The effect of histamine on changes in mental energy and fatigue after a single bout of exercise

Fatigue and perceived energy in a sample of older adults over 10 years: A resting state functional connectivity study of neural correlates

PURPOSE

Declining energy and increasing fatigue, common in older age, predict neurodegenerative conditions, but their neural substrates are not known. We examined brain resting state connectivity in relation to declining self-reported energy levels (SEL) and occurrence of fatigue over time.

METHODS

We examined resting-state functional MRI in 272 community dwelling older adults participating in the Health Aging and Body Composition Study (mean age 83 years; 57.4 % female; 40.8 % Black) with measures of fatigue and SEL collected at regular intervals over the prior ten years. Functional connectivity (FC) between cortex and striatum was examined separately for sensorimotor, executive, and limbic functional subregions. Logistic regression tested the association of FC in each network with prior fatigue state (reporting fatigue at least once or never reporting fatigue), and with SEL decline (divided into stable or declining SEL groups) and adjusted for demographic, physical function, mood, cognition, and comorbidities.

RESULTS

Higher cortico-striatal FC in the right limbic network was associated with lower odds of reporting fatigue (better) at least once during the study period (adjusted odds ratio [95 % confidence interval], p-value: (0.747 [0.582, 0.955], 0.020), independent of SEL. Higher cortico-striatal FC in the right executive network was associated with higher odds of declining SEL (worse) during the study period (adjusted odds ratio [95 % confidence interval], p-value: (1.31 [1.01, 1.69], 0.041), independent of fatigue. Associations with other networks were not significant.

CONCLUSIONS

In this cohort of older adults, the cortico-striatal functional connectivity of declining SEL appears distinct from that underlying fatigue. Studies to further assess the neural correlates of energy and fatigue, and their independent contribution to neurodegenerative conditions are warranted.

Physical Activity and Fatigue Symptoms: Neurotypical Adults and People with Chronic Multisymptom Illnesses

For neurotypical adults, a single bout of low-to-moderate intensity physical activity usually transiently improves feelings of energy. Similar bouts of exercise have the opposite effect of increased feelings of fatigue when performed by samples with chronic multisymptom illnesses (CMIs) such as Long-COVID, Gulf War Illness (GWI), or Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). The short-term adoption of regular moderate intensity physical activity (typical experiments are 1 to 6 months) among neurotypical adults results in small-to-moderate improvements in self-reported feelings of fatigue, energy, and vitality. Small improvements in these feelings, or no change at all, occur for CMIs, but limited data precludes strong conclusions. The mechanisms of exercise effects on fatigue, whether acute or chronic, are poorly understood but likely involve multiple neural circuits and associated transmitters. For CMIs, the mechanisms of acute worsening of fatigue with exercise may be driven by the yet unknown pathophysiological mechanisms of the disease (perhaps involving brain, immune and autonomic system dysfunction, and their interactions). Likewise, fatigue improvements may depend on whether chronic physical activity is a disease-modifying treatment.

Metabolomics of Cerebrospinal Fluid Amino and Fatty Acids in Early Stages of Multiple Sclerosis

Multiple sclerosis (MS) is a demyelinating and neurodegenerative autoimmune disease of the central nervous system (CNS) damaging myelin and axons. Diagnosis is based on the combination of clinical findings, magnetic resonance imaging (MRI) and analysis of cerebrospinal fluid (CSF). Metabolomics is a systematic study that allows us to track amounts of different metabolites in a chosen medium. The aim of this study was to establish metabolomic differences between the cerebrospinal fluid of patients in the early stages of multiple sclerosis and healthy controls, which could potentially serve as markers for predicting disease activity. We collected CSF from 40 patients after the first attack of clinical symptoms who fulfilled revised McDonald criteria of MS, and the CSF of 33 controls. Analyses of CSF samples were performed by using the high-performance liquid chromatography system coupled with a mass spectrometer with a high-resolution detector. Significant changes in concentrations of arginine, histidine, spermidine, glutamate, choline, tyrosine, serine, oleic acid, stearic acid and linoleic acid were observed. More prominently, Expanded Disability Status Scale values significantly correlated with lower concentrations of histidine. We conclude that these metabolites could potentially play a role as a biomarker of disease activity and predict presumable inflammatory changes.

Stair walking effects on feelings of energy and fatigue: Is 4-min enough for benefits?

Purpose

Even low intensity exercise bouts of at least 15 min can improve feelings of energy (FOE) and reduce systolic blood pressure. However, little is known about the psychological outcomes of briefer exercise bouts, particularly for modes of exercise that are more intense than level walking, and readily available to many working adults. This study assessed the effects of a 4-min bout of stair walking on FOE and feelings of fatigue (FOF).

Methods

Thirty-six young adult participants were randomized to either stair walking or seated control groups. All participants walked on level-ground from a laboratory to a nearby stairwell (~90 s) and were seated for 4 min before beginning their experimental condition. Stair-walking participants walked up and down one flight of 16 stairs at their own pace for 4 min, while control participants remained seated during that time. Participants walked back to the laboratory for post-condition assessments. Measures of blood pressure, heart rate, rated perceived exertion (RPE), and the intensity of feelings of mental energy, mental fatigue, physical energy, and physical fatigue were assessed pre-and post-condition. Separate one-way ANOVAs were conducted on change scores for all variables.

Results

The stair climbing group experienced significant increases in heart rate [F(1,34) = 13.167, p < 0.001] and RPE [F(1,34) = 93.844, p < 0.001] that were not observed in the seated control group. Four minutes of self-paced stair climbing resulted in small changes and non-significant differences within and between groups in blood pressure as well as FOE and FOF.

Conclusion

Although a 4-min self-paced exercise bout can convey short-term physiological health benefits, a 4-min bout of self-paced indoor stair walking in a stairwell was insufficient to lower blood pressure or change subjective FOE and fatigue in a sample that exhibited better than typical FOE and FOF at the pre-test.

The Link Between Energy-Related Sensations and Metabolism: Implications for Treating Fatigue

Energy-related sensations include sensation of energy and fatigue as well as subjective energizability and fatigability. First, we introduce interdisciplinary useful definitions of all constructs and review findings regarding the question of whether sensations of fatigue and energy are two separate constructs or two ends of a single dimension. Second, we describe different components of the bodily energy metabolism system (e.g., mitochondria; autonomic nervous system). Third, we review the link between sensation of fatigue and different components of energy metabolism. Finally, we present an overview of different treatments shown to affect both energy-related sensations and metabolism before outlining future research perspectives.

Using Machine Learning to Identify Feelings of Energy and Fatigue in Single-Task Walking Gait: An Exploratory Study

The objective of this study was to use machine learning to identify feelings of energy and fatigue using single-task walking gait. Participants (n = 126) were recruited from a university community and completed a single protocol where current feelings of energy and fatigue were measured using the Profile of Moods Survey–Short Form approximately 2 min prior to participants completing a two-minute walk around a 6 m track wearing APDM mobility monitors. Gait parameters for upper and lower extremity, neck, lumbar and trunk movement were collected. Gradient boosting classifiers were the most accurate classifiers for both feelings of energy (74.3%) and fatigue (74.2%) and Random Forest Regressors were the most accurate regressors for both energy (0.005) and fatigue (0.007). ANCOVA analyses of gait parameters comparing individuals who were high or low energy or fatigue suggest that individuals who are low energy have significantly greater errors in walking gait compared to those who are high energy. Individuals who are high fatigue have more symmetrical gait patterns and have trouble turning when compared to their low fatigue counterparts. Furthermore, these findings support the need to assess energy and fatigue as two distinct unipolar moods as the signals used by the algorithms were unique to each mood.

Trait Energy and Fatigue May Be Connected to Gut Bacteria among Young Physically Active Adults: An Exploratory Study

Recent scientific evidence suggests that traits energy and fatigue are two unique unipolar moods with distinct mental and physical components. This exploratory study investigated the correlation between mental energy (ME), mental fatigue (MF), physical energy (PE), physical fatigue (PF), and the gut microbiome. The four moods were assessed by survey, and the gut microbiome and metabolome were determined from 16 S rRNA analysis and untargeted metabolomics analysis, respectively. Twenty subjects who were 31 ± 5 y, physically active, and not obese (26.4 ± 4.4 kg/m2) participated. Bacteroidetes (45%), the most prominent phyla, was only negatively correlated with PF. The second most predominant and butyrate-producing phyla, Firmicutes (43%), had members that correlated with each trait. However, the bacteria Anaerostipes was positively correlated with ME (0.048, p = 0.032) and negatively with MF (−0.532, p = 0.016) and PF (−0.448, p = 0.048), respectively. Diet influences the gut microbiota composition, and only one food group, processed meat, was correlated with the four moods—positively with MF (0.538, p = 0.014) and PF (0.513, p = 0.021) and negatively with ME (−0.790, p < 0.001) and PE (−0.478, p = 0.021). Only the Firmicutes genus Holdemania was correlated with processed meat (r = 0.488, p = 0.029). Distinct metabolic profiles were observed, yet these profiles were not significantly correlated with the traits. Study findings suggest that energy and fatigue are unique traits that could be defined by distinct bacterial communities not driven by diet. Larger studies are needed to confirm these exploratory findings.

Functional correlates of self-reported energy levels in the Health, Aging and Body Composition Study

BACKGROUND

Effects of fatigue on health in older age are well studied, yet little is known about the clinical relevance of energy perception.

AIMS

To explore cross-sectional associations of self-reported energy with physical and mental health metrics in the Health, Aging, and Body Composition Study.

METHODS

Participants rated their energy from 0 to 10; the outcome was energy dichotomized at the median (≥ 7 = higher energy). Four domains were assessed: depressive symptoms (Center for Epidemiologic Studies Depression Scale); physical performance (function: usual and rapid gait speed; fitness: 400-m walk time); physical activity (casual walking, walking for exercise, and intense exercise); and cognitive function (Modified Mini-Mental State Examination and Digit Symbol Substitution Test). Covariates bivariately associated with energy entered a multivariable logistic regression model, adjusted for demographics, chronic conditions, and strength.

RESULTS

Depressive symptoms, physical performance and activity, but not cognition, were bivariately associated with energy (p < 0.0005). Younger age, male sex, greater strength, and absence of chronic conditions predicted higher energy (p < 0.001). In a multivariable model, depressive symptoms [adjusted odds ratio (aOR) 95% CI 0.69 (0.62, 0.76)] and 400-m walk times [aOR = 0.81 (0.72, 0.91)] were inversely associated with energy; usual and rapid gait speed [aOR = 1.3 (1.2, 1.4); aOR = 1.2 (1.1-1.4)], and time spent in intense exercise [aOR = 1.4 (1.1-1.7)] were positively associated with energy.

DISCUSSION

In this cohort with a range of chronic conditions and fatigue, perceiving higher energy levels may reflect better emotional and physical health.

CONCLUSION

Energy should be considered in multidimensional clinical assessments of older age.

Mild parkinsonian signs, energy decline, and striatal volume in community-dwelling older adults

BACKGROUND

Mild Parkinsonian Signs (MPS), highly prevalent in older adults, predict disability. It is unknown whether energy decline, a predictor of mobility disability, is also associated with MPS. We hypothesized that those with MPS had greater decline in self-reported energy levels (SEL) than those without MPS, and that SEL decline and MPS share neural substrates.

METHODS

Using data from the Health, Aging and Body Composition Study, we analyzed 293 Parkinson's Disease-free participants (83±3 years old, 39% Black, 58% women) with neuroimaging data, MPS evaluation by Unified Parkinson Disease Rating Scale in 2006-2008, and ≥ 3 measures of SEL since 1999-2000. Individual SEL slopes were computed via linear mixed models. Associations of SEL slopes with MPS were tested using logistic regression models. Association of SEL slope with volume of striatum, sensorimotor, and cognitive regions were examined using linear regression models adjusted for normalized total gray matter volume. Models were adjusted for baseline SEL, mobility, demographics, and comorbidities.

RESULTS

Compared to those without MPS (n=165), those with MPS (n=128) had 37% greater SEL decline in the prior eight years (p=0.001). Greater SEL decline was associated with smaller right striatal volume (adjusted standardized β=0.126, p=0.029). SEL decline was not associated with volumes in other regions. The association of SEL decline with MPS remained similar after adjustment for right striatal volume (adjusted OR=2.03, 95% CI: 1.16 - 3.54).

CONCLUSION

SEL decline may be faster in those with MPS. Striatal atrophy may be important for declining energy but does not explain the association with MPS.

Incorporating methods and findings from neuroscience to better understand placebo and nocebo effects in sport

Placebo and nocebo effects are a factor in sports performance. However, the majority of published studies in sport science are descriptive and speculative regarding mechanisms. It is therefore not unreasonable for the sceptic to argue that placebo and nocebo effects in sport are illusory, and might be better explained by variations in phenomena such as motivation. It is likely that, in sport at least, placebo and nocebo effects will remain in this empirical grey area until researchers provide stronger mechanistic evidence. Recent research in neuroscience has identified a number of consistent, discrete and interacting neurobiological and physiological pathways associated with placebo and nocebo effects, with many studies reporting data of potential interest to sport scientists, for example relating to pain, fatigue and motor control. Findings suggest that placebos and nocebos result in activity of the opioid, endocannabinoid and dopamine neurotransmitter systems, brain regions including the motor cortex and striatum, and measureable effects on the autonomic nervous system. Many studies have demonstrated that placebo and nocebo effects associated with a treatment, for example an inert treatment presented as an analgesic or stimulant, exhibit mechanisms similar or identical to the verum or true treatment. Such findings suggest the possibility of a wide range of distinct placebo and nocebo mechanisms that might influence sports performance. In the present paper, we present some of the findings from neuroscience. Focussing on fatigue as an outcome and caffeine as vehicle, we propose three approaches that researchers in sport might incorporate in their studies in order to better elucidate mechanisms of placebo/nocebo effects on performance.

Mental energy: plausible neurological mechanisms and emerging research on the effects of natural dietary compounds

Objective: Lack of mental energy is one of the leading reasons adults turn to dietary supplements, with three out of ten supplement users hoping to improve their energy level; even more consume caffeine-containing products for the same reason. Despite this interest from consumers, there is no consensus scientific definition of mental energy or sole validated instrument for measuring it. We performed this review to summarize main findings from research regarding the influence of natural dietary compounds on three aspects of mental energy: cognition (vigilance), motivation (to do mental work), and mood (feelings of energy and/or absence of feelings of fatigue).Methods: A narrative review of key papers.Results: In addition to caffeine, a number of other compounds, including the polyphenols, which are found in all plant-derived products, and the phytochemicals in culinary herbs and herbal products such as Panax ginseng and Ginkgo biloba, have been shown in animal models to modulate neurotransmitter activity potentially relevant to mental energy. Inadequate intake of B vitamins could also potentially have a negative effect on mental energy due to their role in overall energy production, as precursors of key cofactors in the citric acid cycle, as well as their role in brain function and neurotransmitter synthesis. Consumption of some of these products may have direct or indirect effects on one or more elements of mental energy.Conclusion: Large, prospective clinical trials of these products using appropriate, validated instruments designed to measure mental energy may be worthwhile if sufficient evidence exists to justify such trials.

Fatigue, Sleep, and Autoimmune and Related Disorders

Profound and debilitating fatigue is the most common complaint reported among individuals with autoimmune disease, such as systemic lupus erythematosus, multiple sclerosis, type 1 diabetes, celiac disease, chronic fatigue syndrome, and rheumatoid arthritis. Fatigue is multi-faceted and broadly defined, which makes understanding the cause of its manifestations especially difficult in conditions with diverse pathology including autoimmune diseases. In general, fatigue is defined by debilitating periods of exhaustion that interfere with normal activities. The severity and duration of fatigue episodes vary, but fatigue can cause difficulty for even simple tasks like climbing stairs or crossing the room. The exact mechanisms of fatigue are not well-understood, perhaps due to its broad definition. Nevertheless, physiological processes known to play a role in fatigue include oxygen/nutrient supply, metabolism, mood, motivation, and sleepiness-all which are affected by inflammation. Additionally, an important contributing element to fatigue is the central nervous system-a region impacted either directly or indirectly in numerous autoimmune and related disorders. This review describes how inflammation and the central nervous system contribute to fatigue and suggests potential mechanisms involved in fatigue that are likely exhibited in autoimmune and related diseases.

Serum Histidine is Lower in Fatigued Women with Multiple Sclerosis

BACKGROUND

Disabling persistent perceived fatigue occurs in 50% of people with multiple sclerosis (MS), but mechanisms are poorly understood. Low histidine could contribute to fatigue since it is the neurotransmitter histamine precursor and low serum levels are reported in other diseases where fatigue is common (e.g., breast cancer, kidney disease, diabetes). Serum histidine is also inversely correlated with proinflammatory cytokines (e.g., TNF, IFN-y), which have been linked to MS fatigue.

PURPOSE

To determine if serum histidine is low in fatigued women with MS, and if histidine is related to differences in proinflammatory cytokines.

METHODS

Participants were classified as having elevated (n = 19) or normal (n = 18) perceived fatigue based on a median sample split using Profile of Mood States fatigue scale scores, with the elevated fatigue group having scores >7. Histidine and gene-expression of TNF, IFN-y, and leptin were assayed from a serum sample.

RESULTS

After adjustment for depression, serum histidine was significantly lower in women with MS with elevated fatigue, compared to normal fatigue (64.57 vs. 70.48 nmol/ml, p = .048, g = 0.75). There were no differences between groups in cytokine expression (all p > .24). Gene expression of TNF correlated with histidine only in people with normal fatigue (r = .51, p = .034), while no other cytokines related to histidine levels.

CONCLUSIONS

These results provide evidence that serum histidine is lower in fatigued women with MS, but the study did not find a relationship between histidine and TNF, IFN-y, or leptin gene expression.

"Workplace Physical Activity Program" (WOPAP) study protocol: a four-arm randomized controlled trial on preventing burnout and promoting vigor

Background

WOPAP is a theoretically-grounded workplace physical activity intervention that aims to reduce work-related burnout and to improve vigor at work and other work-related outcomes. Using a randomized controlled trial, we investigate whether a 10-week program including two Nordic walking sessions per week is effective in improving employee well-being at work, in comparison with another attractive leisure activity (Theatre condition) or a waiting list control condition. The design of the study makes it possible to test the effect on burnout and vigor of the instructor’s style during physical activity (i.e., traditional vs. need-supportive style). Finally, this study is also interested in several possible psychological (i.e., detachment, relaxation, mastery, control, relatedness, and positive affects experiences) and physiological (i.e., cardiorespiratory fitness) mechanisms through which the practice of physical activity in the intervention could influence burnout and vigor.

Methods

Employees of the authors’ University (N = 140) will be recruited via email, leaflets, and posters. Participants will be randomized to one of the four arms of the trial: (1) Physical Activity Traditional Style, (2) Physical Activity Need-Supportive Style, (3) Theatre condition, and (4) Waiting List Control. The experimental phase will last 10 weeks, followed by a six-month follow-up. During the ten weeks of the intervention, all groups – except the waiting list control – will carry out two activity sessions per week. Primary outcomes are burnout and vigor, secondary outcomes are work motivation, job satisfaction, work performance and work ability. These variables will be assessed before and after the intervention, and at three and six months after the end of the intervention. Moreover, burnout, vigor, needs satisfaction at work and psychological mediators will be assessed weekly throughout the intervention period.

Discussion

If effective, this study will provide evidence for the promotion of workplace physical activity interventions including a need-supportive climate to improve employee well-being. Results could be used to design new research protocols, but also to implement more efficient programs in the workplace.

Trial registration

ISRCTN12725337. Registered 21 March 2018. Registered retrospectively.

Nucleus accumbens neurochemistry in human anxiety: A 7 T 1H-MRS study

Individual differences in anxiety provide a differential predisposition to develop neuropsychiatric disorders. The neurochemical underpinnings of anxiety remain elusive, particularly in deep structures, such as the nucleus accumbens (NAc) whose involvement in anxiety is being increasingly recognized. We examined the associations between the neurochemical profile of human NAc metabolites involved in neural excitation and inhibition and inter-individual variation in temperamental and situational anxiety. Twenty-seven healthy 20-30 years-old human males were phenotyped with questionnaires for state and trait anxiety (State-Trait Anxiety Inventory, STAI), social anxiety (Liebowitz Social Anxiety Scale), negative mood (Beck Depression Inventory, BDI) and fatigue (Mental and Physical State Energy and Fatigue Scales, SEF). Using proton magnetic resonance spectroscopy (¹H-MRS) at 7 Tesla (7T), we measured metabolite levels for glutamate, glutamine, GABA and taurine in the NAc. Salivary cortisol was also measured. Strikingly, trait anxiety was negatively associated with NAc taurine content. Perceived situational stress was negatively associated with NAc GABA, while positively with the Glu/GABA ratio. No correlation was observed between NAc taurine or GABA and other phenotypic variables examined (i.e., state anxiety, social anxiety, negative mood, or cortisol), except for a negative correlation between taurine and state physical fatigue. This first 7T study of NAc neurochemistry shows relevant metabolite associations with individual variation in anxiety traits and situational stress and state anxiety measurements. The novel identified association between NAc taurine levels and trait anxiety may pave the way for clinical studies aimed at identifying new treatments for anxiety and related disorders.

A Pilot Exploratory Proteomics Investigation of Mental Fatigue and Mental Energy

Fatigue is a common and poorly understood problem that impacts approximately 45% of the United States (US) population. Fatigue has also been associated with fatigue-related driving accidents, school absences, decline in school performance and negative health outcomes. Fatigue has been linked to many diseases and is consistently underreported in medical care. Despite these high financial and societal costs, fatigue is a poorly understood problem and there is no consensus on how to measure fatigue. Proteomics is one of the most unbiased approach to measure differences in the protein levels from various biological fluids in two conditions, i.e. before and after mental exercise, aka fatigue. There are, however, challenges associated with such analyses: proteomics experiments are usually expensive and time consuming and also require a large number of participants. Here, we performed a proteomics experiment of three (pre- and post-fatigue) samples and also three matched controls (pre- and post-non-fatigue). We found no particular protein that has significant changes in fatigue sample upon treatment. We did note a potential association between changes in mental energy and Annexin A1. However, the study has value simply because it is an extra study in the field of fatigue, but also allows other to correlate our results with their results.

Cortical neural arousal is differentially affected by type of physical exercise performed

Critical flicker frequency (CFF) threshold is a visual discrimination task designed to assess cortical neural arousal, where higher values are associated with increased information processing and improved cognitive function. Previous studies using CFF assessments before and after exercise have only used one type of exercise (e.g., short, fatiguing, steady state, time to exhaustion, etc.). Therefore, the purpose of this study was to determine the effect of exercise type and intensity on neural arousal. 22 recreational runners (10 men, 12 women; age 25 ± 6 years) volunteered to participate in the study. They completed a VO_2max test (short, fatiguing trial), and three 30-min treadmill runs (longer, steady-state trials) at rating of perceived exertion (RPE) levels of 13, 15, and 17. Before and after each exercise test, subjects were asked to complete the CFF test; M_tot and M_di were calculated, which are the average and difference of the ascending/descending frequency trials, respectively. There were no main effects found for either intensity (p = 0.641) or time (p = 0.283); there was, however, a significant interaction found (intensity*time; p = 0.001). In the VO_2max test and in the longer, steady-state runs at RPE13 and 15, there was no change in M_tot. There was a significant increase in M_tot after the run at RPE17 (p = 0.019). For M_di, the VO_2max test elicited a significant decrease (p = 0.005), but there was no change after the steady-state runs. The results suggest that short, fatiguing and longer, steady-state exercise affect cortical neural arousal differently. Increases in arousal, and perhaps the related domain of information processing, are more likely to come from steady-state exercise at a vigorous intensity.

Perceived fatigue and energy are independent unipolar states: Supporting evidence

Persistent fatigue is a common problem (∼20-45% of U.S. population), with higher prevalence and severity in people with medical conditions such as cancer, depression, fibromyalgia, heart failure, sleep apnea and multiple sclerosis. There are few FDA-approved treatments for fatigue and great disagreement on how to measure fatigue, with over 250 instruments used in research. Many instruments define fatigue as "a lack of energy", thus viewing energy and fatigue states as opposites on a single bipolar continuum. In this paper, we hypothesize that energy and fatigue are distinct perceptual states, should be measured using separate unipolar scales, have different mechanisms, and deficits should be treated using tailored therapies. Energy and fatigue independence has been found in both exploratory and confirmatory factor analysis studies. Experiments in various fields, including behavioral pharmacology and exercise science, often find changes in energy and not fatigue, or vice versa. If the hypothesis that energy and fatigue are independent is correct, there are likely different mechanisms that drive energy and fatigue changes. Energy could be increased by elevated dopamine and norepinephrine transmission and binding. Fatigue could be increased by elevated brain serotonin and inflammatory cytokines and reduced histamine binding. The hypothesis could be tested by an experiment that attempts to produce simultaneously high ratings of energy and fatigue (such as with two drugs using a randomized, double-blind, placebo-controlled design), which would offer strong evidence against the common viewpoint of a bipolar continuum. If the hypothesis is correct, prior literature using bipolar instruments will be limited, and research on the prevalence, mechanisms, and treatment of low energy and elevated fatigue as separate conditions will be needed. In the immediate future, measuring both energy and fatigue using unipolar measurement tools may improve our understanding of these states and improve therapeutic outcomes.

Effect of Acute Exercise on Fatigue in People with ME/CFS/SEID: A Meta-analysis

PURPOSE

A prominent symptom of myalgic encephalomyelitis, chronic fatigue syndrome, or systemic exertion intolerance disease (ME/CFS/SEID) is persistent fatigue that is worsened by physical exertion. Here the population effect of a single bout of exercise on fatigue symptoms in people with ME/CFS/SEID was estimated and effect moderators were identified.

METHODS

Google Scholar was systematically searched for peer-reviewed articles published between February 1991 and May 2015. Studies were included where people diagnosed with ME/CFS/SEID and matched control participants completed a single bout of exercise and fatigue self-reports were obtained before and after exercise. Fatigue means, standard deviations, and sample sizes were extracted to calculate effect sizes and the 95% confidence interval. Effects were pooled using a random-effects model and corrected for small sample bias to generate mean Δ. Multilevel regression modeling adjusted for nesting of effects within studies. Moderators identified a priori were diagnostic criteria, fibromyalgia comorbidity, exercise factors (intensity, duration, and type), and measurement factors.

RESULTS

Seven studies examining 159 people with ME/CFS/SEID met inclusion criteria, and 47 fatigue effects were derived. The mean fatigue effect was Δ = 0.73 (95% confidence interval = 0.24-1.23). Fatigue increases were larger for people with ME/CFS/SEID when fatigue was measured 4 h or more after exercise ended rather than during or immediately after exercise ceased.

CONCLUSIONS

This preliminary evidence indicates that acute exercise increases fatigue in people with ME/CFS/SEID more than that in control groups, but effects were heterogeneous between studies. Future studies with no-exercise control groups of people with ME/CFS/SEID are needed to obtain a more precise estimate of the effect of exercise on fatigue in this population.

Stair walking is more energizing than low dose caffeine in sleep deprived young women

INTRODUCTION

The acute energizing effect of exercise and caffeine has never been examined in a single study of adults with chronic sleep deprivation but evidence from a study of this type could help individuals choose between these two common alertness-enhancing options.

AIM

The apriori primary aim of this experiment was to compare the influence of 10-min of low-to-moderate intensity stair walking to the consumption of capsules containing 50mg caffeine or flour (placebo) on feelings of energy in physically active, college female caffeine users with chronic insufficient sleep. Effects on secondary outcomes related to feelings of energy also were assessed.

MATERIAL-METHOD

A repeated measures crossover experiment was conducted with 18 college women (18-23years) who reported (i) daily caffeine consumption that was not extreme (40-400mg), (ii) typical leisure time physical activity that was not extreme (at least 2 weekly mild 15-min or longer bouts and no >5 strenuous 15-min or longer bouts), and (iii) sleeping <45h per week. Mood states (POMS-BF), focused on energy feelings (vigor), as well as working memory (N-back), sustained attention (CPT), simple reaction time (SRT), and motivation to complete the cognitive tasks were measured before and after a 10-min exercise condition (20min seated rest followed by 10min of low-to-moderate intensity stair walking) and compared to both a caffeine condition (50mg caffeine capsule followed by 30min of seated rest) and a similar flour (placebo) capsule condition. Condition (exercise, caffeine, placebo)×Time (Baseline, Post-1, Post-2, and for mood Post-3) ANCOVAs (controlling for Condition order) tested the hypothesized effects.

RESULTS

Condition×Time interactions showed that stair walking increased POMS-BF vigor at Post-1 compared to both placebo and caffeine. Other interactions were not significant.

CONCLUSION

A brief bout of low-to-moderate intensity stair walking has transient energizing effects that exceed a low dose of caffeine for active young women with chronic insufficient sleep.

Muscle strengthening exercises during pregnancy are associated with increased energy and reduced fatigue

INTRODUCTION

Physical inactivity likely contributes to fatigue and low energy during pregnancy but whether acute resistance exercise attenuates these symptoms is unknown.

METHODS

Twenty-six women performed six low-to-moderate intensity resistance exercises twice per week from weeks 23 to 35 of pregnancy and measurements were made before and after each workout using the Mental and Physical State Energy and Fatigue Scales.

RESULTS

Acute resistance exercise usually increased perceived physical and mental energy (92% to 96% of workouts, respectively). These increases did not differ significantly across the 24 exercise sessions for feelings of physical energy or mental energy, even after adjusting for variations in attendance (median = 22/24 workouts). Acute resistance exercise usually decreased perceived physical and mental fatigue (79% to 88% of workouts, respectively), and ANCOVA showed these decreases did not differ significantly across the 24 exercise sessions for feelings of physical fatigue or mental fatigue even after adjusting for variations in attendance.

DISCUSSION

The results suggest acute, low-to-moderate intensity muscle strengthening exercise during pregnancy is effective for transiently improving feelings of energy and fatigue.