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1.
J Therm Biol ; 100: 103042, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34503789

RESUMO

Heat acclimation (HA) is a widely recognized physiological phenomenon of human body in hot environments. HA has many benefits, such aspreventing hyperthermia responses, and is an efficient way to improve human responses to hyperthermal environments. However, it is not known whether HA is dependent on the environmental conditions. Moreover, its mechanism and effect on the safety performance remain unexplored. In this study, we created a climate chamber to simulate a hyperthermal environment. Thirty healthy males were recruited for this study, who were then trained under the same ambient conditions (temperature of 38 °C and relative humidity (RH) of 40%). The training involved running on treadmills (at 5 km/h) to simulate heavy manual labor, and performing heat stress tests (HST) under six different conditions (32 °C/40% RH, 35 °C/40%, 38 °C/40%, 32 °C/70%, 35 °C/70%, and 38 °C/70%). Their physiological indices (rectal temperature, heart rate, sweat loss and skin temperature) and one psychological index (thermal sensation) were measured. Furthermore, a hazard avoidance test device (HATD) was designed to evaluate the individual safety performance by detecting human errors. The results show that training and environmental conditions have different effects on HA. After HA, the physiological and psychological strain were significantly improved. More importantly, HA also helped improve the participants' awareness of the dangers and required emergency responses to face potential hazards. Overall, a reasonable HA training under proper conditions is helpful to ensure the safety of human beings. More research is needed to study the role of HA on safety performance.


Assuntos
Reação de Fuga , Resposta ao Choque Térmico , Condicionamento Físico Humano/métodos , Adulto , Temperatura Corporal , Teste de Esforço/instrumentação , Teste de Esforço/métodos , Frequência Cardíaca , Humanos , Masculino , Condicionamento Físico Humano/instrumentação , Tempo de Reação , Segurança , Sensação Térmica
3.
Int J Sport Nutr Exerc Metab ; 31(2): 135-142, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33477112

RESUMO

Elliptical trainers and steppers are proposed as useful exercise modalities in the rehabilitation of injured runners due to the reduced stress on muscles and joints when compared to running. This study compared the physiological responses to submaximal running (treadmill) with exercise on the elliptical trainer and stepper devices at three submaximal but identical workloads. Authors had 18 trained runners (male/female: N = 9/9, age: mean ± SD = 23 ± 3 years) complete randomized maximal oxygen consumption tests on all three modalities. Submaximal tests of 3 min were performed at 60%, 70%, and 80% of peak workload individually established for each modality. Breath-by-breath oxygen consumption, heart rate, fuel utilization, and energy expenditure were determined. The value of maximal oxygen consumption was not different between treadmill, elliptical, and stepper (49.3 ± 5.3, 48.0 ± 6.6, and 46.7 ± 6.2 ml·min-1·kg-1, respectively). Both physiological measures (oxygen consumption and heart rate) as well as carbohydrate and fat oxidation differed significantly between the different exercise intensities (60%, 70%, and 80%) but did not differ between the treadmill, elliptical trainer, and stepper. Therefore, the elliptical trainer and stepper are suitable substitutes for running during periods when a reduced running load is required, such as during rehabilitation from running-induced injury.


Assuntos
Exercício Físico/fisiologia , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/fisiologia , Estudos Transversais , Metabolismo Energético , Feminino , Frequência Cardíaca , Humanos , Masculino , Consumo de Oxigênio , Percepção/fisiologia , Condicionamento Físico Humano/métodos , Esforço Físico/fisiologia , Troca Gasosa Pulmonar , Corrida/fisiologia , Adulto Jovem
4.
Artigo em Inglês | MEDLINE | ID: mdl-33327487

RESUMO

Since the emergence of the quantified self movement, users aim at health behavior change, but only those who are sufficiently motivated and competent with the tools will succeed. Our literature review shows that theoretical models for quantified self exist but they are too abstract to guide the design of effective user support systems. Here, we propose principles linking theory and implementation to arrive at a hierarchical model for an adaptable and personalized self-quantification system for physical activity support. We show that such a modeling approach should include a multi-factors user model (activity, context, personality, motivation), a hierarchy of multiple time scales (week, day, hour), and a multi-criteria decision analysis (user activity preference, user measured activity, external parameters). This theoretical groundwork, which should facilitate the design of more effective solutions, has now to be validated by further empirical research.


Assuntos
Exercício Físico , Comportamentos Relacionados com a Saúde , Condicionamento Físico Humano , Exercício Físico/psicologia , Humanos , Motivação , Condicionamento Físico Humano/instrumentação
5.
J Orthop Sports Phys Ther ; 50(10): 549-563, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32998615

RESUMO

OBJECTIVES: To (1) identify the wearable devices and associated metrics used to monitor workload and assess injury risk, (2) describe the situations in which workload was monitored using wearable technology (including sports, purpose of the analysis, location and duration of monitoring, and athlete characteristics), and (3) evaluate the quality of evidence that workload monitoring can inform injury prevention. DESIGN: Scoping review. LITERATURE SEARCH: We searched the CINAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, HealthSTAR, MEDLINE, PsycINFO, SPORTDiscus, and Web of Science databases. STUDY SELECTION CRITERIA: We included all studies that used wearable devices (eg, heart rate monitor, inertial measurement units, global positioning system) to monitor athlete workload in a team sport setting. DATA SYNTHESIS: We provided visualizations that represented the workload metrics reported, sensors used, sports investigated, athlete characteristics, and the duration of monitoring. RESULTS: The 407 included studies focused on team ball sports (67% soccer, rugby, or Australian football), male athletes (81% of studies), elite or professional level of competition (74% of studies), and young adults (69% of studies included athletes aged between 20 and 28 years). Thirty-six studies of 7 sports investigated the association between workload measured with wearable devices and injury. CONCLUSION: Distance-based metrics derived from global positioning system units were common for monitoring workload and are frequently used to assess injury risk. Workload monitoring studies have focused on specific populations (eg, elite male soccer players in Europe and elite male rugby and Australian football players in Oceania). Different injury definitions and reported workload metrics and poor study quality impeded conclusions regarding the relationship between workload and injury. J Orthop Sports Phys Ther 2020;50(10):549-563. doi:10.2519/jospt.2020.9753.


Assuntos
Traumatismos em Atletas/prevenção & controle , Monitores de Aptidão Física , Condicionamento Físico Humano/instrumentação , Esportes de Equipe , Dispositivos Eletrônicos Vestíveis , Fatores Etários , Traumatismos em Atletas/epidemiologia , Eletrocardiografia Ambulatorial , Europa (Continente) , Sistemas de Informação Geográfica , Humanos , Fatores de Risco , Fatores Sexuais
6.
J Therm Biol ; 93: 102703, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33077124

RESUMO

The purpose of the present study was to evaluate the effectiveness of passive and post-exercise heat acclimation strategies through directly heating the skin with a water-perfused suit. Nineteen young males participated in the heat acclimation (HA) protocols for 10 days, which were conducted at an air temperature of 33oC with 60%RH. The exercise-only condition (N = 6) conducted 1-h treadmill walking (6 km·h-1) followed by 1-h rest. The post-exercise passive-heating condition (N = 6) wore the suit (inflow water temperature 44.2oC) for 1-h after 1-h walking. The passive-heating condition (N = 7) donned the suit for 2 h. Heat tolerance tests (leg immersion in 42oC water for 60 min) were conducted before and after the training to evaluate changes due to the 10-day intervention. Reflecting that suit-wearing for 10 days as both passive and post-exercise HA strategies can effectively induce adaptive changes, significant interaction effects appeared in: increase or decrease in mean skin temperature (P < 0.05) and elevation in whole-body sweat rate (P < 0.05). Reduction in rectal temperature (P < 0.05) and blood pressure (P < 0.05) were found most prominently in the passive-heating condition. These results indicate that this new method of heat acclimation training, donning a skin-heating water-perfused suit, can generate thermoregulatory benefits. The passive HA intervention could be applied to individuals for whom doing exercise regularly are not feasible.


Assuntos
Hipertermia Induzida/métodos , Condicionamento Físico Humano/métodos , Roupa de Proteção/normas , Temperatura Cutânea , Termotolerância , Pressão Sanguínea , Temperatura Alta , Humanos , Umidade , Hipertermia Induzida/instrumentação , Masculino , Condicionamento Físico Humano/instrumentação , Roupa de Proteção/efeitos adversos , Adulto Jovem
7.
Foot (Edinb) ; 45: 101716, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33039905

RESUMO

BACKGROUND: Elliptical training may offer advantages over other cardiorespiratory exercises for those requiring podiatric care, since its constant double-limb support diminishes recurring high-impact plantar forces while allowing exercise in a functional, upright posture. Unknown is the impact of distinct elliptical models, that can alter user's body mechanics, on potential variations in plantar pressure patterns. PURPOSE: To compare plantar pressure variables while exercising on four ellipticals and walking. METHODS: For this cross-sectional pilot study, plantar pressure data were recorded from ten young adults while exercising on four ellipticals (True, Octane, Life Fitness, SportsArt) and walking overground. One-way repeated measures ANOVA identified differences in heel, arch, and forefoot maximum force (MF), peak pressure (PP), and pressure-time integral (PTI). RESULTS: MF was lower under the heel when exercising on all ellipticals compared with walking, with further differences detected between models. PP was lower on all three foot regions when exercising on all ellipticals compared with walking, except Octane under the arch, with differences detected between ellipticals under the heel. PTI was lower under the heel and arch when exercising on some of the ellipticals compared with walking, with differences again detected under the heel between models. CONCLUSION: Plantar pressures were lower when exercising on the ellipticals compared with walking for most variables. Caution is recommended to which elliptical could be incorporated into therapeutic programs given that differences among models were detected under the heel.


Assuntos
Pé/fisiologia , Condicionamento Físico Humano/instrumentação , Caminhada/fisiologia , Suporte de Carga/fisiologia , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Projetos Piloto , Adulto Jovem
8.
Sports Health ; 12(5): 488-494, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32598234

RESUMO

BACKGROUND: Baseball pitching injuries are increasing at an alarming rate. While weighted ball throwing programs may be effective at increasing pitching velocity, previous research has identified a 24% injury rate and a 3.3° increase in shoulder external rotation (ER) range of motion (ROM) after performing a 6-week program. However, previous research has not investigated, separately, the immediate effects of throwing underloaded and overloaded balls on ROM. The purpose of this study was to examine the acute effects of throwing differently weighted baseballs on shoulder ROM. By analyzing these differences, it may be possible to determine the specific weight range that may lead to the greatest increase in ROM and potential injury risk. HYPOTHESIS: Throwing with weighted balls will result in an increase in shoulder ER ROM. STUDY DESIGN: Randomized controlled trial. LEVEL OF EVIDENCE: Level 2. METHODS: A total of 16 male high school baseball pitchers agreed to participate in this study. The participants were (mean ± SD) 17.1 ± 1.0 years of age, 1.81 ± 0.09 m tall, and had a mass of 79.2 ± 11.1 kg. Each participant was tested on 3 different days, 1 week apart, with 3 different conditions in random order: (1) underload throwing, using regulation 5-oz baseballs and 4- and 2-oz balls; (2) overload throwing, using 5-, 6-, and 9-oz balls; and (3) extreme overload throwing, using 5-, 16-, and 32-oz balls. Each testing session began by measuring passive shoulder ROM (external rotation and internal rotation) using standard goniometric measurements. Participants then performed 3 throws with each weighted ball from 3 different positions (kneeling, rocker, and run-and-gun) for a total of 27 throws each test session. ROM measurements were repeated at the end of each test session. The effect of each throwing condition on ROM was compared from pre- to posttraining using a paired t test (P ≤ 0.05). RESULTS: There was no significant difference in ER after throwing at underloaded weights. The overload condition showed a statistically significant increase of 3.3° in external rotation (P = 0.05). The extreme overload condition showed a statistically significant increase in ER of 8.4° (P < 0.001). There were no differences in internal rotation for any group. CONCLUSION: A significant increase in shoulder ER was observed immediately after throwing overload weighted balls. This effect increased as the weights of the balls increased. CLINICAL RELEVANCE: Throwing with overload weighted baseballs causes an immediate increase in shoulder ER ROM. It is unknown why these changes occur; however, the results may explain both the increase in velocity and injury rates previously observed from throwing weighted balls. The current study results may be used to develop more scientifically validated weighted ball programs. Heavier balls should be used with caution, and ROM should be monitored during implementation of these programs.


Assuntos
Beisebol/fisiologia , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/métodos , Ombro/fisiologia , Equipamentos Esportivos , Adolescente , Beisebol/lesões , Humanos , Masculino , Amplitude de Movimento Articular , Estresse Mecânico
9.
Int J Sports Med ; 41(11): 720-728, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32396965

RESUMO

The goal of this systematic review was to evaluate the effects of exercise programs using agility ladders and to assess the quality of available evidence. Search was conducted in October of 2019 using the following databases: Cochrane Library, PEDro, PubMed, Scopus and Web of Science. Study eligibility criteria included randomized trials or randomized controlled trials using agility ladders drills. Participants were healthy humans of any health status. The study appraisal and synthesis methods followed the revised Cochrane risk-of-bias tool for randomized trials (RoB 2) and a qualitative synthesis of the main results of each study were applied. Only five studies met our criteria, lasting between 4 and 8 weeks. Only two studies evaluated the effects of ladder drills on more than one dimension. Lack of description of the specific exercises that were used limits reproducibility of current studies. With one exception, the articles had low risk of bias for most domains. Despite the widespread popularity of agility ladder drills, research is scarce and problematic, with poorly described protocols and mostly unidimensional performance measures. Claims that agility ladders improve agility and other physical skills is premature, given the nature and quality of existing research.


Assuntos
Desempenho Atlético/fisiologia , Destreza Motora/fisiologia , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/métodos , Humanos , Projetos de Pesquisa/normas , Equipamentos Esportivos
10.
Int J Sports Physiol Perform ; 15(2): 154-161, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31743092

RESUMO

PURPOSE: To summarize the evidence on postactivation potentiation (PAP) protocols using flywheel eccentric overload (EOL) exercises. METHODS: Studies were searched using the electronic databases PubMed, Scopus, and Institute for Scientific Information Web of Knowledge. RESULTS: In total, 7 eligible studies were identified based on the following results: First, practitioners can use different inertia intensities (eg, 0.03-0.88 kg·m2), based on the exercise selected, to enhance sport-specific performance. Second, the PAP time window following EOL exercise seems to be consistent with traditional PAP literature, where acute fatigue is dominant in the early part of the recovery period (eg, 30 s), and PAP is dominant in the second part (eg, 3 and 6 min). Third, as EOL exercises require large force and power outputs, a volume of 3 sets with the conditioning activity (eg, half-squat or lunge) seems to be a sensible approach. This could reduce the transitory muscle fatigue and thereby allow for a stronger potentiation effect compared with larger exercise volumes. Fourth, athletes should gain experience by performing EOL exercises before using the tool as part of a PAP protocol (3 or 4 sessions of familiarization). Finally, the dimensions of common flywheel devices offer useful and practical solutions to induce PAP effects outside of normal training environments and prior to competitions. CONCLUSIONS: EOL exercise can be used to stimulate PAP responses to obtain performance advantages in various sports. However, future research is needed to determine which EOL exercise modalities among intensity, volume, and rest intervals optimally induce the PAP phenomenon and facilitate transfer effects on athletic performances.


Assuntos
Contração Muscular , Força Muscular , Músculo Esquelético/fisiologia , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/métodos , Desempenho Atlético/fisiologia , Desenho de Equipamento , Ergometria/instrumentação , Humanos , Projetos de Pesquisa
11.
Res Q Exerc Sport ; 90(4): 470-478, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31282820

RESUMO

Purpose: The purpose of this study was to investigate the differences in metabolic responses between the track and the treadmill (1% inclination) running. The latter is recommended for use in laboratory settings to mimic outdoor running. Method: Seventeen male endurance athletes (mean 25.8, s = 3.8 years) performed 4-min running bouts on an indoor track and the treadmill. Results: At all speeds (11, 13, and 15 km·h-1) athletes showed better economy on the track running compared to the treadmill expressed as oxygen (7.9%, 5.2%, and 2.8%) and caloric (7.0%, 5.3%, and 2.6%) unit cost. Rating of perceived exertion was evaluated substantially higher at all speeds on the treadmill (F(1,16) = 31.45, p < .001, η2p = .663) compared to running on the track. Participants presented lower heart rate (F(1,16) = 13.74, p = .002, η2p = .462) on the track at the speed of 11 and 13 km·h-1 compared to the treadmill, but not at 15 km·h-1 (p = .021). Conclusions: We conclude that constant inclination (i.e.. 1%) during the treadmill test might not be suitable to reproduce comparable effort to running on the track; rather, there is an optimal treadmill inclination for different intensities to reproduce similar effort compared to the track running.


Assuntos
Teste de Esforço , Condicionamento Físico Humano/métodos , Corrida/fisiologia , Atletismo/fisiologia , Adulto , Metabolismo Energético/fisiologia , Frequência Cardíaca/fisiologia , Humanos , Masculino , Consumo de Oxigênio/fisiologia , Percepção/fisiologia , Condicionamento Físico Humano/instrumentação , Resistência Física/fisiologia , Esforço Físico/fisiologia , Propriedades de Superfície , Adulto Jovem
12.
Res Q Exerc Sport ; 90(4): 479-486, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31184984

RESUMO

Purpose: The present study aimed to compare the vertical ground reaction force responses during the performance of the stationary running water-based exercise with and without equipment at different cadences by elderly women. Method: Nineteen elderly women (age: 68.6 ± 5.0 years; body mass: 69.0 ± 9.5 kg; height: 154.9 ± 5.6 cm) completed one session consisting of the performance of the water-based stationary running with elbow flexion and extension immersed to the xiphoid process depth. The exercise was performed in three conditions, without equipment, with water-floating and with water-resistance equipment, at three cadences (80 b·min-1, 100 b·min-1 and maximal) in a randomized order. Peak and impulse of vertical ground reaction force were collected during the exercise using an underwater force plate. Repeated measures two-way ANOVA was used (α = 0.05). Results: Peak vertical ground reaction force (p < .001) and impulse (p ≤ 0.002) resulted in lower values for the water-floating use (0.42-0.48 BW and 0.07-0.13 N.s/BW) in comparison to the water-resistance equipment use (0.46-0.60 BW and 0.09-0.16 N.s/BW) and to the non-use of equipment (0.45-0.60 BW and 0.07-0.17 N.s/BW), except for the impulse at the maximal cadence. In addition, peak vertical ground reaction force at 80 b·min-1 (p = .002) and impulse at the maximal cadence (p < .001) showed lower values compared to the other cadences. Conclusion: The use of water-floating equipment minimizes the vertical ground reaction force during the stationary running water-based exercise performed by elderly women regardless of the cadence.


Assuntos
Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/métodos , Corrida/fisiologia , Água , Idoso , Fenômenos Biomecânicos , Cotovelo/fisiologia , Feminino , Humanos , Imersão , Pessoa de Meia-Idade
13.
Mil Med ; 184(11-12): 882-888, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31067314

RESUMO

INTRODUCTION: Physical Employment Standards (PES) safeguard the requirement to create a suitable job-person fit in military occupations, and in doing so mitigate some operational and musculoskeletal injury risk. The primary purpose of this research was to identify critical - physically demanding tasks performed by UK Royal Navy (RN) seafarers to inform the development of a muscle strength and endurance-based PES. A secondary purpose was to explore possible sex and age-based differences in subjective ratings of occupational task physical demand. MATERIALS AND METHODS: In accordance with the Ministry of Defence Research Ethics Committee, 515 Naval personnel (443 males, 72 females; aged 30.2 ± 7.3 years) completed an anonymous survey that rated the physical demand (from no to very high), criticality (from not to critically important), and frequency (from seldom to several times per day) of 25 common sea-going tasks on a one to five scale. An a priori criteria was applied to down-select a shortlist of the most critical and physically demanding tasks (i.e., median task criticality and task physical demand scores of ≥4, and ≥3, respectively). A Mann-Whitney and Kruskal-Wallis test explored sex and age-based differences in subjective physical demand ratings. RESULTS: Ten (out of 25) tasks met the critical - physical demand criteria, which included the four task categories of fire fighting, damage control, casualty handling, and basic movement/transit tasks. Casualty handling emerged as the single most physically demanding task category performed by seafarers, which was rated to have "high" physical demand (4 on the 1 to 5 scale). Sex and age-based differences in subjective ratings of task physical demand were equivocal, with females rating 3 (out of the 25 tasks), and 40-51 year olds rating 4 (out of 25 tasks) to have a higher physical demand than males and 19-29 year olds, respectively. CONCLUSION: Ten criterion tasks were identified and should undergo a further job analysis to inform the development of strength-based PES for the RN.


Assuntos
Militares/estatística & dados numéricos , Força Muscular , Condicionamento Físico Humano/métodos , Resistência Física , Padrões de Referência , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/estatística & dados numéricos , Aptidão Física/fisiologia , Estatísticas não Paramétricas , Inquéritos e Questionários , Análise e Desempenho de Tarefas , Reino Unido
14.
Rinsho Shinkeigaku ; 59(3): 157-159, 2019 Mar 28.
Artigo em Japonês | MEDLINE | ID: mdl-30814446

RESUMO

A 64-year-old man was diagnosed with spinal and bulbar muscular atrophy (SBMA) in 2014, and began gait training with the hybrid assistive limb (HAL) in 2017. We conducted 2 courses of HAL-based gait training and temporary improvement was confirmed both before and after intervention based on evaluation of the 2-minute walking distance, walking speed, and the Timed Up and Go test. HAL-based gait training may be effective for improving and maintaining walking ability in SBMA. However, long-term observation of this patient will be performed.


Assuntos
Atrofia Bulboespinal Ligada ao X/reabilitação , Terapia por Exercício/instrumentação , Exoesqueleto Energizado , Marcha/fisiologia , Reabilitação Neurológica/instrumentação , Condicionamento Físico Humano/instrumentação , Modalidades de Fisioterapia/instrumentação , Caminhada/fisiologia , Atrofia Bulboespinal Ligada ao X/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento
15.
PLoS One ; 14(2): e0200862, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30794565

RESUMO

Robot-assisted training is a promising tool under development for improving walking function based on repetitive goal-oriented task practice. The challenges in developing the controllers for gait training devices that promote desired changes in gait is complicated by the limited understanding of the human response to robotic input. A possible method of controller formulation can be based on the principle of bio-inspiration, where a robot is controlled to apply the change in joint moment applied by human subjects when they achieve a gait feature of interest. However, it is currently unclear how lower extremity joint moments are modulated by even basic gait spatio-temporal parameters. In this study, we investigated how sagittal plane joint moments are affected by a factorial modulation of two important gait parameters: gait speed and stride length. We present the findings obtained from 20 healthy control subjects walking at various treadmill-imposed speeds and instructed to modulate stride length utilizing real-time visual feedback. Implementing a continuum analysis of inverse-dynamics derived joint moment profiles, we extracted the effects of gait speed and stride length on joint moment throughout the gait cycle. Moreover, we utilized a torque pulse approximation analysis to determine the timing and amplitude of torque pulses that approximate the difference in joint moment profiles between stride length conditions, at all gait speed conditions. Our results show that gait speed has a significant effect on the moment profiles in all joints considered, while stride length has more localized effects, with the main effect observed on the knee moment during stance, and smaller effects observed for the hip joint moment during swing and ankle moment during the loading response. Moreover, our study demonstrated that trailing limb angle, a parameter of interest in programs targeting propulsion at push-off, was significantly correlated with stride length. As such, our study has generated assistance strategies based on pulses of torque suitable for implementation via a wearable exoskeleton with the objective of modulating stride length, and other correlated variables such as trailing limb angle.


Assuntos
Articulação do Tornozelo/fisiologia , Marcha/fisiologia , Articulação do Quadril/fisiologia , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Velocidade de Caminhada/fisiologia , Adulto , Biorretroalimentação Psicológica/fisiologia , Fenômenos Biomecânicos/fisiologia , Teste de Esforço , Terapia por Exercício/instrumentação , Terapia por Exercício/métodos , Exoesqueleto Energizado , Feminino , Humanos , Cinética , Masculino , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/métodos , Robótica/métodos , Torque , Caminhada/fisiologia , Adulto Jovem
16.
J Sports Sci ; 37(13): 1551-1559, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30777492

RESUMO

The aim of this study was to compare cervical spine kinematics in rugby union front row players during machine-based and "live" scrummaging. Cervical spine kinematics was measured via electromagnetic tracking of sensors attached to the head and thorax. Joint angles were extracted from each trial at two time points ("bind" prior to engagement and instant of impact) for comparison between scrummaging conditions. The effect of scrummaging condition on kinematics was evaluated using a mixed effects model and estimations were based on a Bayesian framework. With differences ranging from 38° to 50°, the results show that the cervical spine is consistently more flexed when scrummaging against opponents than against a scrum machine. In contrast, there are little differences in the excursion of lateral-flexion (range 5-8°) and axial rotation (7°) between the two conditions. The findings from this study provide clear information on motion patterns in different scrum formations, and suggest that the current design of scrum machines may not promote the same pattern of movement that occurs in live scrums. The results highlight that findings from previous studies that have investigated kinematics during machine-based scrummaging may not be generalisable to a competitive scrummaging context.


Assuntos
Vértebras Cervicais/fisiologia , Futebol Americano/fisiologia , Condicionamento Físico Humano/instrumentação , Equipamentos Esportivos , Adolescente , Adulto , Teorema de Bayes , Fenômenos Biomecânicos , Fenômenos Eletromagnéticos , Cabeça/fisiologia , Humanos , Masculino , Pescoço/fisiologia , Condicionamento Físico Humano/métodos , Postura , Amplitude de Movimento Articular , Tórax/fisiologia , Estudos de Tempo e Movimento , Adulto Jovem
17.
Sports Biomech ; 18(5): 482-500, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29558238

RESUMO

Little is known about the transmission of vibration to the head when using whole-body vibration (WBV) training machines. This paper investigates the effect of frequency and posture on the transmission of vibration from a vibrating plate to the head of standing people. Nine male participants were exposed to vertical vibration at nine frequencies in the range of 17-46 Hz and vibration acceleration in the range of 7.85-18.64 m/s2 (peak). The participants adopted four standing postures described as standing with locked knee (LK), bent knee (BK), one leg (OL), and one foot to the front and the other to the back (FB). The transmissibility to the head differed among postures (t-test, p < 0.05) and was greatest with the FB posture and smallest with the BK posture. The transmissibility to the head decreased with increasing the frequency (t-test, p < 0.05) but the extent of the decrease depended on the adopted posture. This frequency-posture interaction effect on the transmissibility should be considered when designing a training program. The data will be useful for developing standards/protocols that govern the use of WBV machines as well as for building human body models that can predict potential risks arising from using WBV machines.


Assuntos
Cabeça/fisiologia , Condicionamento Físico Humano/instrumentação , Posição Ortostática , Vibração , Adulto , Fenômenos Biomecânicos , Humanos , Masculino , Pessoa de Meia-Idade , Condicionamento Físico Humano/efeitos adversos , Condicionamento Físico Humano/métodos , Fatores de Risco , Adulto Jovem
18.
Sports Biomech ; 18(6): 649-662, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29768095

RESUMO

Sport climbers frequently use campus board (CB) to improve their upper limb strength under similar conditions of high-difficulty sport climbing routes. The objective of this study was to assess the test-retest reliability of peak force and impulse measured using a CB instrumented with two load cells on starting holds. The same evaluator examined 22 climbers on two days with 48 h between the assessments. The participants performed five concentric lunges (CL) and five lunges with stretch-shortening cycle with 1 min intervals between repetitions and 10 min between exercises. All variables were associated with significant intraclass correlation coefficient (ICC) values (p = 0.001), and none variable showed systematic errors (p > 0.05). Peak force ICC was higher than 0.88, and the standard error of measurement (SEM%) was less than 5%. Impulse ICC for the CL was greater than 0.90, and the SEM% was less than 14%. We conclude that the kinetic variables measured using the CB were reliable. The ability of the hands to maintain contact with the holds (peak force) and the abilities of the arms and shoulders vertically move the centre of mass (impulse) should be taken into account by coaches on CB training prescription as well for further research.


Assuntos
Montanhismo/fisiologia , Força Muscular/fisiologia , Condicionamento Físico Humano/instrumentação , Extremidade Superior/fisiologia , Adulto , Braço/fisiologia , Fenômenos Biomecânicos , Dedos/fisiologia , Humanos , Masculino , Reprodutibilidade dos Testes , Ombro/fisiologia , Punho/fisiologia
19.
Sports Biomech ; 18(6): 636-648, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29768096

RESUMO

A rugby scrum's front row must act uniformly to transfer maximal horizontal force and improve performance. This study investigated the muscle activation patterns of lower extremity muscles in front row forwards during live and machine scrums at professional and amateur levels. Electromyography was collected bilaterally on vastus lateralis, rectus femoris and gastrocnemius muscles of 75 male rugby prop players during live and machine scrums. ANOVAs compared muscle reaction time, rate of change in muscle amplitude and muscle amplitude between groups and conditions. Cross-correlation analysis explored muscle synchronicity. There were significantly greater rates of change in each muscle amplitude in professional players than amateur players. Additionally, there was significantly quicker muscle reaction time in all muscles, and greater amplitude in vastus lateralis and gastrocnemius, during the live scrum vs. machine condition. The professional props produced more synchronised muscle activation than amateur players and all players produced more synchronised muscle activation against the scrum machine vs. live scrummage. The results indicate a higher skill proficiency and muscle synchronicity in professional players. While scrum machine training is ideally suited for functional muscle strengthening during practice, to truly simulate the requirements of the scrum, training should incorporate the live situation as much as possible.


Assuntos
Futebol Americano/fisiologia , Extremidade Inferior/fisiologia , Músculo Esquelético/fisiologia , Adulto , Fenômenos Biomecânicos , Eletromiografia , Humanos , Masculino , Destreza Motora/fisiologia , Força Muscular/fisiologia , Condicionamento Físico Humano/instrumentação , Tempo de Reação , Adulto Jovem
20.
Int J Sports Physiol Perform ; 14(3): 343-350, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30160560

RESUMO

PURPOSE: Stroboscopic training is suggested to improve visuomotor abilities in sports. However, previous research has primarily focused on untrained participants and only considered behavioral data. Because visuomotor performance is substantially determined by neural visual processes, this study aimed to examine the effects of stroboscopic training on visuomotor performance and neural visual function of athletes. METHODS: A total of 10 German top-level badminton players (intervention: n = 5 and control: n = 5) participated in this study. Over a 4-week training period, athletes performed badminton-specific visuomotor tasks either wearing shutter glasses (intervention) or under normal visual conditions (control). Prior to and after the training period, behavioral smash-defense tests and neurophysiologic investigations of the N2 motion onset visual evoked potential were used to identify modulations in the athletes' visuomotor performance and visual perception speed, respectively. RESULTS: Badminton training improved visuomotor performance in both groups; however, stroboscopic training resulted in superior posttraining performance compared with normal visual conditions (P = .007). Training-induced modulations in N2 latency did not reach significance, although a strong relationship was observed between changes in N2 latency and changes in visuomotor performance (r = -.55), indicating that higher performance gains following training were associated with a stronger reduction in N2 latency. CONCLUSIONS: The results indicate that stroboscopic training may be more effective than conventional visuomotor training for improving visuomotor abilities even in athletes performing at high skill levels. Furthermore, visuomotor performance gains could potentially be mediated by neural adaptations in the visual motion system. These findings should be confirmed for athletes from different disciplines.


Assuntos
Destreza Motora/fisiologia , Condicionamento Físico Humano/instrumentação , Condicionamento Físico Humano/métodos , Esportes com Raquete/fisiologia , Percepção Visual/fisiologia , Potenciais Evocados Visuais , Óculos , Feminino , Humanos , Masculino , Tempo de Reação/fisiologia , Adulto Jovem
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