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

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

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

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

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%

Sense Of Effort And Other Unpleasant Sensations During Exercise: Clarifying Concepts And Mechanisms.

The sense of effort is an essential component of all forms of exercise. Although extensively studied, exercise physiologists have failed to reach consensus about whether this sensation is based on afferent sensory feedback or is centrally generated and independent of such feedback. This confusion has led to misunderstandings regarding the neurological mechanisms responsible for the sense of effort as opposed to other specific sensations such as pain and temperature. A mechanism in which the sense of effort is centrally generated and independent of feedback had been proposed more than 150 years ago. However, a more recent concept of sense of effort as a subjective rating of exercise intensity based on various sensations experienced during exercise given by Borg may have caused confusion, especially among exercise physiologists. Many began to use and understand the sense of effort as a sensation that is generated by afferent sensory feedback. The information reviewed in this article, together with the examples given, constitutes a body of evidence in favour of a centrally generated sense of effort. Afferent sensory feedback is important for the conscious awareness of different sensations such as pain and temperature, and plays important roles in the control of homeostasis. However, peripheral sensory feedback does not seem to be important for the generation of the sense of effort. The sense of effort and other specific sensations such as temperature, pain and other muscular sensations present two separate neurological mechanisms. While the former is centrally generated, the latter is based on afferent sensory feedback. An interaction of these sensations is likely the ultimate regulator of exercise performance. However, further investigation is required to fully understand these phenomena.46308-1

Percepção de esforço e dor durante o exercício : mecanismos e limitação do desempenho

Atualmente, os processos sensoriais do corpo humano se tornaram atributo crucial para entender a limitação do desempenho. Sugere-se que as percepções de esforço e dor são provavelmente determinantes para o desempenho em exercícios aeróbios. Mesmo sendo estudada há mais de 100 anos, a percepção de esforço ainda gera controvérsia sobre seu mecanismo gerador. Esta revisão, além de apresentar as discussões de pesquisadores do século passado sobre a percepção de esforço, apresenta também os mecanismos atuais mais aceitos para ambas as percepções: esforço e dor. Enquanto a percepção de esforço parece ser gerada centralmente, a dor é advinda dos processos de feedback aferente. Estudos até a presente data nos sugerem que a percepção de esforço parece ser mais importante do que a percepção de dor em termos de limitação do desempenho. Porém, a influência que a dor tem sobre o esforço ainda é pouco entendida e requer maiores investigações.Currently, the sensory processes of the human body have become crucial attribute to understanding the limitation of performance. It is suggested that the perceptions of effort and pain are likely determinants to performance in aerobic exercises. Despite being studied for over 100 years, the perception of effort is still controversial on its generating mechanism. This review, besides presenting the researchers discussions of the past century about the perception of effort, also presents the current more accepted mechanisms for both perceptions: effort and pain. While the perception of effort appears to be centrally generated, the pain is arising from afferent feedback processes. Studies to date suggest us that the perception of effort seems to be more important than the perception of pain in terms of limiting the performance. However, the influence that pain has on effort is still poorly understood and requires further investigation

Effects of caffeine ingestion on high-intensity aerobic exercise in hypoxia : physiological and perceptual parameters

Orientador: Antonio Carlos de MoraesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação FísicaResumo: Introdução: Apesar de ser uma substância extensivamente estudada no âmbito do desempenho físico, a cafeína e seus efeitos no desempenho em altitude (hipóxia) foram estudados em apenas 2 investigações científicas (Berglund & Hemmingsson 1982; Fulco et al 1994), sugerindo que esta tem seus efeitos potencializados nesse ambiente. As únicas variáveis analisadas foram percepção de esforço e parâmetros cardiorrespiratórios. Porém, um dos mecanismos de ação sugeridos da cafeína é no sistema neuromuscular que, em hipóxia, sofre com uma mais rápida ocorrência de fadiga. Objetivo: Investigar o efeito da cafeína no desempenho aeróbio em hipóxia nos parâmetros psicofisiológicos, em particular seus efeitos na fadiga periférica e central. Métodos: Sete sujeitos (29 ± 6 anos, 179 ± 8 cm, 75 ± 8 kg, VO2máx 51 ± 5 ml.kg-1) participaram desse estudo duplo-cego e randomizado. Primeiro realizaram um teste incremental máximo em hipóxia (FIO2 = 0,15) para determinar a potência pico. A segunda e terceira visita consistiu em um período fixo de 6 min de exercício, seguido de um teste constante até a exaustão, ambos a _80% da potência pico e em hipóxia. Lactato, SpO2, percepção de esforço, frequência cardíaca, e fadiga periférica e central foram mensuradas. Resultados: Durante o teste incremental, a potência pico alcançada foi de 275 ± 38 W, com valores finais de percepção de esforço, lactato, frequência cardíaca e SpO2 de 18 ± 1, 13 ± 2 mmol/l, 179 ± 10 bpm, e 81 ± 5%, respectivamente. Tempo até a exaustão foi significativamente maior (11,8%) na condição cafeína (402 ± 137 s) comparado à condição placebo (356 ± 112 s) (P = 0,016). Tempos individuais foram maiores com cafeína em 6 dos 7 sujeitos. Variação intra-sujeito foi de -5 a 23% (-10 a 74 s). Cafeína teve um impacto significativo na subescala de humor fadiga, apresentando menores valores, enquanto a subescala vigor apresentou tendência a ser maior nessa condição. A percepção de esforço apresentou menores valores para o grupo cafeína durante o teste até exaustão. Tanto para o período de 6 minutos como durante o teste de tempo até a exaustão, a frequência cardíaca foi maior para o grupo cafeína. Enquanto SpO2 foi menor para o grupo cafeína apenas durante o período de 6 minutos, os valores de lactato não diferiram entre os grupos, mas apresentaram tendência a maiores valores na condição cafeína. Os valores de contração voluntária máxima apresentaram declínio significativo, com maior queda para o grupo cafeína. Já os valores de ativação voluntária e estímulos duplos, apesar de decrescerem, não foram diferentes entre as condições. Por fim, todos os parâmetros de oxigenação não diferiram entre as condições. Conclusão: O efeito ergogênico da cafeína em altitude ocorreu concomitantemente a alterações no estado de humor, percepção de esforço, sinais eletromiográficos, frequência cardíaca e contração voluntária máximaAbstract: Introduction: Despite being a substance extensively studied in the physical performance scope, caffeine and its effects on performance in altitude (hypoxia) have been studied only in 2 scientific investigations (Berglund & Hemmingsson 1982; Fulco et al 1994), and it is suggested that is has greater effects in this environment. The variables analyzed were only perception of effort and cardiorespiratory parameters. However, one of the suggested caffeine's mechanisms of action is upon the neuromuscular system that, in hypoxia, presents a faster development of fatigue. Aim: Study the effects of caffeine during aerobic performance in hypoxia in the psychophysiological parameters, in particular its effects on peripheral and central fatigue. Methods: Seven subjects (29 ± 6 years, 179 ± 8 cm, 75 ± 8 kg, VO2max 51 ± 5 ml.kg-1) participated in this randomized double-blind study. First it was performed a maximal incremental test in hypoxia (FIO2 = 0.15) to determine peak power output. The second and third visits consisted of a fixed period of 6 min of exercise, followed by a time to exhaustion test, both at _80% of peak power output and in hypoxia. Lactate, SpO2, perception of effort, heart rate, and peripheral and central fatigue were measured. Results: During the incremental test, peak power output reached was 275 ± 38 W, with end-values of perception of effort, lactate, heart rate and SpO2 of 18 ± 1, 13 ± 2 mmol/l, 179 ± 10 bpm, and 81 ± 5%, respectively. Time to exhaustion was significantly longer (11.8%) with caffeine (402 ± 137 s) compared to placebo (356 ± 112 s) (P = 0.016). Individual times were longer with caffeine in 6 out of 7 subjects. Intra-subject variability was from -5 to 23% (-10 to 74s). Caffeine had a significant impact on the mood subscale fatigue, presenting lower values, while the subscale vigor presented a trend to be higher in this condition. Perception of effort presented lower values in the caffeine condition during time to exhaustion test. Both to the fixed period of 6 minutes and to the time to exhaustion test, heart rate was higher in the caffeine condition. While SpO2 was lower with caffeine only during the fixed period of 6 minutes, lactates values did not differ between groups, but presented a trend to be higher during the caffeine condition. Values of maximal voluntary contraction showed a significant reduction, with greater reduction in the caffeine condition. However, voluntary activation and doublet values, despite decreasing, were not different between conditions. Finally, all the brain oxygenation parameters did not differ between conditions. Conclusion: The ergogenic effect of caffeine at altitude occurred concomitantly with alterations in mood state, perception of effort, electromyographic signals, heart rate and maximal voluntary contractionMestradoBiodinamica do Movimento e EsporteMestre em Educação Físic