Effect of a previous high intensity running exercise on isokinetic muscular strength in individuals with different training backgrounds

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da recuperação na máxima fase estável de lactato sanguíneo

The objective of this study was to compare the power corresponding to maximal lactate steady state determined through continuous (MLSSC) and intermittent protocol with active recovery (MLSSI). Ten trained male cyclists (25 +/- 4 yr., 72.5 +/- 10.6 kg, 178.5 +/- 4.0 cm), performed the following tests on a cycle ergometer: (1) incremental test until voluntary exhaustion to determine the maximal power (Pmax); (2) two to five constant workload tests to determine MLSSC, and; 3) two to three constant workload tests to determine MLSSI, consisting on eight repetitions of four minutes interspersed by two minutes of recovery at 50% Pmax. The MLSSC (273.2 +/- 21.4 W) was significantly lower than MLSSI (300.5 +/- 23.9 W). With base on these data, it can be verified that the intermittent exercise mode utilized in this study, allows an increase of 10% approximately, in the exercise intensity corresponding to MLSS.

Determination of the lactate threshold and maximal blood lactate steady state intensity in aged rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

PHYSIOLOGICAL and PERCEIVED EXERTION RESPONSES AT INTERMITTENT CRITICAL POWER and INTERMITTENT MAXIMAL LACTATE STEADY STATE

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of a single habituation session on neuromuscular isokinetic profile at different movement velocities

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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).

Effects of prolonged running performed at the intensity corresponding to the onset of blood lactate accumulation, on maximum isokinetic strength in active non-athletic individuals

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.

Indexes of power and aerobic capacity obtained in cycle ergometry and treadmill running: comparisons between sedentary, runners, cyclists and triathletes

The objectives of this study were: a) to determine, in a cross-sectional manner, the effect of aerobic training on the peak oxygen uptake, the intensity at O2peak and the anaerobic threshold (AnT) during running and cycling; and b) to verify if the transference of the training effects are dependent on the analized type of exercise or physiological index. Eleven untrained males (UN), nine endurance cyclists (EC), seven endurance runners (ER), and nine triathletes (TR) were submitted, on separate days, to incremental tests until voluntary exhaustion on a mechanical braked cycle ergometer and on a treadmill. The values of O2peak (ml.kg-1.min-1) obtained in running and cycle ergometer (ER = 68.8 ± 6.3 and 62.0 ± 5.0; EC = 60.5 ± 8.0 and 67.6 ± 7.6; TR = 64.5 ± 4.8 and 61.0 ± 4.1; UN = 43.5 ± 7.0 and 36.7 ± 5.6; respectively) were higher in the group that presented specific training in the modality. The UN group presented the lower values of O2peak, regardless of the type of exercise. This same behavior was observed for the AnT (ml.kg-1.min-1) determined in running and cycle ergometer (ER = 56.8 ± 6.9 and 44.8 ± 5.7; EC = 51.2 ± 5.2 and 57.6 ± 7.1; TR = 56.5 ± 5.1 and 49.0 ± 4.8; UN = 33.2 ± 4.2 and 22.6 ± 3.7; respectively). It can be concluded that the transference of the training effects seems to be only partial, independently of the index (O2peak, IO2peak or AnT) or exercise type (running or cycling). In relation to the indices, the specificity of training seems to be less present in the O2peak than in the IO2peak and the AnT.

Quantificação da função esfincteriana pela medida da capacidade de sustentação da pressão de contração voluntária do canal anal

RACIONAL: Tem sido demonstrado que a pressão máxima de contração voluntária e a pressão média de repouso não refletem a real situação clínica do paciente portador de incontinência fecal, não traduzem a realidade funcional do canal anal, além de poder estar comprometendo a conduta a ser tomada devido ao não-encaminhamento à terapêutica específica. OBJETIVO: Com a hipótese de que contrair e manter a contração é mais importante que simplesmente contrair, mesmo com pico momentaneamente elevado de pressão, analisou-se a capacidade de sustentação da pressão de contração voluntária do canal anal com o intuito de quantificar a função esfincteriana relativa à continência fecal. MATERIAL E MÉTODOS: Submeteram-se a exame manométrico anorretal 72 pacientes (56 mulheres) portadores de incontinência fecal de vários graus e 15 (9 mulheres) indivíduos continentes (normais), avaliando-se a pressão média de repouso, a pressão máxima de contração voluntária e a capacidade de sustentação da pressão de contração voluntária. RESULTADOS: Os indivíduos continentes apresentaram valores normais de pressão média de repouso e de pressão máxima de contração voluntária, além de adequada capacidade de sustentação da pressão de contração voluntária. Os pacientes incontinentes apresentaram pressão média de repouso e pressão máxima de contração voluntária com valores pressóricos normais ou abaixo do normal e perfil semelhante de capacidade de sustentação da pressão de contração voluntária, ou seja, moderada na fase inicial e ruim nas fases intermediária e final, com queda da mesma superior a 35% em 78% dos pacientes. A pressão máxima de contração voluntária apresenta excelente especificidade (100%) porém, sensibilidade baixa (46%) para incontinência fecal. Comparativamente, a capacidade de sustentação da pressão de contração voluntária apresenta elevadas especificidade (93%) e sensibilidade (78%) para incontinência fecal. Embora a pressão máxima de contração voluntária não indique falso-positivos, apresenta 72% de falso-negativos. A probabilidade deste fato acontecer com a medida de capacidade de sustentação da pressão de contração voluntária é, praticamente, 20% menor, valor estatisticamente significativo. CONCLUSÃO: O indicativo de função esfincteriana é melhor analisado pela capacidade de sustentação. A capacidade de sustentação traduz com mais exatidão, a capacidade funcional do canal anal em relação à continência voluntária, sendo isoladamente, melhor que a pressão máxima de contração voluntária.

The effect of L-arginine on guinea-pig and rabbit airway smooth muscle function in vitro

We have investigated the effects of L-arginine, D-arginine and L-lysine on airway smooth muscle responsiveness to spasmogens in vitro. Both L-arginine and D-arginine (100 mM) significantly reduced the contractile potency and maximal contractile response to histamine but not to methacholine or potassium chloride in guinea-pig epithelium-denuded isolated trachea. Similarly, the contractile response to histamine was significantly reduced by L-arginine (100 mM) in rabbit epithelium-denuded isolated bronchus. The amino acid L-lysine (100 mM) failed to significantly alter the contractile potency of histamine in guinea-pig isolated trachea (P>0.05). In guinea-pig isolated trachea precontracted with histamine, both L-arginine and D-arginine produced a concentration-dependent relaxation which was not significantly altered by epithelium removal or by the presence of the nitric oxide synthase inhibitor, NG-nitro L-arginine methyl ester (L-NAME; 50 µM). Thus, at very high concentrations, arginine exhibit a non-competitive antagonism of histamine-induced contraction of isolated airway preparations that was independent of the generation of nitric oxide and was not dependent on charge. These observations confirm previous studies of cutaneous permeability responses and of contractile responses of guinea-pig isolated ileal smooth muscle. Taken together, the data suggest that high concentrations of arginine can exert an anti-histamine effect.

Second-order statistics for equal gain and maximal ratio diversity-combining reception

Exact and closed-form expressions for the level crossing rate and average fade duration are presented for equal gain combining and maximal ratio combining schemes, assuming an arbitrary number of independent branches in a Rayleigh environment. The analytical results are thoroughly validated by simulation.

The validity of critical speed determined from track cycling for identification of the maximal lactate steady state

The objective of this study was to determine the critical speed (CS) for track cycling and to assess whether a lactate steady state occurs at this speed. Fourteen competitive cyclists performed the following tests on an official cycling track (333.3 m): 1) incremental test for determination of the intensity corresponding to 4 mM of blood lactate (onset of blood lactate accumulation, OBLA) and maximal oxygen uptake (VO(2)max); 2) CS: 3 maximal bouts for distances of 2, 4 and 6 km executed in random order and with a period of recovery of 40 to 50 min between bouts. CS was determined for each subject from the linear regression between the distance and the time taking to cycle it; 3) Endurance test in which subjects were instructed to pedal at 100% of their individually determined CS for 30 min. At the 10(th) and 30(th) min (or upon exhaustion), 25 mul of blood were collected from ear lobe for later analysis of blood lactate [Lac]b. An increase less than or equal to1 mM between 10 and 30 min of exercise was considered as the criterion for the occurrence of the lactate steady state. CS (49.6 +/- 8.6 ml.kg(-1).min(-1); 36.9 +/- 2.7 km.h(-1)) was significantly higher than OBLA (43.7 8.0 ml.kg(-1).min(-1); 35.24 +/- 2.6 km.h(-1)) although the two parameters were highly correlated (r=0.97). During the endurance test, only 8 of the 14 subjects completed the 30 min period at CS. of these 8 subjects, only 2 presented a lactate steady state. Time to exhaustion at CS was 20.3 +/- 1.6 min for the remaining 6 subjects. The 12 subjects who did not reach a lactate steady state presented mean [Lac]b values of 7.4 +/- 1.3 mM at 10 min and of 9.4 +/- 1.9 mM at the end of the test (exhaustion), characterizing an exercise intensity of high lactacidemia. on the basis of the present results, we can conclude that CS determined by a track cycling test seems to overestimate the intensity of the maximal lactate steady state for most subjects.