Effect of 48 h Fasting on Autonomic Function, Brain Activity, Cognition, and Mood in Amateur Weight Lifters

The impact of continuous calorie restriction and fasting on cognition in adults without eating disorders

Research into the effects of calorie restriction continues to intrigue those interested in whether it may allow humans to live longer and healthier lives. Animal studies of continuous calorie restriction (CCR) and fasting have demonstrated substantial advantages to health and longevity. However, concerns remain about the impact of restricting calorie intake on human health and cognition. Given the emerging evidence of cognitive impairments in eating disorders, studies investigating restricted calorie intake in healthy humans (in an ethical way) may also have implications for understanding restrictive eating disorders. In this review, the published literature on the impact of CCR and fasting on cognitive function in healthy human participants is synthesized. Of the 33 studies of CCR and fasting in humans identified, 23 demonstrated significant changes in cognition. Despite variation across the cognitive domains, results suggest CCR benefits inhibition, processing speed, and working memory, but may lead to impairments in cognitive flexibility. The results of fasting studies suggest fasting is associated with impairments in cognitive flexibility and psychomotor abilities. Overall, the results of these studies suggest the degree (ie, the severity) of calorie restriction is what most likely predicts cognitive improvements as opposed to impairments. For individuals engaging in sustained restriction, this may have serious, irreversible consequences. However, there are mixed findings regarding the impact of CCR and fasting on this aspect of human functioning, suggesting further research is required to understand the costs and benefits of different types of calorie restriction.

The impact of dietary claims on behaviour: Expectations qualify how actual satiety affects cognitive performance

Dietary choices significantly impact health and daily cognitive performance, prompting various recommendations for eating habits. Whereas much research has focused on the effects of actual satiety on cognitive performance, the influence of expectations regarding effects of satiety on performance remains underexplored. This study aims to address this gap by examining how the expectation of satiety influences cognitive outcomes, building on existing findings that highlight the role of placebo effects in shaping eating behaviour. This study manipulated participants' expectations of how their satiety (satiated versus hungry) affects their concentration through verbal placebo suggestions and measured effects on their cognitive performance. The sample consisted of four groups who were either satiated or hungry and either read the suggestion that their satiety state enhances or deteriorates their concentration. The suggestion was formulated as a scientific finding. Cognitive performance was measured remotely using a Simon Task. Results showed that if participants' actual satiety state was paired with a positive expectation regarding the state they were in, their performance was better than if it was paired with a negative expectation regarding their current satiety state. So, actual satiety state was not the main driver of cognitive performance, but what participants were led to believe about their current satiety state was. These findings suggest that instructions in intervention studies should be phrased carefully to avoid expectation-related confounds. Additionally, verbal placebo suggestions could be a promising method to enhance cognitive performance in daily life.

[Effects of intermittent fasting and sports performance: a narrative review]

Recently, fasted exercise has generated interest for its potential to stimulate metabolic and performance adaptations. The present study aims to analyze the effects of fasting and fasted training on performance and metabolism, acutely and chronically. The databases Medline (PubMed), Physiotherapy Evidence Database (PEDro), Cochrane, and Google Scholar were searched. In total, 767 studies were identified. Of those, 51 studies were finally included. Acutely, exercise on fasting promotes fat oxidation at low and moderate intensities, while protein catabolism is not increased. Performance is not affected in efforts lower than 1 hour. Chronically, fasting generates greater efficiency in fat metabolism and the ability to regulate blood glucose in the long term, although it has not been possible to determine whether these findings improve sports performance. More research is needed in elite athletes, with high training loads and with a periodized approach to fasting.

Intermittent fasting alerts neurotransmitters and oxidant/antioxidant status in the brain of rats

Several recent studies have attempted to understand how fasting has benefits for body health, especially the nervous system. To evaluate the impact of intermittent fasting on body weight, brain neurotransmitters, brain oxidative stress, and brain-derived neurotrophic factor (BDNF) in several areas of the brain, this study was conducted in rats. Thirty male Wistar rats were randomly divided into two groups. Group 1 (15 rats) served as the control and group 2 (15 rats) underwent intermittent fasting (IF; 24 h) for 1, 7, or 15 days. The findings demonstrated that intermittent fasting significantly reduced body weight. In this sense, brain monoamines and amino acids, namely dopamine, glutamate, aspartate, and oxidative stress markers (malondialdehyde and nitric oxide), decreased significantly after 1 day of IF. However, norepinephrine, serotonin, gamma-amino butyric acid, and glycine increased significantly. Additionally, glutathione levels were markedly elevated in IF. Surprisingly, the neuromodulatory effect of intermittent fasting fluctuates depending on the IF period. To support this fluctuation, BDNF levels increased after 1 day in the hippocampus and decreased after 15 days of intermittent fasting in all areas of the brain tested. In conclusion, our results show that intermittent fasting has beneficial influences on the brain; however, prolonged intermittent fasting can also induce some unfavorable physiological outcomes that prevent optimal neurological function.

Cobalt protoporphyrin promotes heme oxygenase 1 expression and ameliorates cardiac dysfunction in long-term fasting mice

BACKGROUND

The association between malnutrition and cardiac dysfunction has been reported. Heme oxygenase (HO)-1 played protective roles in the animals functioning as a myocardial infarction, heart failure, or cardiomyopathy model. We hypothesized that the administration of HO-1 inducer, cobalt protoporphyrin (CoPP) reduces oxidative stress and ameliorates cardiac systolic dysfunction in long-term fasting mice.

METHODS

C57BL/6 J mice were classified into three groups: fed mice (fed group), 48-h fasting mice with a single intraperitoneal injection of the corresponding vehicle (fasting group), and 48-h fasting mice with a single intraperitoneal injection of 5 mg/kg CoPP (CoPP group).

RESULTS

The fasting group showed a significant increase in heme and 4-hydroxy-2-nonenal (4HNE) protein in the heart tissue, and reduced left ventricular ejection fraction (LVEF) when compared with the fed group. The CoPP group showed significantly increased protein levels of nuclear factor-erythroid 2-related factor 2 and HO-1, and increased mRNA expression levels of HO-1, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, forkhead box protein O1, sirtuin-1, cyclooxygenase 2, and superoxide dismutase 2, and reduced levels of heme and 4HNE protein when compared with the fasting group. LVEF were significantly higher in the CoPP group than in the fasting group.

CONCLUSIONS

Administration of CoPP reduced heme accumulation and oxidative stress, and ameliorated cardiac systolic dysfunction in long-term fasting mice. This study suggests that heme accumulation may be associated with impaired cardiac function induced by long-term fasting and that HO-1 may be a key factor or therapeutic target.

The Effects of 24-h Fasting on Exercise Performance and Metabolic Parameters in a Pilot Study of Female CrossFit Athletes

Many studies have tested intermittent fasting (IF) in athletes, but its effects on female CrossFit athletes remain relatively unexplored in the existing literature. The aim of this study was to evaluate and compare the effects of 24-h IF on the physical performance of female CrossFit practitioners. Eleven female CrossFit athletes (age: 30.91 ± 3.42, weight: 65.26 ± 7.55 kg, height: 1.66 ± 0.05 m) participated in the study. The study used a crossover design with fasting and eating conditions. Participants completed an exercise test, standing long jump, and handgrip strength assessment. Hydration status, heart rate, blood lactate, blood glucose, rates of perceived exertion, and hunger were measured. Results showed significant differences in blood lactate concentration (F = 5.435, p = 0.042, η2p = 0.352). Resting blood lactate concentration was significantly lower in the fasting trial than in the eating trial (p < 0.001), but post-exercise blood lactate concentrations were higher in the fasting trial than in the eating trial (p < 0.001). No differences were found in performance times (p > 0.05). In conclusion, this pilot study of females suggests that 24-h fasting does not impair exercise performance or negatively affect physiological parameters in CrossFit athletes.

Metabolic shift toward ketosis in asocial cavefish increases social-like affinity

BACKGROUND

Social affinity and collective behavior are nearly ubiquitous in the animal kingdom, but many lineages feature evolutionarily asocial species. These solitary species may have evolved to conserve energy in food-sparse environments. However, the mechanism by which metabolic shifts regulate social affinity is not well investigated.

RESULTS

In this study, we used the Mexican tetra (Astyanax mexicanus), which features riverine sighted surface (surface fish) and cave-dwelling populations (cavefish), to address the impact of metabolic shifts on asociality and other cave-associated behaviors in cavefish, including repetitive turning, sleeplessness, swimming longer distances, and enhanced foraging behavior. After 1 month of ketosis-inducing ketogenic diet feeding, asocial cavefish exhibited significantly higher social affinity, whereas social affinity regressed in cavefish fed the standard diet. The ketogenic diet also reduced repetitive turning and swimming in cavefish. No major behavioral shifts were found regarding sleeplessness and foraging behavior, suggesting that other evolved behaviors are not largely regulated by ketosis. We further examined the effects of the ketogenic diet via supplementation with exogenous ketone bodies, revealing that ketone bodies are pivotal molecules positively associated with social affinity.

CONCLUSIONS

Our study indicated that fish that evolved to be asocial remain capable of exhibiting social affinity under ketosis, possibly linking the seasonal food availability and sociality.

Effects of Fasting on the Physiological and Psychological Responses in Middle-Aged Men

Tracking changes in the body during fasting takes into account indicators of mental well-being and physiological parameters. The aim of the study was to measure psychological and physiological reactions, along with their mutual relations, caused by 8 days of water-only fasting. Fourteen men aged 35 to 60 participated in the study, divided into two groups, younger and elder. In addition to physiological parameters, psychological data were collected using four different tests. The obtained results confirmed reduction in body weight, systolic blood pressure, resting diastolic blood pressure and glucose level, and increase in resting heart rate, cortisol and β-hydroxybutyrate concentration. However, no significant psychological changes were observed under the influence of fasting intervention. A significant interaction effect occurred for the state anxiety variable determined before and after the fasting intervention for both groups. Moreover, negative correlations between physiological (cortisol) and psychological factors of subjectively assessed stress were revealed. The only effect on cognitive ability was seen when responding to simple tasks. The study confirmed the beneficial effect of 8 days of water-only fasting on physiological variables without affecting mental well-being. The relatively high level of well-being after fasting intervention was independent of the physiological indicators of stress.

Effects of Breakfast Omission on Resting, Exercise, and Postexercise Autonomic and Hemodynamic Profile in Men

Purpose: The acute effects of fasting interventions on metabolic dynamics have been widely investigated. However, knowledge about the acute effect of overnight fasting on hemodynamic and cardiac autonomic modulation is limited, especially during and after exercise. Our objective was to investigate the effects of breakfast omission on hemodynamic and cardiac autonomic modulation during different stress conditions. Method: Twenty-one young men [age: 20.3 (20.1, 26.5 years); body mass index: 22.7 (21.4, 24.4 kg/m²)] underwent resting and postexercise blood pressure assessments and heart rate variability (HRV) analysis, using the SD1 and SD2 indices of Poincaré plots, at rest in supine and standing positions, every 10 minutes during moderate cardiorespiratory training and every 10 minutes throughout the postexercise recovery phase, for a total of 30 minutes for each phase (exercise and recovery). All measurements were performed in a randomized order after overnight fasting or 60 minutes after a breakfast containing ~20% of the total recommended daily calories. The normality hypothesis was rejected, and the Wilcoxon test was conducted to compare the interventions (p < .05). Results: No differences between interventions were observed for resting and postexercise blood pressures (p = .21 to 0.87) or for resting, exercise, and postexercise SD1 (p = .10 to 0.82) and SD2 indices (p = .14 to 0.71). Conclusions: We concluded that overnight fasting does not promote significant changes in resting and postexercise blood pressures or cardiac autonomic modulation in young men at rest (in supine and standing positions), during 30 minutes of moderate cardiorespiratory training and throughout a 30-minute postexercise recovery phase.

Stroke volume variation for predicting responsiveness to fluid therapy in patients undergoing cardiac and thoracic surgery: a systematic review and meta-analysis

OBJECTIVE

To evaluate the reliability of stroke volume variation (SVV) for predicting responsiveness to fluid therapy in patients undergoing cardiac and thoracic surgery.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, EMBASE, Cochrane Library, Web of Science up to 9 August 2020.

METHODS

Quality of included studies were assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. We conducted subgroup analysis according to different anaesthesia and surgical methods with Stata V.14.0, Review Manager V.5.3 and R V.3.6.3. We used random-effects model to pool sensitivity, specificity and diagnostic odds ratio with 95% CI. The area under the curve (AUC) of receiver operating characteristic was calculated.

RESULTS

Among the 20 relevant studies, 7 were conducted during thoracic surgery, 8 were conducted during cardiac surgery and the remaining 5 were conducted in intensive critical unit (ICU) after cardiac surgery. Data from 854 patients accepting mechanical ventilation were included in our systematic review. The pooled sensitivity and specificity were 0.73 (95％ CI: 0.59 to 0.83) and 0.62 (95％ CI: 0.46 to 0.76) in the thoracic surgery group, 0.71 (95％ CI: 0.65 to 0.77) and 0.76 (95％ CI: 0.69 to 0.82) in the cardiac surgery group, 0.85 (95％ CI: 0.60 to 0.96) and 0.85 (95％ CI: 0.74 to 0.92) in cardiac ICU group. The AUC was 0.73 (95% CI: 0.69 to 0.77), 0.80 (95% CI: 0.77 to 0.83) and 0.88 (95% CI: 0.86 to 0.92), respectively. Results of subgroup of FloTrac/Vigileo system (AUC=0.80, Youden index=0.38) and large tidal volume (AUC=0.81, Youden index=0.48) in thoracic surgery, colloid (AUC=0.85, Youden index=0.55) and postoperation (AUC=0.85, Youden index=0.63) in cardiac surgery, passive leg raising (AUC=0.90, Youden index=0.72) in cardiac ICU were reliable.

CONCLUSION

SVV had good predictive performance in cardiac surgery or ICU after cardiac surgery and had moderate predictive performance in thoracic surgery. Nevertheless, technical and clinical variables may affect the predictive value potentially.

The Implication of Physiological Ketosis on The Cognitive Brain: A Narrative Review

Optimal cognitive functions are necessary for activities of daily living and self-independence. Cognitive abilities are acquired during early childhood as part of progressive neurodevelopmental milestones; unfortunately, regressive changes can occur as part of physiological aging, or more ominously, pathological diseases, such as Alzheimer’s disease (AD). Cases of AD and its milder subset, mild cognitive impairment (MCI), are rising and would impose a burdensome impact beyond the individual level. Various dietary and nutritional approaches have potential for promising results in managing cognitive deterioration. Glucose is the core source of bioenergy in the body; however, glucose brain metabolism could be affected in aging cells or due to disease development. Ketone bodies are an efficient alternate fuel source that could compensate for the deficient glycolytic metabolism upon their supra-physiologic availability in the blood (ketosis), which, in turn, could promote cognitive benefits and tackle disease progression. In this review, we describe the potential of ketogenic approaches to produce cognitive benefits in healthy individuals, as well as those with MCI and AD. Neurophysiological changes of the cognitive brain in response to ketosis through neuroimaging modalities are also described in this review to provide insight into the ketogenic effect on the brain outside the framework of purely molecular explanations.

The Effect of Fasting on Human Metabolism and Psychological Health

Fasting is a prevalent approach to weight loss and is a feasible method for treating some diseases, such as type 2 diabetes. Meanwhile, the effects of intermittent fasting on health, aging, and disease process are hot issues and are of concern by researchers of multiple areas, even the public. This article introduces the effects of fasting on human lipid metabolism, glucose metabolism, protein metabolism, and neuroendocrine metabolism; demonstrates the metabolic conversion caused by fasting; and describes the effects of fasting on human psychological health, the relationship between mood regulation and glucose, and the emotional enhancing effect induced by fasting.

Comparisons of Mood States Associated With Outcomes Achieved by Female and Male Athletes in High-Level Judo and Brazilian Jiu-Jitsu Championships: Psychological Factors Associated With the Probability of Success

ABSTRACT

Brandt, R, Bevilacqua, GG, Crocetta, TB, Monteiro, CBdM, Guarnieri, R, Hobold, E, Flores, LJF, Miarka, B, and Andrade, A. Comparisons of mood states associated with outcomes achieved by female and male athletes in high-level judo and Brazilian jiu-jitsu championships: psychological factors associated with the probability of success. J Strength Cond Res 35(9): 2518-2524, 2019-Moods can be used to predict the performance of athletes in various sports; accordingly, we selected the Brunel Mood Scale (BRUMS) to evaluate mood states of high-level judo and Brazilian jiu-jitsu (BJJ) athletes. The aims of this study were (a) to compare the mood states of high-level female and male athletes in BJJ and judo championships in relation to their performance outcomes and (b) to verify associations between psychological factors and performance in estimating their probability of success. The subjects were 173 grappling athletes (judo, n = 85 and BJJ, n = 88), separated into male (n = 129, 40 winners and 89 nonwinners) and female (n = 44, 23 winners and 21 nonwinners) groups. Each subject's mood state was assessed 60 minutes before the first match using the BRUMS (tension, depression, anger, vigor, fatigue, and mental confusion dimensions). Descriptive and inferential statistics (including logistic regression and variance analysis) were used to evaluate relations between mood states and performance (i.e., winning/losing), with p ≤ 0.05. Analysis showed significant differences between male and female athletes in vigor and fatigue, and differences between male judo and male BJJ athletes in tension, vigor, confusion, and fatigue. Female judo and female BJJ athletes showed significant differences in depression and vigor. Logistic regression revealed that higher levels of anger and tension increased athletes' chances of performing well in a match by 23 and 13%, respectively. In addition, lower levels of depression increased athletes' chances of better performance by up to 32%. Overall, we observed a significant relationship between mood state and sports performance. Thus, coaching staff and athletes should monitor athletes' mood states before competitions to ensure that they are in optimal condition to perform and use psychological interventions to support judo and BJJ preparation.

Effects of long-term fasting and confinement on the cardiovascular activity

Fasting has been demonstrated to improve health and slow aging in human and other species; however, its impact on the human body in the confined environment is still unclear. This work studies the effects of long-term fasting and confined environment on the cardiovascular activities of human via a 10-day fasting experiment with two groups of subjects being in confined (6 subjects) and unconfined (7 subjects) environments respectively and undergoing the same four-stage fasting/feeding process. It is found that the confinement has significant influences on the autonomic regulation to the heart rate during the fasting process by altering the activity of the parasympathetic nervous system, which is manifested by the significant higher pNN50, rMSSD, and Ln-HF of heart rate variability (HRV) (p < 0.05) and slower heart rate (p < 0.01) in the confined group than that in the unconfined group. Furthermore, the long-term fasting induces a series of changes in both groups, including reduced level of serum sodium (p < 0.01), increased the serum calcium (p < 0.05), prolonged QTc intervals (p < 0.05), and reduced systolic blood pressures (p < 0.05). These effects are potentially negative to human health and therefore need to be treated with caution. Study of the effects of fasting and confinement on the cardiovascular activities.

W. Is Water-Only Fasting Safe?

BACKGROUND

Water-only fasting (WF) is a practice used to improve and maintain health.

OBJECTIVE

The aim of the study was to show whether WF performed for 8 days may be a threat to the health and/or life of people undergoing this practice.

METHODS

Twelve middle-aged men participated in the study. During the 8-day WF, the subjects ate no food except for drinking mineral water. Before and after WF, all subjects had a series of tests performed, beginning with the level of perceived stress and somatic measurements. The concentrations of creatinine, sodium (Na+), potassium (K+), total calcium (Ca), magnesium (Mg++), urea (U), uric acid (UA) and total protein were determined in this urine and in the serum. For these substances, the values ​​of clearance, renal filtration and fractional excretion were calculated. The osmotic clearance and free water clearance as well as the amount of daily urinary excretion of creatinine, Na+, K+, Ca, Mg++, U and UA were also calculated. Moreover, the concentration of glucose in the serum and the concentration of β-hydroxybutyrate in the plasma were determined. In urine, specific gravity, pH and osmolality were also measured.

RESULTS

After 8 days of WF, the study showed a significant reduction in the level of perceived stress, weight loss, changes in body composition, dehydration, increased ketogenesis, hyperuricemia, decreased serum glucose concentration, and hyponatremia. These changes were accompanied by Na+, K+ and protein sparing, decreased serum Ca and Mg++ concentrations, and reduced daily volume of more acidic urine with elevated specific gravity.

CONCLUSIONS

After 8 days of WF, all subjects were found to remain safe and feel the sense of well-being. However, the appearance of the above-mentioned adverse metabolic effects, despite partially effective renal compensations, suggests that the further continuation of fasting intervention by the subjects would be detrimental to their body.

How Experiences Affect Psychological Responses During Supervised Fasting: A Preliminary Study

As an unusual event, fasting can induce strong physiological and psychological reactions, but there is still no clear understanding of how previous fasting experiences affect people’s responses to current fasting. This study aimed to investigate the influence of previous fasting experiences on participants’ basic physiological and psychological responses in a fasting experiment conducted under intensive medical monitoring. For a 22-day experiment divided into four phases (3-day Baseline; 10-day Complete Fasting; 4-day Calorie Restriction; and 5-day Recovery phases), a total of 13 persons participated; the participants were divided into a group with prior fasting experience (Experienced: N = 6) and a group without prior fasting experience (Newbie: N = 7). The results indicate no group differences in physiological responses (i.e., weight, glucose, and ketone bodies); however, differences in psychological states were observed, with the Newbie group showing more negative psychological states overall throughout the experiment (i.e., greater appetite, more negative mood states, more stress, less vitality, and fewer recovery resources). Hence, previous fasting experience may be a buffer against negative feelings during current fasting. For this reason, it is important to consider fasting experiences as a vital factor in future research.

Hunger Potentiates the Habenular Winner Pathway for Social Conflict by Orexin-Promoted Biased Alternative Splicing of the AMPA Receptor Gene

Many animals fight for dominance between conspecifics. Because winners could obtain more resources than losers, fighting outcomes are important for the animal's survival, especially in a situation with insufficient resources, such as hunger. However, it remains unclear whether and how hunger affects fighting outcomes. Herein, we investigate the effects of food deprivation on brain activity and fighting behaviors in zebrafish. We report that starvation induces winning in social conflicts. Before the fights, starved fish show potentiation of the lateral subregion of the dorsal habenula (dHbL)-dorsal/intermediate interpeduncular nucleus (d/iIPN) pathway, which is known to be essential for and potentiated after winning fights. Circuit potentiation is mediated by hypothalamic orexin/hypocretin neuropeptides, which prolong AMPA-type glutamate receptor (AMPAR) activity by increasing the expression of a flip type of alternative splicing variant of the AMPAR subunit. This mechanism may underlie how hungry vertebrates win fights and may be commonly shared across animal phylogeny.

Long-Term Shaping of Corticostriatal Synaptic Activity by Acute Fasting

Food restriction is a robust nongenic, nonsurgical and nonpharmacologic intervention known to improve health and extend lifespan in various species. Food is considered the most essential and frequently consumed natural reward, and current observations have demonstrated homeostatic responses and neuroadaptations to sustained intermittent or chronic deprivation. Results obtained to date indicate that food deprivation affects glutamatergic synapses, favoring the insertion of GluA2-lacking α-Ammino-3-idrossi-5-Metil-4-idrossazol-Propionic Acid receptors (AMPARs) in postsynaptic membranes. Despite an increasing number of studies pointing towards specific changes in response to dietary restrictions in brain regions, such as the nucleus accumbens and hippocampus, none have investigated the long-term effects of such practice in the dorsal striatum. This basal ganglia nucleus is involved in habit formation and in eating behavior, especially that based on dopaminergic control of motivation for food in both humans and animals. Here, we explored whether we could retrieve long-term signs of changes in AMPARs subunit composition in dorsal striatal neurons of mice acutely deprived for 12 hours/day for two consecutive days by analyzing glutamatergic neurotransmission and the principal forms of dopamine and glutamate-dependent synaptic plasticity. Overall, our data show that a moderate food deprivation in experimental animals is a salient event mirrored by a series of neuroadaptations and suggest that dietary restriction may be determinant in shaping striatal synaptic plasticity in the physiological state.

Two Months of Using Global Recommendations for Physical Activity Had No Impact on Cognitive or Motor Functions in Overweight and Obese Middle-Aged Women

BACKGROUND

The effect of globally recommended levels of physical activity on cognition and motor behavior is not completely understood. Therefore, the main aim of this study was to assess the effect of 300 minutes per week of moderate-intensity aerobic exercise on cognitive and motor performance among overweight and obese working-age women.

METHODS

Overweight and obese participants aged 38-56 years were randomized to either a control or an experimental group performing aerobic exercise at 50% to 60% of the peak oxygen consumption for a 2-month period. Changes in aerobic fitness, cardiac autonomic function, brain-derived neurotropic factor levels, and cognitive and motor performance were assessed.

RESULTS

Although aerobic exercise reduced body weight (P < .05) and improved peak oxygen consumption (P < .05), the brain-derived neurotropic factor levels and cognitive and motor performance remained unchanged. Heart rate and blood pressure decreased (P < .05), whereas heart rate variability indices were not affected. No significant correlations between changes in heart rate variability indices and cognition were observed.

CONCLUSIONS

Two months of moderate-intensity aerobic exercise decreased sympathetic activity and improved cardiovascular fitness but had no impact on cognition or motor control among these middle-aged, overweight, and obese women.

Meal skipping and cognition along a spectrum of restrictive eating

OBJECTIVE

Inadequate nutrition adversely impacts brain development and cognitive functioning (Pollitt et al., 1983). Studies examining the acute impact of eating regular meals on cognition have reported inconsistent findings, necessitating the exploration of individual differences in samples contributing to equivocal results. The present study examines the impact of skipping lunch on cognitive ability in college-aged students by including eating restraint as a moderator.

METHODS

Participants were 99 college-aged students (M = 19.7 years, SD = 1.5) randomized to a blinded 'lunch' or 'lunch-omission' condition, and assessed on memory, attention, processing speed, set shifting, and eating disorder symptomology.

RESULTS

Regressing long and short-term memory on the lunch manipulation, eating restraint scores, and their interaction revealed significant interactions: those who had lunch had superior memory performance, but only for those reporting lower levels of eating restraint. Regressing set shifting speed on the manipulation, those who had lunch had slower set shifting speed than those who skipped, but only for those reporting lower levels of eating restraint.

CONCLUSIONS

Results suggest that skipping lunch may have immediate consequences on cognition, however, cognitive enhancing effects may be diminished in the presence of even low levels of eating restraint. Findings highlight the significance of purported subclinical levels of eating restraint and may inform health education strategies.

Prior cortical activity differences during an action observation plus motor imagery task related to motor adaptation performance of a coordinated multi-limb complex task

Motor adaptation is the ability to develop new motor skills that makes performing a consolidated motor task under different psychophysical conditions possible. There exists a proven relationship between prior brain activity at rest and motor adaptation. However, the brain activity at rest is highly variable both between and within subjects. Here we hypothesize that the cortical activity during the original task to be later adapted is a more reliable and stronger determinant of motor adaptation. Consequently, we present a study to find cortical areas whose activity, both at rest and during first-person virtual reality simulation of bicycle riding, characterizes the subjects who did and did not adapt to ride a reverse steering bicycle, a complex motor adaptation task involving all limbs and balance. The results showed that cortical activity differences during the simulated task were higher, more significant, spatially larger, and spectrally wider than at rest for good performers. In this sense, the activity of the left anterior insula, left dorsolateral and ventrolateral inferior prefrontal areas, and left inferior premotor cortex (action understanding hub of the mirror neuron circuit) during simulated bicycle riding are the areas with the most descriptive power for the ability of adapting the motor task. Trials registration Trial was registered with the NIH Clinical Trials Registry (clinicaltrials.gov), with the registration number NCT02999516 (21/12/2016).

Forty-eight-hour fasting declines mental flexibility but improves balance in overweight and obese older women

The purpose of this study was to investigate the effects of a 48-h fast on evoked stress, mood, and cognitive and motor functions in overweight and obese older women. Eleven women (body mass index >25 kg/m²) aged 63-80 years were tested under two randomly allocated conditions: 48-h zero-calorie diet with water provided ad libitum and 48-h usual diet. Autonomic function, cortisol levels, mood state, cognitive performance, visuomotor coordination, motor speed, and balance were evaluated before and after each diet. Fasting increased (P < 0.05) cortisol levels, whereas no changes were observed in heart rate and its variability. Fasting increased (P < 0.05) fatigue, prolonged (P < 0.05) reaction time in the two-choice reaction time test and decreased (P < 0.05) the velocity vector of the center of pressure with eyes closed, whereas no changes in performance were observed in the pursuit tracking and finger tapping tests. Thus, although a 48-h fast resulted in greater hypothalamic-pituitary-adrenal axis activity in overweight and obese older women, autonomic nervous system activity was not affected. Fasting increased fatigue and decreased mental flexibility, but improved balance.

A 10-week yoga practice has no effect on cognition, but improves balance and motor learning by attenuating brain-derived neurotrophic factor levels in older adults

Despite studies investigating the effect of yoga on cognitive and motor functioning in older adults, the effect on dual-task performance and motor learning and the specific mechanisms underlying the positive effect of yoga remain unclear. Thus, the aim of this study was to investigate the effects of yoga on cognition, balance under single- and dual-task conditions, and motor learning. The potential role of brain-derived neurotrophic factor (BDNF) in induced improvement was also explored. Participants aged 60-79 years were randomized to either a control group (n = 15) or a yoga group (n = 18) for a 10-week period. The yoga group received 90-min duration yoga classes two times per week. Changes in cognition, balance under single- and dual-task conditions, and learning fast and accurate reaching movements were assessed. Yoga practice decreased (P < 0.05) the velocity vector of the center of pressure under single- and dual-task conditions, whereas no changes in cognitive performance were observed. Although reaction and movement times during learning were decreased in both groups (P < 0.05), a faster reaction time (P < 0.05) and shorter movement time (P < 0.05) were observed in the yoga group than in the control group. Significant moderate relationships (P < 0.05) between changes in BDNF levels and functional improvements were observed. Thus, 10 weeks of yoga practice resulted in improved balance and learning in the speed-accuracy motor task that were mediated by increased BDNF levels, but had no impact on cognition in older adults.

The Effect of Combined Aerobic Exercise and Calorie Restriction on Mood, Cognition, and Motor Behavior in Overweight and Obese Women

BACKGROUND

The benefits of weight loss programs on mood, cognitive, and motor behavior are largely limited to those of calorie restriction or exercise alone. Our aim was to investigate the effect of combined calorie restriction and aerobic exercise intervention on mood, brain activity, and cognitive and motor behavior in overweight and obese women.

METHODS

Participants aged 36-56 years were randomized to either a control or an experimental group (aerobic exercise + 12.5% energy intake reduction) for a 6-month period. Changes in brain-derived neurotrophic factor levels, mood, prefrontal cortex activity, cognitive and motor performance were assessed.

RESULTS

Confusion and depression increased in the control group (P < .05), whereas tension decreased in the experimental group (P < .05). Brain-derived neurotrophic factor level and learning of a speed-accuracy task remained unchanged. Although prefrontal cortex activity and executive functions were not affected, the reaction time of visual scanning and associative learning were improved in the experimental group (P < .05). An improvement in reaction time during the speed-accuracy task was observed (P < .05).

CONCLUSION

Combined calorie restriction and aerobic exercise intervention improved the psychosocial state, had little impact on cognition, and no effect on brain activity and learning of the speed-accuracy task.

Effect of Ramadan fasting on heart rate variability as a measure of cardiac stress in a Lebanese cohort

BACKGROUND

Intermittent fasting is an annual religious practice of Muslims worldwide, which affects the physiology of the body due to lifestyle alterations. This study aimed to evaluate the effect of Ramadan fasting on the HRV, an indirect measure of cardiac sympathetic stress.

METHODS

This study included 80 healthy Lebanese females (aged 18-25 years old) monitored for 24 h when following normal routine; 38 and 42 females were enrolled before and during Ramadan, respectively.

RESULTS

Our results reveal no effect of fasting on HRV; there was insignificant change in HRV between the first and last weeks of Ramadan (P > 0.05). Morning fasting was significantly the least stressful period (lowest HR, P < 0.001), with lower HR compared with non-fasting day (P < 0.001). Therefore, Ramadan fasting does not alter the autonomic nervous activity of the heart, neither HRV levels.

CONCLUSIONS

This may imply that intermittent fasting is a risk-free practice, which does not interfere with the cardiac autonomic nervous system function.

Exercise Training and Fasting: Current Insights

Fasting is defined as the abstinence from consuming food and/or beverages for different periods of time. Both traditional and modern healthcare systems recommend fasting as a therapeutic intervention for the management of several chronic, non-infectious diseases. Exercising during a fasting state increases lipolysis in adipose tissue while also stimulating peripheral fat oxidation, resulting in increased fat utilization and weight loss. A key focus of this review is to assess whether endurance training performed while fasting induces specific training adaptations, where increased fat oxidation improves long-term endurance levels. Fasting decreases body weight, lean body and fat content in both trained and untrained individuals. Several studies indicate a broader impact of fasting on metabolism, with effects on protein and glucose metabolism in sedentary and untrained subjects. However, there are conflicting data regarding the effects of fasting on glucose metabolism in highly trained athletes. The effects of fasting on physical performance indicators also remain unclear, with some reporting a decreased performance, while others found no significant effects. Differences in experimental design, severity of calorie restriction, duration, and participant characteristics could, at least in part, explain such discordant findings. Our review of the literature suggests that there is little evidence to support the notion of endurance training and fasting-mediated increases in fat oxidation, and we recommend that endurance athletes should avoid high intensity training while fasting.

Fed and fasted states on heart rate variability, hemodynamic heart rate and blood pressure in adults submitted to moderate aerobic exercise

Background

Heart rate variability (HRV) has proven to be a powerful non-invasive tool to investigate cardiac autonomic control and, seems to be influenced by nutritional status and exercise practice. However, the acute effects of fed or fasting states on HRV and blood pressure (BP) during low-to-moderate intensity aerobic exercise are currently unknown. Therefore, we investigated the baseline values and behavior of HRV, BP, and heart rate (HR) before and after low-to-moderate intensity aerobic exercise in fed and fasted states in healthy adults.

Methods

12 healthy individuals with mean age (SD) 59.0 (9.1) years performed two tests on a treadmill at 80% of the mean velocity of the 6-min walking test separated by 48 h: 12 h fasted (FST) or 1 h fed (FED). HRV, BP and HR were analyzed at rest, posttest, and at the third, fifth, and seventh minutes of recovery.

Results

HRV and HR presented no significant alterations between nutritional conditions. HR at baseline was not different between nutritional conditions. Diastolic blood pressure was increased during the fasted baseline state.

Conclusions

The results of the current study provide that 12 h overnight fasting does not seem to be enough to affect significant changes in the autonomic modulation in healthy adults submitted to low-to-moderate intensity aerobic exercise.

Prefrontal Cortex Activity Predicts Mental Fatigue in Young and Elderly Men During a 2 h "Go/NoGo" Task

Background: Although the effects of mental fatigue on cognitive–motor function and psychological state in young adults are well-documented, its effects in the elderly are not completely understood. The aim of this study was to estimate the effect of prolonged cognitive load on the indicators of psychological, cognitive, and motor functions.

Methods: Fifteen young and 15 elderly men were asked to perform a 2 h “Go/NoGo” task. Psychological state (mood and motivation), cognitive (prefrontal cortex activity and cognitive performance), and motor (motor cortex excitability and grip strength) functions were measured before and after the task. During the 2 h task, both groups had a significantly similar increase in the number of “Incorrect NoGo” errors. Only in young men reaction time (RT) of “Incorrect NoGo” and intraindividual variability of RT of “Incorrect NoGo” significantly increased during task. After the task, handgrip strength decreased for the young men, whereas latency of motor evoked potentials prolonged both groups. Nevertheless, both groups indicated that they felt fatigue after the 2 h task; we observed that mental demand increased, whereas intrinsic motivation and mood decreased only in young men. Prolonged task decreased the switching/rest ratio of oxygenated hemoglobin for the young and the elderly men; however, greater for elderly than young men. Interestingly, the more the prefrontal cortex was activated before the 2 h task during the switching task, the fewer of “Incorrect NoGo” errors made by the young men and the greater the number of errors made by the elderly men.

Conclusion: Because of the greater mental load and (possibly) greater activation of prefrontal cortex during the 2 h “Go/NoGo” task, there was greater mental and neuromuscular performance fatigue in young men than in elderly men.

Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting

OBJECTIVE

Intermittent fasting (IF) is a term used to describe a variety of eating patterns in which no or few calories are consumed for time periods that can range from 12 hours to several days, on a recurring basis. This review is focused on the physiological responses of major organ systems, including the musculoskeletal system, to the onset of the metabolic switch: the point of negative energy balance at which liver glycogen stores are depleted and fatty acids are mobilized (typically beyond 12 hours after cessation of food intake).

RESULTS AND CONCLUSIONS

Emerging findings suggest that the metabolic switch from glucose to fatty acid-derived ketones represents an evolutionarily conserved trigger point that shifts metabolism from lipid/cholesterol synthesis and fat storage to mobilization of fat through fatty acid oxidation and fatty acid-derived ketones, which serve to preserve muscle mass and function. Thus, IF regimens that induce the metabolic switch have the potential to improve body composition in overweight individuals. Moreover, IF regimens also induce the coordinated activation of signaling pathways that optimize physiological function, enhance performance, and slow aging and disease processes. Future randomized controlled IF trials should use biomarkers of the metabolic switch (e.g., plasma ketone levels) as a measure of compliance and of the magnitude of negative energy balance during the fasting period.