The psychobiological model: a new explanation to intensity regulation and (in)tolerance in endurance exercise

Os mecanismos que explicam fadiga e exaustão, controle da intensidade e (in)tolerância ao exercício de resistência cardiorrespiratória têm sido estudados há mais de um século. Apesar de diversas teorias científicas atualmente disponíveis, nos últimos cinco anos um novo modelo chamado de Psicobiológico tem sido proposto. Este modelo dá maior importância aos fatores perceptuais e motivacionais em relação aos seus antecessores, bem como a respectiva influência destes fatores no processo consciente de tomada de decisão e controle comportamental. Nesta revisão, nós apresentamos evidências experimentais e sintetizamos os pontos chaves do modelo Psicobiológico que explicam o controle da intensidade e (in)tolerância ao exercício de resistência cardiorrespiratória. Adicionalmente, nós discutimos como o modelo explica as adaptações ao treinamento relacionadas à melhora no desempenho, as manipulações experimentais e suas predições. Ao final, propomos futuras direções para esta área investigativa. O modelo Psicobiológico pode proporcionar uma nova perspectiva aos resultados anteriormente publicados na literatura, ajudando os cientistas a entenderem melhor seus problemas de pesquisa, assim como analisar e interpretar novas evidências mais precisamente.The mechanisms underpinning fatigue and exhaustion, and the specific sources of exercise-endurance intensity regulation and (in)tolerance have been investigated for over a century. Although several scientific theories are currently available, over the past five years a new framework called Psychobiological model has been proposed. This model gives greater attention to perceptual and motivational factors than its antecedents, and their respective influence on the conscious process of decision-making and behavioral regulation. In this review we present experimental evidences and summarize the key points of the Psychobiological model to explain intensity regulation and (in)tolerance in endurance exercise. Still, we discuss how the Psychobiological model explains training-induced adaptations related to improvements in performance, experimental manipulations, its predictions, and propose future directions for this investigative area. The Psychobiological model may give a new perspective to the results already published in the literature, helping scientists to better guide their research problems, as well as to analyze and interpret new findings more accurately

Effects of caffeine on neuromuscular fatigue and performance during high-intensity cycling exercise in moderate hypoxia

Purpose: To investigate the effects of caffeine on performance, neuromuscular fatigue and perception of effort during high-intensity cycling exercise in moderate hypoxia. Methods: Seven adult male participants firstly underwent an incremental exercise test on a cycle ergometer in conditions of acute normobaric hypoxia (fraction inspired oxygen = 0.15) to establish peak power output (PPO). In the following two visits, they performed a time to exhaustion test (78 ± 3% PPO) in the same hypoxic conditions after caffeine ingestion (4 mg kg$^{−1}$) and one after placebo ingestion in a double-blind, randomized, counterbalanced cross-over design. Results: Caffeine significantly improved time to exhaustion by 12%. A significant decrease in subjective fatigue was found after caffeine consumption. Perception of effort and surface electromyographic signal amplitude of the vastus lateralis were lower and heart rate was higher in the caffeine condition when compared to placebo. However, caffeine did not reduce the peripheral and central fatigue induced by high-intensity cycling exercise in moderate hypoxia. Conclusion: The caffeine-induced improvement in time to exhaustion during high-intensity cycling exercise in moderate hypoxia seems to be mediated by a reduction in perception of effort, which occurs despite no reduction in neuromuscular fatigue

Health related quality of life is differently associated with leisure-time physical activity intensities according to gender: a cross-sectional approach

Background: Several studies have demonstrated a positive association between physical activity (PA) and health-related quality of life (HRQL). However, studies have suggested that this association depends both on the PA intensity and the domain of HRQL evaluated. This study aimed to explore the association between physical, mental and overall HRQL with recommended levels of PA. PA levels were divided into moderate and vigorous intensity leisure-time PA and total leisure-time PA.Methods: The study included 1001 adults, 582 women (46 +/- 17 years) and 419 men (43 +/- 16 years), residents in Rio Claro-SP, Brazil. All participants completed the SF-36 questionnaire to assess HRQL and the long version of the International Physical Activity Questionnaire (IPAQ) to assess level and intensities of leisure-time PA. Total leisure-time PA at moderate intensity was classified as: less than 9 min/week, 10-149 min/week, 150-299 min/week and 300 min/ week or more. Total leisure-time PA at vigorous intensity was classified as: less than 9 min/week, 10 to 74.9 min/week, 75-149 min/week and 150 min/week or more. Multiple linear regression was performed in STATA version 12.0.Results: Among women, moderate intensity and total leisure-time PA were associated with physical health. Among men, moderate and vigorous intensity and total leisure-time PA were associated with physical health and overall HRQL. Furthermore, moderate intensity and total leisure-time PA were associated with mental health in men. However, vigorous intensity PA was not associated with mental health for this group.Conclusion: The different domains of HRQL were associated with different levels and intensities of PA in leisure-time according to gender of adults. These findings indicate the complexity and importance of evaluating the HRQL stratified by gender and consider the different levels and intensities of PA.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

The role of sense of effort on self-selected cycling power output

PURPOSE: We explored the effects of the sense of effort and accompanying perceptions of peripheral discomfort on self-selected cycle power output under two different inspired O2 fractions. METHODS: On separate days, eight trained males cycled for 5 min at a constant subjective effort (sense of effort of '3' on a modified Borg CR10 scale), immediately followed by five 4-s progressive submaximal (sense of effort of "4, 5, 6, 7, and 8"; 40 s between bouts) and two 4-s maximal (sense of effort of "10"; 3 min between bouts) bouts under normoxia (NM: fraction of inspired O2 [FiO2] 0.21) and hypoxia (HY: [FiO2] 0.13). Physiological (Heart Rate, arterial oxygen saturation (SpO2) and quadriceps Root Mean Square (RMS) electromyographical activity) and perceptual responses (overall peripheral discomfort, difficulty breathing and limb discomfort) were recorded. RESULTS: Power output and normalized quadriceps RMS activity were not different between conditions during any exercise bout (p > 0.05) and remained unchanged across time during the constant-effort cycling. SpO2 was lower, while heart rate and ratings of perceived difficulty breathing were higher under HY, compared to NM, at all time points (p < 0.05). During the constant-effort cycling, heart rate, overall perceived discomfort, difficulty breathing and limb discomfort increased with time (all p < 0.05). All variables (except SpO2) increased along with sense of effort during the brief progressive cycling bouts (all p < 0.05). During the two maximal cycling bouts, ratings of overall peripheral discomfort displayed an interaction between time and condition with ratings higher in the second bout under HY vs. NM conditions. CONCLUSION: During self-selected, constant-effort and brief progressive, sub-maximal, and maximal cycling bouts, mechanical work is regulated in parallel to the sense of effort, independently from peripheral sensations of discomfort

The Relationship Between Rating of Perceived Exertion and Muscle Activity During Exhaustive Constant-Load Cycling

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The aims of this study were to verify the relationship between rating of perceived exertion (RPE) and electromyography (EMG) increases during exhaustive constant-load cycling bouts and, to compare and to correlate the power outputs corresponding to perceived exertion threshold (PET) and neuromuscular fatigue threshold (NFT). 11 men completed 3-4 different exhaustive constant-load cycling bouts on a cycle ergometer, being RPE and EMG measured throughout the bouts. The linear regression of the RPE(slope) and EMG(slope) against the power output identified the PET and NFT intensity, respectively. There was a significant relationship between RPE slope and EMG(slope) (R(2) = 0.69; P < 0.01). However, the linearity of RPE(slope) (R(2) = 0.93 +/- 0.07) was significantly higher (P < 0.001) than EMG(slope) (R(2) = 0.63 +/- 0.25). In addition, the RPE(slope) and EMG(slope) were related to time to exhaustion (r = -0.59 and r = -0.60; P < 0.001). There was no significant difference (P = 0.42) between PET (201.5 +/- 27.9W) and NFT (210.3 +/- 22.6W) and they were significantly correlated (r = 0.78; P = 0.005). Therefore, the RPE and EMG increases during exhaustive constant-load cycling bouts are related and, PET and NFT intensities are similar and closely associated.3110683688Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [04/12589-0

Electronic music effects on neuromuscular and cardiovascular systems and psychophysiological parameters during exhaustive incremental test

The aim of this study was to analyze the music effects on physiological and psychophysiological responses, as well as on the maximum power output attained during an incremental test. A sample of 10 healthy individuals (20.8 ± 1.4 years, 77.0 ± 12.0 kg, 179.2 ± 6.3 cm) participated in this study. It was recorded the electromyographic activity (muscles Rectus Femoris − RF and Vastus Lateralis − VL), heart rate (HR), rating of perceived exertion (RPE), ratings of perceived time (RPT) and the maximum power output attained (PMax) during music (WM) and without music (WTM) conditions. The individuals completed four maximal incremental tests (MIT) ramp-like on a cycle simulator with initial load of 100 W and increments of 10 W·min-1. The mean values of PMax between conditions WTM (260.5 ± 27.7 W) and WM (263.2 ± 17.2 W) were not statistically different. The comparison between the rates of increase of the values expressed in root-mean-square (RMS) and median frequency (MF) for both muscles (RF and VL) also showed no statistical difference, as well as HR, RPE and RPT. It is concluded that the use of the electronic music during an incremental test to exhaustion showed no effect on the analyzed variables for the investigated group

Mongolian and Japanese Joint Conference on "Echinococcosis: diagnosis, treatment and prevention in Mongolia" June 4, 2009

The first Mongolian-Japanese Joint Conference on "Echinococcosis: diagnosis, treatment and prevention in Mongolia" was held in Ulaanbaatar on June 4th, 2009. It was the first chance for Mongolian experts (clinicians, pathologists, parasitologists, biologists, epidemiologists, veterinarians and others working on echinococcosis) joined together. Increase in the number of cystic echinococcosis (CE) cases year by year was stressed. CE in children may be more than adult cases. Alveolar echinococcosis was suspected chronic malignant hepatic tumors or abscesses. Main discussion was as to how to introduce modern diagnostic tools for pre-surgical diagnosis, how to establish the national system for the data base of echinococcosis with the establishment of a network system by experts from different areas. The importance of molecular identification of the parasites in domestic and wild animals was also stressed

Use of statistics in Physical Education: analysis of national publications between 2009 and 2011

O objetivo do presente estudo foi verificar o padrão de uso da estatística em artigos científicos publicados em periódicos nacionais da área da Educação Física. Para tal, foram analisados todos os artigos publicados no triênio 2009-2011 de periódicos da área de Educação Física com estratificação B2 ou superior no QUALIS CAPES (Área 21) vigente. No levantamento bibliográfico foram encontrados 872 artigos nas cinco revistas pesquisadas, que foram classificados em sem estatística, estatística descritiva e estatística analítica. Para as análises, utilizou-se a estatística descritiva e o intervalo de confiança de 95% para comparar a diferença entre as proporções e, quando necessário, o teste qui-quadrado e regressão logística. Observou-se uma menor proporção de trabalhos com análise descritiva (7,1%; IC95% = 5,4%-8,8%) quando comparados com os artigos sem estatística (46,3%; IC95% = 42,9%-49,6%) e com estatística analítica (46,6%; IC95% = 43,2%-49,9%). O padrão de uso de procedimentos estatísticos variou entre as cinco revistas científicas e entre as áreas de concentração (Saúde, Esporte, Lazer, Educação e Outras). A proporção dos artigos que não atenderam aos pressupostos básicos para a utilização de testes paramétricos foi de 43,3%. Essa proporção não apresentou diferença significativa ao longo dos três anos analisados, região de afiliação dos primeiros e últimos autores ou em relação à titulação dos primeiros e últimos autores. O presente estudo aponta um cenário preocupante no que tange à utilização da estatística na área de Educação Física, pois, além do alto índice de trabalhos que não seguem os pressupostos básicos para utilização da estatística, essa situação parece ser comum independente da titulação dos autores, região de afiliação ou revista de publicação.The purpose of the present study was to verify the pattern of use of statistics in scientific articles published in national journals of the Physical Education area. Thus, all articles published in the 2009-2011triennium of the Physical Education journals stratified at B2 or higher in the current QUALIS CAPES (Field 21) were analyzed. The bibliographic search found 872 articles in the five journals selected, which were classified into no statistics, descriptive statistics and analytical statistics. For the analysis, descriptive statistics was performed and the 95% confidence interval to compare the difference between the proportions and, when necessary, the chi-square test and Logistic Regression. There was a lower proportion of articles with descriptive analysis (7.1%, 95%CI=5.4%-8.8%) compared with those with no statistics (46.3%, 95%CI=42.9%-49.6%) and analytical statistics (46.6%, 95%CI=43.2%-49.9%). The pattern of use of statistical procedures ranged among the five scientific journals and across fields of concentration (Health, Sport, Leisure, Education and Others). The proportion of articles which did not meet the basic assumptions for the use of parametric test was 43.3%. This proportion was not significantly different over the three years analyzed, first and last authors' region of affiliation of or for the first and last authors' degree. The present study points out a worrying scenario regarding the use of statistics in the area of Physical Education, because besides the high amount of work which do not follow the basic assumptions for statistical use , this situation seems to be common regardless of authors' degree, region of affiliation or journal of publication

Psychological determinants of whole-body endurance performance

Background: No literature reviews have systematically identified and evaluated research on the psychological determinants of endurance performance, and sport psychology performance-enhancement guidelines for endurance sports are not founded on a systematic appraisal of endurance-specific research. Objective: A systematic literature review was conducted to identify practical psychological interventions that improve endurance performance and to identify additional psychological factors that affect endurance performance. Additional objectives were to evaluate the research practices of included studies, to suggest theoretical and applied implications, and to guide future research. Methods: Electronic databases, forward-citation searches, and manual searches of reference lists were used to locate relevant studies. Peer-reviewed studies were included when they chose an experimental or quasi-experimental research design, a psychological manipulation, endurance performance as the dependent variable, and athletes or physically-active, healthy adults as participants. Results: Consistent support was found for using imagery, self-talk, and goal setting to improve endurance performance, but it is unclear whether learning multiple psychological skills is more beneficial than learning one psychological skill. The results also demonstrated that mental fatigue undermines endurance performance, and verbal encouragement and head-to-head competition can have a beneficial effect. Interventions that influenced perception of effort consistently affected endurance performance. Conclusions: Psychological skills training could benefit an endurance athlete. Researchers are encouraged to compare different practical psychological interventions, to examine the effects of these interventions for athletes in competition, and to include a placebo control condition or an alternative control treatment. Researchers are also encouraged to explore additional psychological factors that could have a negative effect on endurance performance. Future research should include psychological mediating variables and moderating variables. Implications for theoretical explanations of endurance performance and evidence-based practice are described

Efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP)

Caffeine is an ergogenic substance used to enhance sports performance. With central and peripheral effects, it may influences the perception of fatigue during exhaustive efforts with central and peripheral effects. The present study aimed to investigate the effects of caffeine ingestion on the perceived exertion threshold (PET). After completing maximum work load (Wmax) test on cycling ergometer, eight men executed four constant load tests (80, 90, 100 and 110% of Wmax) under caffeine (CAF) or placebo (PLA) ingestion for PET determination. The “t” Student paired test was used to compare PET under the analyzed conditions. There were no significant differences between CAF and PLA conditions for PET. However, during 100 and 110% constant load tests, CAF conditions presented longer exhausting time (P < 0,01) and the tests between 80% and 100% presented lower increasing ratings of perceived exertion (RPE) (P < 0,01). According to the results, it is possible to conclude that PET was not modified with CAF supplementation, even with higher performance during the most intensive tests and attenuation of the increasing rate of RPE in 80% and 100% loads.A cafeína é substância ergogênica utilizada para aprimorar o rendimento esportivo. Com efeitos centrais e periféricos, pode interferir na percepção de fadiga durante esforços exaustivos. O presente estudo objetivou investigar o efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP). Após estabelecer a carga máxima de trabalho (Wmax) por teste incremental em cicloergômetro, oito homens realizaram quatro testes de carga constante (80, 90, 100 e 110% da Wmax) sob ingestão de cafeína (CAF) ou placebo (PLA) para determinação do LEP. Para contrastar os dados, utilizou-se o teste “t” de Student pareado. Não foram encontradas diferenças significativas entre os valores de LEP em nenhuma das condições, porém, na condição CAF os testes constantes de 100 e 110% apresentaram maior tempo de exaustão (P < 0,01), e os testes de 80 e 100% apresentaram menor taxa de aumento da percepção subjetiva de esforço (PSE) (P < 0,01). De acordo com os resultados, é possível concluir que o LEP não foi modificado com a suplementação de CAF, mesmo com desempenho superior durante os testes mais intensos e atenuação da taxa de aumento da PSE nas cargas 80 e 100%