Why Pheidippides could not believe in the 'Central Governor Model': Popper's philosophy applied to choose between two exercise physiology theories.

An important epistemological problem has been faced by Exercise Physiologists. On one hand, one theory explains the fatigue through a ceiling effect of oxygen uptake. On the other hand, the new theory proposes that an encephalon mechanism would stop the effort before a catastrophic homeostasis failure. Many physiologists have looked for evidence to support their favourite theory even though the induction logic problem does not allow to prove whether truth is discovered; however, it is possible to prove that it does not occur. When some researchers fail to test their hypotheses, they use relativism to bring up their theories again. Noakes and his colleagues have based their theory on relativism, because it is impossible to refute by empirical observation. It also doesn't explain all phenomena that the oldest Hill's theory is able to explain. Noakes's theory isn't more accurate in its previsions. Noakes did not check whether the oxygen uptake plateau occurs in suitable tests to measure on the mouth what happens in the muscles. Finally, it doesn't propose new tests for the encephalon role during maximal effort, as that is expected in scientific work. For all of these reasons, it is possible to conclude there are no advantages in switching to the "Central Governor" theory.

Different Signatures of High Cardiorespiratory Capacity Revealed With Metabolomic Profiling in Elite Athletes.

PURPOSE: High cardiorespiratory capacity is a key determinant of human performance and life expectancy; however, the underlying mechanisms are not fully understood. The objective of this pilot study was to investigate biochemical signatures of endurance-performance athletes using high-resolution nontargeted metabolomics. METHODS: Elite long-distance runners with similar training and anthropometrical records were studied. After athletes' maximal oxygen consumption (V˙O2max) was measured, they were divided into 2 groups: low V˙O2max (<65 mL·kg-1·min-1, n = 7) and high V˙O2max (>75 mL·kg-1·min-1, n = 7). Plasma was collected under basal conditions after 12 hours of fasting and after a maximal exercise test (nonfasted) and analyzed by high-resolution LC-MS. Multivariate and univariate statistics were applied. RESULTS: A total of 167 compounds were putatively identified with an LC-MS-based metabolomics pipeline. Partial least-squares discriminant analysis showed a clear separation between groups. Significant variations in metabolites highlighted group differences in diverse metabolic pathways, including lipids, vitamins, amino acids, purine, histidine, xenobiotics, and others, either under basal condition or after the maximal exercise test. CONCLUSIONS: Taken together, the metabolic alterations revealed in the study affect cellular energy use and availability, oxidative stress management, muscle damage, central nervous system signaling metabolites, nutrients, and compound bioavailability, providing new insights into metabolic alterations associated with exercise and cardiorespiratory fitness levels in trained athletes.

A Multidimensional Approach to Assessing Anthropometric and Aerobic Fitness Profiles of Elite Brazilian Endurance Athletes and Military Personnel.

INTRODUCTION: Military personnel must remain physically active to meet operational requirements. Military physical training not only provides the performance capabilities required for performing occupational tasks but also fosters the development of sport. Thus, Armed Forces across the world have historically invested in developing elite- and Olympic-level athletes. This study aimed to assess the anthropometric and physiological differences among groups of Brazilian military athletes (MA), non-military athletes (A), and military non-athletes (M). MATERIALS AND METHODS: Seventy-five individuals participated in the study: 17 MA (23.7 ± 4.8 years), 27 A (24.7 ± 5.3 years), and 31 M (26.9 ± 3.3 years). MA and A individuals specialized in endurance sports, and had a mean weekly training volume of (100.0 ± 34.8 and 106.3 ± 40.5 Km; F = 0.894, p = 0.6), respectively. Anthropometric measures and maximal oxygen uptake (V̇O2máx) were assessed in all participants. Ergospirometry and anthropometry variables were analyzed with one-way analysis of variance (ANOVA) for independent measures. Comparisons of weekly training volume (km) and training experience (years) were performed only between the A and MA using the Student's t-test for independent samples. For a multidimensional approach, Partial least squares discriminant analysis (PLS-DA) was performed for all variables using the online tool MetaboAnalyst. RESULTS: We found no differences in anthropometric and physiological profiles between A and MA, but significant differences between M and MA/A in body mass index (kg/m2) (BMI), body fat percentage, fat mass (kg), waist circumference (cm) (WC), somatotype, and V̇O2máx (mL min-1 kg-1). CONCLUSION: In conclusion, military endurance athletes have similar anthropometric and physiological profiles to non-military athletes and superior levels to non-athlete military. These findings indicate that the Brazilian Armed Forces scouting system has been successful in identifying endurance athletic talent in line with their historic role of developing sport in Brazil.

Acute effect of Ethanol and Taurine on frontal cortex absolute beta power before and after exercise.

Ethanol (ET) is a substance that modulates the Central Nervous System (CNS). Frequently, ET intake occurs combined with energy drinks, which contain taurine (TA), an important amino acid found in the body (i.e brain and muscles). Although TA administration has been used in the improvement of physical performance, the impact of TA, ET and exercise remains unknown. This study aimed to analyze the acute effect of 6g of Taurine (TA), 0.6 mL∙kg-1 of Ethanol (ET), and Taurine combined with Ethanol (TA+ET) ingestion on the electrocortical activity before and after a moderate intensity exercise in 9 subjects, 5 women (counterbalanced experimental design). In each of the 4 treatments (Placebo-PL, TA, ET and TA+ET), electroencephalography (EEG) tests were conducted in order to analyze changes in absolute beta power (ABP) in the frontal lobe in 3 moments: baseline (before ingestion), peak (before exercise) and post-exercise. In the PL treatment, the frontal areas showed decrease in ABP after exercise. However, in the ET+TA treatment, ABP values were greater after exercise, except for Fp1. The ET treatment had no effect on the Superior Frontal Gyrus area (F3, Fz and F4) and ABP decreased after exercise in Fp1 and Fp2. In the TA treatment, ABP increased after exercise, while it decreased at the peak moment in most of the frontal regions, except for Fp1, F3 and Fz. We concluded that after a moderate intensity exercise, a decrease in cortical activity occurs in placebo treatment. Moreover, we found a inhibitory effect of TA on cortical activity before exercise and a increased in cortical activity after exercise. A small ET dose is not enough to alter ABP in all regions of the frontal cortex and, in combination with TA, it showed an increase in the frontal cortex activity at the post-exercise moment.

Acute ethanol and taurine intake affect absolute alpha power in frontal cortex before and after exercise.

Taurine and alcohol has been popularly ingested through energy drinks. Reports from both compounds shows they are active on nervous system but little is known about the acute effect of these substances on the frontal cortex in an exercise approach. The aim of this study was to determine the effects of 0,6mldL-1 of ethanol (ET), 6g of taurine (TA), and taurine with ethanol (TA+ET) intake on absolute alpha power (AAP) in the frontal region, before and after exercise. Nine participants were recruited, five women (22±3years) and four men (26±5years), for a counterbalanced experimental design. For each treatment, the tests were performed considering three moments: "baseline", "peak" and "post-exercise". In the placebo treatment (PL), the frontal areas showed AAP decrease at the post-exercise. However, in the TA, AAP decreased at peak and increased at post-exercise. In the ET treatment, AAP increased at the peak moment for the left frontal electrodes. In the TA+ET treatment, an AAP increase was observed at peak, and it continued after exercise ended. These substances were able to produce electrocortical activity changes in the frontal regions after a short duration and low intensity exercise. Left and right regions showed different AAP dynamics during peak and post-exercise moments when treatments were compared.

Effects of Sprint versus High-Intensity Aerobic Interval Training on Cross-Country Mountain Biking Performance: A Randomized Controlled Trial.

OBJECTIVES: The current study compared the effects of high-intensity aerobic training (HIT) and sprint interval training (SIT) on mountain biking (MTB) race simulation performance and physiological variables, including peak power output (PPO), lactate threshold (LT) and onset of blood lactate accumulation (OBLA). METHODS: Sixteen mountain bikers (mean ± SD: age 32.1 ± 6.4 yr, body mass 69.2 ± 5.3 kg and VO2max 63.4 ± 4.5 mL∙kg(-1)∙min(-1)) completed graded exercise and MTB performance tests before and after six weeks of training. The HIT (7-10 x [4-6 min--highest sustainable intensity / 4-6 min-CR100 10-15]) and SIT (8-12 x [30 s--all-out intensity / 4 min--CR100 10-15]) protocols were included in the participants' regular training programs three times per week. RESULTS: Post-training analysis showed no significant differences between training modalities (HIT vs. SIT) in body mass, PPO, LT or OBLA (p = 0.30 to 0.94). The Cohen's d effect size (ES) showed trivial to small effects on group factor (p = 0.00 to 0.56). The interaction between MTB race time and training modality was almost significant (p = 0.08), with a smaller ES in HIT vs. SIT training (ES = -0.43). A time main effect (pre- vs. post-phases) was observed in MTB race performance and in several physiological variables (p = 0.001 to 0.046). Co-variance analysis revealed that the HIT (p = 0.043) group had significantly better MTB race performance measures than the SIT group. Furthermore, magnitude-based inferences showed HIT to be of likely greater benefit (83.5%) with a lower probability of harmful effects (0.8%) compared to SIT. CONCLUSION: The results of the current study suggest that six weeks of either HIT or SIT may be effective at increasing MTB race performance; however, HIT may be a preferable strategy. TRIAL REGISTRATION: ClinicalTrials.gov NCT01944865.

The influence of levetiracetam in cognitive performance in healthy individuals: neuropsychological, behavioral and electrophysiological approach.

OBJECTIVE: The present study sought to analyze the influence of Levetiracetam (LEV) in cognitive performance by identifying the changes produced by LEV in reaction time, in neuropsychological assessment of attention and memory and in absolute theta power in frontal activity. METHODS: Twelve healthy subjects (5 men and 7 women; mean age, 30.08 years, standard deviation, 4.71) were recruited for this study. The neuropsychological tests: Trail Making Test (A and B), Digit Span (direct and indirect numerical orders/working memory); Stroop test (inhibitory control of attention); Tower of London (planning and decision-making) and a quantitative electroencephalography were applied in 2 different days after and before the participants ingested the capsule of placebo or 500 mg LEV. RESULTS: A two-way-ANOVA was implemented to observe the interaction between conditions (placebo or LEV 500 mg) and moments (pre- and post-ingestion of LEV or placebo). The data were analyzed by the SPSS statistical package (p<0.05). For the neuropsychological parameter, the Trail Making Test (A) was the only test that showed significant difference for condition in the task execution time (p=0.026). Regarding the reaction time in the behavioral parameter, an interaction between both factors (p=0.034) was identified through a two-way-ANOVA (condition versus moment). Electrophysiological measures showed a significant interaction for electrodes: F7, F3, and FZ. CONCLUSIONS: The findings showed that LEV promotes an important cognitive enhancement in the executive functions.

Influência do protocolo ergométrico na ocorrência de diferentes critérios de esforço máximo / Influence of the ergometric protocol in the onset of diferent criteria for maximal effort

INTRODUÇÃO E OBJETIVO: Neste estudo investigamos a influência de diferentes protocolos ergométricos na ocorrência dos critérios de esforço máximo. MÉTODOS: Nove sujeitos fisicamente ativos (23 ± 4 anos, 177 ± 10cm, e 77,1 ± 16kg) realizaram três testes de esforço (PR1 - 15W·min-1, PR2 - 50W·3 min-1, e PR3 - 50W·5 min-1) no cicloergômetro. O consumo de oxigênio foi medido em circuito aberto e integrado a cada 20s. Adotaram-se como critérios de esforço máximo: o platô no consumo de oxigênio < 150 mL·min-1; frequência cardíaca máxima (FCmáx) > 95 por cento prevista pela idade; lactato > 8,0 mM; e RER > 1,1. RESULTADOS: O VO2máx não apresentou diferenças entre os protocolos (2,68 ± 1,0; 2,58 ± 1,0 e 2,99 ± 1,3L·min-1 para PR1, PR2 e PR3, p = 0,72). A maior ocorrência do platô foi observada em PR1 (cinco sujeitos). O critério da frequência cardíaca máxima foi satisfeito em três sujeitos em PR3, e o critério do lactato em seis sujeitos, no mesmo protocolo (PR3). O RER > 1,1 foi observado em seis sujeitos em PR1. CONCLUSÃO: Concluímos que a ocorrência de diferentes critérios de esforço máximo é influenciada pela escolha do protocolo ergométrico, não indicando, contudo, valores distintos de VO2máx.

INTRODUCTION AND OBJECTIVES: The aim of this study was to investigate the influence of different exercise protocols in the onset of maximal effort parameters. METHODS: Nine healthy individuals (23 ± 4 year old; 177 ± 10 cm; and 77.1 ± 16 kg) participated in three progressive exercise tests (PR1 - 15 W•min-1, PR2 - 50 W•3 min-1, and PR3 - 50 W•5 min-1) in a cycle ergometer. Oxygen consumption was measured in open circuit and was calculated at 20 s intervals. The maximal effort parameters considered here were: plateau in oxygen consumption < 150 mL•min-1; maximal heart rate > 95 percent predicted by age; blood lactate concentration (8.0 mM; and RER > 1.1. RESULTS: The VO2max was not different among exercise tests (2.68 ± 1.0; 2.58 ± 1.0 and 2.99 ± 1.3 L•min-1 for PR1; PR2 and PR3, p = 0.72). The highest plateau occurrence was in PR1 (5 individuals). The heart rate criterion was observed in 3 individuals in PR3, while the lactate criterion was fulfilled in 6 subjects in the same PR3 protocol. Regarding the RER parameter, only 6 subjects in PR1 achieved values > 1.1. CONCLUSION: It was concluded that the maximal effort parameters evaluated in this study are influenced by the exercise test, even when there are no differences in the VO2max.

Exercise and mental health: many reasons to move.

The relationship between physical activity and mental health has been widely investigated, and several hypotheses have been formulated about it. Specifically, during the aging process, physical exercise might represent a potential adjunctive treatment for neuropsychiatric disorders and cognitive impairment, helping delay the onset of neurodegenerative processes. Even though exercise itself might act as a stressor, it has been demonstrated that it reduces the harmful effects of other stressors when performed at moderate intensities. Neurotransmitter release, neurotrophic factor and neurogenesis, and cerebral blood flow alteration are some of the concepts involved. In this review, the potential effects of exercise on the aging process and on mental health are discussed, concerning some of the recent findings on animal and human research. The overwhelming evidence present in the literature today suggests that exercise ensures successful brain functioning.

Electroencephalographic frontal asymmetry and depressive symptoms in the elderly.

Although neurophysiological changes of aging are well known, there is still much to learn about cortical asymmetry in older depressed subjects. This study aimed at assessing differences between depressed and normal elderly subjects on alpha asymmetry, and to observe the correlations of this measure with depressive symptoms and quality of life. Thirty-six subjects (14 normal and 22 depressed) were assessed by EEG, depression rating scales, and SF-36. Despite the fact that compared to healthy elderly, depressive elderly subjects showed relatively greater right frontal activity (F4F3) and relatively greater left parietal activity (P4P3); this difference was not significant. The relationship between depression and frontal asymmetry was better observed in healthy elderly, where relatively greater left frontal activity was associated with less depressive symptoms.

O exercício físico no tratamento da depressão em idosos: revisão sistemática / Physical exercise in the treatment of depression in the elderly: a systematic review

OBJETIVOS: Revisar a literatura quanto (I) ao possível efeito protetor do exercício físico sobre a incidência de depressão e (II) à eficácia do exercício físico como intervenção no tratamento da depressão. MÉTODO: Revisão sistemática de artigos em inglês e português nas bases ISI, PubMed, SciELO e LILACS de janeiro de 1993 a maio de 2006, utilizando conjuntamente os termos "depressão", "idosos" e "exercício". Artigos que avaliaram o efeito do exercício em idosos com doenças clínicas ou que utilizaram escalas para depressão somente para um diagnóstico inicial foram excluídos. RESULTADOS: Do total de 155 artigos, 22 atenderam aos critérios de inclusão, e oito foram acrescentados com busca manual. Os artigos de corte transversal (n = 8) utilizaram somente questionários de auto-avaliação para medir os níveis de atividade física. Os artigos longitudinais (n = 22) utilizaram também pedômetro digital, consumo direto de oxigênio e o exercício físico como intervenção metodológica. Os estudos que atenderam ao objetivo I apontaram para uma relação inversamente proporcional entre atividade física e alterações nos níveis de depressão. Os trabalhos que utilizaram o exercício como intervenção terapêutica na depressão encontraram resultados divergentes e apontaram para a interferência de fatores fisiológicos e psicológicos nessa relação. CONCLUSÃO: O papel do exercício e da atividade física no tratamento da depressão direciona-se para duas vertentes: a depressão promove redução da prática de atividades físicas; a atividade física pode ser um coadjuvante na prevenção e no tratamento da depressão no idoso.

OBJECTIVES: To review the literature on the (I) possible protective effect of physical activity on the incidence of depression, and (II) on the efficacy of physical exercise as a therapeutic intervention in depression. METHODS: Systematic review of ISI, PubMed, LILACS and SciELO articles in English and Portuguese from January 1993 to May 2005 using the keywords "depression," "elderly," and "exercise." Articles assessing the effect of physical exercise in the elderly with clinical diseases or that used depression scales only for initial diagnosis were excluded. RESULTS: We found 155 articles, 22 of which met the inclusion criteria. Other eight studies were included after a manual search. Cross-sectional studies (n = 8) used only self-evaluation questionnaires to measure the levels of physical activity. Longitudinal studies (n = 22) also used digital pedometer, direct measurements of oxygen consumption and physical exercise as methodological intervention. The studies meeting the first objective pointed to an inverse relationship between physical activity and changes in levels of depression. The studies that used physical activity as a therapeutic intervention in depression found divergent results and pointed to the interference of physiological and psychological factors on this relation. CONCLUSION: There are two aspects involved in the role of physical activity and exercise in the treatment of depression. Depression decreases the practice of physical activities; physical activity may be useful in the treatment and prevention of depression in the elderly.

Method for diagnosis and control of aerobic training in rats based on lactate threshold.

We propose a protocol for determination of lactate threshold (LT) and test the validity of one aerobic training based on LT in rats. In group I, V(LTi) (velocity at LT before training) was determined in all rats (n=10), each rat training at its own V(LTi) and in group II, animals (n=7) ran at 15 m min(-1), the mean V(LTi) of group I. The training consisted of daily runs at V(LTi) for 50 min, 5 days/week, for 4 weeks. In group I, this program increased V(LT) (V(LTi) 14.90+/-1.49 m min(-1) and V(LTf), after training, 22.60+/-1.17 m min(-1)) and the velocity at exhaustion (19.50+/-1.63 m min(-1) and 27.60+/-1.17 m min(-1)). [Lactate] at LT (2.62+/-0.43 mmol L(-1) versus 2.11+/-0.15 mmol L(-1)) and relative values of LT (76+/-3% versus 82+/-2%) stayed unaltered. In group II the V(LTf) was 20+/-1.8 m.mim(-1), the [lactate] at the LT, 2.02+/-0.17 mmol.L(-1); the exhaustion speed, 23.57+/-2.11 m.mim(-1) and relative value of LT, 82.71+/-2.29%. There were no significant differences in these parameters between groups I and II. Thus, this protocol based on LT is effective and the mean V(LT) determined in a small number of healthy untrained rats can be used for aerobic training in a larger group of healthy animals of same gender and age.

A acurácia da determinação do VO2max e do limiar anaeróbio / Accuracy of VO2max and anaerobic threshold determination

São raros estudos que tratam da acurácia de parâmetros de trocas gasosas durante o esforço, com a população brasileira. OBJETIVO: Determinar a confiabilidade do consumo máximo de oxigênio (VO2max) e do limiar anaeróbio (LAn), assim como, a objetividade do segundo (LAn) em adultos jovens saudáveis. MÉTODOS: Foram aplicados dois testes de esforço máximo, a partir dos quais dois observadores independentes determinaram o LAn através do método de inspeção visual. Os dados foram tratados por meio da análise de regressão, coeficiente de correlação intraclasse (CCI), ANOVA com dois fatores com teste post hoc de Tukey e teste t pareado para alfa < 0,05. As variações intra-observadores e intra-sujeitos foram determinadas por meio do erro típico (s) e coeficiente de variação (CV). RESULTADOS: Não houve diferença significativa entre os testes para o VO2max e LAn. Não foram observadas diferenças significativas entre testadores para a determinação do LAn. O VO2max apresentou entre os dois testes CCI = 0,97, s = ± 0,14L ò min-1 e CV = ± 5,5 por cento e para o LAn o CCI = 0,90, s = ± 0,14L ò min , e CV = ± 9,2 por cento. A determinação do LAn interobservadores apresentou CCI = 0,95, s = ± 0,10L ò min-1 e CV = ± 5,6 por cento. CONCLUSAO: O VO2max e o LAn foram medidas satisfatoriamente precisas.

Areas de seccão transversa do braco: implicacões técnicas e aplicacões para avaliacão da composicão corporal e da forca dinâmica máxima / Arm cross-section areas: technical implications and applications for body composition and maximal dynamic strength evaluation

As áreas do tecido muscular (A MB) e do anel de gordura do braco (A GB), podem ser estimadas por medidas antropométricas. OBJETIVO: Investigar a validade e o erro intertestador da antropometria para inferência A MB e do A GB. Secundariamente, estudou-se a previsão da forca dos membros superiores e tronco através da A MB. MÉTODOS: Foram voluntários para este estudo 40 adultos masculinos jovens (25 n 6 anos; 72,6 n 9,4kg), divididos aleatoriamente nos grupos de validade interna (VI, n = 30) e validade externa (VE, n = 10). Determinou-se para VI, através de conceitos geométricos, a área total do braco (A TB), A MB, A GB e área percentual de gordura do braco. O somatório de oito dobras cutâneas (S DC8) foi empregado como índice da adiposidade corporal. A forca dos membros superiores e do tronco foi medida através da carga máxima alcancada no exercício supino reto livre (1-RM). As medidas antropométricas foram realizadas por dois avaliadores independentes. Os dados foram tratados por meio da análise de regressão, coeficiente de correlacão intraclasse (ICC) e teste t de Student pareado (a < 0,05). RESULTADOS: A variância do S DC8 pode ser explicada em 93 por cento (EPE = 14,6mm) a partir da A GB e do peso corporal. A A MB explicou em 66,1 por cento (EPE = 9kg) a 1-RM. Não se observou diferenca significativa, para o grupo VE, entre os valores medidos (84,2 n 16,2kg) e preditos (78,4 n 14,2kg) de 1-RM. Observou-se pouca variacão entre os avaliadores para A MB (ICC = 0,99), A GB (ICC = 0,96) e A TB (ICC = 0,99). CONCLUSAO: A antropometria pode ser empregada para inferência da A MB e do A GB, com boa concordância entre avaliadores, para estimativa da adiposidade corporal e da forca dos membros superiores e tronco.