Resposta metabólica e cardiovascular durante o triatlo de meio Ironman: relação com a performance

The aims of this work were: 1) to determine the correlation between the Anaerobic Threshold (AT) and the performance on the triathlon of Half lronman; 2) to describe and to compare the Heart Rate (HR) and the correspondent speed at AT in swimming. cycling and running. with the HR and the speed of these events during the triathlon; 3) to describe the behavior of the lactate (LAC) and glucemia (GLU) during the events. Six males triathletes between the ages of 18 to 24 participated in this study. AT was defined as the speed corresponding to a lactate concentration of 4 mM and was determined by measuring plasma lactate concentration after each bout of swimming (3x200 m progressive), cycling (3x2400 m progressive) and running (3x1200 m progressive) tests. The speed at 4 mM lactate concentration was calculated by linear interpolation. The data were obtained during a Half Ironman (1.9 km swimming, 90 km cycling and 21 km running) competition. HR, LAC and GLU were determinated during the transition of the events and the end of the competition. HR was also determinated in three others points of control in the cycling and running course. Swimming and cycli1'!g AT were significantly correlated with the competition speed in these events (r = 0.92 and r = 0.92, respectively). However, the same did not occur in the running (r = 0.63). The swimming event speed (64.8 m/min) was not different from the speed at AT (65.5 m/min). On the other hand. the speed of cycling (538.0 m/min) and running (201.0 m/min) were significantly lower than the speed at AT (639.0 and 264.0 m/min respectively). The HR at swimming was higher (p > 0.05) than HR of AT. At running, only HR in the last two parts of the event, was significantly lower than HR of AT. During cycling , there were not significant differences between HR of the event and HR of AT. as well as HR among the four parts of the competition. The concentration of LAC in swimming was higher than cycling and running, but in these last two events there were no differences. GLU was lower just after the running, when compared to the figure obtained after swimming. These results suggest that: 1) AT is able to predict the performance of swimming and cycling during the triathlon competition of Half Ironman, but the same does not occur at running; 2) The use of HR to control the competition intensity. mainly during cycling and running, might present limitations.Os objetivos deste estudo foram: 1) determinar a correlação entre o Limiar Anaeróbio (LAn) e a performance no triatlo de Meio lronman; 2) descrever e comparar a FC e a velocidade correspondentes ao LAn da natação, ciclismo e corrida. com a FC e a velocidade destas provas durante o triatlo; 3) descrever o comportamento do lactato (LAC) e da glicemia (Gil) durante a prova. Participaram do estudo 6 triatletas do sexo masculino com idade entre 18 e 24 anos. O LAn foi definido como a velocidade correspondente a concentração de 4 mM de LAC e foi determinado medindo-se sua concentração após cada tiro nos testes de natação (3x200 m progressivos). ciclismo (3x2400 m progressivos) e corrida (3x1200 m progressivos). A velocidade de cada evento correspondente a 4 mM foi calculada por interpolação linear. Os dados de competição foram obtidós durante uma prova de Meio lronman (1,9 Km natação, 90 Km ciclismo e 21 Km corrida). A FC, o LAC e a Gil foram determinados durante a transição dos eventos e ao final da competição. A FC também foi determinada em mais três pontos de controle existentes no percurso do ciclismo e corrida. O LAn da natação e do ciclismo correlacionou¬se significantemente com a velocidade de prova nestes eventos (r = 0,92 e r = 0,92, respectivamente). O mesmo não ocorreu entre a velocidade do LA e velocidade de prova na corrida (r = 0,63). A velocidade de prova da natação (64,8 m/min) não foi diferente do que a velocidade equivalente ao LAn (65.5 m/min). Por outro lado, as velocidades de prova do ciclismo (538,0 m/min) e da corrida (201.0 m/min) foram significantemente menores do que as velocidades do LAn (639.0 e 264.0 m/min respectivamente). Na natação a FC de prova foi maior do que a FC do LAn. Na corrida. somente a FC nos dois últimos trechos de prova, foi significantemente menor do que a FC do LAn. Durante o ciclismo, não houve diferenças significantes entre a FC de prova e a FC do LAn. bem como entre as FC dos quatro trechos de prova. A concentração de LAC na natação foi maior do que no ciclismo e corrida. sendo que entre estas duas últimas provas, não houve diferença. A Gil foi menor logo após a corrida. quando comparado com os valores obtidos após a natação. Deste modo podemos concluir que: 1) O LAn é capaz de predizer a performance da natação e do ciclismo durante o triatlo de Meio Ironman. o mesmo não acontecendo com a corrida; 2) O uso da FC para controlar a intensidade de prova, principalmente durante o ciclismo e a corrida, pode apresentar limitações

Efeitos da corrida prolongada realizada na intensidade correspondente ao início do acúmulo do lactato no sangue na força máxima isocinética em indivíduos ativos não atletas

OBJECTIVE: The objective of this study was to analyze the effects of prolonged continuous running performed at the intensity corresponding to the onset of blood lactate accumulation (OBLA), on the peak torque of the knee extensors, analyzed in relation to different types of contraction and movement velocities in active individuals. METHOD: Eight men (23.4 ± 2.1 years; 75.8 ± 8.7 kg; 171.1 ± 4.5 cm) participated in this study. First, the subjects performed an incremental test until volitional exhaustion to determine the velocity corresponding to OBLA. Then, the subjects returned to the laboratory on two occasions, separated by at least seven days, to perform five maximal isokinetic contractions of the knee extensors at two angular velocities (60 and 180º.s-1) under eccentric and concentric conditions. Eccentric peak torque (EPT) and Concentric peak torque (CPT) were measured at each velocity. One session was performed after a standardized warm-up period (5 min at 50% VO2max). The other session was performed after continuous running at OBLA until volitional exhaustion. These sessions were conducted in random order. RESULTS: There was a significant reduction in CPT only at 60º.s-1 (259.0 ± 46.4 and 244.0 ± 41.4 N.m). However, the reduction in EPT was significant at 60º.s-1 (337.3 ± 43.2 and 321.7 ± 60.0 N.m) and 180º.s-1 (346.1 ± 38.0 and 319.7 ± 43.6 N.m). The relative strength losses after the running exercise were significant different between contraction types only at 180º.s-1. CONCLUSION: We can conclude that, in active individuals, the reduction in peak torque after prolonged continuous running at OBLA may be dependent on the type of contraction and angular velocity.OBJETIVO: O objetivo deste estudo foi analisar os efeitos da corrida contínua prolongada realizada na intensidade correspondente ao início do acúmulo do lactato no sangue (OBLA) sobre o torque máximo dos extensores do joelho analisado em diferentes tipos de contração e velocidade de movimento em indivíduos ativos. MÉTODO: Oito indivíduos do gênero masculino (23,4 ± 2,1 anos; 75,8 ± 8,7 kg; 171,1 ± 4,5 cm) participaram deste estudo. Primeiramente, os sujeitos realizaram um teste incremental até a exaustão voluntária para determinar a velocidade correspondente ao OBLA. Posteriormente, os sujeitos retornaram ao laboratório em duas ocasiões, separadas por pelo menos sete dias, para realizar 5 contrações isocinéticas máximas para os extensores do joelho em duas velocidades angulares (60 e 180º.s-1) sob as condições excêntrica (PTE) e concêntrica (PTC). Uma sessão foi realizada após um período de aquecimento padronizado (5 min a 50%VO2max). A outra sessão foi realizada após uma corrida contínua no OBLA até a exaustão voluntária. Essas sessões foram executadas em ordem randômica. RESULTADOS: Houve redução significante do PTC somente a 60º.s-1 (259,0 ± 46,4 e 244,0 ± 41,4 N.m). Entretanto, a redução do PTE foi significante a 60º.s-1 (337,3 ± 43,2 e 321,7 ± 60,0 N.m) e 180º.s-1 (346,1 ± 38,0 e 319,7 ± 43,6 N.m). As reduções relativas da força após o exercício de corrida foram significantemente diferentes entre os tipos de contração somente a 180º.s-1. CONCLUSÃO: Podemos concluir que, em indivíduos ativos, a redução no torque máximo após uma corrida contínua prolongada no OBLA pode ser dependente do tipo de contração e da velocidade angular.Universidade Estadual Paulista Júlio de Mesquita Filho Instituto de Biociências de Rio Claro Departamento de Educação FísicaUniversidade Federal de São Paulo (UNIFESP) Departamento de Psicobiologia Instituto do SonoUNIFESP, Depto. de Psicobiologia Instituto do SonoSciEL

Severe Obesity Shifts Metabolic Thresholds but Does Not Attenuate Aerobic Training Adaptations in Zucker Rats

Severe obesity affects metabolism with potential to influence the lactate and glycemic response to different exercise intensities in untrained and trained rats. Here we evaluated metabolic thresholds and maximal aerobic capacity in rats with severe obesity and lean counterparts at pre- and post-training. Zucker rats (obese: n = 10, lean: n = 10) were submitted to constant treadmill bouts, to determine the maximal lactate steady state, and an incremental treadmill test, to determine the lactate threshold, glycemic threshold and maximal velocity at pre and post 8 weeks of treadmill training. Velocities of the lactate threshold and glycemic threshold agreed with the maximal lactate steady state velocity on most comparisons. The maximal lactate steady state velocity occurred at higher percentage of the maximal velocity in Zucker rats at pre-training than the percentage commonly reported and used for training prescription for other rat strains (i.e., 60%) (obese = 78 +/- 9% and lean = 68 +/- 5%, P 0.05), whereas increase in maximal velocity was greater in the obese group (P < 0.05 vs. lean). In conclusion, lactate threshold, glycemic threshold and maximal lactate steady state occurred at similar exercise intensity in Zucker rats at pre- and post-training. Severe obesity shifted metabolic thresholds to higher exercise intensity at pre-training, but did not attenuate submaximal and maximal aerobic training adaptations.Coordination for the Improvement of Higher Education Personnel (CAPES)Univ Fed Sao Paulo, Grad Program Translat Med, Sao Paulo, BrazilUniv Catolica Brasilia, Grad Program Phys Educ & Hlth, Brasilia, DF, BrazilUniv Sao Paulo, Sch Publ Hlth, Dept Nutr, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Nephrol, Sao Paulo, BrazilSao Paulo State Univ, Dept Phys Educ, Human Performance Lab, Rio Claro, BrazilUniv Fed Sao Paulo, Dept Physiol, Sao Paulo, BrazilUniv Fed Sao Paulo, Grad Program Translat Med, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Nephrol, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Physiol, Sao Paulo, BrazilWeb of Scienc

Muscle damage slows oxygen uptake kinetics during moderate-intensity exercise performed at high pedal rate

This study aimed to investigate the dependence of oxygen uptake (VO2) kinetics on pedal cadence during moderate-intensity exercise following exercise-induced muscle damage (EIMD). Twenty untrained males were randomly assigned to a 50 revolution per minute (rpm) (age, 23.3 +/- 1.8 years; VO2max, 38.9 +/- 2.8 mL . kg(-1) . min(-1)) or 100 rpm group (age, 24.4 +/- 3.5 years, VO2max, 42.9 +/- 4.3 mL . kg(-1) . min(-1)). Participants completed "step" tests to moderate-intensity exercise from an unloaded baseline on a cycle ergometer before (baseline) and at 24 and 48 h after muscle-damaging exercise (10 sets of 10 eccentric contractions performed on an isokinetic dynamometer with a 2-min rest between each set). Pedal cadence was kept constant throughout each cycling trial (50 or 100 rpm). There were no changes in phase II pulmonary VO2 kinetics following EIMD for the 50 rpm group (baseline = 35 +/- 4 s; 24 h = 35 +/- 7 s; and 48 h = 36 +/- 9 s). However, the phase II VO2 was significantly greater at 24 h (59 +/- 27 s) compared with baseline (39 +/- 6 s) and 48 h (40 +/- 9 s) for the 100 rpm group. It is concluded that the effects of EIMD on phase II VO2 kinetics during moderate-intensity cycling exercise is dependent on pedal cadence. The slower VO2 kinetics after muscle damage suggests that type II fibers are involved during transition to moderate-intensity exercise at high pedal cadence.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

The highest intensity and the shortest duration permitting attainment of maximal oxygen uptake during cycling: effects of different methods and aerobic fitness level

The aims of this study were: (1) to verify the validity of previous proposed models to estimate the lowest exercise duration (T (LOW)) and the highest intensity (I (HIGH)) at which VO(2)max is reached (2) to test the hypothesis that parameters involved in these models, and hence the validity of these models are affected by aerobic training status. Thirteen cyclists (EC), eleven runners (ER) and ten untrained (U) subjects performed several cycle-ergometer exercise tests to fatigue in order to determine and estimate T (LOW) (ET (LOW)) and I (HIGH) (EI (HIGH)). The relationship between the time to achieved VO(2)max and time to exhaustion (T (lim)) was used to estimate ET (LOW). EI (HIGH) was estimated using the critical power model. I (HIGH) was assumed as the highest intensity at which VO2 was equal or higher than the average of VO(2)max values minus one typical error. T (LOW) was considered T (lim) associated with I (HIGH). No differences were found in T (LOW) between ER (170 +/- 31 s) and U (209 +/- 29 s), however, both showed higher values than EC (117 +/- 29 s). I (HIGH) was similar between U (269 +/- 73 W) and ER (319 +/- 50 W), and both were lower than EC (451 +/- 33 W). EI (HIGH) was similar and significantly correlated with I-HIGH only in U (r = 0.87) and ER (r = 0.62). ET (LOW) and T (LOW) were different only for U and not significantly correlated in all groups. These data suggest that the aerobic training status affects the validity of the proposed models for estimating I (HIGH)