Fabrizio Caputo

Effects of aerobic endurance training status and specificity on oxygen uptake kinetics during maximal exercise.

The main purpose of this study was to analyze the effects of exercise mode, training status and specificity on the oxygen uptake (V̇O2) kinetics during maximal exercise performed in treadmill running and cycle ergometry. Seven runners (R), nine cyclists (C), nine triathletes (T) and eleven untrained subjects (U), performed the following tests on different days on a motorized treadmill and on a cycle ergometer: (1) incremental tests in order to determine the maximal oxygen uptake (V̇O2max) and the intensity associated with the achievement of V̇O2max (IV̇O2max); and (2) constant work-rate running and cycling exercises to exhaustion at IV̇O2max to determine the “effective” time constant of the V̇O2 response (τV̇O2). Values for V̇O2max obtained on the treadmill and cycle ergometer [R=68.8 (6.3) and 62.0 (5.0); C=60.5 (8.0) and 67.6 (7.6); T=64.5 (4.8) and 61.0 (4.1); U=43.5 (7.0) and 36.7 (5.6); respectively] were higher for the group with specific training in the modality. The U group showed the lowest values for V̇O2max, regardless of exercise mode. Differences in τV̇O2 (seconds) were found only for the U group in relation to the trained groups [R=31.6 (10.5) and 40.9 (13.6); C=28.5 (5.8) and 32.7 (5.7); T=32.5 (5.6) and 40.7 (7.5); U=52.7 (8.5) and 62.2 (15.3); for the treadmill and cycle ergometer, respectively]; no effects of exercise mode were found in any of the groups. It is concluded that τV̇O2 during the exercise performed at IV̇O2max is dependent on the training status, but not dependent on the exercise mode and specificity of training. Moreover, the transfer of the training effects on τV̇O2 between both exercise modes may be higher compared with V̇O2max.

Oxygen Uptake Kinetics and Time to Exhaustion in Cycling and Running: a Comparison Between Trained and Untrained Subjects

The objective of the present study was to compare pulmonary gas exchange kinetics (VO2 kinetics) and time to exhaustion (Tlim) between trained and untrained individuals during severe exercise performed on a cycle ergometer and treadmill. Eleven untrained males in running (UR) and cycling (UC), nine endurance cyclists (EC), and seven endurance runners (ER) were submitted to the following tests on separate days: (i) incremental test for determination of maximal oxygen uptake (VO2max) and the intensity associated with the achievement of VO2max (IVO2max) on a mechanical braked cycle ergometer (EC and UC) and on a treadmill (ER and UR); (ii) all-out exercise bout performed at IVO2max to determine the time to exhaustion at IVO2max (Tlim) and the time constant of oxygen uptake kinetics (τ). The τ was significantly faster in trained group, both in cycling (EC = 28.2 ± 4.7 s; UC = 63.8 ± 25.0 s) and in running (ER = 28.5 ± 8.5 s; UR = 59.3 ± 12.0 s). Tlim of untrained was signifi-cantly lower in cycling (EC = 384.4 ± 66.6 s vs. UC; 311.1 ± 105.7 s) and higher in running (ER = 309.2 ± 176.6 s vs. UR = 439.8 ± 104.2 s). We conclude that the VO2 kinetic response at the onset of severe exercise, carried out at the same relative intensity is sensitive to endurance training, irrespective of the exercise type. The endurance training seems to differently influence Tlim during exercise at IVO2max in running and cycling.

Intracellular Shuttle: The Lactate Aerobic Metabolism

Lactate is a highly dynamic metabolite that can be used as a fuel by several cells of the human body, particularly during physical exercise. Traditionally, it has been believed that the first step of lactate oxidation occurs in cytosol; however, this idea was recently challenged. A new hypothesis has been presented based on the fact that lactate-to-pyruvate conversion cannot occur in cytosol, because the LDH enzyme characteristics and cytosolic environment do not allow the reaction in this way. Instead, the Intracellular Lactate Shuttle hypothesis states that lactate first enters in mitochondria and only then is metabolized. In several tissues of the human body this idea is well accepted but is quite resistant in skeletal muscle. In this paper, we will present not only the studies which are protagonists in this discussion, but the potential mechanism by which this oxidation occurs and also a link between lactate and mitochondrial proliferation. This new perspective brings some implications and comes to change our understanding of the interaction between the energy systems, because the product of one serves as a substrate for the other.

Ischemic Preconditioning and Exercise Performance: A Systematic Review and Meta-Analysis

Although the amount of evidence demonstrating the beneficial effects of ischemic preconditioning (IPC) on exercise performance is increasing, conclusions about its efficacy cannot yet be drawn. Therefore, the purposes of this review were to determine the effect of IPC on exercise performance and identify the effects of different IPC procedures, exercise types, and subject characteristics on exercise performance. The analysis comprised 19 relevant studies from 2000 to 2015, 15 of which were included in the meta-analyses. Effect sizes (ES) were calculated as the standardized mean difference. Overall, IPC had a small beneficial effect on exercise performance (ES = 0.43; 90% confidence interval [CI], 0.28 to 0.51). The largest ES were found for aerobic (ES = 0.51; 90% CI, 0.35 to 0.67) and anaerobic (ES = 0.23; 90% CI, -0.12 to 0.58) exercise. In contrast, an unclear effect was observed in power and sprint performance (ES = 0.16; 90% CI, -0.20 to 0.52). In conclusion, IPC can effectively enhance aerobic and anaerobic exercise performance.

Effects of ischemic preconditioning on maximal constant load cycling performance

This study investigated the effects of ischemic preconditioning (IPC) on the ratings of perceived exertion (RPE), surface electromyography, and pulmonary oxygen uptake (V̇o2) onset kinetics during cycling until exhaustion at the peak power output attained during an incremental test. A group of 12 recreationally trained cyclists volunteered for this study. After determination of peak power output during an incremental test, they were randomly subjected on different days to a performance protocol preceded by intermittent bilateral cuff pressure inflation to 220 mmHg (IPC) or 20 mmHg (control). To increase data reliability, the performance visits were replicated, also in a random manner. There was an 8.0% improvement in performance after IPC (control: 303 s, IPC 327 s, factor SDs of ×/÷1.13, P = 0.01). This change was followed by a 2.9% increase in peak V̇o2 (control: 3.95 l/min, IPC: 4.06 l/min, factor SDs of ×/÷1.15, P = 0.04), owing to a higher amplitude of the slow component of the V̇o2 kinetics (control: 0.45 l/min, IPC: 0.63 l/min, factor SDs of ×/÷2.21, P = 0.05). There was also an attenuation in the rate of increase in RPE (P = 0.01) and a progressive increase in the myoelectrical activity of the vastus lateralis muscle (P = 0.04). Furthermore, the changes in peak V̇o2 (r = 0.73, P = 0.007) and the amplitude of the slow component (r = 0.79, P = 0.002) largely correlated with performance improvement. These findings provide a link between improved aerobic metabolism and enhanced severe-intensity cycling performance after IPC. Furthermore, the delayed exhaustion after IPC under lower RPE and higher skeletal muscle activation suggest they have a role on the ergogenic effects of IPC on endurance performance.

Heavy-intensity aerobic exercise affects the isokinetic torque and functional but not conventional hamstrings:quadriceps ratios

Running exercises are frequently related to muscular injuries, which may be a result of muscular imbalance. The present study aimed to verify the effects of heavy-intensity continuous running exercise on the functional and conventional hamstrings:quadriceps ratios, and also in the knee flexors and extensors EMG activity in active non-athletic individuals. Sixteen active males performed maximal isokinetic concentric and eccentric knee flexions and extensions at 60 degrees s(-1) and 180 degrees s(-1). In another session, the same procedure was conducted after a continuous running exercise at 95% onset of blood lactate accumulation. Torque and electromyographic ratios were calculated from peak torque and integrated electromyographic activity (knee flexor and extensors). Creatine kinase was measured before and 24h after running exercise. Eccentric torque (knee flexion and extension) decreased significantly after running only at 180 degrees s(-1) (p<0.05). No differences were found for the conventional torque ratios (p>0.05), however, the functional torque ratios at 180 degrees s(-1) decreased significantly after running (p<0.05). No effects on the electromyographic activity and electromyographic ratios were found (p>0.05). Creatine kinase increased slightly 24 h after running (p<0.05). Heavy-intensity continuous running exercise decreased knee flexor and extensor eccentric torque, and functional torque ratios under fast velocities (180 degrees s(-1)), probably as result of peripheral fatigue.

Comparação entre a utilização de saliva e sangue para determinação do lactato mínimo em cicloergômetro e ergômetro de braço em mesa-tenistas

The aim of this study was to verify if it is possible to determine the lactate minimum test (LMT) by saliva sodium (Na + ), potassium (K + ) and lactate (LAC) concentrations in arm ergometer and cycle ergometers. Eight male international-level table tennis players participated in this study. To induce increases of lactate concentration in both ergometers, 30 seconds maximal tests were used with maximal force application in constant 102 rpm in isokinetic arm ergometer (Cybex UBE 2432), and loads of 7.5% of body weight (Kp) in cycle ergometer (mechanical Monark). After the anaerobic stimulus in arm ergometer, the incremental test was applied at constant 60 rpm, started at 49 watts and increment loads of 16 watts each three minutes. The LMT intensity was determined with the analysis of the blood lactate (LACmin arm ) and the saliva concentrations of sodium (Na + minarm-saliva) and potassium (K + minarm-saliva). For the cycle ergometer, the incremental test started with an intensity of 85 watts and increments of 17 watts at constant speed of 70 rpm. The stages were also of three minutes. The LACmin was determined using blood and saliva samples (LACmincycle; Na + mincyclesaliva , K +min cycle-saliva and LACmin cycle-saliva , respectively). In both ergometers, the intensity obtained in lactate minimum test was correspondent to zero derived polynomial adjustments by metabolite concentrations versus exercise intensities. The statistical analysis included one way ANOVA test, paired t-test and Pearson’s correlations. For all tests applications, the significance level was prefixed at 5%. The several LACmin determinations using blood and saliva samples did not show significant differences in arm and cycle ergometers (LACminarm 91.71 ± 12.43; Na + minarm-saliva 71.99 ± 23.42;O objetivo do estudo foi verificar a possibilidade de determinar o teste de lactato minimo (TLM) com concentracoes de sodio (Na+), potassio (K+) e lactato (LAC) na saliva em ergometro de braco e cicloergometro. Foram participantes deste estudo oito mesa-tenistas de nivel internacional. Como estimulo anaerobio no TLM em ambos os ergometros foram utilizados testes maximos de 30 segundos. No ergometro de braco isocinetico (Cybex Ube 2432) foi aplicada a forca maxima com rotacao fixa em 102rpm e no cicloergometro, aplicada a carga de 7,5% do peso corporal (Kp). Apos o estimulo anaerobio no ergometro de braco, foi iniciado um teste incremental com rotacoes na manivela constante a 60rpm, iniciado a 49 watts com aumento de 16 watts a cada estagio de tres minutos de exercicio. A intensidade correspondente ao TLM foi determinado com amostras de sangue e saliva (LACminbraco; Na+minbraco-saliva e K+minbraco-saliva, respectivamente). Para o cicloergometro, a carga inicial foi de 85 watts e aumento de 17 watts com rotacao do pedal constante a 70rpm. Cada estagio de exercicio tambem teve a duracao de tres minutos. O LACmin foi determinado utilizando amostras de sangue e saliva (LACminciclo; Na+minciclo-saliva, K+minciclo-saliva e LACminciclo-saliva, respectivamente). Em ambos os ergometros, as intensidades obtidas no TLM foram correspondentes a derivada zero do ajuste polinomial entre metabolito versus intensidade. Foram utilizados, como procedimentos estatisticos, o teste ANOVA One Way, teste t de Student pareado e teste de correlacao de Pearson com niveis de significância de 5%. Os LACmin determinados com amostras de sangue e de saliva, tanto para o ergometro de braco (LACminbraco 91,71 ± 12,43; Na+minbraco-saliva 71,99 ± 23,42; K+minbraco-saliva 79,67 ± 17,72), quanto para cicloergometro (LACminciclo 157,68 ± 13,48; LACminciclo-saliva 135,49 ± 33,2; Na+minciclo-saliva 121,81 ± 51,31; K+minciclo-saliva 135,49 ± 33,21), nao foram diferentes significativamente. Contudo, essas intensidades nao apresentaram correlacoes significativas. Pode-se entao concluir que a utilizacao de metabolitos na saliva para determinacao do TLM nao parece ser possivel para esse protocolo quando os ergometros utilizados sao o ergometro de braco isocinetico e o cicloergometro.

Exercício aeróbio: aspectos bioenergéticos, ajustes fisiológicos, fadiga e índices de desempenho: [revisão]

The objective of this study was to present relevant updated information regarding the physiological determinants of aerobic training and performance. In contrast to common concepts, the aerobic metabolism rapidly responds to energy requirements, with the anaerobic and aerobic energy systems equally contributing to total energy production during maximal exercise lasting about 75 s. However, in the case of longer exercise duration the possible mechanisms of fatigue related to anaerobic metabolism are still the main determinants of exercise tolerance. Prolonged exercise (more than one hour) can be limited by several factors such as substrate depletion, water and electrolyte disturbance, or problems related to thermoregulation leading to an increase in body temperature. The most important variables of endurance performance have been organized into a model that integrates factors such as maximum oxygen uptake (VO2max), blood lactate thresholds, and muscle efficiency. For highly trained athletes, in addition to a high VO2max, success in endurance events also requires the ability to exercise for prolonged periods at a high percentage of VO2max, as well as to efficiently convert the energy produced into muscle work. Depending on the duration of the aerobic event, the training sessions should be aimed at improving VO2max, anaerobic lactate capacity and acidosis tolerance in the case of short-lasting events and aerobic capacity for events of intermediate duration, and at increasing muscle glycogen content and fat utilization in the case of long-lasting events.

Increased platelet oxidative metabolism, blood oxidative stress and neopterin levels after ultra-endurance exercise

Abstract The purpose of the present investigation was to identify muscle damage, inflammatory response and oxidative stress blood markers in athletes undertaking the ultra-endurance MultiSport Brazil race. Eleven well-trained male athletes (34.3 ± 3.1 years, 74.0 ± 7.6 kg; 172.2 ± 5.1 cm) participated in the study and performed the race, which consisted of about 90 km of alternating off-road running, mountain biking and kayaking. Twelve hours before and up to 15 minutes after the race a 10 mL blood sample was drawn in order to measure the following parameters: lactate dehydrogenase and creatine kinase activities, lipid peroxidation, catalase activity, protein carbonylation, respiratory chain complexes I, II and IV activities, oxygen consumption and neopterin concentrations. After the race, plasma lactate dehydrogenase and creatine kinase activities were significantly increased. Erythrocyte TBA-RS levels and plasma protein carbonylation were markedly augmented in post-race samples. Additionally, mitochondrial complex II activity and oxygen consumption in post-race platelet-rich plasma were also increased. These altered biochemical parameters were accompanied by increased plasma neopterin levels. The ultra-endurance event provoked systemic inflammation (increased neopterin) accompanied by marked oxidative stress, likely by increasing oxidative metabolism (increased oxidative mitochondrial function). This might be advantageous during prolonged exercise, mainly for efficient substrate oxidation at the mitochondrial level, even when tissue damage is induced.

Efeitos do estado e especificidade do treinamento aeróbio na relação %VO2max versus %FCmax durante o ciclismo

OBJECTIVE: To determine the effects of the status and specificity of exercise training in the ratio between maximum oxygen consumption (%VO2max) and the percentage of maximal heart rate (%HRmax) during incremental exercise on a cycle ergometer. METHODS: Seven runners, 9 cyclists, 11 triathletes, and 12 sedentary individuals, all male and apparently healthy, underwent exhaustive incremental exercise on cycle ergometers. Linear regressions between %VO2max x %HRmax were determined for each individual. Based on these regressions, %HRmax was assessed corresponding to a determined %VO2max (50, 60, 70, 80, and 90%) from each participant. RESULTS: Significant differences were not found between the groups in %HRmax for each of the %VO2max assessed. Analyzing the volunteers as a single group, the average of the corresponding %HRmax to 50, 60, 70, 80, and 90% %VO2max were 67, 73, 80, 87, and 93%, respectively. CONCLUSION: The ratio between %VO2max and %HRmax in the groups assessed during incremental exercise on the bicycle is not dependent on the status and specificity of aerobic exercise training.