Exercise and neuromodulators: choline and acetylcholine in marathon runners

Possible role of exercise therapy on depression: Effector neurotransmitters as key players

About 280 million people suffer from depression as the most common neurological disorder and the most common cause of death worldwide. Exercise with serotonin released in the brain by the 5-HT3-IGF-1 mechanism can lead to antidepressant effects. Swimming exercise has antidepressant effects by increasing the sensitivity of serotonin 5-HT2 receptors and postsynaptic 5-HT1A receptors, increasing 5-HT and 5HIAA levels, increasing TPH and serotonin, and decreasing inflammatory levels of IFN-γ and TNF-α. Anaerobic and aerobic exercises increase beta-endorphin, enkephalin, and dynorphin and have antidepressant effects. Exercise by increasing dopamine, D1R, and D2R leads to the expression of BDNF and activation of TrkB and has antidepressant behavior. Exercise leads to a significant increase in GABAAR (γ2 and α2 subunits) and reduces neurodegenerative disorders caused by GABA imbalance through anti-inflammatory pathways. By increasing glutamate and PGC1α and reducing glutamatergic neurotoxicity, exercise enhances neurogenesis and synaptogenesis and prevents neurodegeneration and the onset of depression. Irisin release during exercise shows an important role in depression by increasing dopamine, BDNF, NGF, and IGF-1 and decreasing inflammatory mediators such as IL-6 and IL-1β. In addition, exercise-induced orexin and NPY can increase hippocampal neurogenesis and relieve depression. After exercise, the tryptophan to large neutral amino acids (TRP/LNAA) ratio and the tryptophan to branched-chain amino acids (BCAA) ratio increase, which may have antidepressant effects. The expression of M5 receptor and nAChR α7 increases after exercise and significantly increases dopamine and acetylcholine and ameliorates depression. It appears that during exercise, muscarinic receptors can reduce depression through dopamine in the absence of acetylcholine. Therefore, exercise can be used to reduce depression by affecting neurotransmitters, neuromodulators, cytokines, and/or neurotrophins.

Krill-Oil-Dependent Increases in HS-Omega-3 Index, Plasma Choline and Antioxidant Capacity in Well-Conditioned Power Training Athletes

There is evidence that both omega-3 polyunsaturated fatty acids (n-3 PUFAs) and choline can influence sports performance, but information establishing their combined effects when given in the form of krill oil during power training protocols is missing. The purpose of this study was therefore to characterize n-3 PUFA and choline profiles after a one-hour period of high-intensity physical workout after 12 weeks of supplementation. Thirty-five healthy power training athletes received either 2.5 g/day of Neptune krill oil^TM (550 mg EPA/DHA and 150 mg choline) or olive oil (placebo) in a randomized double-blind design. After 12 weeks, only the krill oil group showed a significant HS-Omega-3 Index increase from 4.82 to 6.77% and a reduction in the ARA/EPA ratio (from 50.72 to 13.61%) (p < 0.001). The krill oil group showed significantly higher recovery of choline concentrations relative to the placebo group from the end of the first to the beginning of the second exercise test (p = 0.04) and an 8% decrease in total antioxidant capacity post-exercise versus 21% in the placebo group (p = 0.35). In conclusion, krill oil can be used as a nutritional strategy for increasing the HS-Omega-3 Index, recover choline concentrations and address oxidative stress after intense power trainings.

Metabolomic signatures in elite cyclists: differential characterization of a seeming normal endocrine status regarding three serum hormones

INTRODUCTION

Serum phenotyping of elite cyclists regarding cortisol, IGF1 and testosterone is a way to detect endocrine disruptions possibly explained by exercise overload, non-balanced diet or by doping. This latter disruption-driven approach is supported by fundamental physiology although without any evidence of any metabolic markers.

OBJECTIVES

Serum samples were distributed through Low, High or Normal endocrine classes according to hormone concentration. A ¹H NMR metabolomic study of 655 serum obtained in the context of the longitudinal medical follow-up of 253 subjects was performed to discriminate the three classes for every endocrine phenotype.

METHODS

An original processing algorithm was built which combined a partial-least squares-based orthogonal correction of metabolomic signals and a shrinkage discriminant analysis (SDA) to get satisfying classifications. An extended validation procedure was used to plan in larger size cohorts a minimal size to get a global prediction rate (GPR), i.e. the product of the three class prediction rates, higher than 99.9%.

RESULTS

Considering the 200 most SDA-informative variables, a sigmoidal fitting of the GPR gave estimates of a minimal sample size to 929, 2346 and 1408 for cortisol, IGF1 and testosterone, respectively. Analysis of outliers from cortisol and testosterone Normal classes outside the 97.5%-confidence limit of score prediction revealed possibly (i) an inadequate protein intake for outliers or (ii) an intake of dietary ergogenics, glycine or glutamine, which might explain the significant presence of heterogeneous metabolic profiles in a supposedly normal cyclists subgroup.

CONCLUSION

In a next validation metabolomics study of a so-sized cohort, anthropological, clinical and dietary metadata should be recorded in priority at the blood collection time to confirm these functional hypotheses.

Effects of Krill Oil and Race Distance on Serum Choline and Choline Metabolites in Triathletes: A Field Study

Choline is an essential nutrient that has been implicated in athletic performance due to its role in maintaining normal muscle function. The concentration of free choline in serum may decrease during long-distance high-intensity exercise, yet few nutritional strategies to counteract this potentially performance-depleting loss in choline have been investigated outside the laboratory. This exploratory field study was performed to investigate if pre-race supplementation with phosphatidylcholine from krill oil can counteract the expected drop in choline and some of its metabolites during triathlon competitions. Forty-seven triathletes, 12 females and 35 males ranging in age from 25 to 61 years, were recruited from participants in the Ironman-distance Norseman Xtreme triathlon and the Sprint/Olympic-distance Oslo Triathlon. Twenty-four athletes were randomly allocated to the krill oil group, receiving 4 g of SuperbaBoost™ krill oil daily for 5 weeks prior to the race, and 23 athletes were randomly allocated to the placebo group, receiving 4 g of mixed vegetable oil daily. Blood samples were obtained before the race, immediately after completion of the race, and the day after the race for analysis of choline and its metabolites. The results showed that serum choline concentrations significantly decreased from pre-race to race finish in all races, with a more pronounced decrease observed in the Ironman-distance Norseman Xtreme triathlon (34% decrease) relative to the Sprint/Olympic-distance Oslo Triathlon (15% decrease). A reduction in betaine was also observed, while dimethylglycine (DMG) concentrations remained stable across all time points. Significantly higher concentrations of choline (9.4% on average) and DMG (21.4% on average) were observed in the krill oil compared to the placebo group, and the krill oil group showed a significantly greater increase in serum choline following race completion. In conclusion, krill oil may help to prevent that circulating choline concentrations become limiting during endurance competitions.

LC-QTOF-MS and 1H NMR Metabolomics Verifies Potential Use of Greater Omentum for Klebsiella pneumoniae Biofilm Eradication in Rats

Bacterial wound infections are a common problem associated with surgical interventions. In particular, biofilm-forming bacteria are hard to eradicate, and alternative methods of treatment based on covering wounds with vascularized flaps of tissue are being developed. The greater omentum is a complex organ covering the intestines in the abdomen, which support wound recovery following surgical procedures and exhibit natural antimicrobial activity that could improve biofilm eradication. We investigated changes in rats’ metabolome following Klebsiella pneumoniae infections, as well as the greater omentum’s ability for Klebsiella pneumoniae biofilm eradication. Rats received either sterile implants or implants covered with Klebsiella pneumoniae biofilm (placed in the peritoneum or greater omentum). Metabolic profiles were monitored at days 0, 2, and 5 after surgery using combined proton nuclear magnetic resonance (¹H NMR) and high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC–QTOF-MS) measurements of urine samples followed by chemometric analysis. Obtained results indicated that grafting of the sterile implant to the greater omentum did not cause major disturbances in rats’ metabolism, whereas the sterile implant located in the peritoneum triggered metabolic perturbations related to tricarboxylic acid (TCA) cycle, as well as choline, tryptophan, and hippurate metabolism. Presence of implants colonized with Klebsiella pneumoniae biofilm resulted in similar levels of metabolic perturbations in both locations. Our findings confirmed that surgical procedures utilizing the greater omentum may have a practical use in wound healing and tissue regeneration in the future.

Ultramarathon Plasma Metabolomics: Phosphatidylcholine Levels Associated with Running Performance

The purpose of this study was to identify plasma metabolites associated with superior endurance running performance. In 2016, participants at the Western States Endurance Run (WSER), a 100-mile (161-km) foot race, underwent non-targeted metabolomic testing of their post-race plasma. Metabolites associated with faster finish times were identified. Based on these results, runners at the 2017 WSER underwent targeted metabolomics testing, including lipidomics and choline levels. The 2017 participants’ plasma metabolites were correlated with finish times and compared with non-athletic controls. In 2016, 427 known molecules were detected using non-targeted metabolomics. Four compounds, all phosphatidylcholines (PCs) were associated with finish time (False Discovery Rate (FDR) < 0.05). All were higher in faster finishers. In 2017, using targeted PC analysis, multiple PCs, measured pre- and post-race, were higher in faster finishers (FDR < 0.05). The majority of PCs was noted to be higher in runners (both pre- and post-race) than in controls (FDR < 0.05). Runners had higher choline levels pre-race compared to controls (p < 0.0001), but choline level did not differ significantly from controls post-race (p = 0.129). Choline levels decreased between the start and the finish of the race (p < 0.0001). Faster finishers had lower choline levels than slower finishers at the race finish (p = 0.028).

Phosphatidylcholine from krill increases plasma choline and its metabolites in dogs

Background and Aim:

Choline and its metabolites have multiple physiological roles in the body, which are important for muscle function, memory, methylation reactions, and hepatic lipid transport. This study aimed to investigate, if inclusion of phosphatidylcholine (PC) from Antarctic krill (Euphausia superba) can increase the concentration of choline and its metabolites in plasma of sled dogs in comparison to a control group.

Materials and Methods:

Ten adult Alaskan Huskies of both genders were supplemented with PC from 8% dietary krill meal inclusion for 6 weeks, while another ten dogs received no krill meal supplementation. Blood measurements of the two groups were taken at baseline and end of the study and compared for choline and its metabolite concentrations.

Results:

The choline concentration of the krill meal-supplemented dogs was significantly higher after 6 weeks of krill meal feeding compared to the control group (mean increase = 4.53 µmol/L in the supplemented versus 1.21 µmol/L in the control group, p=0.014). Furthermore, krill meal-supplemented dogs showed significantly more pronounced increases in betaine (p<0.001), dimethylglycine (p<0.01), trimethylamine-N-oxide (p<0.001), and trimethyllysine (p<0.001) compared to the control group. Significant correlations between changes in choline and changes in its metabolites were observed.

Conclusion:

The results showed that krill meal supplementation was associated with significantly higher plasma choline concentrations, which correlated with changed concentrations of choline metabolites.

Sport Nutrigenomics: Personalized Nutrition for Athletic Performance

An individual's dietary and supplement strategies can influence markedly their physical performance. Personalized nutrition in athletic populations aims to optimize health, body composition, and exercise performance by targeting dietary recommendations to an individual's genetic profile. Sport dietitians and nutritionists have long been adept at placing additional scrutiny on the one-size-fits-all general population dietary guidelines to accommodate various sporting populations. However, generic "one-size-fits-all" recommendations still remain. Genetic differences are known to impact absorption, metabolism, uptake, utilization and excretion of nutrients and food bioactives, which ultimately affects a number of metabolic pathways. Nutrigenomics and nutrigenetics are experimental approaches that use genomic information and genetic testing technologies to examine the role of individual genetic differences in modifying an athlete's response to nutrients and other food components. Although there have been few randomized, controlled trials examining the effects of genetic variation on performance in response to an ergogenic aid, there is a growing foundation of research linking gene-diet interactions on biomarkers of nutritional status, which impact exercise and sport performance. This foundation forms the basis from which the field of sport nutrigenomics continues to develop. We review the science of genetic modifiers of various dietary factors that impact an athlete's nutritional status, body composition and, ultimately athletic performance.

Early metabolic response after resistance exercise with blood flow restriction in well-trained men: a metabolomics approach

The present study aimed to compare the early metabolic response between high-load resistance exercise (HL-RE) and low-load resistance exercise with blood flow restriction (LL-BFR). Nine young, well-trained men participated in a randomized crossover design in which each subject completed LL-BFR, HL-RE, or condition control (no exercise) with a 1-week interval between them. Blood samples were taken immediately before and 5 min after the exercise sessions. Nuclear magnetic resonance spectroscopy identified and quantified 48 metabolites, 6 of which presented significant changes among the exercise protocols. The HL-RE promoted a higher increase in pyruvate, lactate, and alanine compared with the LL-BFR and the control. HL-RE and LL-BFR promoted a higher increase in succinate compared with the control; however, there was no difference between HL-RE and LL-BFR. Also, while there was no difference in acetoacetate between HL-RE and LL-BFR, a greater decrease was observed in both compared with the control. Finally, LL-BFR promoted a greater decrease in choline compared with the control. In conclusion, this study provides by metabolomics a new insight in metabolic response between LL-BFR and HL-RE by demonstrating a distinct response to some metabolites that are not commonly analyzed.

Evaluation of the effects of two doses of alpha glycerylphosphorylcholine on physical and psychomotor performance

Background

Recent studies have suggested that alpha glycerylphosphorylcholine (A-GPC) may be an effective ergogenic aid. The present study was designed to assess the efficacy of two doses of A-GPC in comparison to placebo and caffeine for increasing countermovement jump performance, isometric strength, and psychomotor function.

Methods

Forty-eight healthy, college aged males volunteered for the present study and underwent baseline assessment of countermovement jump (CMJ), isometric mid thigh pull (IMTP), upper body isometric strength test (UBIST), and psychomotor vigilance (PVT). Following this assessment participants were randomly assigned to groups consisting of 500 mg A-GPC, 250 mg A-GPC, 200 mg Caffeine or Placebo taken daily. Blood samples were collected 1 h and 2 h post initial dose to quantify serum free choline and thyroid stimulating hormone then subjects returned after 7 days of supplementation to repeat CMJ, IMTP, UBIST and PVT.

Results

No differences were noted between groups for IMTP, UBIST or PVT performance. Serum free choline was found to be elevated in the two A-GPC groups as compared to placebo (132% and 59% respectively). Serum TSH was found to be significantly depressed in the 500 mg A-GPC group compared to other treatments (p < 0.04). Group differences were noted for maximum velocity and maximum mechanical power on the CMJ (p < 0.05) with the 250 mg A-GPC group demonstrating the greatest improvements in result.

Conclusions

Based upon this evidence, and previous evidence regarding A-GPC, it should be considered as an emerging ergogenic supplement.

The Effects of Acute Exercise on Mood, Cognition, Neurophysiology, and Neurochemical Pathways: A Review

A significant body of work has investigated the effects of acute exercise, defined as a single bout of physical activity, on mood and cognitive functions in humans. Several excellent recent reviews have summarized these findings; however, the neurobiological basis of these results has received less attention. In this review, we will first briefly summarize the cognitive and behavioral changes that occur with acute exercise in humans. We will then review the results from both human and animal model studies documenting the wide range of neurophysiological and neurochemical alterations that occur after a single bout of exercise. Finally, we will discuss the strengths, weaknesses, and missing elements in the current literature, as well as offer an acute exercise standardization protocol and provide possible goals for future research.

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

The purpose of this research was to determine if histamine, acting on brain H1 receptors, influences changes in feelings of energy and fatigue or cognitive test performance after acute exercise. Women (n=20) with low vigor and high fatigue were administered the H1 antagonist drug doxepin hydrocholoride (6 mg) in tomato juice and tomato juice alone (placebo) in a randomized, double-blinded, cross-over experiment before performing 30 min of light intensity cycling exercise and completing energy, fatigue, sleepiness, and motivation scales, and cognitive tasks. After exercise, mental fatigue increased for the doxepin condition (p=0.014) but not placebo (p=0.700), while mental energy decreased for both PLA and DOX (p<0.001) and cognitive task performance was unaffected. It is inferred that histamine binding to H1 receptors in the brain has a role in exercise-induced reductions in mental fatigue, but not increases in energy.

Neuromuscular fatigue in healthy muscle: underlying factors and adaptation mechanisms

OBJECTIVES

This review aims to define the concept of neuromuscular fatigue and to present the current knowledge of the central and peripheral factors at the origin of this phenomenon. This review also addresses the literature that focuses on the mechanisms responsible for the adaption to neuromuscular fatigue.

METHOD

One hundred and eighty-two articles indexed in PubMed (1954-2010) have been considered.

RESULTS

Neuromuscular fatigue has central and peripheral origins. Central fatigue, preponderant during long-duration, low-intensity exercises, may involve a drop in the central command (motor, cortex, motoneurons) elicited by the activity of cerebral neurotransmitters and muscular afferent fibers. Peripheral fatigue, associated with an impairment of the mechanisms from excitation to muscle contraction, may be induced by a perturbation of the calcium ion movements, an accumulation of phosphate, and/or a decrease of the adenosine triphosphate stores. To compensate for the consequent drop in force production, the organism develops several adaptation mechanisms notably implicating motor units.

CONCLUSION

Fatigue onset is associated with an alteration of the mechanisms involved in force production. Then, the interaction between central and peripheral mechanisms leads to a series of events that ultimately contribute to the observed decrease in force production.

The effects of acute and prolonged CRAM supplementation on reaction time and subjective measures of focus and alertness in healthy college students

Background

The purpose of this study was to examine the effect of acute and prolonged (4-weeks) ingestion of a supplement designed to improve reaction time and subjective measures of alertness, energy, fatigue, and focus compared to placebo.

Methods

Nineteen physically-active subjects (17 men and 2 women) were randomly assigned to a group that either consumed a supplement (21.1 ± 0.6 years; body mass: 80.6 ± 9.4 kg) or placebo (21.3 ± 0.8 years; body mass: 83.4 ± 18.5 kg). During the initial testing session (T1), subjects were provided 1.5 g of the supplement (CRAM; α-glycerophosphocholine, choline bitartrate, phosphatidylserine, vitamins B3, B6, and B12, folic acid, L-tyrosine, anhydrous caffeine, acetyl-L-carnitine, and naringin) or a placebo (PL), and rested quietly for 10-minutes before completing a questionnaire on subjective feelings of energy, fatigue, alertness and focus (PRE). Subjects then performed a 4-minute quickness and reaction test followed by a 10-min bout of exhaustive exercise. The questionnaire and reaction testing sequence was then repeated (POST). Subjects reported back to the lab (T2) following 4-weeks of supplementation and repeated the testing sequence.

Results

Reaction time significantly declined (p = 0.050) between PRE and POST at T1 in subjects consuming PL, while subjects under CRAM supplementation were able to maintain (p = 0.114) their performance. Significant performance declines were seen in both groups from PRE to POST at T2. Elevations in fatigue were seen for CRAM at both T1 and T2 (p = 0.001 and p = 0.000, respectively), but only at T2 for PL (p = 0.029). Subjects in CRAM maintained focus between PRE and POST during both T1 and T2 trials (p = 0.152 and p = 0.082, respectively), whereas significant declines in focus were observed between PRE and POST in PL at both trials (p = 0.037 and p = 0.014, respectively). No difference in alertness was seen at T1 between PRE and POST for CRAM (p = 0.083), but a significant decline was recorded at T2 (p = 0.005). Alertness was significantly lower at POST at both T1 and T2 for PL (p = 0.040 and p = 0.33, respectively). No differences in any of these subjective measures were seen between the groups at any time point.

Conclusion

Results indicate that acute ingestion of CRAM can maintain reaction time, and subjective feelings of focus and alertness to both visual and auditory stimuli in healthy college students following exhaustive exercise. However, some habituation may occur following 4-weeks of supplementation.

Limitation of physical performance in a muscle fatiguing handgrip exercise is mediated by thalamo-insular activity

In this study, we investigated central/supraspinal processes mediating cessation of a muscle fatiguing exercise. Fifteen male subjects performed 39 intermittent, isometric handgrip contractions (13 s on, 5-6 s off) with the dominant right hand while brain activation was assessed by means of functional magnetic resonance imaging (fMRI). An adaptive, partly stochastic protocol was designed such that in approximately 50% of the contraction trials the required force could not be held until the end of the trial (task failure trial). Trials performed in compliance with the force requirements (succeeded trial) were compared with task failure trials concerning neural activity during a small time window before task failure occurred. The data revealed significantly increased activation contralaterally in both the mid/anterior insular cortex and the thalamus during the investigated time window in the case of subsequent task failure. In accordance with other studies investigating sensations that alert the organism to urgent homeostatic imbalance such as air hunger, hunger for food, and pain, we assume that an increased thalamo-insular activation in the context of a fatigue-induced handgrip exercise could reflect increased homeostatic disturbance in the exercising muscle and may be of essential importance by mediating task failure to maintain the integrity of the organism.

A history of medical reports on the Boston Marathon: 112 years and still running

INTRODUCTION/METHODS

We performed a systematic search for medical reports on the Boston Marathon, run annually since April 19, 1897 and studied medically since 1899.

RESULTS

We identified 66 articles: 25 were related to cardiology; 10, exercise physiology; 8, metabolism; 5, neurology; 4, gastroenterology; 3, hematology; 3, several disciplines; and 8, nephrology, orthopedics, and general topics. The predominance of cardiology articles reflects concerns about the cardiac risks of exercise present in the early 20th century and persistent to this day. The authors and contributors included luminaries from the medical and exercise community including Drs. Paul Dudley White, Samuel Levine, Kenneth Cooper, Paul Zoll, Ellsworth Buskirk, and David Costill. The articles identified or confirmed many of the presently accepted principles of marathon medicine.

CONCLUSIONS

Medical studies on the Boston Marathon not only provide lessons applicable to managing modern athletes but also demonstrate the interests and concerns of researchers who have used the event to study the physiology of prolonged exercise for more than a century.

Phospholipids and sports performance

Phospholipids are essential components of all biological membranes. Phosphatidylcholine (PC) and Phosphatidylserine (PS) are Phosphatidyl-phospholipids that are required for normal cellular structure and function. The participation in physical activity often challenges a variety of physiological systems; consequently, the ability to maintain normal cellular function during activity can determine sporting performance. The participation in prolonged intense exercise has been shown to reduce circulatory choline concentrations in some individuals. As choline is a pre-cursor to the neurotransmitter Acetylcholine, this finding has encouraged researchers to investigate the hypothesis that supplementation with PC (or choline salts) could enhance sporting performance. Although the available data that evaluates the effects of PC supplementation on performance are equivocal, acute oral supplementation with PC (~0.2 g PC per kg body mass) has been demonstrated to improve performance in a variety of sporting activities where exercise has depleted circulatory choline concentrations. Short term oral supplementation with soy-derived PS (S-PS) has been reported to attenuate circulating cortisol concentrations, improve perceived well-being, and reduce perceived muscle soreness after exercise. More recently, short term oral supplementation (750 mg per day of S-PS for 10 days) has been demonstrated to improve exercise capacity during high intensity cycling and tended to increase performance during intermittent running. Although more research is warranted to determine minimum dietary Phospholipid requirements for optimal sporting performance, these findings suggest that some participants might benefit from dietary interventions that increase the intakes of PC and PS.

Central fatigue: the serotonin hypothesis and beyond

The original central fatigue hypothesis suggested that an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its well known effects on sleep, lethargy and drowsiness and loss of motivation. Several nutritional and pharmacological studies have attempted to manipulate central serotonergic activity during exercise, but this work has yet to provide robust evidence for a significant role of serotonin in the fatigue process. However, it is important to note that brain function is not determined by a single neurotransmitter system and the interaction between brain serotonin and dopamine during prolonged exercise has also been explored as having a regulative role in the development of fatigue. This revised central fatigue hypothesis suggests that an increase in central ratio of serotonin to dopamine is associated with feelings of tiredness and lethargy, accelerating the onset of fatigue, whereas a low ratio favours improved performance through the maintenance of motivation and arousal. Convincing evidence for a role of dopamine in the development of fatigue comes from work investigating the physiological responses to amphetamine use, but other strategies to manipulate central catecholamines have yet to influence exercise capacity during exercise in temperate conditions. Recent findings have, however, provided support for a significant role of dopamine and noradrenaline (norepinephrine) in performance during exercise in the heat. As serotonergic and catecholaminergic projections innervate areas of the hypothalamus, the thermoregulatory centre, a change in the activity of these neurons may be expected to contribute to the control of body temperature whilst at rest and during exercise. Fatigue during prolonged exercise clearly is influenced by a complex interaction between peripheral and central factors.

The brain and fatigue: new opportunities for nutritional interventions?

It is clear that the cause of fatigue is complex, influenced by events occurring in both the periphery and the central nervous system. Work conducted over the last 20 years has focused on the role of brain serotonin and catecholamines in the development of fatigue, and the possibility that manipulation of neurotransmitter precursors may delay the onset of fatigue. While there is some evidence that branched-chain amino acid and tyrosine ingestion can influence perceived exertion and some measures of mental performance, the results of several apparently well-controlled laboratory studies have not demonstrated a positive effect on exercise capacity or performance under temperate conditions. As football is highly reliant upon the successful execution of motor skills and tactics, the possibility that amino acid ingestion may help to attenuate a loss in cognitive function during the later stages of a game would be desirable, even in the absence of no apparent benefit to physical performance. There are several reports of enhanced performance of high-intensity intermittent exercise with carbohydrate ingestion, but at present it is difficult to separate the peripheral effects from any potential impact on the central nervous system. The possibility that changes in central neurotransmission play a role in the aetiology of fatigue when exercise is performed in high ambient temperatures has recently been examined, although the significance of this in relation to the pattern of activity associated with football has yet to be determined.

Relação da síndrome do excesso de treinamento com estresse, fadiga e serotonina

A grande exigência do esporte competitivo tem provocado sérias conseqüências em atletas envolvidos em treinamento de alto nível. Por sua vez, a mudança dos padrões estéticos tem levado indivíduos a buscarem, por meio do exercício físico, a redução da massa corporal, o aumento da massa muscular e do condicionamento aeróbio. É comum atletas e não atletas excederem os limites de suas capacidades físicas e psicológicas ocasionando o desenvolvimento da síndrome do excesso de treinamento (overtraining), a qual é definida como um distúrbio neuroendócrino (hipotálamo-hipofisário) que resulta do desequilíbrio entre a demanda do exercício e a possibilidade de assimilação de treinamento, acarretando alterações metabólicas, com conseqüências que abrangem não apenas o desempenho, mas também outros aspectos fisiológicos e emocionais. Altos índices de estresse físico, sócio-cultural e psíquico são fatores que colaboram com o seu aparecimento, bem como alterações neuroendócrinas provocadas por aspectos nutricionais, que levam a flutuações serotoninérgicas. Alterações nos níveis de serotonina cerebral podem ser associadas ao aparecimento do estado de fadiga física, que pode se estabelecer de forma crônica, constituindo-se um dos sintomas do quadro. Deficiências ou desequilíbrios em neurotransmissores e neuromoduladores também podem ser causados por severo ou longo estresse. O objetivo do presente artigo de revisão é fazer uma análise dos fatores que contribuem de forma sinérgica para o aparecimento da síndrome do excesso de treinamento.

Evidence for complex system integration and dynamic neural regulation of skeletal muscle recruitment during exercise in humans

A model is proposed in which the development of physical exhaustion is a relative rather than an absolute event and the sensation of fatigue is the sensory representation of the underlying neural integrative processes. Furthermore, activity is controlled as part of a pacing strategy involving active neural calculations in a "governor" region of the brain, which integrates internal sensory signals and information from the environment to produce a homoeostatically acceptable exercise intensity. The end point of the exercise bout is the controlling variable. This is an example of a complex, non-linear, dynamic system in which physiological systems interact to regulate activity before, during, and after the exercise bout.

Exercise and Its Effects on the Central Nervous System

Exercise can have profound effects on numerous biologic systems within the human body, including the central nervous system (CNS). The inherent complexity of the CNS, and the methodologic difficulties in evaluating its in vivo neurochemistry in humans, provide challenges to investigators studying the impact of exercise on the CNS. As a result, our knowledge in this area of exercise science remains relatively limited. However, advances in research technology are allowing investigators to gain valuable insight into the neurobiologic mechanisms that contribute to the bidirectional communication that occurs between the periphery and the CNS during exercise. This article examines how exercise-induced alterations in the CNS contribute to central fatigue and the overtraining syndrome, and how exercise can influence psychologic wellbeing and cognitive function.

Nuclear Magnetic Resonance Analysis of Indomethacin-Induced Gastric Ulcers

Acetonitrile extracts of ulcerated and control rat stomachs were studied by various NMR techniques in an attempt to understand how indomethacin, a common and powerful nonsteroidal antiinflammatory drug (NSAID), induces ulcers in the stomach. One- (1D) and two-dimensional (2D) NMR spectra of extracts of ulcerated and control stomachs revealed that glycolytic and Krebs cycle enzymes were partially inhibited in the ulcerated stomach as shown by the lactate/glucose ratio. The (total choline)/lactate ratio was also higher in the extract from the control stomach than in the ulcerated stomach. Glycerophosphoethanolamine and glycerophosphocholine concentrations were higher in the ulcerated stomach extract as compared with the control stomach extract. These results explain the gastrointestinal protective effect of D-glucose and Krebs cycle intermediates on NSAID-induced ulceration.

Cerebral perturbations provoked by prolonged exercise

This review addresses cerebral metabolic and neurohumoral alterations during prolonged exercise in humans with special focus on associations with fatigue. Global energy turnover in the brain is unaltered by the transition from rest to moderately intense exercise, apparently because exercise-induced activation of some brain regions including cortical motor areas is compensated for by reduced activity in other regions of the brain. However, strenuous exercise is associated with cerebral metabolic and neurohumoral alterations that may relate to central fatigue. Fatigue should be acknowledged as a complex phenomenon influenced by both peripheral and central factors. However, failure to drive the motorneurons adequately as a consequence of neurophysiological alterations seems to play a dominant role under some circumstances. During exercise with hyperthermia excessive accumulation of heat in the brain due to impeded heat removal by the cerebral circulation may elevate the brain temperature to >40 degrees C and impair the ability to sustain maximal motor activation. Also, when prolonged exercise results in hypoglycaemia, perceived exertion increases at the same time as the cerebral glucose uptake becomes low, and centrally mediated fatigue appears to arise as the cerebral energy turnover becomes restricted by the availability of substrates for the brain. Changes in serotonergic activity, inhibitory feed-back from the exercising muscles, elevated ammonia levels, and alterations in regional dopaminergic activity may also contribute to the impaired voluntary activation of the motorneurons after prolonged and strenuous exercise. Furthermore, central fatigue may involve depletion of cerebral glycogen stores, as signified by the observation that following exhaustive exercise the cerebral glucose uptake increases out of proportion to that of oxygen. In summary, prolonged exercise may induce homeostatic disturbances within the central nervous system (CNS) that subsequently attenuates motor activation. Therefore, strenuous exercise is a challenge not only to the cardiorespiratory and locomotive systems but also to the brain.

Homocysteine increases during endurance exercise

Hyperhomocysteinemia is a risk factor for cardiovascular and other diseases. Recently many endogenous and exogenous modulators of homocysteine (Hcy) have become known, e.g., B-vitamins. However, little is known about the effect of exercise on Hcy. The purpose of this study was to investigate the effect of three different types of acute endurance exercise on serum Hcy. We measured Hcy in 100 recreational athletes (87 males, 13 females) who participated in a marathon race (n = 46), a 100 km run (100 km; n = 12) or a 120 km mountain bike race (n = 42). Blood samples were taken before, 15 min and 3 h after the race. In athletes with pre-race Hcy > 12 micromol/l we also determined folate and vitamin B12. Marathon running induced a Hcy increase of 64%, while mountain biking and 100 km running had no significant effect on Hcy. Pre-race Hcy (25th-75th percentile) overall; marathon race; 100 km; mountain bike race was 9.7 (7.1-11.5) micromol/l; 9.8 (7.4-11.1) micromol/l; 10.2 (6.6-13.2) micromol/l; 9.1 (6.9-13.5) micromol/l, respectively. At 15 min and 3 h post-race, Hcy was 11.9 (8.4-16.4) micromol/l; 16.1 (12.7-20.4) micromol/l; 9.5 (7.8-15.9) micromol/l; 8.8 (7.1-11.2) micromol/l, respectively, and 11.5 (8.9-15.7) micromol/l; 14.9 (11.5-20.0) micromol/l; 10.0 (8.1-11.8) micromol/l; 9.4 (7.4-12.1) micromol/l, respectively. The change in Hcy correlated negatively with the running time. Twenty-three athletes had pre-race Hcy levels > 12 micromol/l, which were associated with relatively low folate (14.3 (11.6-18.9) nmol/l) and vitamin B12 levels (231 (183-261) pmol/l). Endurance exercise may induce a considerable Hcy increase, which varies between different disciplines and is most probably determined by the duration and intensity of exercise. Furthermore, about 25% of recreational endurance athletes exhibited hyperhomocysteinemia in association with low vitamin B12 and folate levels.

The effect of lecithin supplementation on plasma choline concentrations during a marathon

BACKGROUND

Previous studies have shown that plasma and urinary free choline concentrations decrease significantly during a marathon, and that these decreases may be associated with decreased performance.

OBJECTIVE

In a pilot study, we sought to determine whether lecithin supplementation prior to a marathon would maintain plasma free and urinary choline concentrations and improve performance versus placebo.

METHODS

12 accomplished marathon runners, males (7) and females (5), 21 to 50 years of age were randomized to receive lecithin (4 capsules BID; PhosChol 900) or placebo beginning one day prior to the 2000 Houston-Methodist Health Care Marathon. The lecithin supplement provided approximately 1.1 g of choline on a daily basis (2.2 g total). Runners estimated finish time based on recent performance and training. Fasting, pre- and post-marathon plasma and a five-hour urine collection were analyzed for free choline and plasma for phospholipid-bound choline. Pre-race predicted, as well as the actual finish time, were recorded.

RESULTS

All subjects completed the marathon. Plasma free choline decreased significantly in the placebo group and increased significantly in the lecithin group (9.6 +/- 3.6 to 7.0 +/- 3.6 nmol/mL vs. 8.0 +/- 1.2 to 11.7 +/- 3.6 nmol/mL, p = 0.001 for the delta between groups). No significant changes in plasma phospholipid-bound choline concentration were observed. There was a non-significant decrease in urine free choline in both groups. Actual finish time was 256.3 +/- 46.3 minutes for the lecithin group vs. 240.8 +/- 62.0 for the placebo group and the actual:predicted time was 1.03 +/- 0.06 (lecithin) and 1.07 +/- 0.08 (placebo), p = 0.36.

CONCLUSION

Short-term lecithin supplementation prior to a marathon maintains normal plasma free choline concentration during the race, but failed to improve performance.

Caffeine, carnitine and choline supplementation of rats decreases body fat and serum leptin concentration as does exercise

The effect of a combination of caffeine, carnitine and choline with or without exercise on changes in body weight, fat pad mass, serum leptin concentration and metabolic indices was determined in 20 male, 7-wk-old Sprague-Dawley rats. They were given free access to a nonpurified diet without or with caffeine, carnitine and choline at concentrations of 0.1, 5 and 11.5 g/kg diet, respectively. In a 2x2 factorial design, one-half of each dietary group was exercised, and the other half was sedentary. Body weight and food intake of all rats were measured every day for 28 d. Rats were killed and blood and tissue samples were collected and analyzed for biochemical markers. Food intake of the groups was not different, but the body weight was significantly reduced by exercise in both dietary groups. Fat pad weights and total lipids of epididymal, inguinal and perirenal regions were significantly reduced by the supplements as well as by exercise. Regardless of exercise, supplements significantly lowered triglycerides in serum but increased levels in skeletal muscle. Serum leptin concentrations were equally lowered by supplements and exercise. Serum leptin was correlated with body weight (r = 0.55, P< or =0.01), fat pad weight (r = 0.82, P< or =0.001) and serum glucose (r = 0.51, P< or =0.05). We conclude that the indices of body fat loss due to dietary supplements were similar to those due to mild exercise, and there were no interactive effects of the two variables.

Plasma free, phospholipid-bound and urinary free choline all decrease during a marathon run and may be associated with impaired performance

BACKGROUND

Previous investigations have shown that plasma free choline decreases during long distance running.

OBJECTIVE

This study was undertaken to determine if body choline status changes during a marathon run and whether performance is thereby adversely affected.

DESIGN

Twenty-three accomplished marathon runners 25 to 49 years of age were studied before and after the 1997 Houston-Methodist Marathon. Fasting blood and five-hour urine samples were obtained in the morning, 14 days prior to the race, immediately after the race and approximately 48 hours after completion of the race. Runners were asked to predict their finish times two weeks prior to the race. Performance was indicated by the ratio of predicted to actual time.

RESULTS

Both plasma free and phospholipid-bound choline concentrations as well as urinary free choline concentration decreased immediately following the race (19.2+/-4.5 to 14.6+/-4.2 nmol/mL, p=0.005, and 2565.2+/-516.4 to 2403.4+/-643.0 nmol/mL, p=0.068, respectively) and, except for the phospholipid-bound choline, rebounded towards baseline after 48 hours (15.6+/-3.2 and 2299.9+/-426.7 nmol/mL), although plasma concentrations remained significantly below baseline. Plasma free and phospholipid-bound choline concentrations were significantly correlated (r=0.46, p=0.0001), although urinary free choline concentration was not correlated with either. There was no correlation between plasma free, phospholipid-bound or urinary free choline concentration and actual finish time or the ratio of predicted to actual finish time. However, the percent decrease in urinary free choline concentration was significantly correlated with the ratio of predicted to actual time (r=0.47, p=0.036). No relationship was seen between this ratio and the percent decrease in either plasma free or phospholipid-bound choline concentrations immediately after the race.

CONCLUSION

Our finding of both decreased free and phospholipid-bound choline suggests the decrease in choline status is related to accelerated choline metabolism or enhanced choline uptake by tissues rather than decreased hepatic choline release. The role of choline supplementation during endurance running requires further investigation.

Decreased serum choline concentrations in humans after surgery, childbirth, and traumatic head injury

The serum levels of choline decreased by approximately 50% in patients having a surgery under general as well as epidural anesthesia. The decrease is lasts for two days after surgery. Intravenous administration of succinylcholine, either by a single bolus injection or by a slow continuous infusion, increased the serum choline levels several folds during surgery. In these patients, a significant decrease in the serum choline levels was observed one and two days after surgery. In 16 pregnant women at the term, serum choline levels were higher than the value observed in 19 nonpregnant women. The serum choline levels decreased by about 40% or 60% after having a childbirth either by vaginal delivery or caesarean section, respectively. Serum choline levels in blood obtained from 9 patients with traumatic head injury were significantly lower than the observed levels in blood samples obtained from healthy volunteers. These observations show that serum choline levels increase during pregnancy and decrease during stressful situations in humans.

Optimal physical performance in athletes: key roles of dopamine in a specific neurotransmitter/hormonal mechanism

It is proposed that exercise training leads to resetting of the central autonomic nervous system (ANS) status, modifies neuroendocrine function and consistently results in upgraded efficiency of physiological/metabolic regulations. The initiating neurotransmitter mechanism is widely held to be due, essentially, to activation of certain brain cholinergic neurons (amygdala n.), stimulation of the hypothalamic-pituitary-adrenocortical pathway, and to cortisol as the dominant peripheral effector of overall improved efficiency. This thesis raises certain questions. The present analysis, based on studies of sedentary and exercise trained humans, proposes the following: that (1) the ANS profile in exercise consists in enhanced dopaminergic (DA) relative to noradrenergic (NA) activity and increased vagal tone; (2) DA is the principal catecholamine neuromodulator/neurotransmitter of the brain, directly involved in motor control in the striatum and is key to the mechanism underlying increased and maintained efficiency of exercise trained humans; (3) DA is a major participant in many aspects of motor function which include the regulation of cardiovascular and renal function (heart rate, blood pressure, and other), muscle tone, visual processing, calcium homeostasis, protein synthesis and conceivably the optimal utilization of food intake; (4) the peripheral actions of DA reflect and are functionally interrelated to the observed global activation of brain DA systems in exercising animals, and probably man; (5) that a different enzyme profile evolves in exercise training which may potentiate DA synthesis and preserve the structural and functional integrity of central DA neurons; (6) that a shift to enhanced DA vs. NA activity occurs in exercise trained Whites which resembles the norm for sedentary Africans and confers distinct physiological advantages; (7) there is unequivocal evidence for the physiological efficiency of a DA dominated ANS profile which can be correlated to the low incidence of DA related diseases in aging Africans; (8) data suggests that the superiority of top-class African athletes in distance running and their endurance capacity are related to an inherent neurophysiological advantage, to efficient DA and protein synthesis, a decreased rate of DA decline during aging and to improved calcium homeostasis, inter alia. Throughout this study, the term sedentary refers to subjects not undergoing specific exercise training of defined intensity and duration.

Nutritional ergogenics in athletics

Nutritional ergogenic aids may be theorized to improve performance in athletics in a variety of ways, primarily by enhancing energy efficiency, energy control or energy production. Athletes have utilized almost every nutrient possible, ranging from amino acids to zinc, as well as numerous purported nutritional substances, such as ginseng, in attempts to enhance physical performance. This review focuses primarily on nutritional ergogenic aids thought to enhance performance by favourably affecting energy metabolism. Although most purported nutritional ergogenic aids have not been shown to enhance physical performance in well-trained, well-nourished athletes, some reliable scientific data support an ergogenic efficacy of several substances, including caffeine, creatine and sodium bicarbonate, but additional research is needed to evaluate their potential for enhancing performance in specific athletics events.