small Changes in Muscle Activation and Voluntary Force

Background: Repetitive sit-to-stand (rSTS) is a fatigue perturbation model to examine the age-effects on adaptability in posture and gait, yet the age-effects on muscle activation during rSTS per se are unclear. We examined the effects of age and exhaustive rSTS on muscle activation magnitude, onset, and duration during ascent and descent phases of the STS task. Methods: Healthy older (n = 12) and younger (n = 11) adults performed rSTS, at a controlled frequency dictated by a metronome (2 s for cycle), to failure or for 30 min. We assessed muscle activation magnitude, onset, and duration of plantar flexors, dorsiflexors, knee flexors, knee extensors, and hip stabilizers during the initial and late stages of rSTS. Before and after rSTS, we measured maximal voluntary isometric knee extension force, and rate of perceived exertion, which was also recorded during rSTS task. Results: Older vs. younger adults generated 35% lower maximum voluntary isometric knee extension force. During the initial stage of rSTS, older vs. younger adults activated the dorsiflexor 60% higher, all 5 muscle groups 37% longer, and the hip stabilizers 80% earlier. Older vs. younger adults completed 467 fewer STS trials and, at failure, their rate of perceived exertion was ~17 of 20 on the Borg scale. At the end of the rSTS, maximum voluntary isometric knee extension force decreased 16% similarly in older and younger, as well as the similar age groups decline in activation of the dorsiflexor and knee extensor muscles (all p < 0.05). Conclusion: By performing 467 fewer STS trials, older adults minimized the potential effects of fatigability on muscle activation, voluntary force, and motor function. Such a sparing effect may explain the minimal changes in gait after rSTS reported in previous studies, suggesting a limited scope of this perturbation model to probe age-effects on muscle adaptation in functional tasks

Optimal measurements for simultaneous quantum estimation of multiple phases

A quantum theory of multiphase estimation is crucial for quantum-enhanced sensing and imaging and may link quantum metrology to more complex quantum computation and communication protocols. In this Letter, we tackle one of the key difficulties of multiphase estimation: obtaining a measurement which saturates the fundamental sensitivity bounds. We derive necessary and sufficient conditions for projective measurements acting on pure states to saturate the ultimate theoretical bound on precision given by the quantum Fisher information matrix. We apply our theory to the specific example of interferometric phase estimation using photon number measurements, a convenient choice in the laboratory. Our results thus introduce concepts and methods relevant to the future theoretical and experimental development of multiparameter estimation