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2.
Br J Sports Med ; 54(2): 110-115, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31420319

RESUMO

INTRODUCTION: The brain plays a key role in the perceptual regulation of exercise, yet neuroimaging techniques have only demonstrated superficial brain areas responses during exercise, and little is known about the modulation of the deeper brain areas at different intensities. OBJECTIVES/METHODS: Using a specially designed functional MRI (fMRI) cycling ergometer, we have determined the sequence in which the cortical and subcortical brain regions are modulated at low and high ratings perceived exertion (RPE) during an incremental exercise protocol. RESULTS: Additional to the activation of the classical motor control regions (motor, somatosensory, premotor and supplementary motor cortices and cerebellum), we found the activation of the regions associated with autonomic regulation (ie, insular cortex) (ie, positive blood-oxygen-level-dependent (BOLD) signal) during exercise. Also, we showed reduced activation (negative BOLD signal) of cognitive-related areas (prefrontal cortex), an effect that increased during exercise at a higher perceived intensity (RPE 13-17 on Borg Scale). The motor cortex remained active throughout the exercise protocol whereas the cerebellum was activated only at low intensity (RPE 6-12), not at high intensity (RPE 13-17). CONCLUSIONS: These findings describe the sequence in which different brain areas become activated or deactivated during exercise of increasing intensity, including subcortical areas measured with fMRI analysis.


Assuntos
Exercício Físico/fisiologia , Córtex Motor/fisiologia , Adolescente , Adulto , Cerebelo/fisiologia , Córtex Cerebral/fisiologia , Ergometria/métodos , Humanos , Imagem por Ressonância Magnética , Masculino , Percepção/fisiologia , Esforço Físico/fisiologia , Córtex Pré-Frontal/fisiologia , Adulto Jovem
3.
J Strength Cond Res ; 34(1): 104-113, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30707143

RESUMO

Soria, M, Ansón, M, Lou-Bonafonte, JM, Andrés-Otero, MJ, Puente, JJ, and Escanero, J. Fat oxidation rate as a function of plasma lipid and hormone response in endurance athletes. J Strength Cond Res 34(1): 104-113, 2020-Plasma lipid changes during incremental exercise are not well known. The aim of this study was to investigate the relationship among fat oxidation rate, plasma lipids, and hormone concentrations in well-trained athletes. Twenty-six trained triathletes completed a graded cycle ergometer test to exhaustion increasing by 0.5 W·kg every 10 minutes. Fat oxidation rates were determined using indirect calorimetry. For each individual, maximal fat oxidation (MFO), the intensity at which MFO occurred (Fatmax), and the intensity at which fat oxidation became negligible (Fatmin) were determined. Blood samples for lipids and hormones analysis were collected at the end of each stage of the graded exercise test. All variables studied except insulin showed an increase at the end of incremental protocol with respect to basal levels. Free fatty acid reached significant increase at 60%VO2max and maximal levels at 70%VO2max. Low-density lipoprotein (LDL) and triglycerides (TG) decreased and showed lowest levels at 60%VO2max and reaching significant increases after 80%VO2max. High-density lipoprotein reached significant increase at 60%VO2max. Adrenaline and noradrenaline increased until the end of the incremental exercise, and significant differences were from 50%VO2max. These results suggest that exercise intensities are related to plasma lipids levels. In the zone when lipids oxidation is maximal, plasma LDL and TG variation differs from other lipids. These results may have application for the more adequate exercise intensity prescription to maximize the beneficial effects of exercise.


Assuntos
Tecido Adiposo/metabolismo , Hormônios/sangue , Metabolismo dos Lipídeos , Lipídeos/sangue , Resistência Física , Adulto , Atletas , Calorimetria Indireta , Catecolaminas/sangue , Ergometria , Exercício Físico/fisiologia , Teste de Esforço , Ácidos Graxos não Esterificados/sangue , Humanos , Insulina/sangue , Masculino , Oxirredução , Consumo de Oxigênio
4.
Scand J Med Sci Sports ; 30(2): 361-369, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31621945

RESUMO

BACKGROUND: There is some evidence that upper-body training modalities can improve not only aerobic capacity but also seated balance in people with spinal cord injury (SCI), even in those classified with motor-complete paralysis above T6. Here, we evaluated the effect of arm crank ergometry (ACE) "spin" training on trunk muscle recruitment and its effects on seated balance and aerobic capacity. METHODS: Eight individuals with high-level complete and 6 with either a low-level complete or a motor-incomplete SCI participated in this study. Participants completed 5 weeks of a group ACE "spin" training protocol which featured modulations in cadence and resistance as well as back-supported and unsupported bouts. Surface electromyography was used to confirm trunk muscle recruitment during unsupported ACE. Changes in aerobic capacity (peak oxygen consumption) and seated balance control (center of pressure parameters) were assessed at pre- and post-intervention. RESULTS: Unsupported ACE was effective for eliciting trunk muscle activity (P < .05). Following training, peak oxygen consumption significantly improved by an average of 16% (P = .005). Static sitting balance significantly improved from pre- to post-intervention, but only when tested with eyes closed as measured by a reduction in area (P = .047) and velocity of center of pressure (P = .013). No significant changes were observed in static sitting balance with eyes open or in dynamic sitting balance. CONCLUSION: Group ACE "spin" classes may benefit not only aerobic fitness but also static seated balance control in people with SCI.


Assuntos
Aptidão Cardiorrespiratória , Terapia por Exercício/métodos , Tolerância ao Exercício , Equilíbrio Postural , Traumatismos da Medula Espinal/terapia , Adulto , Braço , Ergometria , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/fisiologia , Consumo de Oxigênio , Postura Sentada , Tronco
5.
J Sports Sci ; 38(1): 21-28, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31613188

RESUMO

Subjective evaluations of balance performance, like the modified Balance Error Scoring System (mBESS), are highly popular. Alternatively, quantitative measures may offer additional clarity in identifying balance dysfunction. A novel measure to define balance impairments is time to boundary (TTB), which represents the amount of time available to make corrective postural adjustments prior to the centre of pressure (CoP) reaching the edge of the base of support. The purpose of this investigation was to assess TTB and traditional measures of CoP displacement of young adults performing the mBESS on a BTrackS balance plate. Path length and TTB were calculated in anterior-posterior (AP) and medio-lateral (ML) directions, respectively. AP and ML path lengths were largest in Single stance (109.2 & 118.1 cm, respectively) and smallest in Dual stance (27.1 & 36.4 cm, respectively). The average AP and ML TTBs were higher in Dual (10.67 & 7.27 s, respectively) compared to Single (3.54 & 1.20 s, respectively) or Tandem (10.11 & 1.94 s, respectively) stances, and lower in Single stance compared to Tandem. Given the effect sizes for TTB were greater than those of path length in both directions, TTB more adequately differentiates these stance conditions than path length or subjective scores.


Assuntos
Ergometria/métodos , Equilíbrio Postural/fisiologia , Concussão Encefálica/diagnóstico , Feminino , Humanos , Masculino , Movimento/fisiologia , Fatores de Tempo , Adulto Jovem
6.
Rev. int. med. cienc. act. fis. deporte ; 19(76): 699-718, dic. 2019. ilus, graf, tab
Artigo em Espanhol | IBECS | ID: ibc-187241

RESUMO

Objetivos: se analizaron la condición cardiorrespiratoria y la intensidad de esfuerzo durante la práctica recreativa del esquí náutico de slalom. Metodología: participaron tres esquiadores náuticos con paraplejia moderadamente activos. Realizaron un test incremental en un ergómetro de brazos para determinar su VO2pico y los umbrales ventilatorios y completaron 3 sesiones de práctica de esquí náutico, separadas por 48h, registrándose la FC cada 5 s. Resultados: obtuvieron un VO2pico de 22,3 ± 0,6 mL·kg-1·min-1 y los umbrales ventilatorios se analizaron al ~80 y ~50% del VO2pico. La FC media en las sesiones de esquí náutico fue de 111 ppm, lo que representó una intensidad de ~45% de la FC de reserva (FCR), permaneciendo por encima del 40% de la FCR ~12 min. Conclusión: la intensidad moderada de la práctica recreativa de esquí náutico de slalom podría servir para mantener o mejorar la condición cardiorrespiratoria en estas tres personas con paraplejia


Objectives: the cardiorespiratory fitness and the intensity of effort were analyzed during the recreational practice of slalom water skiing. Methodology: three moderately active water skiers with paraplegia participated. They performed an incremental test on an arm ergometer to determine their VO2peak and ventilatory thresholds and completed 3 sessions of water skiing, separated by 48h, where the HR was recorded every 5 s. Results: they obtained a VO2peak of 22.3 ± 0.6 mL·kg-1·min-1 and the ventilatory thresholds were analyzed at ~80 and ~50% of the VO2peak. The average heart rate in the water ski sessions was 111 bpm, which represented an intensity of ~45% of the heart rate reserve (HRR), remaining above 40% of the HRR ~12 min. Conclusion: the moderate intensity of recreational slalom skiing could serve to maintain or improve the cardiorespiratory fitness in these three people with paraplegia


Assuntos
Humanos , Masculino , Adulto , Esportes Aquáticos/fisiologia , Paraplegia/fisiopatologia , Esforço Físico/fisiologia , Frequência Cardíaca , Atividade Motora , Esportes Aquáticos/normas , Paraplegia/reabilitação , Índice de Massa Corporal , Ergometria/instrumentação
7.
Eur J Appl Physiol ; 119(11-12): 2629-2639, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31624950

RESUMO

PURPOSE: To investigate (1) whether maximal stroke volume (SVmax) occurs at submaximal exercise intensities, (2) sex differences in SVmax once fat-free mass (FFM) has been controlled for, and, (3) the contribution of concurrent changes in FFM and SVmax to the sex-specific development of peak oxygen uptake [Formula: see text]. METHODS: The peak [Formula: see text] s of 61 (34 boys) 11-12-year-olds were determined and their SV determined during treadmill running at 2.28 and 2.50 m s-1 using carbon dioxide rebreathing. The SVmax and peak [Formula: see text] of 51 (32 boys) students who volunteered to be tested treadmill running at 2.50 m s-1 on three annual occasions were investigated using multilevel allometric modelling. The models were founded on 111 (71 from boys) determinations of SVmax, FFM, and peak [Formula: see text]. RESULTS: Progressive increases in treadmill running speed resulted in significant (p < 0.01) increases in [Formula: see text], but SV levelled-off with nonsignificant (p > 0.05) changes within ~ 2-3%. In the multilevel models, SVmax increased proportionally to FFM0.72 and with FFM controlled for, there were no significant (p > 0.05) sex differences. Peak [Formula: see text] increased with FFM but after adjusting for FFM0.98, a significant (p < 0.05) sex difference in peak [Formula: see text] remained. Introducing SVmax to the multilevel model revealed a significant (p < 0.05), but small additional effect of SVmax on peak [Formula: see text]. CONCLUSIONS: Fat-free mass explained sex differences in SVmax, but with FFM controlled for, there was still a ~ 5% sex difference in peak [Formula: see text]. SVmax made a modest additional contribution to explain the development of peak [Formula: see text] but there remained an unresolved sex difference of ~ 4%.


Assuntos
Exercício Físico/fisiologia , Consumo de Oxigênio/fisiologia , Oxigênio/metabolismo , Volume Sistólico/fisiologia , Adolescente , Composição Corporal/fisiologia , Criança , Ergometria/métodos , Teste de Esforço/métodos , Feminino , Humanos , Masculino , Corrida/fisiologia , Caracteres Sexuais , Fatores Sexuais
8.
Nat Commun ; 10(1): 4623, 2019 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-31604916

RESUMO

Reactive oxygen species (ROS) act as intracellular compartmentalized second messengers, mediating metabolic stress-adaptation. In skeletal muscle fibers, ROS have been suggested to stimulate glucose transporter 4 (GLUT4)-dependent glucose transport during artificially evoked contraction ex vivo, but whether myocellular ROS production is stimulated by in vivo exercise to control metabolism is unclear. Here, we combined exercise in humans and mice with fluorescent dyes, genetically-encoded biosensors, and NADPH oxidase 2 (NOX2) loss-of-function models to demonstrate that NOX2 is the main source of cytosolic ROS during moderate-intensity exercise in skeletal muscle. Furthermore, two NOX2 loss-of-function mouse models lacking either p47phox or Rac1 presented striking phenotypic similarities, including greatly reduced exercise-stimulated glucose uptake and GLUT4 translocation. These findings indicate that NOX2 is a major myocellular ROS source, regulating glucose transport capacity during moderate-intensity exercise.


Assuntos
Citosol/metabolismo , Glucose/metabolismo , Músculo Esquelético/metabolismo , NADPH Oxidase 2/metabolismo , Esforço Físico , Espécies Reativas de Oxigênio/metabolismo , Adulto , Animais , Ergometria , Transportador de Glucose Tipo 4/metabolismo , Humanos , Masculino , Camundongos , Músculo Esquelético/citologia , Oxirredução , Fosforilação , Condicionamento Físico Animal , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
9.
Int J Sports Med ; 40(13): 871-875, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31590189

RESUMO

High amounts of sitting increase the risk of non-communicable disease and mortality. Treadmill desks make it possible to reduce sitting during the desk-based worker's day. This study investigated the acute effect on postural stability of interrupting prolonged sitting with an accumulated 2-h of light-intensity treadmill desk walking. Twenty-one sedentary adults participated in this randomized acute crossover trial, with two 6.5 h conditions: 1) uninterrupted sitting and 2) interrupted sitting with accumulated 2 h light-intensity treadmill desk walking. Pre- and post-condition, participants performed four postural stability tests on a pressure plate (bipedal and unipedal standing stance, eyes open and eyes closed). Anteroposterior center of pressure amplitude showed a significant condition x time interaction in bipedal eyes closed (F(1,20)=4.62, p=0.046) and unipedal eyes open (F(1,20)=9.42, p=0.006) tests, and mediolateral center of pressure amplitude in bipedal eyes closed (F(1,20)=6.12, p=0.023) and bipedal eyes open (F(1,12)=5.55, p=0.029) tests. In the significant interactions, amplitude increased pre to post condition in the uninterrupted sitting condition. The accumulated 2 h light-intensity treadmill desk walking ameliorated the negative effect of 6.5 h prolonged sitting on postural sway, supporting workplace treadmill desk use.


Assuntos
Ergometria/instrumentação , Equilíbrio Postural/fisiologia , Postura Sentada , Caminhada/fisiologia , Local de Trabalho , Adulto , Estudos Cross-Over , Feminino , Humanos , Decoração de Interiores e Mobiliário , Masculino , Pessoa de Meia-Idade , Saúde do Trabalhador , Análise e Desempenho de Tarefas
11.
Med Biol Eng Comput ; 57(11): 2471-2482, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471785

RESUMO

The objective was to assess the performance and robustness of a novel strategy for automatic control of heart rate (HR) during cycle ergometry. Control design used a linear plant model and direct shaping of the closed-loop input-sensitivity function to achieve an appropriate response to disturbances attributable to broad-spectrum heart rate variability (HRV). The controller was evaluated in 73 feedback control experiments involving 49 participants. Performance and stability robustness were analysed using a separately identified family of 73 plant models. The controller gave highly accurate and stable HR tracking performance with mean root-mean-square tracking error between 2.5 beats/min (bpm) and 3.1 bpm, and with low average control signal power. Although plant parameters varied over a very wide range, key closed-loop transfer functions remained invariant to plant uncertainty in important frequency bands, while infinite gain margins and large phase margins (> 62∘) were preserved across the whole plant model family. Highly accurate, stable and robust HR control can be achieved using LTI controllers of remarkably simple structure. The results highlight that HR control design must focus on disturbances caused by HRV. The input-sensitivity approach evaluated in this work provides a transparent method of addressing this challenge. Graphical Abstract Heart rate control using a cycle ergometer.


Assuntos
Ergometria/métodos , Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Adulto , Desenho de Equipamento , Ergometria/instrumentação , Retroalimentação , Humanos , Masculino , Modelos Biológicos , Processamento de Sinais Assistido por Computador , Adulto Jovem
12.
Amino Acids ; 51(10-12): 1433-1441, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31482309

RESUMO

This study investigated the effects of acute oral taurine ingestion on: (1) the power-time relationship using the 3-min all-out test (3MAOT); (2) time to exhaustion (TTE) 5% > critical power (CP) and (3) the estimated time to complete (Tlim) a range of fixed target intensities. Twelve males completed a baseline 3MAOT test on a cycle ergometer. Following this, a double-blind, randomised cross-over design was followed, where participants were allocated to one of four conditions, separated by 72 h: TTE + taurine; TTE + placebo; 3MAOT + taurine; 3MAOT + placebo. Taurine was provided at 50 mg kg-1, whilst the placebo was 3 mg kg-1 maltodextrin. CP was higher (P < 0.05) in taurine (212 ± 36 W) than baseline (197 ± 40 W) and placebo (193 ± 35 W). Work end power was not affected by supplement (P > 0.05), yet TTE 5% > CP increased (P < 0.05) by 1.7 min after taurine (17.7 min) compared to placebo (16.0 min) and there were higher (P < 0.001) estimated Tlim across all work targets. Acute supplementation of 50 mg kg-1 of taurine improved CP and estimated performance at a range of severe work intensities. Oral taurine can be taken prior to exercise to enhance endurance performance.


Assuntos
Suplementos Nutricionais , Tolerância ao Exercício/efeitos dos fármacos , Taurina/administração & dosagem , Adulto , Estudos Cross-Over , Método Duplo-Cego , Ergometria , Exercício Físico , Humanos , Ácido Láctico/sangue , Masculino , Resistência Física/efeitos dos fármacos , Esforço Físico/efeitos dos fármacos , Distribuição Aleatória , Taurina/farmacologia , Adulto Jovem
13.
PLoS One ; 14(8): e0220943, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31425557

RESUMO

OBJECTIVE: The objective of the current study was to investigate the effect of four different crank fore-aft positions on elbow flexion and shoulder protraction, the consequent propulsion kinetics and the physiological responses during handcycling. METHODS: Twelve able-bodied male participants volunteered in this study. Crank fore-aft positions were standardised at 94%, 97%, 100% and 103% of the participants' arm length. Two submaximal 3 min trials were performed at a fixed cadence (70 rpm), in a recumbent handcyle attached to an ergometer at two fixed power outputs (30W and 60W). Elbow flexion, shoulder protraction, propulsion kinetics and physiological responses of the participants were continuously measured. RESULTS: As crank fore-aft distance increased, a decrease in elbow flexion (42±4, 37±3, 33±3, 29±3°) and an increase shoulder protraction was observed (29±5, 31±5, 34±5, 36±5°). The percentage of work done in the pull phase increased as well (62±7, 65±7, 67±6, 69±8%, at 60W), which was in line with an increased peak torque during the pull phase (8.8±1.6, 9.0±1.4, 9.4±1.5, 9.7±1.4Nm, at 60W) and reduced peak torque during the push phase (6.0±0.9, 5.6±0.9,5.6±0.9, 5.4±1.0Nm, in 60W condition). Despite these changes in work distribution, there were no significant changes in gross mechanical efficiency (15.7±0.8, 16.2±1.1, 15.8±0.9, 15.6±1.0%, at 60W). The same patterns were observed in the 30W condition. CONCLUSIONS: From a biomechanical perspective the crank position closest to the trunk (94%) seems to be advantageous, because it evens the load over the push and pull phase, which reduces speed fluctuations, without causing an increase in whole body energy expenditure and hence a decrease of gross mechanical efficiency. These findings may help handcyclists to optimize their recumbent handcycle configuration.


Assuntos
Ciclismo/fisiologia , Mãos/fisiologia , Amplitude de Movimento Articular/fisiologia , Adulto , Fenômenos Biomecânicos , Articulação do Cotovelo/fisiologia , Metabolismo Energético/fisiologia , Ergometria , Humanos , Masculino , Articulação do Ombro/fisiologia , Tronco/fisiologia , Adulto Jovem
14.
Eur J Appl Physiol ; 119(10): 2275-2286, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31435767

RESUMO

PURPOSE: To examine the effects of stage duration on power output (PO), oxygen uptake (VO2), and heart rate (HR) at peak level and ventilatory thresholds during synchronous arm crank ergometry. METHODS: Nineteen healthy participants completed a ramp, 1-min stepwise, and 3-min stepwise graded arm crank exercise test. PO, VO2, and HR at the first and second ventilatory threshold (VT1, VT2) and peak level were compared among the protocols: a repeated measures analysis of variance was performed to test for systematic differences, while intraclass correlation coefficients (ICC) and Bland-Altman plots were calculated to determine relative and absolute agreement. RESULTS: Systematic differences among the protocols were found for PO at VT1, VT2, and peak level. At peak level, PO differed significantly among all protocols (ramp: 115 ± 37 W; 1-min stepwise: 108 ± 34 W; 3-min stepwise: 94 ± 31 W, p ≤ 0.01). No systematic differences for HR or VO2 were found among the protocols. VT1 and VT2 were identified at 52% and 74% of VO2peak, respectively. The relative agreement among protocols varied (ICC 0.02-0.97), while absolute agreement was low with small-to-large systematic error and large random error. CONCLUSIONS: PO at VTs and peak level was significantly higher in short-stage protocols compared with the 3-min stepwise protocol, whereas HR and VO2 showed no differences. Therefore, training zones based on PO determined in short-stage protocols might give an overestimation. Moreover, due to large random error in HR at VTs between the protocols, it is recommended that different protocols should not be used interchangeably within individuals.


Assuntos
Limiar Anaeróbio , Ergometria/normas , Contração Muscular , Adulto , Braço/fisiologia , Ergometria/métodos , Feminino , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Esforço Físico
15.
PLoS One ; 14(8): e0220826, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31437177

RESUMO

AIM AND METHODS: The aim of this study was to compare the dynamics of heart rate (HR) response to exercise using a cycle ergometer (CE) and a treadmill (TM). Using a sample of 25 healthy male participants, the time constant of HR dynamics was estimated for both modalities in response to square-wave excitation. RESULTS: The principal finding was that the time constant of heart-rate dynamics around somewhat-hard exercise intensity (Borg rating of perceived exertion = 13) does not differ significantly between the CE and TM (68.7 s ± 21.5 s vs. 62.5 s ± 18.5 s [mean ± standard deviation]; CE vs. TM; p = 0.20). An observed moderate level of evidence that root-mean-square model error was higher for the CE than for the TM (2.5 bpm ± 0.5 bpm vs. 2.2 bpm ± 0.5 bpm, p = 0.059) may reflect a decrease in heart rate variability with increasing HR intensity because, in order to achieve similar levels of perceived intensity, mean heart rate for the CE was ∼25 bpm lower than for the TM. CONCLUSION AND SIGNIFICANCE: These results have important implications for model-based design of automatic HR controllers, because, in principle, the same dynamic controller, merely scaled according to the differing steady-state gains, should be able to be applied to the CE and TM exercise modalities.


Assuntos
Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Consumo de Oxigênio/fisiologia , Adulto , Metabolismo Energético/fisiologia , Ergometria/métodos , Teste de Esforço/métodos , Voluntários Saudáveis , Humanos , Masculino , Esforço Físico/fisiologia
16.
J Sci Med Sport ; 22(11): 1206-1212, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31371258

RESUMO

OBJECTIVES: Despite the high prevalence of low back pain (LBP) in rowers, there are few studies investigating changes in lumbar muscle activation in rowers with a recent history of LBP. Such knowledge is relevant to understand potential mechanisms contributing to the maintenance and recurrence of LBP in rowers. For the first time, we evaluate the spatial distribution of erector spinae (ES) activity in rowers with and without a recent history of LBP, using a novel application of high-density surface electromyography (HDEMG). DESIGN: Cross-sectional study. METHODS: Asymptomatic rowers (N=10) and rowers with a recent history of LBP (N=8) performed 7×4-min exercise bouts (rowing ergometer) until volitional exhaustion. HDEMG signals were acquired bilaterally over the lumbar ES and the root mean square (RMS) amplitude and entropy were analyzed. In addition, the y-axis coordinate of the barycentre (RMS-map) was used to assess changes in ES spatial activation. RESULTS: As the load increased, rowers with LBP showed higher amplitude (p<0.01) and less complexity (entropy) of the HDEMG signals (p<0.001). In addition, rowers with LBP showed opposite displacements of the barycentre, specifically showing a caudal shift of muscle activity at high intensities (p<0.001). CONCLUSIONS: Both the magnitude of activation and distribution of ES activity were altered in rowers with a recent history of LBP. The lower complexity of signals together with the caudal displacements of the barycentre suggest an inefficient recruitment of the ES as the load progressed. Modification of the rowing technique in conjunction with feedback from HDEMG might prove useful in future studies.


Assuntos
Dor Lombar/fisiopatologia , Região Lombossacral , Músculos Paraespinais/fisiologia , Esportes Aquáticos/fisiologia , Adolescente , Adulto , Estudos Transversais , Eletromiografia , Ergometria , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
17.
Ann Agric Environ Med ; 26(2): 361-368, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31232072

RESUMO

OBJECTIVES: The aim of this study was to discover the relationship between the performance of different mechanical movements of rowers, and define its effect on the motor programs of the cyclic movement in athletes living in rural and urban areas. MATERIAL AND METHODS: Twenty-two male rowers participated in the experiment using a rowing ergometer (Concept2, USA). The experiment consisted of 3 tests examining the maximal power of the pull-ups (MPbpu). The movement mechanogram was registered with a specialized complex Noraxon's 3D MyoMotion (Noraxon Inc., USA). The software of the complex allowed calculation of the values of the joint angles from the accelerometer data. The Origin Lab 8.5 program was used for the mathematical and statistical processing of the signals from the mechanograms. RESULTS: It was found that all experiment participants had a stepped controlled increase in the power of single bar pull-ups leading to a corresponding proportional increase in the frequency of rowing - test 1 and, conversely, a stepped controlled increase in the rowing frequency accompanied by a proportional increase in the power of the bar pull-ups - test 2. The involuntary dependence of the power and the rate was due to the peculiarities of the central cyclic movement programming, according to which the forces and durations of the active and passive bar pull-ups phases were interconnected and regulated together. The voluntary power-rate dependence control led to the breakdown of these links in the motor program of cyclic movements and to the separate control of these parameters. CONCLUSIONS: Motor programs in cyclic movement may be created in the same pattern in tope level sport and recreation, as well in different environmental conditions - gym halls (movement simulators), professional and recreational water sport tracks.


Assuntos
Desempenho Atlético/fisiologia , Esportes Aquáticos/fisiologia , Atletas/estatística & dados numéricos , Desempenho Atlético/estatística & dados numéricos , Ergometria , Humanos , Masculino , Esportes Aquáticos/estatística & dados numéricos , Adulto Jovem
18.
J Sports Sci Med ; 18(2): 264-270, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31191096

RESUMO

This study compared biomechanical characteristics and physiological responses during rowing on three devices: (i) stable ergometer (STE), (ii) transversally compliant ergometer (TCE) and (iii) frontally compliant ergometer (FCE). Eleven young competitive rowers completed a 2000 meter simulated race under each of the ergometer conditions in a randomized order. Stroke rate, average force, power output, velocity and amplitude of the handle and stretcher or seat, heart rate and blood lactate were measured at 500 m intervals. Force and power at the stretcher were significantly lower (p < 0.03) for TCE, while stroke rate and velocities of the handle and the seat were higher (p < 0.01). No significant differences were observed between STE and FCE in biomechanical parameters. The lowest rowing performance was observed in FCE (p = 0.007), and was accompanied with the highest average heart rate (p = 0.031). Our findings indicate that in TCE, rowers modified their technique, but were able to maintain physiological strain and performance. In contrast, FCE had no effect on rowing biomechanics, but decreased rowing performance and increased physiological strain. It seems plausible that transversal, but not frontal compliance, elicited a biomechanical technique that might reduce the discrepancy between a rowing ergometer and on-water rowing.


Assuntos
Desempenho Atlético/fisiologia , Ergometria/instrumentação , Esportes Aquáticos , Adolescente , Fenômenos Biomecânicos , Frequência Cardíaca , Humanos , Ácido Láctico/sangue , Masculino
19.
Rev. Soc. Cardiol. Estado de Säo Paulo ; 29(Suppl. 2b): 198-198, Jun. 2019.
Artigo em Português | Sec. Est. Saúde SP, SESSP-IDPCPROD, Sec. Est. Saúde SP | ID: biblio-1010249

RESUMO

INTRODUÇÃO: As síncopes em crianças correspondem em sua maioria a casos dramáticos que trazem grande ansiedade aos cuidadores e as equipes médicas. Apesar de frequentes na população pediátrica, a diferenciação entre quadros neuromediados e cardíacos necessita de uma cuidadosa interpretação do quadro clínico, exame físico e complementação laboratorial. Síncopes de origem cardíaca, principalmente as geradas por síndromes eletrogenéticas, podem ser o prenuncio real de morte e devem merecer total atenção de pediatras e cardiologistas. OBJETIVO: Descrever o caso de uma paciente pré-adolescente portadora de síncope e histórico familiar de morte súbita. RELATO DE CASO: Menina de 9 anos previamente hígida e com quadro de síncope hà 2 anos com pródromos de tontura durante atividade recreativa. Apresentava história familiar de morte inexplicada em parentes de primeiro grau (4 casos durante a adolescência/adulto jovem) todos durante momentos de stress emocional. Foi avaliada em serviço especializado em arritmia pediátrica. Apresentava coração estruturalmente normal assim como padrão normal de eletrocardiograma em repouso (Figura 1). Durante avaliação, apresentava queixa de tontura e foi realizado teste ergométrico. o mesmo demonstrava extrassístoles ventriculares polimórficas que progrediram para taquicardia ventricular polimórfica de padrão bidirecional no pico do esforço. (Figura 2). Foi introduzido e otimizado a dose do betabloqueador (Propranolol 60 mg/dia) com remissão do quadro arrítmico nos exames de controle. Segue assintomática em avaliação para implante de cardiodesfibrilador implantável devido à gravidade do quadro familiar. CONCLUSÕES: 1) Apesar da presença de pródromos, as síncopes de origem arrítmica devem ser suspeitadas em jovens com ocorrência durante a atividade física. 2) A anamnese, o exame físico e o histórico familiar são essenciais nos casos de síndromes elétricas, sendo entidades raras, como a TVC (1:10000 casos), potencialmente fatais de não estabelecer o diagnóstico. 3) O teste de esforço, mesmo em jovens, é essencial para o diagnóstico de taquicardias induzidas por catecolamina, servindo de diagnóstico e controle após o uso de terapia betabloqueadora. (AU)


Assuntos
Humanos , Síncope , Ergometria , Taquicardia Ventricular , Diagnóstico
20.
COPD ; 16(1): 37-44, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-31056954

RESUMO

Exercise can improve walking capacity in persons with chronic obstructive pulmonary disease (COPD). However, most endurance training programs use cycle ergometers. The objectives of this study were: (i) to evaluate the feasibility of a randomized controlled trial (RCT) comparing outdoor walking training (OWT) to cycle ergometer training (CT) during inpatient rehabilitation in persons with severe COPD; (ii) to estimate the effect of OWT and CT on health-related quality of life, physical capacity and physical activity; and (iii) to estimate the required sample size for a RCT. A single-blind randomized controlled feasibility trial was conducted with three months' follow-up in the rehabilitation center in Walenstadtberg, Switzerland. Sixteen patients were included in the study, which had a recruitment rate of 33% (16/48). Patients were allocated to an OWT (n = 8) or CT (n = 8) group. Participants completed 75% of scheduled training and the follow-up rate was 75%. All participants in the OWT group were satisfied with the training. The OWT group had better health-related quality of life after three weeks' training compared to the CT group (p = 0.042, 95% confidence interval (95% CI) 1.06-49.94, effect size (d)=1.19). No exacerbations occurred in the OWT group, but three occurred in the CT group after three months' follow-up. There was no significant difference in the other outcomes. In conclusion, the study design and the OWT are feasible. Health-related quality of life improved in the OWT group compared to the CT group after three weeks' inpatient rehabilitation. A minimum of 46 participants is needed for a RCT. Trial registration: www.who.int/trialsearch DRKS00010977.


Assuntos
Treino Aeróbico/métodos , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/reabilitação , Caminhada/fisiologia , Idoso , Atitude do Pessoal de Saúde , Ergometria , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Resistência Física , Qualidade de Vida , Tamanho da Amostra , Método Simples-Cego , Resultado do Tratamento , Teste de Caminhada
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