Traffic-related air pollution and endurance exercise: Characterizing non-targeted serum metabolomics profiling.

Although the exposure to traffic-related air pollution (TRAP) has emerged as one of main problem worldwide to inhabitants' health in urban centers, its impact on metabolic responses during exercise is poorly understood. The aim of study was to characterize the profile of non-target serum metabolomics during prolonged exercise performed under TRAP conditions. Ten healthy men completed two 90 min constant-load cycling trials under conditions of either TRAP or filtered air. Experimental trials were performed in a chamber located on an avenue with a high volume of vehicle traffic. Blood samples were taken at 30 min, 60 min, and 90 min of exercise. Based on Nuclear Magnetic Resonance metabolomics, the non-target analysis was used to assess the metabolic profile. Twelve, 16 and 18 metabolites were identified as discriminants. These were: at 30 min of exercise, the coefficient of determination (R2) 0.98, the predictive relevance, (Q2) 0.12, and the area under the curve (AUC) 0.91. After 60 min of exercise: (R2: 0.99, Q2: 0.09, AUC: 0.94); and at 90 min of exercise (R2: 0.91, Q2: <0.01, AUC: 0.89), respectively. The discriminant metabolites were then considered for the target analysis, which demonstrated that the metabolic pathways of glycine and serine metabolism (p = 0.03) had been altered under TRAP conditions at 30 min of exercise; arginine and proline metabolism (p = 0.04) at 60 min of exercise; and glycolysis (p = 0.05) at 90 min of exercise. The present results suggest that exposure to TRAP during prolonged exercise leads to a significant change in metabolomics, characterized by a transitional pattern and lastly, impairs the glucose metabolism.

Exercising in the urban center: Inflammatory and cardiovascular effects of prolonged exercise under air pollution.

The aim of this study was to investigate, in a well-controlled experimental environment, whether air pollution from an urban center would affect inflammatory and cardiorespiratory responses during prolonged moderate exercise (i.e., 90 min). Ten healthy men performed two experimental trials under filtered and polluted air, inside an environmental chamber located in Sao Paulo downtown, Brazil. Blood samples were obtained at rest, 30, 60, and 90 min of the exercise to determine the serum cytokines concentration, while arterial pressure was recorded immediately after the exercise. The serum cytokines were not altered until 60 min of exercise for both conditions (P > 0.05). Otherwise, at 90 min of exercise, the IL-6 (P = 0.047) and vascular endothelial growth factor (VEGF) (P = 0.026) were significantly higher and IL-10 tended to decrease (P = 0.061) in polluted air condition compared to filtered air condition. In addition, both systolic (P = 0.031) and diastolic (P = 0.009) arterial pressure were higher in polluted air condition than filtered air condition. These findings demonstrate that the exercise of longer duration (i.e., 90 min), but not of shorter duration (i.e., <60 min), performed in vehicular air pollution condition results in pronounced pro-inflammatory and increased arterial pressure responses.

Estimation of minute ventilation by heart rate for field exercise studies.

The aim of this study was to develop predictive equations for minute ventilation based on heart rate, and to test the precision of the equations in two forms of endurance exercise. Eighteen men (age 27.8 ± 5.4 years old, maximal oxygen uptake 45.4 ± 8.3 ml·kg-1·min-1) performed a maximal progressive cycle test in which minute ventilation and heart rate were continually measured and further used to establish the proposed equations with quadratic and exponential adjustments. In the second and third laboratory visits, sixteen participants completed two cycling bouts, one high-intensity interval exercise and one low-intensity continuous exercise. The minute ventilation and heart rate were measured in both exercises and the validity of the equations tested. The Bland-Altman analysis showed agreement between the minute ventilation and estimated equations for interval and continuous exercise. There was no difference between the minute ventilation obtained from both equations and the minute ventilation directly measured during the interval exercise. However, the quadratic equation underestimated the minute ventilation during continuous exercise (p < 0.05). While both equations seem to be suitable to estimate minute ventilation during high-intensity interval exercise, the exponential equation is recommended for low-intensity continuous exercise.

Exercising in Air Pollution: The Cleanest versus Dirtiest Cities Challenge.

Background: Aerobic exercise is recommended to improve health. However, the increased ventilation might increase the doses of inhaled air pollutants, negating the health benefits in highly polluted areas. Our objective was to estimate the inhaled dose of air pollutants during two simulated exercise sessions at cleanest and dirtiest cities reported by World Health Organization (WHO) considering air quality. Methods: Minute ventilation data were extracted from laboratory-based exercise of 116 incremental running tests and used to calculate total ventilation of a hypothetical 30-min moderate continuous exercise routine. Afterwards, total ventilation values were combined with particulate matter (PM) data reported by the WHO for the 10 cleanest and 10 dirtiest cities, to calculate inhaled doses and the relative risk of all-cause mortality by exercising in different air pollution concentrations. Findings: The dirtiest cities are located at less developed countries compared to cleanest cities. The inhaled dose of PM2.5 and PM10 were significantly higher in the dirtiest cities compared to the cleanest cities at rest and exercise, and significantly higher during exercise compared to the rest at dirtiest cities. The relative risk of all-cause mortality analysis showed that, while exercise in the cleanest cities improved health benefits throughout up to 90 min, there were no further health benefits after 15 min of exercise in the dirtiest cities, and the air pollution health risks surpassed the exercise benefits after 75 min. Interpretation: Our findings suggest that a traditional 30-min of moderate aerobic exercise session might induce inhalation of high levels of pollutants when performed at dirtiest cities. Considering several adverse health effects from air pollutants inhalation, so the results suggest that the air pollution levels of the cities should be taken into account for physical exercise recommendations.

Parasympathetic activity delayed after self-paced exercise.

The main purpose of this study was to compare the effect of the constant load and self-paced exercise with similar total work on autonomic control after endurance exercise. Ten physically active men were submitted to (i) a maximal incremental exercise test, (ii) a 4-km cycling time trial (4-km TT), and (iii) a constant workload test with identical total external work performed at 4-km TT. Gas exchange was measured throughout the tests, while blood lactate, heart rate, and heart rate variability (HRV) were measured during the passive recovery. Power output measured at the last lap (i.e. 3600-4000 m) of 4-km TT (316 ± 89 W) was statistically higher than power output measured at the end of the constant workload exercise (211 ± 42 W). The 4-km TT produced higher values of blood lactate concentration (8.8 ± 2.1 mmol L-1) than the constant workload test (7.8 ± 2.1 mmol L-1). The heart rate recovery measured at 60 s (constant workload: 37 ± 7 bpm; 4-km TT: 30 ± 6) and 120 s (constant workload: 57 ± 9 bpm; 4-km TT: 51 ± 9 bpm) were higher in the constant workload than in the self-paced exercise. The HRV (i.e. RMSSD30s) was statistically higher in the constant load exercise measured at 120, 420, 450, 480, 540, and 570 s than the self-paced exercise. These findings suggest that the autonomic control responses were dependent of the endurance exercise modalities, with parasympathetic activity being delayed after self-paced exercise, as evidenced by post-exercise heart rate indices.

Determinant factors of peak treadmill speed in physically active men.

BACKGROUND: The aim of the present study was to determine whether physiological factors and maximal dynamic strength are able to determine the peak treadmill speed (PTS) in physically active individuals. METHODS: One hundred and fifty physically active healthy males voluntarily visit the laboratory on three separate occasions and underwent the following activities: first visit - IPAQ (short version), anthropometric measurements, and a maximal incremental test performed for physiological variables (maximal oxygen uptake [V̇O2] and respiratory compensation point [RCP]); second visit - constant speed test for running economy (RE) measurement, and familiarization with the Maximum Dynamic Strength (1RM) Test in the leg press exercise; third visit - 1RM test. RESULTS: The stepwise multiple regression model selected four independent variables to predict PTS (RCP, V̇O2, RE, and 1RM). RCP explained 59% (P<0.001) of variance in PTS, whereas V̇O2, RE and 1RM accounted for additional 8% (P<0.001), 4% (P<0.001), and 1.4% (P=0.038), respectively. CONCLUSIONS: In conclusion, the results of the present study demonstrate that PTS, an important predictor of endurance performance, is determined by both physiological (i.e., RCP, V̇O2, and RE) and muscular (1RM) parameters in healthy active individuals. These results demonstrate that, during a physical evaluation, PTS is able to represent physiological and muscular parameters of physically active individuals. This has the advantage during aerobic fitness evaluations of not requiring expensive equipment and specialized software.

O sonho de Accattone: Psicanálise e cinema na obra de Pier Paolo Pasolini / The dream of Accattone: Psychoanalysis and Cinema in the work of Pier Paolo Pasolini

Esse artigo procura estabelecer uma relação entre as interpretações a respeito dos sonhos teorizadas pela psicanálise e sua representação plástica realizada pelo cinema. Para tanto, escolheu-se como exemplo a cena de um sonho do primeiro filme do cineasta italiano Pier Paolo Pasolini Desajuste social (Accattone, 1960). O material onírico presente nessa obra confirma as hipóteses levantadas por Sigmund Freud e Sándor Ferenczi sobre o simbolismo onírico da ponte – interpretada como representante do falo, da angústia de castração e morte; e o simbolismo do duplo – como personificação de uma parte do próprio ego corporal do personagem: seu pênis, com sua potência e vitalidade. Por fim, o sonho de Accattone nos possibilita conhecer as ideias de Pasolini em relação ao inconsciente, ao processo primário, o trabalho do sonho, o simbolismo onírico e seus significados(AU)

This article tries to establish a relation between the interpretations about the dreams theorized by Psychoanalysis and its plastic representation realized by the cinema. To do so, we chose as an example the scene of a dream from the first film by Italian filmmaker Pier Paolo Pasolini: (Accattone, 1960). The dream material present in this work confirms the hypotheses raised by Sigmund Freud and Sàndor Ferenczi on the dream symbolism of the Bridge - interpreted as representative of the phallus, anxiety of castration and death; The symbolism of the double (when the character dreams of going to his own funeral) - as the personification of a part of the character's own body ego: his penis, with its potency and vitality. Finally, Accattone's dream enables us to know Pasolini's ideas about the unconscious, the primary process, the work of the dream, the dream symbolism and its meanings(AU)

The Association of ACE Genotypes on Cardiorespiratory Variables Related to Physical Fitness in Healthy Men.

Aerobic power (VO2max), aerobic capacity (RCP), and running efficiency (RE) are important markers of aerobic fitness. However, the influence of the angiotensin converting enzyme (ACE) polymorphism on these markers has not been investigated in healthy individuals. One hundred and fifty physically active young men (age 25 ± 3 years; height 1.77 ± 0.06 m; body mass 76.6 ± 0.9 kg; VO2max 47.7 ± 5.5 ml·kg-1·min-1) visited the laboratory on two separate occasions, and performed the following tests: a) a maximal incremental treadmill test to determine VO2max and RCP, and b) two constant-speed running tests (10 km·h-1 and 12 km·h-1) to determine RE. The genotype frequency was II = 21%; ID = 52%; and DD = 27%. There was a tendency for higher VO2max with the ACE II genotype (p = 0.08) compared to DD and ID genotypes. Magnitude based inferences suggested a likely beneficial effect on VO2max with the ACE II genotype. There was no association between genotypes for other variable. These findings suggest that individuals with the ACE II genotype have a tendency towards better values in aerobic power, but not with aerobic capacity or running economy.

GEDAE-LaB: A Free Software to Calculate the Energy System Contributions during Exercise.

PURPOSE: The aim of the current study is to describe the functionality of free software developed for energy system contributions and energy expenditure calculation during exercise, namely GEDAE-LaB. METHODS: Eleven participants performed the following tests: 1) a maximal cycling incremental test to measure the ventilatory threshold and maximal oxygen uptake (V̇O2max); 2) a cycling workload constant test at moderate domain (90% ventilatory threshold); 3) a cycling workload constant test at severe domain (110% V̇O2max). Oxygen uptake and plasma lactate were measured during the tests. The contributions of the aerobic (AMET), anaerobic lactic (LAMET), and anaerobic alactic (ALMET) systems were calculated based on the oxygen uptake during exercise, the oxygen energy equivalents provided by lactate accumulation, and the fast component of excess post-exercise oxygen consumption, respectively. In order to assess the intra-investigator variation, four different investigators performed the analyses independently using GEDAE-LaB. A direct comparison with commercial software was also provided. RESULTS: All subjects completed 10 min of exercise at moderate domain, while the time to exhaustion at severe domain was 144 ± 65 s. The AMET, LAMET, and ALMET contributions during moderate domain were about 93, 2, and 5%, respectively. The AMET, LAMET, and ALMET contributions during severe domain were about 66, 21, and 13%, respectively. No statistical differences were found between the energy system contributions and energy expenditure obtained by GEDAE-LaB and commercial software for both moderate and severe domains (P > 0.05). The ICC revealed that these estimates were highly reliable among the four investigators for both moderate and severe domains (all ICC ≥ 0.94). CONCLUSION: These findings suggest that GEDAE-LaB is a free software easily comprehended by users minimally familiarized with adopted procedures for calculations of energetic profile using oxygen uptake and lactate accumulation during exercise. By providing availability of the software and its source code we hope to facilitate future related research.

The genetics of human running: ACTN3 polymorphism as an evolutionary tool improving the energy economy during locomotion.

BACKGROUND: Covering long distances was an important trait to human evolution and continues to be highlighted for health and athletic status. This ability is benefitted by a low cost of locomotion (CoL), meaning that the individuals who are able to expend less energy would be able to cover longer distances. The CoL has been shown to be influenced by distinct and even 'opposite' factors, such as physiological and muscular characteristics, which are genetically inherited. In this way, DNA alterations could be important determinants of the characteristics associated with the CoL. A polymorphism in the ACTN3 gene (R577X) has been related to physical performance, associating the X allele with endurance and the R allele with strength/power abilities. AIM: To investigate the influence of ACTN3 genotypes on the CoL. SUBJECTS AND METHODS: One hundred and fifty healthy male individuals performed two constant speed tests (at 10 and 12 km/h) to determine the CoL. RESULTS: Interestingly, the results showed that heterozygous individuals (RX genotype) presented significantly lower CoL compared to RR and XX individuals. CONCLUSIONS: It is argued that RX genotype might generate an intermediate strength-to-endurance phenotype, leading to a better phenotypic profile for energy economy during running and, consequently, for long-term locomotion.

Influence of ACTN3 R577X polymorphism on ventilatory thresholds related to endurance performance.

The purpose of this study was to verify the association between ACTN3 polymorphism and physiological parameters related to endurance performance. A total of 150 healthy male volunteers performed a maximal incremental running test to determine the speeds corresponding to ventilatory threshold (VT) and respiratory compensation point (RCP). Participants were genotyped and divided into terciles based on the analysed variables. Genotype frequencies were compared through χ(2) test between lower and higher terciles, with the lowest or highest values of each analysed variable. ACTN3 XX genotype was over-represented in higher tercile for VT and RCP. Odds ratio also showed significantly higher chances of XX individuals to be in higher tercile compared to RR (7.3) and RR + RX (3.5) for VT and compared to RR genotype (8.1) and RR + RX (3.4) for RCP. Thus, XX individuals could attain the VT and RCP at higher speeds, suggesting that they are able to sustain higher running speeds in lower exercise intensity domains. It could result in higher lipid acids oxidation, saving muscle glycogen and delaying the fatigue during prolonged exercises, which could be the advantage mechanism of this genotype to endurance performance.

Head-to-head running race simulation alters pacing strategy, performance, and mood state.

The objective of this study was to analyze the influence of the presence and absence of competitors on pacing, overall running performance, and mood state during a self-paced 3-km run. Nine recreational runners participated in this study. They performed the following tests: a) an incremental test to exhaustion to measure the respiratory compensation point (RCP), maximal oxygen uptake, and peak treadmill speed; b) a submaximal speed constant test to measure running economy; and c) two 3-km running time trials performed collectively (COL, head-to-head competition) or individually (IND, performed alone) to establish pacing and running performance. The COL condition was formed of a group of four runners or five runners. Runners were grouped by matched performance times and to retain head-to-head characteristics.A mood state profile questionnaire was completed before and after the 3-km running time trial. The overall performance was better in the COL than in the IND (11.75 ± 0.05 min vs. 12.25 ± 0.06 min, respectively; p = 0.04). The running speeds during the first 500 m were significantly greater in COL (16.8 ± 2.16 km·h−1) than in IND (15.3 ± 2.45 km·h−1) (p = 0.03).The gain in running speed from IND to COL during the first 400 m (i.e. running speed in COL less running speed in IND) was significantly correlated with the RCP (r = 0.88; p = 0.05). The vigor score significantly decreased from pre- to post-running in COL (p=0.05), but not in IND (p=0.20). Additionally, the post running vigor was significantly higher in IND compared to COL (p = 0.03).These findings suggested that the presence of competitors induces a fast start, which results in an improved overall performance and reduced post-exercise vigor scores, compared to an individual run.

Effects of resistance training on neuromuscular characteristics and pacing during 10-km running time trial.

PURPOSE: The purpose of this study was to analyze the impact of an 8-week strength training program on the neuromuscular characteristics and pacing adopted by runners during a self-paced endurance running. METHODS: Eighteen endurance runners were allocated into either strength training group (STG, n = 9) or control group (CG, n = 9) and performed the following tests before and after the training period: (a) incremental test, (b) running speed-constant test, (c) 10-km running time trial, (d) drop jump test, (e) 30-s Wingate anaerobic test, (f) maximum dynamic strength test (1RM). During 1RM, the electromyographic activity was measured. RESULTS: In the STG, the magnitude of improvement for 1RM (23.0 ± 4.2 %, P = 0.001), drop jump (12.7 ± 4.6 %, P = 0.039), and peak treadmill speed (2.9 ± 0.8 %, P = 0.013) was significantly higher compared to CG. This increase in the 1RM for STG was accompanied by a tendency to a higher electromyographic activity (P = 0.080). The magnitude of improvement for 10-km running performance was higher (2.5 %) for STG than for CG (-0.7 %, P = 0.039). Performance was improved mainly due to higher speeds during the last seven laps (last 2800 m) of the 10-km running trial. There were no significant differences between before and after training period for maximal oxygen uptake, respiratory compensation point, running economy, and anaerobic performance for both groups (P > 0.05). CONCLUSIONS: These findings suggest that a strength training program offers a potent stimulus to counteract fatigue during the last parts of a 10-km running race, resulting in an improved overall running performance.

Is the COL5A1 rs12722 gene polymorphism associated with running economy?

The COL5A1 rs12722 polymorphism is considered to be a novel genetic marker for endurance running performance. It has been postulated that COL5A1 rs12722 may influence the elasticity of tendons and the energetic cost of running. To date, there are no experimental data in the literature supporting the relationship between range of motion, running economy, and the COL5A1 rs12722 gene polymorphism. Therefore, the main purpose of the current study was to analyze the influence of the COL5A1rs12722 polymorphism on running economy and range of motion. One hundred and fifty (n = 150) physically active young men performed the following tests: a) a maximal incremental treadmill test, b) two constant-speed running tests (10 km · h(-1)) and 12 km · h(-1)) to determine the running economy, and c) a sit-and-reach test to determine the range of motion. All of the subjects were genotyped for the COL5A1 rs12722 single-nucleotide polymorphism. The genotype frequencies were TT = 27.9%, CT = 55.8%, and CC = 16.3%. There were no significant differences between COL5A1 genotypes for running economy measured at 10 km · h(-1) (p = 0.232) and 12 km · h(-1) (p = 0.259). Similarly, there were no significant differences between COL5A1 genotypes for range of motion (p = 0.337). These findings suggest that the previous relationship reported between COL5A1 rs12722 genotypes and running endurance performance might not be mediated by the energetic cost of running.

Static stretching alters neuromuscular function and pacing strategy, but not performance during a 3-km running time-trial.

PURPOSE: Previous studies report that static stretching (SS) impairs running economy. Assuming that pacing strategy relies on rate of energy use, this study aimed to determine whether SS would modify pacing strategy and performance in a 3-km running time-trial. METHODS: Eleven recreational distance runners performed a) a constant-speed running test without previous SS and a maximal incremental treadmill test; b) an anthropometric assessment and a constant-speed running test with previous SS; c) a 3-km time-trial familiarization on an outdoor 400-m track; d and e) two 3-km time-trials, one with SS (experimental situation) and another without (control situation) previous static stretching. The order of the sessions d and e were randomized in a counterbalanced fashion. Sit-and-reach and drop jump tests were performed before the 3-km running time-trial in the control situation and before and after stretching exercises in the SS. Running economy, stride parameters, and electromyographic activity (EMG) of vastus medialis (VM), biceps femoris (BF) and gastrocnemius medialis (GA) were measured during the constant-speed tests. RESULTS: The overall running time did not change with condition (SS 11:35±00:31 s; control 11:28±00:41 s, p = 0.304), but the first 100 m was completed at a significantly lower velocity after SS. Surprisingly, SS did not modify the running economy, but the iEMG for the BF (+22.6%, p = 0.031), stride duration (+2.1%, p = 0.053) and range of motion (+11.1%, p = 0.0001) were significantly modified. Drop jump height decreased following SS (-9.2%, p = 0.001). CONCLUSION: Static stretch impaired neuromuscular function, resulting in a slow start during a 3-km running time-trial, thus demonstrating the fundamental role of the neuromuscular system in the self-selected speed during the initial phase of the race.

Impact of acute static-stretching on the optimal height in drop jumps / Impacto agudo do alongamento estático sobre a altura ideal de queda no salto em profundidade / Impacto agudo del estiramiento estático sobre la altura óptima de caída en el salto en profundidad

This study analyzed the effect of static stretching on performance during drop jumps. Furthermore, we investigated if a reduction in drop height would compensate the stretching-caused alterations. Ten physically active male subjects performed drop jumps at four different drop heights without static stretching for the optimal drop height determination. After, they performed drop jumps on two drop heights with static stretching previously. The jump height, contact time and reactive strength index were significantly affected by static stretching. However, only the contact time was significantly improved by the reduction in drop height with previous static stretching. Our results suggest that the decrement in performance after static stretching could be partially compensated by a reduction in drop height, which decreases the contact time near a non-stretching jump condition. This can be explained by the lower landing velocity and, possibly, the smaller reduction in the activation of the plantar flexors muscles. In conclusion, the reduction in drop height seems to be interesting after a static stretching session, aiming to expose the athletes to lower impact forces to maintain jump performance.

O presente estudo analisou o efeito do alongamento estático sobre o desempenho no salto em profundidade. Adicionalmente, foi investigada a redução na altura de queda poderia compensar as alterações causadas pelo alongamento prévio. Dez homens fisicamente ativos realizaram o salto em profundidade em quatro alturas de queda diferentes sem alongamento estático prévio, para determinação da altura de queda ideal, em duas alturas com o alongamento prévio. A altura de salto, o tempo de contato e o índice de força reativa foram significativamente afetados pelo alongamento estático. Contudo, apenas o tempo de contato foi significativamente melhorado com a redução na altura de queda do salto após o alongamento. Nossos resultados sugerem que a diminuição no desempenho após o alongamento pode ser parcialmente compensada com uma redução na altura de queda, diminuindo o tempo de contato para valores próximos ao salto sem alongamento prévio. Isso pode ser explicado pelo menor velocidade de aterrissagem e, possivelmente, pela menor redução na ativação dos músculos flexores plantares. Assim, a diminuição na altura de queda parece ser interessante após a realização do alongamento estático, visando submeter os atletas a menores forças de impacto e manter o desempenho do salto.

En este estudio se analizó el efecto del estiramiento estático sobre el rendimiento en saltos en profundidad. Además, se investigó si una reducción de la altura de caída compensaría las alteraciones causadas por el estiramiento previo. Diez hombres físicamente activos realizaron el salto en profundidad en cuatro alturas diferentes de caída sin estiramiento estático, para la determinación de la altura de caída óptima y en dos alturas con el estiramiento estático previo. La altura del salto, el tiempo de contacto y el índice de fuerza reactiva fueron afectados significativamente por el estiramiento estático. Sin embargo, sólo el tiempo de contacto mejoró significativamente por la reducción de la altura de caída del salto, después del estiramiento. Nuestros resultados sugieren quela disminución en el rendimiento después del estiramiento estático, podría ser parcialmente compensada con una reducción en la altura de caída, disminuyendo el tiempo de contacto para valores próximos al del salto sin estiramiento previo. Esto se puede explicar por la menor velocidad de aterrizaje y, posiblemente, por la menor reducción en la activación de los músculos flexores plantares. En conclusión, la reducción de la altura de caída parece ser interesante después de realizar una sesión de estiramientos estáticos, con el objetivo de someter a los atletas a menores fuerzas de impacto y mantener el rendimiento en el salto.

Pacing strategy determinants during a 10-km running time trial: contributions of perceived effort, physiological, and muscular parameters.

The purpose of this study was to identify the main determinants of the self-selected pacing strategy during a 10-km running time trial. Twenty eight male long-distance runners performed the following tests: (a) maximal incremental treadmill test, (b) economy running test, (c) maximum dynamic strength test, and (d) 10-km running time trial on an outdoor track. A stepwise multiple regression model was used to identify the contribution of rating of perceived exertion (RPE), physiological, and muscular parameters on the pacing strategy adopted by athletes. In the start phase (first 400 m), RPE accounted for 72% (p = 0.001) of the pacing variance. Peak treadmill speed (PTS) measured during a maximal incremental test explained 52% (p = 0.001) of the pacing variance during the middle phase (400-9,600 m), whereas maximal oxygen uptake and maximum dynamic strength accounted for additional 23% (p = 0.002) and 5% (p = 0.003), respectively. In the end phase (last 400 m), PTS accounted alone for 66% (p = 0.003) of the pacing variance. These data suggest that predictors of the pacing strategy during a 10-km running time trial have a transitional behavior from perceptive (start phase) to muscular and physiological factors (middle and end phases).

Estratégia adotada em provas de natação estilo crawl: uma análise das distâncias de 800 e 1500m / Pacing strategy adopted in crawl swimming competitions: an analysis of the 800-m and 1500-m distances

Em competições de natação de longa distância não está bem estabelecida qual a estratégia de prova (EP) ótima. Desta forma, o objetivo desse estudo foi caracterizar as EP adotadas por atletas de nível internacional em provas de natação de 800m (feminino) e 1500m (masculino) crawl. Foram analisadas as parciais de tempo (a cada 50m) dos atletas (n = 60) participantes das semifinais e finais dos últimos três campeonatos mundiais de natação, ocorridos no período de 2006 a 2010. A análise dos dados foi realizada por meio do teste estatístico CHAID (Chi-Squared Automatic Interaction Detection), que é uma estatística χ2 (qui-quadrado) para detectar comportamento de homogeneidade entre as variáveis. Os principais resultados encontrados foram: para as duas provas analisadas, o comportamento da velocidade em função do tempo mostrou-se semelhante à estratégia parabólica (formato em U), caracterizada por um início significativamente mais rápido (P < 0,05), seguido por uma diminuição do ritmo no trecho médio da prova, quando ocorre um novo aumento significativo (P < 0,05) na velocidade no trecho final. Desta forma, tais achados indicam que este perfil de EP pode ser classificado como ótimo para as provas de natação consideradas de longa duração, visto que foi o perfil preferencialmente adotado por atletas de nível mundial.

In long distance swimming competitions, the optimal pacing strategy is not well established. The objective of this study was to characterize the pacing strategy adopted by international level athletes in 800-m (female) and 1500-m (male) crawl swimming events. We analyzed the time of each 50 m splits for semi-finalists and finalists athletes of the last three world swimming championships from 2006 to 2010. The data analysis was performed through the statistic method named CHAID (Chi-Squared Automatic Interaction Detection), which is a statistic χ2 to detect a homogeneity behavior among the variables. The main results found were: for the two events analyzed, the velocity-versus-distance curve was similar to the parabolic pacing strategy (U-shaped), characterized by a significantly faster start (p<0.05) than mean velocity for the race, followed by a gradual decline in velocity in the middle splits, when athletes increase the velocity again (p<0.05) to produce an end spurt. In conclusion, these findings indicate that this pacing strategy profile can be classified as optimal for the long distance swimming events since it was preferentially adopted by international level athletes.

Anthropometric, physiological, performance, and nutritional profile of the Brazil National Canoe Polo Team.

The purpose of this study was to determine the physiological, anthropometric, performance, and nutritional characteristics of the Brazil Canoe Polo National Team. Ten male canoe polo athletes (age 26.7 ± 4.1 years) performed a battery of tests including assessments of anthropometric parameters, upper-body anaerobic power (Wingate), muscular strength, aerobic power, and nutritional profile. In addition, we characterized heart rate and plasma lactate responses and the temporal pattern of the effort/recovery during a simulated canoe polo match. The main results are as follows: body fat, 12.3 ± 4.0%; upper-body peak and mean power, 6.8 ± 0.5 and 4.7 ± 0.4 W · kg(-1), respectively; 1-RM bench press, 99.1 ± 11.7 kg; peak oxygen uptake, 44.3 ± 5.8 mL · kg(-1) · min(-1); total energy intake, 42.8 ± 8.6 kcal · kg(-1); protein, carbohydrate, and fat intakes, 1.9 ± 0.1, 5.0 ± 1.5, and 1.7 ± 0.4 g · kg(-1), respectively; mean heart rate, 146 ± 11 beats · min(-1); plasma lactate, 5.7 ± 3.8 mmol · L(-1) at half-time and 4.6 ± 2.2 mmol · L(-1) at the end of the match; effort time (relative to total match time), 93.1 ± 3.0%; number of sprints, 9.6 ± 4.4. The results of this study will assist coaches, trainers, and nutritionists in developing more adequate training programmes and dietary interventions for canoe polo athletes.

Bioenergetics and neuromuscular determinants of the time to exhaustion at velocity corresponding to VO2max in recreational long-distance runners.

The purpose of this study was to investigate the main bioenergetics and neuromuscular determinants of the time to exhaustion (T(lim)) at the velocity corresponding to maximal oxygen uptake in recreational long-distance runners. Twenty runners performed the following tests on 5 different days: (a) maximal incremental treadmill test, (b) 2 submaximal tests to determine running economy and vertical stiffness, (c) exhaustive test to measured the T(lim), (d) maximum dynamic strength test, and (e) muscle power production test. Aerobic and anaerobic energy contributions during the T(lim) test were also estimated. The stepwise multiple regression method selected 3 independent variables to explain T(lim) variance. Total energy production explained 84.1% of the shared variance (p = 0.001), whereas peak oxygen uptake (V(O2)peak) measured during T(lim)and lower limb muscle power ability accounted for the additional 10% of the shared variance (p = 0.014). These data suggest that the total energy production, V(O2)peak, and lower limb muscle power ability are the main physiological and neuromuscular determinants of T(lim)in recreational long-distance runners.