Insular cortex activity during food-specific inhibitory control is associated with academic achievement in children.

BACKGROUND/OBJECTIVES: Inhibitory control (IC) is usually poorer in children with overweight and obesity and has been associated with unhealthy eating behaviors and lower academic achievement. Food-specific IC tasks depicting salient unhealthy foods may be more sensitive to predicting fat accumulation and unhealthy behaviors than traditional IC tasks. However, the neural activation patterns in response to food-specific IC remain unclear, especially in developing children`s brains. Here, we investigated brain activity associated with food-specific IC in children with accumulated fat mass. SUBJECTS/METHODS: 36 children with overweight and obesity performed a food-specific Go/No-Go task in an MRI scanner. We assessed the children's body composition with dual-energy x-ray absorptiometry, academic achievement, somatic maturation, and cardiorespiratory fitness. RESULTS: The left insular cortex was significantly activated during successful inhibition of palatable food cues and was associated with higher academic achievement. Also, linear regression showed that academic achievement correlated with insular cortex activation even when controlling for somatic maturation, cognitive performance, and cardiorespiratory fitness. CONCLUSION: Our results indicate that insular cortex activation, an area known for rational and emotional processing, is associated with successful inhibitory control in response to food images in children with overweight and obesity, while academic performance seems to play a role in the magnitude of this activation.

Effects of 12 weeks of high-intensity interval, moderate-intensity continuous and self-selected intensity exercise training protocols on cognitive inhibitory control in overweight/obese adults: A randomized trial.

Growing evidence shows that aerobic exercise improves cognitive function. However, it is unclear how exercising at different exercise intensities affects cognitive inhibitory control in overweight/obese adults. Herein we compared the effects of 12 weeks of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and self-selected intensity training (SSIT) on cognitive inhibitory control in overweight/obese adults. A total of 64 adults (59.4% women, 31.3 ± 7.1 years, 29 ± 2.5 kg/m²) were randomized into three walking/running groups: HIIT, MICT and SSIT. All groups performed three exercise sessions per week on an outdoor running track for 12 weeks. Cognitive inhibitory control was assessed at baseline and after the exercising programs using a computerized version of the Stroop Color-Words test. The HIIT and SSIT resulted in a faster Stroop effect (i.e. enhanced performance) when compared to MICT (p=.018; p= .026), however, there were no significant differences between the HIIT and SSIT groups (p> .05). The enhanced Stroop effect was correlated with increases in cardiorespiratory fitness after HIIT (r= -.521, p= .018) and decreases in body fat after MICT (r= .671, p= .001). These findings may suggest that overweight/obese adults performing exercise interventions at higher intensities or self-selected intensity may enhance their cognitive ability to inhibit automated behavioral responses.Highlights HIIT and/or SSIT are more effective than MICT in improving cognitive inhibitory control after 12-weeks in overweight/obese adults.Increases in cardiorespiratory fitness and decreases in body fat after HIIT and MICT were correlated with improvements in cognitive inhibitory control.Our study highlights the possibility of performing different exercise programs in an outdoor environment to improve cognitive function in overweight/obese adults.

Housing type is associated with objectively measured changes in movement behavior during the COVID-19 pandemic in older adults with hypertension: An exploratory study.

PURPOSE: To investigate the association between housing characteristics with objectively measured changes in physical activity (PA) and sedentary behavior (SB) during the COVID-19 pandemic in older adults with hypertension. METHODS: Thirty-five older adults with hypertension were included in this exploratory study. Accelerometer-based PA and SB measures were assessed before and during a period of social distancing policy imposed due to the COVID-19 pandemic. Housing type, housing surface area and household size were tested as predictors of changes in PA and SB. A generalized linear mixed model was used for the analysis. RESULTS: Housing type was associated with changes in PA and SB. Individuals residing in an apartment showed a greater decrease in light PA on weekdays (ß= -65 min/day, p=0.035) and a trend for an increase in SB (ß= 55 min/day, p=0.056) compared to those residing in a detached house. Individuals residing in a row house showed a greater decrease in moderate-vigorous PA (ß= -10 min/day, p=0.037) and steps/day (ß= -2064, p=0.010) compared to those residing in a detached house. Individuals residing in an apartment showed a greater decrease in light PA on the weekends (ß= -83 min/day, p=0.015) and an increase in SB (ß= 72 min/day, p=0.036) compared to those residing in a detached house. No association was found for housing surface area and household size. CONCLUSIONS: Older adults with hypertension residing in an apartment or row house have greater unhealthy changes in movement behavior during the COVID-19 pandemic. Further studies are needed to confirm our preliminary findings.

Systolic blood pressure mediates the association between body mass index and inhibitory control in children.

Here, we examine whether systolic blood pressure (SBP) mediates the relationship between body mass index (BMI) and inhibitory control in children. Twenty children with high blood pressure (HBP) were approximately matched with twenty children with low blood pressure (LBP) by fitness, BMI, somatic maturation, sex and age. Inhibitory control was measured by a cognitive Go/Nogo task, where number of commission errors during Nogo trials and reaction time during Go trials were used as performance. We compared performance between the two groups and conducted a mediation analysis using SBP as mediator of the relationship between BMI and commission errors. Results revealed that HBP children presented higher number of commission errors, compared to LBP children. Moreover, SBP mediated the relation between BMI and number of errors. Thus, early exposure to high levels of SBP can negatively impact inhibitory control and SBP acts as a mediator between BMI and inhibitory functioning in children.

Modulation of cortical and subcortical brain areas at low and high exercise intensities.

INTRODUCTION: The brain plays a key role in the perceptual regulation of exercise, yet neuroimaging techniques have only demonstrated superficial brain areas responses during exercise, and little is known about the modulation of the deeper brain areas at different intensities. OBJECTIVES/METHODS: Using a specially designed functional MRI (fMRI) cycling ergometer, we have determined the sequence in which the cortical and subcortical brain regions are modulated at low and high ratings perceived exertion (RPE) during an incremental exercise protocol. RESULTS: Additional to the activation of the classical motor control regions (motor, somatosensory, premotor and supplementary motor cortices and cerebellum), we found the activation of the regions associated with autonomic regulation (ie, insular cortex) (ie, positive blood-oxygen-level-dependent (BOLD) signal) during exercise. Also, we showed reduced activation (negative BOLD signal) of cognitive-related areas (prefrontal cortex), an effect that increased during exercise at a higher perceived intensity (RPE 13-17 on Borg Scale). The motor cortex remained active throughout the exercise protocol whereas the cerebellum was activated only at low intensity (RPE 6-12), not at high intensity (RPE 13-17). CONCLUSIONS: These findings describe the sequence in which different brain areas become activated or deactivated during exercise of increasing intensity, including subcortical areas measured with fMRI analysis.

Rewiring the Addicted Brain Through a Psychobiological Model of Physical Exercise.

Drug addiction is a worldwide public health problem, resulting from multiple phenomena, including those both social and biological. Chronic use of psychoactive substances has been shown to induce structural and functional changes in the brain that impair cognitive control and favor compulsive seeking behavior. Physical exercise has been proven to improve brain function and cognition in both healthy and clinical populations. While some studies have demonstrated the potential benefits of physical exercise in treating and preventing addictive behaviors, few studies have investigated its cognitive and neurobiological contributions to drug-addicted brains. Here, we review studies in humans using cognitive behavioral responses and neuroimaging techniques, which reveal that exercise can be an effective auxiliary treatment for drug addictive disorders. Moreover, we describe the neurobiological mechanisms by which exercise-induced neuroplasticity in the prefrontal cortex improves executive functions and may decrease compulsive behaviors in individuals prone to substance use disorders. Finally, we propose an integrative cognitive-psychobiological model of exercise for use in future research in drug addiction and practical guidance in clinical settings.

Cardiorespiratory Fitness Predicts Greater Vagal Autonomic Activity in Drug Users Under Stress.

While drug use has been shown to impair cardiac autonomic regulation, exercise might overcome some of the damage. Herein, we describe how individuals with substance use disorder (SUD) have their heart rate variability (HRV) and drug-related behaviors negatively affected in response to a stressor. However, we show how cardiorespiratory fitness may attenuate those impairments in autonomic control. Fifteen individuals with SUD were matched with 15 non-SUD individuals by age, weight, height, and fitness level, and had their HRV responses under stress induced by the Cold Pressor Test (CPT). The SUD group had lower mean of R-R intervals before and after the CPT when compared with the non-SUD group. In addition, in individuals with SUD, higher cardiorespiratory fitness level predicted greater vagal activity before, during, and after CPT. Moreover, for individuals with SUD, days of abstinence predicted greater mean of R-R intervals during recovery from the CPT. Finally, years of drug use negatively predicted mean of R-R intervals during recovery. Thus, our results suggest that chronic drug use impairs cardiac autonomic regulation at rest and after a physical stress. However, cardiorespiratory fitness might attenuate these impairments by increasing vagal autonomic activity.

Influence of Judo Experience on Neuroelectric Activity During a Selective Attention Task.

OBJECTIVE: We compared the cognitive performance and neuroelectric responses during a selective attentional task in judo athletes with different levels of expertise. METHODS: Judo black and white belt athletes performed both general and specific fitness tests while simultaneously completing a Stroop color-word test recorded by 64 electroencephalogram channels. RESULTS: Cognitive behavioral performance and event-related spectral perturbation (ERSP) present no differences between groups. However, the topographic analysis found different neural source patterns in each group. Judo black belts compared to judo white belts presented a greater peak amplitude of P300 in the middle frontal gyrus and of N200 in the cuneus, but slower latency of P300 in the precuneus. CONCLUSION: Despite no difference in cognitive behavioral performance, judo expertise causes a difference in the allocation of attentional and conflict detection neural resources.

Cognitive Deficit in Heart Failure and the Benefits of Aerobic Physical Activity.

Heart Failure is a clinical syndrome prevalent throughout the world and a major contribution to mortality of cardiac patients in Brazil. In addition, this pathology is strongly related to cerebral dysfunction, with a high prevalence of cognitive impairment. Many mechanisms may be related to cognitive loss, such as cerebral hypoperfusion, atrophy and loss of gray matter of the brain, and dysfunction of the autonomic nervous system. The literature is clear regarding the benefits of aerobic physical activity in healthy populations in the modulation of the autonomic nervous system and in brain functions. Studies have shown that in the population of patients with heart failure, exercise is associated with an improvement in cognitive function, as well as in cardiac autonomic regulation. However, little emphasis has been given to the mechanisms by which aerobic physical activity can benefit brain functioning, the autonomic nervous system and result in better cognitive performance, particularly in patients with heart failure. Therefore, the present work presents the ways in which brain areas responsible for cognition also act in the modulation of the autonomic nervous system, and emphasizes its importance for the understanding of cognitive impairment in relation to the pathophysiology of heart failure. It is also described the way in which aerobic physical activity can promote benefits when it is integrated into the therapy, associated to a better prognosis of the clinical picture of these patients.

Affect during incremental exercise: The role of inhibitory cognition, autonomic cardiac function, and cerebral oxygenation.

BACKGROUND: Pleasure is a key factor for physical activity behavior in sedentary individuals. Inhibitory cognitive control may play an important role in pleasure perception while exercising, especially at high intensities. In addition, separate work suggests that autonomic regulation and cerebral hemodynamics influence the affective and cognitive responses during exercise. PURPOSE: We investigated the effects of exercise intensity on affect, inhibitory control, cardiac autonomic function, and prefrontal cortex (PFC) oxygenation. METHODS: Thirty-seven sedentary young adults performed two experimental conditions (exercise and control) in separate sessions in a repeated-measures design. In the exercise condition, participants performed a maximum graded exercise test on a cycle ergometer as we continuously measured oxygen consumption, heart rate variability (HRV), and PFC oxygenation. At each of 8 intensity levels we also measured inhibitory control (Stroop test), associative and dissociative thoughts (ADT), and affective/pleasure ratings. In the control condition, participants sat motionless on a cycle ergometer without active pedaling, and we collected the same measures at the same points in time as the exercise condition. We evaluated the main effects and interactions of exercise condition and intensity level for each measure using two-way repeated measures ANOVAs. Additionally, we evaluated the relationship between affect and inhibitory control, ADT, HRV, and PFC oxygenation using Pearson's correlation coefficients. RESULTS: For exercise intensities below and at the ventilatory threshold (VT), participants reported feeling neutral, with preservation of inhibitory control, while intensities above the VT were associated with displeasure (p<0.001), decreased inhibitory control and HRV (p<0.001), and increased PFC oxygenation (p<0.001). At the highest exercise intensity, pleasure was correlated with the low-frequency index of HRV (r = -0.34; p<0.05) and the low-frequency/high-frequency HRV ratio (r = -0.33; p<0.05). PFC deoxyhemoglobin was correlated with pleasure two stages above the VT (r = -0.37; p<0.05). CONCLUSION: Our results support the notion that exercise at high intensities influences inhibitory control and one's perception of pleasure, which are linked to changes in cardiac autonomic control and cerebral hemodynamics. These findings strengthen the existence of an integrated brain-heart-body system and highlight the importance of exercise intensity in exercise-related behavior in sedentary individuals.

Brincando e aprendendo: aprimorando o desempenho escolar e comportamento de crianças através de aulas de reforço de educação física escolar integradas ao conteúdo escolar / Playing and learning: improving the scholar achievement and children´s behavior through physical education classes integrating basic school contents

A motricidade e a ludicidade são elementos essenciais no desenvolvimento integral de crianças. Este estudo investigou a influência de aulas lúdicas de educação física integradas ao conteúdo escolar sobre o desempenho escolar e a percepção (relato) dos pais e professoras sobre o comportamento de crianças. Durante três meses, crianças com baixo desempenho escolar receberam aulas de reforço com jogos e brincadeiras integrando o conteudo básico das disciplinas escolares. Foi observado melhora na leitura e no desempenho escolar geral, assim como, pais e professores relataram que as crianças se tornaram mais comunicativas, atentas e prestativas.

It is well know that motricity and ludicity are essential elements to promote whole child development. This study investigated the influence of ludic classes of physical education integrated to school subjects on the school achievement and self reports from parents and teachers from children´s behavior. During three months, children with low academic records received extra classes with fun activities and games integrating the regular school subjects. We have found an improvement in both reading and total academic achievement, as well as children became more communicative and cooperative with higher attention.

Improving cerebral oxygenation, cognition and autonomic nervous system control of a chronic alcohol abuser through a three-month running program.

The abusive use of alcohol has shown to be associated to cerebral damage, impaired cognition, poor autonomic nervous control, impaired cardiovascular health, increased levels of stress and anxiety, depression symptoms and poor quality of life. Aerobic exercise has shown to be an efficient tool to reduce and overcome these issues. In this case report, a patient (forty-four years old, male) under treatment in public psychiatric hospital, classified as having a substance use disorder, underwent a three-month running program. The maximal oxygen consumption increased from 24.2 ml/kg/min to 30.1 ml/kg/min, running time increased from 6 min to 45 min (650%) and distance covered from 765 m to 8700 m (1037.2%). In prefrontal cortex oxygenation, oxyhemoglobin levels improved by 76.1%, deoxyhemoglobin decreased 96.9% and total hemoglobin increased 78.8% during exercise. Reaction time in the cognitive test during rest decreased 23%, and the number of correct answers increased by 266.6%. Parasympathetic cardiac parameters increased in several heart rate variability indices. Thus, we conclude that running exercise performed by an alcoholic patient hospitalized in a psychiatric hospital improves cerebral function, cognition and cardiovascular health.

Brain stimulation modulates the autonomic nervous system, rating of perceived exertion and performance during maximal exercise.

BACKGROUND: The temporal and insular cortex (TC, IC) have been associated with autonomic nervous system (ANS) control and the awareness of emotional feelings from the body. Evidence shows that the ANS and rating of perceived exertion (RPE) regulate exercise performance. Non-invasive brain stimulation can modulate the cortical area directly beneath the electrode related to ANS and RPE, but it could also affect subcortical areas by connection within the cortico-cortical neural networks. This study evaluated the effects of transcranial direct current stimulation (tDCS) over the TC on the ANS, RPE and performance during a maximal dynamic exercise. METHODS: Ten trained cyclists participated in this study (33±9 years; 171.5±5.8 cm; 72.8±9.5 kg; 10-11 training years). After 20-min of receiving either anodal tDCS applied over the left TC (T3) or sham stimulation, subjects completed a maximal incremental cycling exercise test. RPE, heart rate (HR) and R-R intervals (as a measure of ANS function) were recorded continuously throughout the tests. Peak power output (PPO) was recorded at the end of the tests. RESULTS: With anodal tDCS, PPO improved by ~4% (anodal tDCS: 313.2±29.9 vs 301.0±19.8 watts: sham tDCS; p=0.043), parasympathetic vagal withdrawal was delayed (anodal tDCS: 147.5±53.3 vs 125.0±35.4 watts: sham tDCS; p=0.041) and HR was reduced at submaximal workloads. RPE also increased more slowly during exercise following anodal tDCS application, but maximal RPE and HR values were not affected by cortical stimulation. CONCLUSIONS: The findings suggest that non-invasive brain stimulation over the TC modulates the ANS activity and the sensory perception of effort and exercise performance, indicating that the brain plays a crucial role in the exercise performance regulation.

Estimulação cerebral na promoção da saúde e melhoria do desempenho físico / Brain stimulation for health and exercise performance improvement

O avanço tecnológico das últimas décadas tem proporcionado o uso eficaz de técnicas não-invasivas na neuromodulação cerebral. Atualmente, as principais técnicas de neuromodulação são a estimulação magnética transcraniana (EMT) e a estimulação transcraniana por corrente contínua (ETCC). Por meio de revisão da literatura, o presente estudo aborda: a) história da estimulação cerebral; b) mecanismos de ação estudados através da neurofisiologia motora, farmacologia, neuroimagem e animais experimentais; c) perspectivas de aplicações da estimulação cerebral para promoção da saúde e melhoria do desempenho físico, incluindo o controle autonômico cardíaco e hipotensão pós-exercício, o controle de apetite e a modulação da fadiga e desempenho físico; e d) aspectos de segurança referentes ao uso da ETCC. Dessa forma, a ETCC parece ser uma técnica efetiva e segura para modular a função cerebral e podemos vislumbrar algumas perspectivas de aplicação no âmbito da ingestão alimentar, saúde cardiovascular e desempenho físico...

The technological advances of the last decades have provided the effective use of noninvasive techniques in neuromodulation with concomitant health benefits. Currently, the main neuromodulation techniques are transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). Through literature review, this study addresses the a) history of brain stimulation and the b) mechanisms of action studied by motor neurophysiology, pharmacology, neuroimaging, and experimental animals. Moreover, it is presented the c) perspectives for applications of brain stimulation for promoting health and improving physical performance, including cardiac autonomic control and post-exercise hypotension, control and modulation of appetite, fatigue and physical performance. Finally, we describe d) the security aspects related to the use of tDCS. Thus, tDCS seems to be an effective and safe technique to modulate brain function and suggests some application associated to food intake, cardiovascular health and physical performance...

Can neuromuscular fatigue threshold be determined by short and non-exhaustive bouts? / Pode o limiar de fadiga neuromuscular ser determinado por testes curtos e não exaustivos?

The present study determined the neuromuscular fatigue threshold (NFT) using four different time-periods of analysis of the electromyographic signal and compared these estimations with critical power (CP). Fifteen healthy young men (73.6 ± 5.1 kg, 177.8 ± 7.0 cm, 23.4 ± 5.2 years) performed 3-4 different severe constant workload trials until exhaustion on a cycle ergometer with simultaneous SEMG signals acquisition. The obtained data permitted NFT estimation with four different periods of analysis as follows: initial 30s (T30), 1min (T1), 2min (T2) and total time (TT), as well as CP. T30 and T1 were significantly higher than TT and CP and, T2 and TT did not differ between each other, and both were significantly higher than CP. In addition, TT was significantly correlated to CP (0.72; P < 0.05) and to T2 (0.58; P < 0.05). We conclude that NFT overestimates CP, independent of the time-period analysis used for its determination.

O presente estudo determinou o Limiar de Fadiga Neuromuscular - LFNM usando quatro diferentes períodos de análise do sinal eletromiográfico e comparou essas estimativas com a Potência Crítica - PC. Quinze homens saudáveis do sexo masculino (73,6 ± 5,1 kg, 177,8 ± 7,0 cm, 23,4 ± 5,2 anos) realizaram 3-4 testes severos de carga constante até a exaustão em um cicloergômetro com simultânea aquisição de sinais SEMG. Os dados obtidos permitiram a estimativa de LFNM em quatro períodos diferentes: 30 segundos iniciais (T30), um minuto (T1), dois minutos (T2), tempo total (TT), assim como PC. T30 e T1 foram significativamente maiores do que TT e PC e, T2 e TT não se diferiram entre si e foram maiores que PC. Além disso, TT foi significativamente correlacionado com PC (0,72; P < 0,05) e com T2 (0,58; P < 0,05). Dessa forma, conclui-se que LFNM superestima PC, independente do tempo de análise utilizado para sua determinação.

Transcranial direct current stimulation influences the cardiac autonomic nervous control.

To investigate whether the manipulation of brain excitability by transcranial direct current stimulation (tDCS) modulates the heart rate variability (HRV), the effect of tDCS applied at rest on the left temporal lobe in athletes (AG) and non-athletes (NAG) was evaluated. The HRV parameters (natural logarithms of LF, HF, and LF/HF) was assessed in 20 healthy men before, and immediately after tDCS and sham stimulation. After anodal tDCS in AG the parasympathetic activity (HF(log)) increased (P<0.01) and the sympathetic activity (LF(log)) and sympatho-vagal balance (LF/HF(log)) decreased (P<0.01), whereas no significant effects were detected in NAG (P>0.05). No significant changes in HRV indexes were provoked by sham stimulation in both AG and NAG (P>0.05). In conclusion, tDCS applied on the left temporal lobe significantly increased the overall HRV in AG, enhancing the parasympathetic and decreasing the sympathetic modulation of heart rate. Consequently the sympatho-vagal balance decreased at rest in AG but not in NAG. Releasing a weak electric current to stimulate selected brain areas may induce favorable effects on the autonomic control to the heart in highly fit subjects.

O nível de treinamento não influencia a percepção subjetiva de esforço durante um teste incremental / Training level does not influence the rating of perceived exertion during an incremental test

Níveis de treinamento distintos, associados à experiência em realizar esforços exaustivos podem produzir diferentes sensações frente à fadiga. O objetivo deste estudo foi comparar a percepção subjetiva de esforço (PSE) entre ciclistas e não-ciclistas durante teste incremental máximo (TIMAX). Participaram do estudo 23 indivíduos que foram divididos em grupo ciclistas (GC) (n = 12; idade 26,5 ± 4,7 anos; massa corporal 68,2 ± 11kg; estatura 176 ± 8,6cm) e grupo não-ciclistas (GNC) (n=11; idade 25,2 ± 4,0 anos; massa corporal 72,9 ± 9kg; estatura 175,1 ± 6,3cm). Todos realizaram um TIMAX, até a exaustão, do tipo rampa em ciclossimulador, com início a 0 W e incrementos de 20 W.min-1. Durante TIMAX a PSE foi aferida e anotada a cada 30 segundos de teste e, ao final, a potência máxima (PMAX) atingida pelos indivíduos. O tempo total de cada teste foi normalizado em porcentagens (de 10% a 100%, intervalos de 10%), e foi anotada a respectiva PSE para cada intervalo. Os valores de PMAX para GC e GNC foram 368 ± 12,7W e 256 ± 11,2W, respectivamente (P < 0,01). Os valores das medianas das PSE para GC e GNC não apresentaram diferença significativa para nenhuma porcentagem de tempo. Conclui-se que as respostas de PSE não sofreram alterações entre GC e GNC durante TIMAX, sugerindo que o nível de treinamento não influencia a PSE.

Different training levels, combined with experience in performing exhaustive exercise, may produce different sensations of fatigue. The objective of this study was to compare the rating of perceived exertion (RPE) between cyclists and non-cyclists during a maximal incremental test (ITMAX). Twenty-three subjects were recruited and divided into a cyclist group (CG) (n = 12; age: 26.5 ± 4.7 years, body weight: 68.2 ± 11kg, height: 176 ± 8.6 cm) and a non-cyclist group (NCG) (n = 11; 25.2 ± 4.0 years, body weight: 72.9 ± 9 kg, height: 175.1 ± 6.3 cm). All subjects performed an ITMAX until exhaustion on a cycling simulator, starting at 0 W and with increments of 20 W.min-1. RPE was measured at 30-second intervals during ITMAX and the maximal power output (PMAX) of each subject was also recorded. The total time of each test was normalized to the percentage of completed trial (10% to 100%, intervals of 10%), and the corresponding RPE was recorded. PMAX was 368 ± 12.7 W and 256 ± 11.2 W for CG and NCG, respectively (P < 0.01). No significant difference in median RPE was observed between groups at any time point. In conclusion, RPE responses did not differ between CG and NCG during ITMAX, suggesting that training level does not influence RPE.

Efeito da ingestão de cafeína sobre os parâmetros da potência crítica / Effect of caffeine intake on critical power model parameters determined on a cycle ergometer

The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r2) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.

The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r2) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.

Efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP) / Effect of ingestion of caffeine on perceived exertion threshold (PET)

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 ciclo ergômetro, 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 menor que 0,01), e os testes de 80 e 100% apresentaram menor taxa de aumento da percepção subjetiva de esforço (PSE) (P menor que 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%.

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 smaller that 0,01) and the tests between 80% and 100% presented lower increasing ratings of perceived exertion (RPE) (P smaller that 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.