Eighteen untrained males [age: 23 +/- 0.6 yr (SEM)] were randomized into high intensity (HIT: above lactate threshold, LT), moderate intensity (LIT: below the LT) or no training (NT) groups. Subjects trained on a cycle ergometer 4 days.wk-1 for 6 wk with the power output held constant. Maximal cycle ergometry was performed before and after the training period to determine changes in power output and oxygen consumption (VO2) at the LT and peak exertion. Before training and after 1, 2, 4, and 6 wk, subjects performed high constant-load (HCL) cycling bouts to quantify training adaptations in the SC. Training was designed to keep total work equivalent between the HIT and LIT groups. Increases in power output and VO2 at LT and peak exercise after 6 wk were noted in the HIT and LIT groups in comparison to NT group (p<0.05). No differences were noted between HIT and LIT. Two-way repeated measures ANOVA revealed a significant trial*group interaction for adaptation in the SC (p<0.001). After 1wk of training, a significant reduction in the SC was noted for HIT [mean+/-SEM]: (pre-training (PT): 703 +/- 61 ml.min-1; 1 wk: 396 +/- 60 ml.min-1) (- 44% from PT). Further adaptation for the HIT was also noted at 4 wk: 202 +/- 45 ml.min-1 (-71% from PT). For LIT, a significant reduction was noted at 2 wk (PT: 588+/-76 ml.min-1; 2 wk: 374 +/- 50ml.min-1) (-36% from PT). Further adaptation for LIT group was noted at 6 wk (252 +/- 38 ml.min-1) (- 57% from PT). Adaptation in SC was not noted at any interval for NT. Temporal changes in blood lactate (r = 0.40) and ventilation (r = 0.72) were significantly correlated with the changes for SC over the 6 wk training period (p<0.05). In conclusion, it was demonstrated that training at supra-LT and sub-LT intensities produces similar improvement in VO2 and power output at peak exercise and in the LT, when total work output is controlled. However, training at supra-LT intensity promotes larger and faster adaptations in the SC than training at the sub-LT levels. / Ph. D.

Made available in DSpace on 2014-06-11T19:30:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-20Bitstream added on 2014-06-13T21:01:28Z : No. of bitstreams: 1 machado_fa_dr_rcla_prot.pdf: 683590 bytes, checksum: 781129a241d3ca2dcd4443ff6f9b3f86 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A cinética do consumo de oxigênio (V02) descreve o comportamento respiratório durante a transição repouso-exercício. Os parâmetros derivados dos ajustes (componente lento - CL e constante de tempo - t ou Tau) são utilizados para quantificar a magnitude das alterações ocorridas nesse sistema. Os objetivos deste estudo foram: 1) verificar a influência de diferentes modelos de análise [modelo matemático com três termos exponenciais (Exp3) vs. diferença do V02 entre o sexto e o terceiro minuto de exercício (AVO2 6-3 mm)] na caracterização do CL durante o exercício acima do limiar de lactato (LL) em corrida; 2) verificar os efeitos do tipo de exercício [corrida em esteira rolante (ER) vs. exercício em bicicleta ergométrica (BE)] no pico do consumo de oxigênio (VO210) e LL (expresso em ml/kg/mim e % VO2pjc) e; 3) verificar os efeitos do tipo de exercício no tVO2 e no CL da cinética do V02 durante o exercício acima do LL em meninos de 11-12 anos de idade. Participaram do estudo 20 crianças do gênero masculino aparentemente saudáveis e ativos (11,48 l 0,41 anos; 41,38 l 10,45 kg; 147,45 l 6,56 cm), nível maturacional 1 e 2 (pilosidade pubiana) que realizaram dois testes incrementais, um na ER e outro na BÊ para determinação do VO20 e do LL. Para determinação da cinética do VO2 foram realizadas duas transições de 6 minutos em cada ergômetro na intensidade de 75%A [75% A = LL + 0,75 x (VO2pico - LL)]... / The oxygen uptake kinetic (V02) explaian the respiratory behavior during restexercise transition. The parameters from the adjustment (slow component - SC and time constant - t or Tau) are usual to measure the magnitude of the alterations on this structure. The objectives of this study were: 1) to verify the influence of the two different mathematical models [three-exponential model (Exp3) and AVO2 6-3 mm] on the SC of V02 in children during running exercise, performed at above lactate threshold intensity domain (75%A); 2) to verify the effects of exercise mode (running x cycling) on the indexes related to aerobic fitness (VO2peak and blood lactate response to exercise); 3) to verify the effect of the exercise mode (running x cycling) on the tVO2 and the SC of the VO2 in children aged 11 to 12 years during above lactate threshold intensity exercise (75%). Twenty apparently healthy active boys (age = 11,48 l 0,41 years; body mass = 41,38 l 10,45 kg; hemght = 147,45 l 6,56 cm), sexual maturation levels 1 and 2 (pubic hair) took part of this study. These children performed in different days on a motorized treadmill (TM) and on a cycle ergometer (CE) the following tests: 1) an incremental test in order to determine the peak oxygen uptake (VO2peak) and the LT and; 2) a series of square-wave transitions of 6-min \- 02peak - iJ1) 111 OTT 'Lo Õe'Lerffilne Yne V02 kinetics (tVO2 and SC). The SC values determined by model Exp3 (129,69 l 75,71 mi/min and 8,4 l 2,92 %) were higher than values determined by model VO2 6-3 mm (68,69 l 102,54 mi/min and 3,6 l 7,34%)... (Complete abstract click electronic access below)

Orientador: Benedito Sérgio Denadai / Banca: Mara Patrícia T. Chacon-Mikahil / Banca: Miguel de Arruda / Banca: Luiz Guilherme Antonacci Guglielmo / Banca: Emerson Franchini / Resumo: A cinética do consumo de oxigênio (V02) descreve o comportamento respiratório durante a transição repouso-exercício. Os parâmetros derivados dos ajustes (componente lento - CL e constante de tempo - t ou Tau) são utilizados para quantificar a magnitude das alterações ocorridas nesse sistema. Os objetivos deste estudo foram: 1) verificar a influência de diferentes modelos de análise [modelo matemático com três termos exponenciais (Exp3) vs. diferença do V02 entre o sexto e o terceiro minuto de exercício (AVO2 6-3 mm)] na caracterização do CL durante o exercício acima do limiar de lactato (LL) em corrida; 2) verificar os efeitos do tipo de exercício [corrida em esteira rolante (ER) vs. exercício em bicicleta ergométrica (BE)] no pico do consumo de oxigênio (VO210) e LL (expresso em ml/kg/mim e % VO2pjc) e; 3) verificar os efeitos do tipo de exercício no tVO2 e no CL da cinética do V02 durante o exercício acima do LL em meninos de 11-12 anos de idade. Participaram do estudo 20 crianças do gênero masculino aparentemente saudáveis e ativos (11,48 l 0,41 anos; 41,38 l 10,45 kg; 147,45 l 6,56 cm), nível maturacional 1 e 2 (pilosidade pubiana) que realizaram dois testes incrementais, um na ER e outro na BÊ para determinação do VO20 e do LL. Para determinação da cinética do VO2 foram realizadas duas transições de 6 minutos em cada ergômetro na intensidade de 75%A [75% A = LL + 0,75 x (VO2pico - LL)]... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The oxygen uptake kinetic (V02) explaian the respiratory behavior during restexercise transition. The parameters from the adjustment (slow component - SC and time constant - t or Tau) are usual to measure the magnitude of the alterations on this structure. The objectives of this study were: 1) to verify the influence of the two different mathematical models [three-exponential model (Exp3) and AVO2 6-3 mm] on the SC of V02 in children during running exercise, performed at above lactate threshold intensity domain (75%A); 2) to verify the effects of exercise mode (running x cycling) on the indexes related to aerobic fitness (VO2peak and blood lactate response to exercise); 3) to verify the effect of the exercise mode (running x cycling) on the tVO2 and the SC of the VO2 in children aged 11 to 12 years during above lactate threshold intensity exercise (75%). Twenty apparently healthy active boys (age = 11,48 l 0,41 years; body mass = 41,38 l 10,45 kg; hemght = 147,45 l 6,56 cm), sexual maturation levels 1 and 2 (pubic hair) took part of this study. These children performed in different days on a motorized treadmill (TM) and on a cycle ergometer (CE) the following tests: 1) an incremental test in order to determine the peak oxygen uptake (VO2peak) and the LT and; 2) a series of square-wave transitions of 6-min \- 02peak - iJ1) 111 OTT 'Lo Õe'Lerffilne Yne V02 kinetics (tVO2 and SC). The SC values determined by model Exp3 (129,69 l 75,71 mi/min and 8,4 l 2,92 %) were higher than values determined by model VO2 6-3 mm (68,69 l 102,54 mi/min and 3,6 l 7,34%)... (Complete abstract click electronic access below) / Doutor

This study evaluated novel submaximal indicators of cardio-respiratory fitness during high constant-load (HCL) exercise tests in response to detraining. A central variable was the slow component VO₂ (SC); SC is defined as the difference between end-exercise VO₂ and 3-min VO₂ (Gaesser et a1. ESSR, 1996). Terminal heart rate (HR) and blood lactate (HLa) were taken at the end of HCL tests. Ten sedentary males (18-30 yr) were screened and gave informed consent. Subjects completed a maximal and HCL exercise test for baseline assessment. The maximal test variables, VO₂ peak and lactate threshold (LT), were used to set loads for the HCL tests and the training protocol. Cycle ergometer training was done ~30 min/day, 5 days/week for 6 weeks at . 70(LT – VO₂ peak). Subjects were tested at week six of training and then detrained for two weeks. HCL tests were repeated at one and two weeks of detraining and an additional maximal test was performed after week two. Significant differences (p<0.001) were found in terminal heart rate following one and two weeks of detraining compared to post-training values, with increases of 6.20% and 5%, respectively. No significant changes occurred for SC and HLa. While terminal heart rate is known to exhibit a rapid time course change in detraining, SC and HLa need to be studied for a longer detraining period. / Master of Science

The primary aim of this thesis was to develop a better understanding of the physiology and perceptual responses associated with the performance of continuous (CE) and intermittent exercise (IE) in patients with moderate chronic obstructive pulmonary disease (COPD). A secondary aim was to examine factors that could potentially limit exercise tolerance in COPD patients, particularly in relation to the dynamics of the cardiovascular system and muscle metabolism. The results of the four studies conducted to achieve these aims are presented in this thesis. In Study 1, the physiological, metabolic and perceptual responses to an acute bout of IE and CE were examined in 10 individuals with moderate COPD. Each subject completed an incremental exercise test to exhaustion on a cycle ergometer. Subjects then performed IE (1 min exercise: 1 min rest ratio) and CE tests at 70% of peak power in random order on separate days. Gas exchange, heart rate, plasma lactate concentration, ratings of breathlessness, inspiratory capacity and the total amount of work completed were measured during each exercise test. Subjects were able to complete a significantly greater amount of work during IE (71 ± 32 kJ) compared with CE (31 ± 24 kJ). Intermittent exercise was associated with significantly lower values for oxygen uptake, expired ventilation and plasma lactate concentration when compared with CE. Subjects also reported a significantly lower rating of breathlessness during IE compared to CE. The degree of dynamic lung hyperinflation (change in end-expiratory lung volume) was lower during IE (0.23 ± 0.07 L) than during CE (0.52 ± 0.13 L). The results suggest that IE may be superior to CE as a mode of training for patients with COPD. The greater amount of total work performed and the lower measured physiological responses attained with intermittent exercise could potentially allow greater training adaptations to be achieved in individuals with more limited lung function. The purpose of Study 2 was to compare the adaptations to 8 wk of supervised intermittent and continuous cycle ergometry training, performed at the same relative intensity and matched for total work completed, in patients with COPD. Nineteen subjects with moderate COPD were stratified according to age, gender, and pulmonary function, and then randomly assigned to either an IE (1 min exercise: 1 min rest ratio) or CE training group. Subjects trained 3 d per week for 8 wk and completed 30 min of exercise. Initial training intensity, i.e., the power output applied during the CE bouts and during the exercise interval of the IE bouts, was determined as 50% of the peak power output achieved during incremental exercise and was increased by 5% each week after 2 wk of training. The total amount of work performed was not significantly different (P=0.74) between the CE (750 ± 90 kJ) and IE (707 ± 92 kJ) groups. The subjects who performed IE (N=9) experienced significantly lower levels of perceived breathlessness and lower limb fatigue during the exercise-training bouts than the group who performed CE (N=10). However, exercise capacity (peak oxygen uptake) and exercise tolerance (peak power output and 6-min walk distance) improved to a similar extent in both training groups. During submaximal constant-load exercise, the improved (faster) phase II oxygen uptake kinetic response with training was independent of exercise mode. Furthermore, training-induced reductions in submaximal exercise heart rate, carbon dioxide output, expired ventilation and blood lactate concentrations were not different between the two training modes. Exercise training also resulted in an equivalent reduction for both training modes in the degree of dynamic hyperinflation observed during incremental exercise. Thus, when total work performed and relative intensity were the same for both training modes, 8 wk of CE or IE training resulted in similar functional improvements and physiological adaptations in patients with moderate COPD. Study 3 examined the relationship between exercise capacity (peak oxygen uptake) and lower limb vasodilatory capacity in 9 patients with moderate COPD and 9 healthy age-matched control subjects. While peak oxygen uptake was significantly lower in the COPD patients (15.8 ± 3.5 mL·min-1·kg-1) compared to the control subjects (25.2 ± 3.5 mL·kg-1·min-1), there were no significant differences between groups in peak calf blood flow or peak calf conductance measured 7 s post-ischemia. Peak oxygen uptake was significantly correlated with peak calf blood flow and peak conductance in the control group, whereas there was no significant relationship found between these variables in the COPD group. However, the rate of decay in blood flow following ischemia was significantly slower (p less than 0.05) for the COPD group (-0.036 ± 0.005 mL·100 mL-1·min-1·s-1) when compared to the control group (-0.048 ± 0.015 mL·100 mL-1·min-1·s-1). The results of this study suggest that the lower peak exercise capacity in patients with moderate COPD is not related to a loss in leg vasodilatory capacity. Study 4 examined the dynamics of oxygen uptake kinetics during high-intensity constant-load cycling performed at 70% of the peak power attained during an incremental exercise test in 7 patients with moderate COPD and 7 healthy age-matched controls. The time constant of the primary component (phase II) of oxygen uptake was significantly slower in the COPD patients (82 ± 8 s) when compared to healthy control subjects (44 ± 4 s). Moreover, the oxygen cost per unit increment in power output for the primary component and the overall response were significantly higher in patients with COPD than in healthy control subjects. A slow component was observed in 5 of the 7 patients with COPD (49 ± 11 mL·min-1), whereas all of the control subjects demonstrated a slow component of oxygen uptake (213 ± 35 mL·min-1). The slow component comprised a significantly greater proportion of the total oxygen uptake response in the healthy control group (18 ± 2%) than in the COPD group (10 ± 2%). In the COPD patients, the slow component amplitude was significantly correlated with the decrease in inspiratory capacity (r = -0.88, P less than 0.05; N=5), indicating that the magnitude of the slow component was larger in individuals who experienced a greater degree of dynamic hyperinflation. This study demonstrated that most patients with moderate COPD are able to exercise at intensities high enough to elicit a slow component of oxygen uptake during constant-load exercise. The significant correlation observed between the slow component amplitude and the degree of dynamic hyperinflation suggests that the work of breathing may contribute to the slow component in patients with COPD.