Effect of a sex stereotype on cortical activity during a self-paced exercise: A motor-related cortical potential approach.

Recent research has shown that inducing a negative stereotype toward women does not always decrease the subsequent motor performance of women, but can increase it, especially during endurance tasks. The mechanisms involved are nonetheless still poorly understood. The main aim of the present study was to investigate the effect of a negative stereotype toward women on men's and women's performance during an endurance task, and to analyze the neuropsychological mechanisms involved through motor-related cortical potentials and motivation toward men/women. Thirty-four participants were assigned to a negative stereotype toward women condition and a nullified-stereotype condition and performed 80 self-paced intermittent isometric elbow contractions at a moderate perceived intensity. Results showed that women performed better when assigned to the negative stereotype toward women condition, they were more motivated to outperform men, and their MRCP amplitudes were higher in this same condition over the prefrontal cortex (i.e., FP1 and FP2). Concerning men, they also performed better when the negative stereotype toward women was induced. However, no effect emerged on motivation toward women and MRCP amplitudes. This study showed that inducing a negative stereotype during an endurance task led to a performance increase in women, which is contrary to the stereotype threat theory, strengthening the idea of a task-dependency effect when inducing a negative stereotype. This performance improvement observed in women may be caused by increased motivation to outperform men and a planning of the upcoming movement. Concerning men, more research is needed to clarify the mechanisms involved in such performance improvement.

Cognitive inhibition behavioral tasks in online and laboratory settings: Data from Stroop, SART and Eriksen Flanker tasks.

The provided dataset represents the performance of adult individuals in three experimental tasks measuring cognitive inhibition: the Stroop task; the SART task and the Eriksen Flanker task. All tasks were initially completed in a web setting (online) by 485 individuals. Additionally, randomly selected participants completed all these tasks one more time (220 participants) or two more times (100 participants) during separate laboratory session(s) offline. The provided dataset contains data both from the offline and online experimental sessions. For the Stroop and Flanker tasks, we have provided data on mean reaction times for correct answers and the percent of correct answers for both congruent and incongruent trials. For the SART task, we have provided data on the number and the percent of commission and omission errors; the mean correct reaction times in "go" trials; the standard deviations of correct reaction times in "go" trials; the coefficients of variability for correct reaction times in "go" trials; the mean reaction times for successful "go" trials proceeding successful "no-go" trials; and the mean reaction times for correct "go" trials proceeding failed "no-go" trials. Data from both laboratory sessions contains information on the age and gender of participants. Additionally, we have provided the dates and hours of all experimental sessions. This dataset can potentially be reused for exploratory research on cognitive inhibition, i.e., the stability of individual cognitive inhibition capacity over time; intercorrelations of various inhibition task performance measures; individual differences in cognitive inhibition; or the influence of task setting (web vs laboratory) on inhibition performance measured in different settings (web vs laboratory).

Effects of inhibitory control capacity and cognitive load on involuntary past and future thoughts: A laboratory study.

The present study focused on involuntary thoughts about personal past events (i.e., involuntary autobiographical memories; IAMs), and involuntary thoughts about future events and plans (i.e., involuntary future thoughts; IFTs). The frequency of these involuntary thoughts is influenced by cognitive demands of ongoing activities, but the exact underlying mechanism(s) has yet to be revealed. The present study tested two possible explanations: (1) the special inhibitory mechanism switches on when one is engaged in attentionally demanding activities; (2) different levels of cognitive load interfere with cue-noticing that act as triggers for IAMs and IFTs. We report a study with pre-selected groups of participants that differed in terms of their individual level of inhibitory control capacity (high vs. low), and completed both standard and attentionally demanding versions of a laboratory vigilance task with irrelevant cue-words to trigger IAMs and IFTs, and random thought-probes to measure their frequency. To examine the level of incidental cue-noticing, participants also completed an unexpected cue-recognition task. Despite large differences between groups in inhibitory control capacity, the number of IFTs and IAMs, reported in the attentionally demanding condition, was comparable. In addition, high cognitive load reduced the number of IAMs, but not IFTs. Finally, the recognition of incidental cues encountered in the vigilance task was reduced under high cognitive load condition, indicating that poor cue-noticing may be the main underlying mechanism of cognitive load effect rather than the lack of inhibitory resources needed to suppress involuntary retrieval. This and other possible mechanisms and avenues for future research are discussed.

Does the Effect of Stereotypes in Older People Depend Upon Task Intensity?

This study examined the effect of negative and positive stereotypes on the strength produced by older adults at different perceived effort intensities, reflecting different levels of task difficulty. Fifty older women were randomly assigned to a positive stereotype, a negative stereotype, or a control condition. Before (T1) and after (T2) the stereotype manipulation, they were asked to perform a voluntary isometric contraction at a level of muscular effort that corresponded to four perceived effort intensities ("easy," "moderate," hard" and "very hard"). Results showed that participants attained greater strength during the easy and hard tasks after exposure to both positive and negative stereotypes. At the moderate and very hard intensities, stereotype induction did not significantly change the strength from the baseline performance. While these results are not fully in line with the stereotype threat theory, they provide evidence that task difficulty could modulate the effect of aging stereotypes during physical tasks.

An Inquisit-web protocol for calculating composite inhibitory control capacity score: An individual differences approach.

In the present paper, we provide a protocol for experimentally measuring and calculating individual inhibitory control capacity index in adult participants in an online Inquisit-based setting. We believe that this method can serve other researchers in the standardized assessment of individual inhibitory control capacity that can be used in studies on the possible role of inhibitory control in many every-day cognitive phenomena. Thus, the paper focuses mainly on the calculation of a composite inhibitory control capacity score from two inhibitory control tasks. Specifically, it is calculated on the basis of participants' performance in two well-established experimental paradigms: the Stroop Task and the Eriksen Flanker Task. The methods described in this protocol have already been successfully applied in both lab and online settings. In the first part of the article, we provide a short theoretical background and a brief description of the previous usage of this method in our two original studies. In the following parts, we provide step-by-step instructions for measuring and calculating the individual inhibitory control capacity index using web-based methodology. The protocol is supplemented with slides of original experimental tasks and instructions for participants (both translated from Polish).

The role of inhibitory control and ADHD symptoms in the occurrence of involuntary thoughts about the past and future: An individual differences study.

In everyday life, people often experience involuntary thoughts about their personal past and future events in response to incidental cues in the environment. Yet, despite the abundance of such cues, our consciousness is not constantly flooded by these involuntary autobiographical memories (IAMs) and involuntary future thoughts (IFTs). The main goal of the present study was to further investigate the possibility that cognitive inhibitory control keeps these involuntary cognitions at bay. To test this inhibition hypothesis, we conducted a large-scale study (n = 157) in which groups of participants with different levels of inhibitory control (low, medium, high) and individuals with ADHD spectrum symptoms were engaged in a laboratory vigilance task in which the frequency of IFTs and IAMs was assessed. Contrary to predictions, although participants across groups differed significantly in terms of their individual inhibitory control capacity, the number of IFTs and IAMs reported during the vigilance task was comparable. In addition, individuals with the ADHD spectrum symptoms did not report more spontaneous thoughts compared to other groups. Together, these findings lend little support for the idea that inhibition is a key mechanism that regulates the occurrence of IAMs and IFTs in everyday life. Other possible mechanisms and avenues for future research are discussed.

Moving Sport and Exercise Science Forward: A Call for the Adoption of More Transparent Research Practices.

The primary means of disseminating sport and exercise science research is currently through journal articles. However, not all studies, especially those with null findings, make it to formal publication. This publication bias towards positive findings may contribute to questionable research practices. Preregistration is a solution to prevent the publication of distorted evidence resulting from this system. This process asks authors to register their hypotheses and methods before data collection on a publicly available repository or by submitting a Registered Report. In the Registered Report format, authors submit a stage 1 manuscript to a participating journal that includes an introduction, methods, and any pilot data indicating the exploratory or confirmatory nature of the study. After a stage 1 peer review, the manuscript can then be offered in-principle acceptance, rejected, or sent back for revisions to improve the quality of the study. If accepted, the project is guaranteed publication, assuming the authors follow the data collection and analysis protocol. After data collection, authors re-submit a stage 2 manuscript that includes the results and discussion, and the study is evaluated on clarity and conformity with the planned analysis. In its final form, Registered Reports appear almost identical to a typical publication, but give readers confidence that the hypotheses and main analyses are less susceptible to bias from questionable research practices. From this perspective, we argue that inclusion of Registered Reports by researchers and journals will improve the transparency, replicability, and trust in sport and exercise science research. The preprint version of this work is available on SportR[Formula: see text]iv: https://osf.io/preprints/sportrxiv/fxe7a/.

Testing the role of cognitive inhibition in physical endurance using high-definition transcranial direct current stimulation over the prefrontal cortex.

The aim of this study was to clarify the role of the prefrontal cortex (PFC) in physical effort regulation. We hypothesized that the PFC would be progressively involved in physical endurance through the engagement of cognitive inhibition, which would be necessary to maintain effort by inhibiting fatigue-related cues. This hypothesis was examined using a double-blind, sham-controlled, within-subjects study (N = 20) using high-definition (HD) transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (dlPFC). Participants had to maintain a knee extensor contraction at 30% of their maximal force while simultaneously performing an Eriksen flanker task to evaluate their inhibition performance during the task. Anodal stimulation of the dlPFC influenced response to the cognitive task during exercise, as seen by slower response times and better accuracy. However, it did not lead to any measureable improvement in cognitive inhibition and did not influence endurance time. There was no correlation between cognitive inhibition and the maintenance of physical effort. This result does not indicate a relationship between cognitive inhibition and endurance performance. The contribution of the PFC in physical endurance could be explained through its involvement on decisional processes.

Put on your (fNIRS) thinking cap: Frontopolar activation during augmented state creativity.

Thinking creatively requires the ability to consciously augment creative insight through processes such as analogical reasoning and relational cognition. Prior work has examined augmented states of creativity using a modified verb generation task which requires brief engagement in attempts to think creatively during MRI. In this study, we employed the verb generation task to examine augmented creative states and frontopolar cortex activation in a less-constrained setting using functional near infrared spectroscopy (fNIRS). Participants (n = 29) were presented with a noun and were required to think of an associated verb. In 50% of the trials, participants were instructed to 'think creatively' (cued condition) as opposed to stating the first or most prominent verb that came to mind (uncued condition). The task was administered in French to native speakers. Hemodynamic responses were recorded over the frontopolar cortex using fNIRS. The relatedness of the noun-verb pairs was calculated and other measures of creativity (the Alternate Uses Test, Compound Remote Associate Test and the Biographical Inventory of Creative Behaviors) were recorded. We showed that in the cued condition, semantic scores were higher (indicating more creative responses), positively associated with other measures of creativity, and changes in oxygenated hemoglobin were larger and more extensive in the left frontopolar cortex, than in the uncued condition. Our findings support the use of the verb generation task (administered in French) to augment creative states and provides further validation of the use of the task to capture creativity (i.e., processes involved in generating creative responses through distant associations). We highlight the use of fNIRS to measure associated regional changes in frontopolar cortex activity during augmented states of creativity.

Testing the ego-depletion effect in optimized conditions.

The observation that exerting self-control in an initial task impairs subsequent self-control performance in a following task has been used to explain a wide range of phenomena. If evidence for this "ego-depletion" effect was initially believed to be strong, it is now questioned. Recent meta-analyses indicated that this effect was sensitive to publication bias and that it was greatly reduced after control for this bias. In a pre-registered replication attempt where an ego-depletion protocol was conducted in multiple independent laboratories, the effect was not distinguishable from zero. Here, a different approach is adopted to examine the validity of this effect by improving the experimental protocol with the addition of important methodological precautions: 1) a pre-test measurement, 2) a learning period, 3) a prolonged depleting task, 4) a similar control condition, and 5) valid indexes of self-control. Accordingly, a well-learned Simon task was done before and after 1h of continuous practice of a Stroop task in a high inhibition demands condition (75% of incongruent trials) or in a control condition (0% of incongruent trials). Datasets from between-subjects (Study 1, N = 82) and within-subjects (Study 2, N = 52) experiments were analyzed using generalized linear mixed models. A significant ego-depletion effect was found in Study 1 (greater interference effect and accuracy decline in high inhibition demands than in control condition) but not in Study 2. Because it is difficult to explain this difference in results, the findings suggest that, even in a context chosen to optimize the observation of an ego-depletion effect, it seems difficult to be conclusive about the existence of this effect.

Influence of cognitive load on the dynamics of neurophysiological adjustments during fatiguing exercise.

We aimed to determine the neurophysiological mechanisms associated with reduced endurance performance during cognitive-motor dual task at different levels of cognitive load, compared to a motor task alone. Eighteen healthy men performed isometric quadriceps contractions at 15% of maximal voluntary contraction (blocks of 170 s interspaced by neuromuscular evaluations) until exhaustion. This task was performed on three separate days: (a) in the absence of concomitant cognitive task, (b) with concomitant 1-back task, and (c) with concomitant 2-back task. Autonomic nervous system activity, perceived exertion, and cognitive performance were continuously monitored. Peripheral and central determinants of neuromuscular function were assessed at rest, between each block, and at task failure using femoral nerve stimulation. Endurance time was shorter during 2-back (982 ± 545 s) and 1-back (1,128 ± 592 s) conditions, compared with control (1,306 ± 836 s). Voluntary activation level was lower in 2-back (87.1%; p < 0.001) and 1-back (88.6%; p = 0.04) conditions compared to control (91.2%) at isotime (100% of the shortest test duration). Sympathetic activity showed a greater increase in 2-back condition compared to control. Perceived muscular exertion was higher during 2-back than during control. Cognitive performance decreased similarly with time during both cognitive-motor dual task but was always lower during 2-back condition. Motor performance is reduced when adding a concomitant demanding memory task to a prolonged isometric exercise. This can be explained by the interaction of various psychological and neurophysiological factors including higher perceived exertion, greater perturbations of autonomic nervous system activity, and cerebral impairments leading to earlier onset of central fatigue.

Why are we not flooded by involuntary thoughts about the past and future? Testing the cognitive inhibition dependency hypothesis.

In everyday life, involuntary thoughts about future plans and events occur as often as involuntary thoughts about the past. However, compared to involuntary autobiographical memories (IAMs), such episodic involuntary future thoughts (IFTs) have become a focus of study only recently. The aim of the present investigation was to examine why we are not constantly flooded by IFTs and IAMs given that they are often triggered by incidental cues while performing undemanding activities. One possibility is that activated thoughts are suppressed by the inhibitory control mechanism, and therefore depleting inhibitory control should enhance the frequency of both IFTs and IAMs. We report an experiment with a between-subjects design, in which participants in the depleted inhibition condition performed a 60-min high-conflict Stroop task before completing a laboratory vigilance task measuring the frequency of IFTs and IAMs. Participants in the intact inhibition condition performed a version of the Stroop task that did not deplete inhibitory control. To control for physical and mental fatigue resulting from performing the 60-min Stroop tasks in experimental conditions, participants in the control condition completed only the vigilance task. Contrary to predictions, the number of IFTs and IAMs reported during the vigilance task, using the probe-caught method, did not differ across conditions. However, manipulation checks showed that participants' inhibitory resources were reduced in the depleted inhibition condition, and participants were more tired in the experimental than in the control conditions. These initial findings suggest that neither inhibitory control nor physical and mental fatigue affect the frequency of IFTs and IAMs.

"As du Coeur" study: a randomized controlled trial on quality of life impact and cost effectiveness of a physical activity program in patients with cardiovascular disease.

BACKGROUND: Physical activity programs (PAP) in patients with cardiovascular disease require evidence of cost-utility. To assess improvement in health-related quality of life (QoL) and reduction of health care consumption of patients following PAP, a randomized trial was used. METHODS: Patients from a health insurance company who had experienced coronary artery disease or moderate heart failure were invited to participate (N = 1891). Positive responders (N = 50) were randomly assigned to a progressively autonomous physical activity (PAPA) program or to a standard supervised physical activity (SPA) program. The SPA group had two supervised sessions per week over 5 months. PAPA group had one session per week and support to aid habit formation (written tips, exercise program, phone call). To measure health-related quality of life EQ-5D utility score were used, before intervention, 6 months (T6) and 1 year later. Health care costs were provided from reimbursement databases. RESULTS: Mobility, usual activities and discomfort improved significantly in both group (T6). One year later, EQ-5D utility score was improved in the PAPA group only. Total health care consumption in the intervention group decreased, from a mean of 4097 euros per year before intervention to 2877 euros per year after (p = 0.05), compared to a health care consumption of 4087 euros and 4180 euros per year, in the total population of patients (N = 1891) from the health insurance company. The incremental cost effectiveness ratio was 10,928 euros per QALYs. CONCLUSION: A physical activity program is cost-effective in providing a better quality of life and reducing health care consumption in cardiovascular patients. TRIAL REGISTRATION: ISRCTN77313697 , retrospectively registered on 20 November 2015.

Impact of Physical and Cognitive Exertion on Cognitive Control.

In a recent study, the differential effects of prolonged physiologically challenging exercise upon two executive processes (cognitive control and working memory) were investigated. However, the impact of exercise on the selective inhibition task employed was debatable and needed further analysis to dissociate the effects induced by exercise intensity from those induced by the time spent on task upon cognitive control outcomes. In this study, we propose a thorough analysis of these data, using a generalized mixed model on a trial-by-trial basis and a new measure of the strength of the automatic response based on reaction time distribution, to disentangle the effect of physical fatigue from cognitive fatigue. Despite the prolonged duration of exercise, no decline in cognitive performance was found in response to physical fatigue. The only change observed during 60-min exercise was an acceleration of the correct trials and an increase of errors for incompatible trials. This pattern, shown during low and physiologically challenging exercise, supports the occurrence of cognitive fatigue induced by the repetition of the cognitive tasks over time.

The long and winding road: Effects of exercise intensity and type upon sustained attention.

Aerobic exercise enhances the ability to sustain attention (peaking at moderate intensities) by stimulating noradrenergic activity, which affects the fronto-parietal attention network. Prior exercise studies examining attention have focused on the influence of exercise intensity, yet few studies have examined the influence of the type of exercise protocol administered. Here, we propose that sustained attention is greater during (a) moderate compared to low intensity exercise, and (b) moderate intensity exercise administered at a varied-load compared to a constant-load but the same overall intensity. To test this hypothesis, we recorded attentional focus in twelve male cyclists during a sustained attention to response task (SART) in four conditions; at rest, and during exercise at a low constant-, moderate constant- and moderate varied-load intensity. The change in α-amylase (indicative of the noradrenergic response) from saliva samples and activation of the right prefrontal and parietal cortices using near-infrared spectroscopy were recorded. The findings revealed that moderate intensity exercise at a constant-load leads to faster responses and less accuracy in the SART than rest and low intensity exercise. Moderate intensity exercise at a variable-load leads to even faster responses but with no loss of accuracy in the SART. This pattern of results is explained by a larger increase in salivary α-amylase during moderate (constant and varied) intensity cycling and higher activation in the dorso-lateral prefrontal cortex during the varied, but not the constant-load condition. In conclusion, we show that, in addition to exercise intensity, the type of exercise also has important implications upon attentional focus. While moderate intensity exercise generally enhances attentional focus, monotonous exercise at a constant-load may mask such benefits.

Avoiding sedentary behaviors requires more cortical resources than avoiding physical activity: An EEG study.

Why do individuals fail to exercise regularly despite knowledge of the risks associated with physical inactivity? Automatic processes regulating exercise behaviors may partly explain this paradox. Yet, these processes have only been investigated with behavioral outcomes (i.e., based on reaction times). Here, using electroencephalography, we investigated the cortical activity underlying automatic approach and avoidance tendencies toward stimuli depicting physical activity and sedentary behaviors in 29 young adults who were physically active or physically inactive but with the intention of becoming physically active. Behavioral results showed faster reactions when approaching physical activity compared to sedentary behaviors and when avoiding sedentary behaviors compared to physical activity. These faster reactions were more pronounced in physically active individuals and were associated with changes during sensory integration (earlier onset latency and larger positive deflection of the stimulus-locked lateralized readiness potentials) but not during motor preparation (no effect on the response-locked lateralized readiness potentials). Faster reactions when avoiding sedentary behaviors compared to physical activity were also associated with higher conflict monitoring (larger early and late N1 event-related potentials) and higher inhibition (larger N2 event-related potentials), irrespective of the usual level of physical activity. These results suggest that additional cortical resources were required to counteract an attraction to sedentary behaviors. Data and Materials [https://doi.org/10.5281/zenodo.1169140]. Preprint [https://doi.org/10.1101/277988].

Flow experience and the mobilization of attentional resources.

The present study attempts to better identify the neurophysiological changes occurring during flow experience and how this can be related to the mobilization of attentional resources. Self-reports of flow (using a flow feelings scale) and attention (using thought probes), autonomic activity (heart rate, heart rate variability, and breathing rate), and cerebral oxygenation (using near-infrared spectroscopy) in two regions of the frontoparietal attention network (right lateral frontal cortex and right inferior parietal lobe) were measured during the practice of two simple video games (Tetris and Pong) played at different difficulty conditions (easy, optimal, hard, or self-selected). Our results indicated that an optimal level of difficulty, compared with an easy or hard level of difficulty led to greater flow feelings and a higher concentration of oxygenated hemoglobin in the regions of the frontoparietal network. The self-selected, named autonomy condition did not lead to more flow feelings than the optimal condition; however, the autonomy condition led to greater sympathetic activity (reduced heart rate variability and greater breathing rate) and higher activation of the frontoparietal regions. Our study suggests that flow feelings are highly connected to the mobilization of attentional resources, and all the more in a condition that promotes individuals' choice and autonomy.

"As du Coeur" study: a randomized controlled trial on physical activity maintenance in cardiovascular patients.

BACKGROUND: The benefits of supervised physical activity programs in cardiac rehabilitation have been amply demonstrated, but the quantity of physical activity often declines quickly once supervision ends. This trial assesses the effectiveness of an experimental intervention drawing on habit formation theory to maintain physical activity. METHODS: Cardiovascular patients (N = 47) were randomly assigned to one of two groups. The first group participated in two supervised physical activity (SPA) sessions per week for 20 weeks. The second group was offered a progressively autonomous physical activity (PAPA) program as follows: the same supervised program as the SPA group for 10 weeks and then a further 10 weeks with one supervised session replaced by a strategy to build and sustain the habit of autonomous physical activity. The International Physical Activity Questionnaire (IPAQ; Craig et al. Med Sci Sports Exerc 35(8):1381-1395, 2003) was used to measure the quantity of physical activity, which was the primary outcome. The number of participants was limited, and we thus took multiple IPAQ measurements (at 0, 5, 7, 9 and 12 months after the start of the intervention) and used a mixed model for analysis. Physical condition, automaticity of the physical activity behavior, motivation, and quality of life were examined for changes. RESULTS: No significant between-group differences were noted for physical activity behaviors after the program, physical condition, motivation, or behavioral automaticity. The PAPA group nevertheless completed more PA sessions during the intervention, and their quality of life was significantly higher than that of the SPA group at 12 months. CONCLUSION: Although the number of supervised sessions was lower, the progressively autonomous PA program resulted in the same or even higher positive outcomes than the fully supervised PA program. TRIAL REGISTRATION: Current Controlled Trials ISRCTN77313697 , retrospectively registered on 20 November 2015.

Behavioral and Neural Evidence of the Rewarding Value of Exercise Behaviors: A Systematic Review.

BACKGROUND: In a time of physical inactivity pandemic, attempts to better understand the factors underlying the regulation of exercise behavior are important. The dominant neurobiological approach to exercise behavior considers physical activity to be a reward; however, negative affective responses during exercise challenge this idea. OBJECTIVE: Our objective was to systematically review studies testing the automatic reactions triggered by stimuli associated with different types of exercise behavior (e.g. physical activity, sedentary behaviors) and energetic cost variations (e.g. decreased energetic cost, irrespective of the level of physical activity). We also examined evidence supporting the hypothesis that behaviors minimizing energetic cost (BMEC) are rewarding. METHODS: Two authors systematically searched, screened, extracted, and analyzed data from articles in the MEDLINE database. RESULTS: We included 26 studies. Three outcomes of automatic processes were tested: affective reactions, attentional capture, and approach tendencies. Behavioral results show that physical activity can become attention-grabbing, automatically trigger positive affect, and elicit approach behaviors. These automatic reactions explain and predict exercise behaviors; however, the use of a wide variety of measures prevents drawing solid conclusions about the specific effects of automatic processes. Brain imaging results are scarce but show that stimuli associated with physical activity and, to a lesser extent, sedentary behaviors activate regions involved in reward processes. Studies investigating the rewarding value of behaviors driving energetic cost variations such as BMEC are lacking. CONCLUSION: Reward is an important factor in exercise behavior. The literature based on the investigation of automatic behaviors seems in line with the suggestion that physical activity is rewarding, at least for physically active individuals. Results suggest that sedentary behaviors could also be rewarding, although this evidence remains weak due to a lack of investigations. Finally, from an evolutionary perspective, BMEC are likely to be rewarding; however, no study has investigated this hypothesis. In sum, additional studies are required to establish a strong and complete framework of the reward processes underlying automatic exercise behavior.

Extending the limits of force endurance: Stimulation of the motor or the frontal cortex?

Previous findings indicate that facilitation of primary motor cortex (PMC) activity using trans-cranial direct current stimulation (tDCS) could improve resistance to physical fatigue. However, studies have failed to consistently replicate these results. Using non-focal-tDCS during a fatiguing task, recent work showed no enhancement of corticospinal excitability of the PMC despite a longer endurance time and suggested that contamination in other brain regions involved in motor command may have occurred. In accordance with recent evidence supporting the role of the prefrontal cortex (PFC) in exercise maintenance, this double-blind sham-controlled crossover study (N = 22) compared the effect of high definition (HD)-tDCS of the PMC or the PFC on endurance time of a sustained contraction task of the elbow flexor. Brain activity was monitored using near infrared spectroscopy (NIRS) to measure the neurovascular response elicited by HD-tDCS. Electromyography (EMG) and force obtained during maximal voluntary and evoked contractions were assessed before and after the contraction task to explore the effect of brain stimulation on peripheral and central fatigue. While the stimulation affected the brain response in the PFC during the contraction task, no effects of the stimulation were observed on endurance time or fatigue indices. These results are discussed in relation to the neurocognitive models of physical effort.