The effects of high-intensity intermittent training on metabolic or circulatory parameters and exercise time during 30s lasting exhaustive exercise / 体力科学

Present study aimed to examine the effects of high-intensity intermittent training on metabolic or circulatory parameters and exercise time during 30s-lasting exhaustive exercise. Six healthy males (22 ± 1yrs) had an intermittent training four days a week for four weeks. The intermittent training consisted of 8 or more sets of 20s exercise bout at an intensity of 170%VO2 max separated by 10-s recovery. Before and after training period, VO2 max and maximal accumulated O2 deficit (MAOD) were determined as indices of metabolic capacity. During 30s-lasting exhaustive exercise, VO2, O2 deficit, and circulatory parameters, such as heart rate, stroke volume, and cardiac output, were also determined every 10s. After the training, VO2 max and MAOD were significantly increased. During 30s-lasting exhaustive exercise, exercise time, stroke volume, and cardiac output were also significantly enhanced. However, no significant differences were observed in VO2 and O2 deficit every 10s during 30s-lasting exhaustive exercise. Therefore, these findings suggest that high-intensity intermittent training enhances exercise time during 30s-lasting exhaustive exercise and that the improvement of exercise performance is closely related to an increase in anaerobic capacity.

Effect of temperature for cooling leg on intermittent exercise performance during half-time in a hot environment / 体力科学

Intermittent exercise performance in a hot environment is lower than in temperate conditions. Cooling strategies at rest are important; however, the appropriate cooling temperature is not clear. The purpose of this study was to investigate the effect of temperature for cooling leg during half-time (HT) on intermittent exercise performance. Eleven men performed two pre-tests and three experimental trials of a 2 × 30 min intermittent exercise protocol in the heat (33°C; 50% relative humidity). During HT, three experimental conditions were set: no cooling (CON), cooling at the thigh using 12°C ice packs (COOL), and cooling at the thigh using 0°C ice packs (ICE) for 15 min. During the 2nd half, which consisted of 5 s maximal power pedaling every minute separated by 50 s of unloaded pedaling (80 rpm) and rest (5 s), the subjects repeated 2 × 15 sets of the intermittent exercise protocol. The peak power output under the COOL condition (694 ± 80 W) was significantly higher than that of the CON (653 ± 84 W). Thigh skin and deep temperatures showed a significant difference between each condition. In the COOL, thermal sensation was significantly lower, and thermal comfort was significantly higher. In a protocol that simulates intermittent athletic competitions such as soccer in a hot environment, using ice packs at 12°C to cool the thigh during HT lowered thigh skin and deep temperatures and improved heat perception and intermittent exercise performance. This cooling strategy is practical, suggesting that it would be effective for actual competitive situations.

Can the elite slalom kayaker's performance be correlated with anthropometric, nutritional, genetic, psychological as sleep traits?

Abstract AIMS The aims of this study were to investigate and characterize the anthropometric, nutritional, genetic, psychological and sleep variables of slalom kayakers, and to verify the correlation of these variables with the slalom kayakers' performance. METHODS Ten elite Brazilian team slalom kayakers participated of this study. Nutritional analysis was made by the Food Record (three days), 24 Hour Dietary Recall and Food Frequency Questionnaire. The ACE I/D, AGTMet235Thr, ACTN3R577X and BDKRB2+9/-9 were genotyped for genetic profile. The Profile of Mood States (POMS) and Sports Competition Anxiety Test (SCAT) were applied to investigate the psychological variables. The Pittsburgh Sleep Quality Index (PSQI), Epworth Sleep Scale (ESS) and Morningness-eveningness questionnaire (MEQ) were used for sleep traits analysis. Performance trials were performed on a white-water course with 24 gates, and finish time was considered as the variable related to performance. RESULTS Significant correlations were obtained between Performance Time Trial and %Fat (r=0.77), Energy (r=-0.75), Protein (r=-0.76), Carbohydrate (r=-0.72), Vitamin B6 (r=-0.87), Vitamin A (r=-0.82), Thiamine (r=-0.77), Riboflavin (r=-0.71), Magnesium (r=-0.86) and Phosphorus (r=-0.74) intake, besides the Fatigue mood domain (r=0.73) and the SCAT score (r=0.67). Athletes genotyped with the I, T, R and +9 alelle also presented better performances. CONCLUSIONSIn summary, the novel results provided by this study reinforce the necessity of considering several aspects during athlete development in order to achieve better performance in competitions.

Refining Music Tempo For An Ergogenic Effect On Stationary Cycling Exercise1 / Refinando o tempo da música para um efeito ergogênico no exercício do ciclismo ergomêtrico

Abstract Aburto-Corona, J. & Aragón-Vargas, L.F. (2017). Refining music tempo for an ergogenic effect on stationary cycling exercise. PENSAR EN MOVIMIENTO: Revista de Ciencias del Ejercicio y la Salud, 15(2), 1-12. The effect of music on exercise performance has been studied from many perspectives, but the results have not been as clear as expected, probably due to a lack of appropriate controls. The purpose of this study was to measure stationary cycling performance in a warm environment under carefully controlled conditions, modifying only the presence of music and its tempo. Ten physically active students, 24.5 ±3.6 years (mean±SD) selected their favorite exercise music and performed a maximum cycling test. During subsequent visits to the laboratory, they pedaled at their preferred speed against a constant resistance (70% of maximum) in an environmentally controlled chamber (28.6±0.5 °C db and 65±3% rh) for 30 min, on three different days, without music (NM), medium tempo music (MT-120 bpm) or fast tempo music (FT-140 bpm), in random order. Perceived exertion (PE), heart rate (HR) and total work performed (W) were recorded. There was no significant difference among conditions for PE (4.47±1.52; 4.22±1.5; 3.83±2.06 a.u. for NM, MT and FT, respectively, p=.162) or HR (142.4±24.53; 142.6±24.37; 142.9±18.36 bpm for NM, MT and FT, respectively, p=.994), but W was different (43.4±19.02; 46.1±20.34; 47.1±20.97, kJ for NM, MT and FT, respectively, p=.009); post-hoc analysis showed that the W difference was only between FT and NM. Using individually selected preferred music in a carefully controlled environment, participants improved their spontaneous cycling performance only when the music had a fast tempo of 140 bpm.

Resumo Aburto-Corona, J. & Aragón-Vargas, L.F. (2017). Refinando o tempo da música para um efeito ergogênico no exercício do ciclismo ergométrico. PENSAR EN MOVIMIENTO: Revista de Ciencias del Ejercicio y la Salud, 15(2), 1-12. O efeito da música durante o exercício tem sido estudado desde muitas perspectivas, mas os resultados não tem sido totalmente claros, provavelmente pela falta apropriada de controle na pesquisa. O propósito deste estudo foi medir o rendimento físico em uma bicicleta ergométrica em um ambiente quente, em condições cuidadosamente controladas, modificando apenas o tempo da música. Dez estudantes fisicamente ativos, 24.5±3.6 anos de idade (média ± desvio padrão), escolheram sua música favorita para fazer exercício e realizaram uma prova de máximo esforço na bicicleta. Durante as seguintes visitas ao laboratório, os participantes mantiveram uma cadência de sua preferência e uma resistência constante (70% da carga máxima) dentro de uma sala de clima controlado (28.6±0.5°C e 65±3%HR) por 30 minutos em três dias diferentes, sem música (NM), com música de ritmo moderado (MT-120bpm) ou música de ritmo rápido (FT-140bpm) em ordem aleatória. Foi registrado o esforço percebido (PE), a frequência cardíaca (HR) e o trabalho realizado (W). Não se encontrou diferença significativa entre condições PE (4.47±1.52; 4.22±1.5; 3.83±2.06u.a. para NM, MT e FT, respectivamente, p=.162) nem HR (142.4±24.53; 142.6±24.37; 142.9±18.36bpm para NM, MT e FT, respectivamente, p=.994). Porém, sim foram encontradas diferenças em W (43.4±19.02; 46.1±20.34; 47.1±20.97kJ para NM, MT e FT, respectivamente, p=.009); a análise post-hoc demonstrou que essas diferenças em W eram entre FT e NM. Ao utilizar música que cada pessoa gosta de ouvir enquanto se exercita em um ambiente cuidadosamente controlado, os participantes melhoraram o rendimento físico somente com ritmo rápido de 140bpm.

Effects of carbohydrate restriction on exercise performance / 体力科学

<p>Carbohydrate is a crucial energy fuel for exercise, and carbohydrate supplementation as peri-exercise has beneficial effects on exercise performance. However, recent studies have indicated the possibility that periodized carbohydrate restriction improves exercise performance. Carbohydrate restriction before exercise increases fatty-acid oxidation (FAO) and alternatively prevents carbohydrate consumption during exercise. This may contribute to the prevention of muscle glycogen depletion during endurance exercise competition. Additionally, acute and chronic studies have shown that peri-exercise carbohydrate restriction enhances molecular and functional adaptation related to FAO. Similarly, exercise training in a low-muscle glycogen state accompanied by carbohydrate restriction was reported to enhance mitochondrial biogenesis and improve FAO capacity, aerobic capacity, and endurance performance in untrained and highly trained subjects. The potential mechanism of these metabolic adaptations may be related to elevated circulating fatty-acid and adrenaline concentration during exercise with carbohydrate restriction and/or a low-muscle glycogen state. In addition, a decrease in muscle glycogen content may trigger signaling pathways related to FAO and mitochondria biogenesis by activating proteins with a glycogen-binding domain. This article reviews the effects of exercise with carbohydrate restriction and/or low-muscle glycogen state on metabolic adaptation and exercise performance and describes the molecular mechanisms and availability.</p>

Conjugated linoleic acid supplementation does not maximize motor performance and abdominal and trunk fat loss induced by aerobic training in overweight women / Suplementação de ácido linoléico conjugado não maximiza o desempenho motor e a perda de gordura de tronco e abdominal induzida pelo treinamento aeróbio em mulheres com excesso de peso

ABSTRACT Objective: To analyze the effect of eight weeks of conjugated linoleic acid supplementation on physical performance, and trunk and abdominal fat in overweight women submitted to an aerobic training program. Methods: Twenty-eight overweight women (body mass index ³25 kg/m2) were divided randomly and double-blindly to receive conjugated linoleic acid or placebo, both associated with an aerobic exercise program (frequency = three times a week, duration=30 min/session, intensity=80% of maximum heart rate). Conjugated linoleic acid (3.2 g) and placebo (4.0 g) supplements were consumed daily (four capsules) for eight weeks. Maximum speed and time to exhaustion were determined in incremental treadmill test. Trunk fat was estimated by dual-energy X-Ray absorptiometry. Waist circumference was used as indicator of abdominal fat. Results: Main effect of time (p<0.05) showed increased maximum speed (conjugated linoleic acid=+6.3% vs. placebo=+7.5%) and time to exhaustion (conjugated linoleic acid=+7.1% vs. placebo=+8.6%) in the incremental treadmill test, with no differences between the groups (p>0.05). Similarly, significant reductions (p<0.05) in trunk fat (conjugated linoleic acid=-1.7% vs. placebo=-1.5%) and abdominal fat (conjugated linoleic acid=-4.7% vs. placebo=-4.0%) were found after eight weeks of intervention, with no differences between the groups (p>0.05). Conclusion: The results of this study suggest that conjugated linoleic acid supplementation does not maximize motor performance, and loss of body and abdominal fat induced by aerobic training in overweight women.

RESUMO Objetivo: Analisar o efeito de oito semanas de suplementação de ácido linoleico conjugado sobre o desempenho físico, a gordura de tronco e abdominal em mulheres com excesso de peso submetidas a um programa de treinamento aeróbio. Métodos: Vinte e oito mulheres com excesso de peso (índice de massa corporal ³ 25 kg/m2) foram separadas aleatoriamente por meio de um delineamento duplo cego para receber suplementação de ácido linoleico ou placebo associado a um programa de exercícios aeróbios (frequência = três sessões semanais, duração=30 min/sessão, intensidade=80% da frequência cardíaca máxima). A suplementação de ácido linoleico (3,2 g) ou de placebo (4,0 g) foi consumida diariamente (quatro cápsulas), durante oito semanas. As variáveis velocidade máxima atingida e tempo de permanência até a exaustão foram determinadas em teste incremental em esteira. A gordura de tronco foi estimada por absortometria radiológica de dupla energia. A circunferência de cintura foi utilizada como indicador de gordura abdominal. Resultados: Efeito principal do tempo (p<0,05) revelou aumento da velocidade máxima atingida (suplementação de ácido linoleico=+6,3% versus placebo=+7,5%) e tempo de duração até a exaustão (suplementação de ácido linoleico=+7,1% versus placebo=+8,6%) em teste incremental em esteira, sem diferenças entre os grupos (p>0,05). De forma similar, uma redução significante (p<0,05) na gordura relativa de tronco (suplementação de ácido linoleico=-1,7% versus placebo=-1,5%) e na gordura abdominal (suplementação de ácido linoleico=-4,7% versus placebo=-4,0%) foi encontrada após oito semanas de intervenção, sem diferenças entre os grupos (p>0,05). Conclusão: Os resultados do presente estudo sugerem que a suplementação de ácido linoleico não maximiza o desempenho motor e a redução da gordura de tronco e abdominal induzida pelo treinamento aeróbio em mulheres com excesso de peso.

Improvement effect of interval training on respiratory function and exercise performance of asthmatic children / 吉林大学学报(医学版)

Objective:To observe the effects of 8-week interval anaerobic training on the respiratory function, airway inflammatoion and exercise performance in the asthmatic children,and to provide theoretic and practical evidence for special exercise prescription for the asthmatic children.Methods:Forty-six mild asthmatic children were willingly divided into exercise group (n=23)and control group (n=23).The children in exercise group conducted 8 weeks interval anaerobic training while the children in control group maintained intrinsical lifestyle.Before and after experiment,the respiratory function,airway inflammatory reaction and exercise performance were determined by pneumonometer,nitric oxide determinator and cycle ergometer.Results:One patient of each group was lost to follow up.509 persons in exercise group finished the training;11 persons had adverse reaction and the incidence was 2.2%.After experiment,compared with before experiment,the peak expiratory flow (PEF)in exercise group after experiment was increased (P 0.05).Compared with control group after experiment,all indexes above (PEF,FeNO,MP and PP)in exercise group existed statistical differences (P <0.05).Conclusion:Interval anaerobic training has safetiveness and effectiveness under proper supervision and could improve the respiratory function,reduce the airway inflammation and enhance the exercise performance in the mild asthmatic children.

Muscle Activation Pattern During Isometric Ab Wheel Rollout Exercise in Different Shoulder Angle-Positions / Padrão isométrico de ativação muscular durante o exercício AB Wheel Rollout em diferentes posições do complexo articular do ombro

OBJECTIVE: To investigate muscle activation of the shoulder extensors and trunk stabilizers by surface electromyography (sEMG) activity during the isometric Ab Wheel Rollout exercise in different shoulder joint positions. METHOD: We recruited 8 young, healthy, resistance trained men (age: 25 ± 3 years, height: 178 ± 5 cm, and total body mass: 81 ± 2 kg). All subjects performed two sets of 10 sec. maximal isometric contractions of the Ab Wheel Rollout exercise keeping the knees fixed on the floor and the arms taut. To perform the exercise, all subjects were randomly assessed in the following three positions related to the angle between the arms and trunk, in random order: arms aligned vertically with the Ab Wheel Rollout exercise (neutral); 90º and 150º. A rest period of 5 minutes was provided between tests. The sEMG signals were recorded in the following muscles: Latissimus Dorsi; Pectoralis Major; Erector Spinae; Rectus Abdominis. RESULTS: There were significant increases in Rectus Abdominis muscle activity between: neutral vs. 90º, neutral vs. 150º and 90º vs. 150º. There was a significant increase in Pectoralis Major muscle activity between neutral x 150º. CONCLUSION: The present findings indicate that (a) Ab Wheel Rollout exercise emphasizes the muscle action of the Pectoralis Major and Rectus Abdominis more than the Latissimus Dorsi and Erector Spinae; (b) the level of muscle activation depends on the external force created by the body mass and lever arm from the center of mass.

RESUMO OBJETIVO: O objetivo do estudo foi investigar o padrão de atividade muscular isométrica de extensores de ombro e estabilizadores de tronco através de eletromiografia de superfície (sEMG) durante diferentes posições do complexo articular do ombro durante o exercício Ab Wheel Rollout. MÉTODO: Foram recrutados 8 voluntários jovens e treinados em força, com idade: 25 ± 3 anos, estatura: 178 ± 5 cm, e massa corporal total: 81 ± 2 kg. Os participantes realizaram duas séries de 10 segundos em contração isométrica utilizando o Ab Wheel Rollout, e mantiveram os joelhos apoiados no chão e os braços estendidos. Três posições de ombro (em relação ao tronco) foram avaliadas de forma aleatória entre os participantes: braços posicionados na vertical e alinhado ao eixo do Ab Wheel Rollout (neutra); 90 graus and 150 graus. Um período de cinco minutos de repouso foi respeitado entre posições e tentativas. Os sinais mioelétricos foram medidos para os seguintes músculos: Latíssimo do Dorso; Peitoral Maior; Eretor da Coluna; Reto do Abdome. RESULTADOS: Foi observado um aumento significante da atividade muscular isométrica para o músculo Reto do Abdome entre as posições: neutra x 90º, neutra x 150º e 90º x 150º. Houve aumento significante na ativação muscular isométrica do Peitoral Maior entre a posição neutra x 150º. CONCLUSÃO: O presente estudo indica que (a) o exercício Ab Wheel Rollout enfatiza a ação muscular do Peitoral Maior e do Reto do Abdome em relação ao Latíssimo do Dorso e aos Eretores da Coluna; (b) o nível de ativação mioelétrica depende das forças externas criadas pelo peso corporal e pelo braço de alavanca do centro de massa.

Effects of a full season on stabilometric parameters of team handball elite athletes / Efeitos da temporada completa em parâmetros estabilométricos em atletas de handebol de elite / Efectos de la temporada completa en parámetros estabilométricos en atletas de balonmano de élite

It is unclear whether athletes change their postural control over the course of a full sport season, or become more asymmetrical with respect to their neuromuscular performance over the same period. The aim of this study was to investigate the effects of a full sport season on the postural control of team handball elite athletes. Ten healthy, elite male team handball players performed bipodal standing (BP) and right and left unipodal standing (UP) during 30s. We used the RMS and speed of the center of pressure to describe postural sway. For the BP task, the sway was lower at the end of the season (p<0.005). For the UP tasks, the sway was lower at the end of the season only for the non-dominant limb (p<0.001). Differences between limbs were observed only at the end of the season (p<0.03). In conclusion, a full team handball season did not lead to deterioration of the athletes' postural control, but by the end of the season, the athletes were more asymmetrical.

Não é claro na literatura científica se atletas mudam seu controle postural ao longo de uma temporada esportiva, ou mesmo se tornam mais assimétricos em relação ao seu desempenho neuromuscular durante o mesmo período. O objetivo deste estudo foi investigar os efeitos de uma temporada esportiva completa no controle postural de atletas de elite do handebol. Dez jogadores de elite de handebol, saudáveis, realizaram a tarefa de postura ereta quieta bipodal (BP) e unipodal direito e esquerdo durante 30 segundos. Foi utilizada a RMS e a velocidade do centro de pressão para descrever a oscilação postural. Para a tarefa de BP, a oscilação foi menor após a temporada esportiva (p < 0,005). Para as tarefas unipodais, a oscilação foi menor após temporada esportiva apenas para o membro não dominante (p < 0,001). Apenas após a temporada, foram observadas diferenças entre os membros (p < 0,03). Em conclusão, uma temporada esportiva para o handebol não levou à deterioração do controle postural dos atletas, entretanto no final da temporada, os atletas apresentaram-se mais assimétricos.

No está claro en la literatura científica si los atletas cambian su control postural a lo largo de una temporada deportiva o incluso si llegan a ser más asimétricas en relación con su rendimiento neuromuscular durante el mismo período. El objetivo de este estudio fue investigar los efectos de una temporada deportiva completa en control postural de deportistas de elite de balonmano. Diez jugadores de balonmano de élite, sanos, llevaron a cabo la tarea de la tranquilidad de la postura de pie bipodal (BP) y unipodal izquierda y derecha durante 30 segundos. RMS fue utilizado y la velocidad del centro de presión para describir el balanceo postural. Para la tarea de BP, la oscilación fue menor después de la temporada de deportes (p < 0,005). Para unipodais las tareas, la oscilación fue menor después de la temporada deportiva para el miembro no dominante (p < 0,001). Solamente después de la temporada, se observaron diferencias entre los miembros (p < 0,03). En conclusión, una temporada de deportes para el balonmano no conduce al deterioro del control postural de los atletas, sin embargo al final de la temporada, los atletas presentaron más asimétrica.

Efeito do nadar sobre o desempenho do pedal e corrida no triathlon super-sprint / Effect of swimming on the cycling and running performances during the super-sprint triathlon

A influência da sub-disciplina natação sobre o subsequente desempenho ciclismo/corrida parece aumentar com a redução da distância do triathlon. Assim, o objetivo do presente estudo foi analisar o efeito da natação sobre o desempenho do ciclismo e corrida no triathlon super-sprint. Oito triatletas amadores realizaram um teste de triathlon super-sprint, consistindo em nadar 375 m, pedalar 10 km e correr 2,5 km (Tri) e outro no qual deveriam apenas pedalar 10 km e correr 2,5 km (PC). A realização da sub-disciplina natação impactou de forma negativa o subsequente desempenho do ciclismo (-8,4%) e o tempo total (ciclismo + corrida; -5,4%) quando comparados à realização das mesmas sem a presença prévia da natação. Com exceção da corrida no protocolo PC, todas as sub-disciplinas apresentaram significativas correlações com o tempo total (r ≥ 0,84) para ambos os protocolos. Em conclusão, a realização da sub-disciplina natação afeta negativamente o desempenho do pedal e do tempo total (pedal + corrida) durante o triathlon super-sprint.

The influence of the swimming sub-discipline upon the subsequent cycling/running performance seems to increase with the reduction of the triathlon's length. Thus, the purpose of this study was to analyze the effects of swimming upon the cycling and running performance during the super-sprint triathlon. Eight amateur triathletes performed a bout of super-sprint triathlon, consisting of swimming 375 m, cycling 10 km and running 2.5 km (Tri) and another bout consisting of only cycling 10 km and running 2.5 km (CR). Performing the swimming sub-discipline had a negative impact (p < 0.05) in the cycling performance (-8.4%) and total time (cycling + running; -5.4%) when compared to the performance achieved without the swimming sub-discipline. The running performance was not affected. Except running in CR protocol, all the other sub-disciplines presented high and significant correlations with the total time (r ≥ 0.84) for both protocols. In conclusion, performing the swimming sub-discipline has a negative impact in the subsequent cycling and total time (cycling + running) during the super-sprint triathlon.

The psychobiological model: a new explanation to intensity regulation and (in)tolerance in endurance exercise

The mechanisms underpinning fatigue and exhaustion, and the specific sources of exercise-endurance intensity regulation and (in)tolerance have been investigated for over a century. Although several scientific theories are currently available, over the past five years a new framework called Psychobiological model has been proposed. This model gives greater attention to perceptual and motivational factors than its antecedents, and their respective influence on the conscious process of decision-making and behavioral regulation. In this review we present experimental evidences and summarize the key points of the Psychobiological model to explain intensity regulation and (in)tolerance in endurance exercise. Still, we discuss how the Psychobiological model explains training-induced adaptations related to improvements in performance, experimental manipulations, its predictions, and propose future directions for this investigative area. The Psychobiological model may give a new perspective to the results already published in the literature, helping scientists to better guide their research problems, as well as to analyze and interpret new findings more accurately...

Os mecanismos que explicam fadiga e exaustão, controle da intensidade e (in)tolerância ao exercício de resistência cardiorrespiratória têm sido estudados há mais de um século. Apesar de diversas teorias científicas atualmente disponíveis, nos últimos cinco anos um novo modelo chamado de Psicobiológico tem sido proposto. Este modelo dá maior importância aos fatores perceptuais e motivacionais em relação aos seus antecessores, bem como a respectiva influência destes fatores no processo consciente de tomada de decisão e controle comportamental. Nesta revisão, nós apresentamos evidências experimentais e sintetizamos os pontos chaves do modelo Psicobiológico que explicam o controle da intensidade e (in)tolerância ao exercício de resistência cardiorrespiratória. Adicionalmente, nós discutimos como o modelo explica as adaptações ao treinamento relacionadas à melhora no desempenho, as manipulações experimentais e suas predições. Ao final, propomos futuras direções para esta área investigativa. O modelo Psicobiológico pode proporcionar uma nova perspectiva aos resultados anteriormente publicados na literatura, ajudando os cientistas a entenderem melhor seus problemas de pesquisa, assim como analisar e interpretar novas evidências mais precisamente...

INFLUENCE OF RUNNING SPEED AND EXERCISE DURATION ON BLOOD GLUCOSE THRESHOLD DURING LONG-DISTANCE RUNNING / 体力科学

This study was intended to clarify 1) the difference of the exercise intensity at blood lactate threshold (LT) and blood glucose threshold (GT), 2) the effect of exercise duration on the LT and GT during two sets of incremental running test. Ten male runners (age 25.0±3.2 yr, height 171.2±5.5 cm, body mass 57.9±4.0 kg, VO_2max 64.6±3.0 ml/kg/min) completed two sets of incremental running test (each set was set to run ten stages at 60-90% VO_2max). Second set was repeated after 8 min recovery. LT and GT speed were investigated at the first set. Lactate minimum (LM) and glucose minimum (GM) speed were selected where the blood lactate and glucose concentration were at the lowest during the second set. Using the indirect calorimetry (VO₂, VCO₂), fat and carbohydrate oxidation rates were calculated. GT was observed in all runners. VO₂ and energy expenditure were similar between the two incremental running tests, however, fat oxidation was significantly higher and carbohydrate oxidation was significantly lower during the first half of the second set. This change was regarded as the influence of the exercise duration in the first set. Furthermore, GM speed was significantly lower than GT speed, but LM speed and LT speed were not different. It was considered that the shift of GT was affected by the substrate utilization change during prolonged exercise.

Effects of Angiotensin-Converting Enzyme Inhibitor on Arterial Stiffness, Diastolic Function, and Exercise Performance in Patients with Hypertension

BACKGROUND: The aim of this study was to investigate the relations between arterial stiffness, diastolic function, and exercise performance and the effects of angiotensin-converting enzyme inhibitor(ACEI), perindopril, in these three areas in patients with hypertension(HT). METHODS: A total of 39 patients(60.9+/-4.9 years, 23 males) with a newly diagnosed or untreated HT, stage I, were enrolled. Arterial stiffness measured by pulse wave velocity, diastolic function measured by echocardiography, and exercise performance and hemodynamic parameters measured by a treadmill exercise test were compared before and after 6 months of medical treatment with an ACEI. RESULTS: The parameters for arterial stiffness, diastolic function, and exercise performance did not show significant correlations with each other at baseline. Systolic(from 147.6+/-6.5mmHg to 134.3+/-9.6mmHg, p<0.001) and diastolic blood pressures(from 87.7+/-7.5mmHg to 82.9+/-6.2mmHg, p<0.001) decreased significantly after 6 months of ACEI treatment. Except for duration of total exercise time, the parameters for arterial stiffness, diastolic function, and the hemodynamic response to exercise also improved significantly after 6 months of ACEI treatment. CONCLUSION: Though the parameters for arterial stiffness, diastolic function, and exercise performance were not asso- ciated with each other at baseline, they all improved significantly after 6 months of medical treatment with an ACEI in elderly patients with stage I HT. The results of this study suggest the possibility of additional benefits of ACEI beyond lowering blood pressure.

Effects of Dietary Supplementation of Taurine, Carnitine or Glutamine on Endurance Exercise Performance and Fatigue Parameters in Athletes

The effects of taurine, carnitine or glutamine supplementation on endurance exercise performance along with related fatigue factors were evaluated in male college students in the Department of Physical Education, who''s maximal oxygen consumption rates (VO2max) were equivalent to those of endurance athletes. Twenty four subjects were randomly divided into 4 groups (n=6), and given placebo, taurine (4 g/day), carnitine (4 g/day), or glutamine (4 g/day) tablets for 2 weeks. Subjects could run 6.9 min or 9.0 min longer until exhausted on a treadmill at the intensity of 75% VO2max following taurine or camitine supplementation for 2 weeks, respectively, compared to the value measured prior to each supplementation. Glutamine or placebo supplementation did not improve the endurance exercise performance based on the running time until exhausted on a treadmill. Serum lactate concentrations measured 1 hr after the initiation of the endurance exercise, as well as at all-out state tended to be decreased by taurine, carnitine, or glutamine supplementation, and were significantly lowered (43% decrease) by carnitine supplementation (p<0.05). Taurine supplementation significantly reduced the serum inorganic phosphorus concentration measured at all-out state (14% decrease, p<0.05), while carnitine supplementation significantly lowered the resting state serum inorganic phosphorus level (20% decrease, p<0.05). Taurine (32% reduction) or carnitine (23% reduction) supplementation significantly decreased serum ammonia concentration measured at all-out state (p<0.05). From these results, 4 g/day of taurine or carnitine supplementation appears to improve the endurance exercise performance and related human fatigue factors.

Development of Dietary Supplement for the Growth and Exercise Performance Improvement / 대한지역사회영양학회지

We developed a dietary supplement using natural herbs and nutrients for the growth and exercise performance improvement. It called 50-22 supplement containing distilled extracts of natural herbs to remove bitterness and the addition of Vitamin B1, B6, Ca and xylitol. We investigated on the effect of 10-22 supplementation on the maximal exercise performance, IGF-1 (insulin like growth factor-1) concentration and antioxidant activity in SD rat model. In result, JR-22 supplement group was better than control group about 10% in exercise performance test and increased about 63% of IGF-1 concentration in blood. In addition, the oxidative damage induced by exercise was reduced by JR-22 supplementation. Therefore, we suggested that 50-22 supplementation enhanced effectively exercise performance and IGF-1 concentration and reduced to oxidative stress in muscles. Also, we analysed biochemical factors in blood for the safety of JR-22 supplement. We known that there is no change of blood lactic acid, ammonia, inorganic phosphorous ion and creatine kinase activity.

EFFECT OF CARNOSINE CONCENTRATION IN MUSCLE AND IMPROVEMENT OF EXERCISE PERFORMANCES DUE TO LONG-TERM INTAKE OF CHICKEN BREAST EXTRACT / 体力科学

The present study examined the effect of the long-term intake of chicken breast extract (CBEX), which contains carnosine and anserine, on carnosine content in skeletal muscles of humans and on short-period exercise performance with high intensity.<BR>Before and after CBEX was orally given to 13 healthy male subjects for 30 days, pieces of their muscle (<I>M. vastus lateralis</I>) were excised and carnosine concentration in the muscle was measured. Before and after the test period, the subjects exercise performance (mean and peak power body weight) was determined by pedaling for 30 sec. On the basis of baseline concentrations of carnosine, the subjects were classified into two groups: low (n=8) and high (n=5) carnosine-baseline groups. In the former group, intake of CBEX increased carnosine concentration in the muscle (p<0.05), resulting in significant correlation between increased rate of carnosine concentration and mean power. These results suggest that exercise performance depends on carnosine concentration in the muscle, and that taking carnosine-containing foods may improve exercise performance.

The Influence of Fat-Free Mass to Maximum Exercise Performance in Patients with Chronic Obstructive Pulmonary Disease / 결핵

BACKGROUND: Dyspnea and a limitation in exercise performance are important cause of disability in patients with chronic obstructive pulmonary disease (COPD). A depleted nutritional state is a common problem in pati ents with a severe degree of chronic airflow limitation. This study was carried out to assess the factors determining the maximum exercise capacity in patients with COPD. METHODS: The resting pulmonary function, nutritional status, and maximum exercise performance was assessed in 83 stable patients with moderate to severe COPD. The nutritional status was evaluated by bioelectrical impedance analysis. Maximum exercise performance was evaluated by maximum oxygen uptake(VO2max). RESULTS: Among the 83 patients, 59% were characterized by nutritional depletion. In the delpleted group, a significantly lower peak expiratory flow rate(p<0.05), Kco(p<0.01) and maximum inspiratory pressure(p<0.05), but a significantly higher airway resistance(p<0.05) was observed. The maximum oxygen uptake and the peak oxygen pulse were lower in the depleted group. The VO2max correlated with some of the measures of the body composition : fat-free mass (FFM), fat mass (FM), body mass index(BMI), intracellular water index (ICW index), and pulmonary function: forced vital capacity(FVC), forced inspiratory vital capacity(FIVC), diffusion capacity(DLCO) : or maximum respiratory pressure: maximum inspiratory pressure(PImax), maximum expiratory pressure(PEmax). Stepwise regression analysis demonstrated that the FFM, DLCO and FIVC accounted for 68.8% of the variation in the VO2max. CONCLUSIONS: The depletion of the FFM is significant factor for predicting the maximum exercise performance in patients with moderated to severe COPD.

The Effect of "Living High and Training Low" with a Normobaric Hypoxic Tabernacle on Exercise Performance of Rowers / 中国运动医学杂志

This study was to investigate the influnce of 4 weeks of living high-training low on exercise performance of rowers. Twenty rowers were divided into two groups: ten subjects spent 8-10h per night in a tabernacle simulated at an altitude of 2500m in normobaric hypoxia; 10 control subjects slept at near sea level. During the 4-week periods, all rowers were trained at the same relative or at the same intensity of work in normoxia state. The red cell volume (RCV) , haemoglobin mass (Hb) and hematocrit (HCT) were measured before test, 15th and 30th day of study,and measurements were done on a rowing ergometer at sea-level, which included an ergometer test at 4 mmol/L lactate anaerobic threshold and performance in exercise tasks of 2km, 5km, and a Wingate Anaerobic Test before test and 30th day of study. The results showed that adaptation to simulated moderate altitude can stimulate red cell production sufficiently: increase in red cell volume (RCV) , haemoglobin mass (Hb) and hematocrit (Hct). And there were significant increases in all important parameters at 4 mmol/L lactate anaerobic threshold as well as performance of 5km, while the performance of 2km showed no significant improvement, the mean values of both mean power per kilogram body weight and peak power per kilogram body weight were not increased significantly. In the control group, there were no significant changes in the all abovementioned parameters. The results of this study indicate that living high-training low can improve the aerobic energy-supply systems. We conclude that 4-week of living high and training low can improve sea level endurance performance in rowers.

Effect of astragalus complanatus on liver free radical metabolism in rats of exercise training / 西安交通大学学报(医学版)

Objective To study the effect of astragalus complanatus on the metabolism of free radicals in liver and exercise performance in models of exhaustive training rats.Methods After 7 d adaptive training,we randomly divided rats into three groups: quiet control group(A),sport training group(B) and astragalus complanatus training group(C).We measured rat liver indices such as the activities of total superoxide dismutase(T-SOD),glutathione peroxidase(GSH-Px),catalase(CAT) and content of malonaldehyde(MDA).Results The activity of astragalus complanatus groups(C) T-SOD(78.17?0.17),GSH-Px(35.42?1.68) and CAT(17.61?0.05) in liver tissue increased and the content of MDA(6.70?0.53) decreased remarkably compared with that in sport training group(B).Conclusion As an efficient free radical scavenger,astragalus complanatus can strongly enhance anti-oxidative status and improve exercise performance in trained rats.