Coagulation activity and thrombotic risk following high-volume endurance exercise in recreationally active cyclists.

Despite the prognostic effect of physical activity, acute bouts of high-volume endurance exercise can induce cardiac stress and postexercise hypercoagulation associated with increased thrombotic risk. The aim of this study was to explore the effect of high-volume endurance exercise on coagulation and thrombotic activity in recreational cyclists. Thirty-four recreational cyclists completed 4.8 ± 0.3 h of cycling at 45 ± 5% of maximal power output on a bicycle ergometer. Intravenous blood samples were collected preexercise, immediately postexercise, 24 and 48 h postexercise, and analyzed for brain natriuretic peptide (BNP), cardiac troponin (cTn), C-reactive protein (CRP), D-dimer, thrombin-antithrombin (TAT) complex, tissue factor (TF), tissue factor pathway inhibitor (TFPI), and TF-to-TFPI ratio (TF:TFPI). An increase in cTn was observed postexercise (P < 0.001). CRP concentrations were increased at 24 and 48 h postexercise compared with preexercise concentrations (P ≤ 0.001). TF was elevated at 24 h postexercise (P < 0.031) and TFPI was higher immediately postexercise (P < 0.044) compared with all other time points. TF:TFPI was increased at 24 and 48 h postexercise compared with preexercise (P < 0.025). TAT complex was reduced at 48 h postexercise compared with preexercise (P = 0.015), D-dimer was higher immediately postexercise compared with all other time points (P ≤ 0.013). No significant differences were observed in BNP (P > 0.05). High-volume endurance cycling induced markers of cardiac stress among recreational cyclists. However, plasma coagulation and fibrinolytic activity suggest no increase in thrombotic risk after high-volume endurance exercise.NEW & NOTEWORTHY In this study, a high-volume endurance exercise protocol induced markers of cardiac stress and altered plasma coagulation and fibrinolytic activity for up to 48 h in recreationally active cyclists. However, analysis of coagulation biomarkers indicates no increase in thrombotic risk when appropriate hydration and rest protocols are implemented.

Effect of repeated prolonged exercise on liver fat content and visceral adipose tissue in well-trained older men.

INTRODUCTION: Liver fat (LF) and visceral adipose tissue (VAT) content decreases with training, however, this has mainly been investigated in sedentary obese or healthy participants. The aim of this study was to investigate the effects of repeated prolonged exercise on LF and VAT content in well-trained older men and to compare baseline LF and VAT content to recreationally active older men. METHOD: A group of five well-trained older men were tested before and after cycling a total distance of 2558 km in 16 consecutive days. VAT content and body composition was measured using DXA before a bicycle ergometer test was performed to determine maximal fat oxidation (MFO), maximal oxygen consumption ( VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ ), and the relative intensity at which MFO occurred (Fatmax). LF content was measured on a separate day using MRI. For comparison of baseline values, a control group of eight healthy age- and BMI-matched recreationally active men were recruited. RESULTS: The well-trained older men had lower VAT (p = 0.02), and a tendency toward lower LF content (p = 0.06) compared with the control group. The intervention resulted in decreased LF content (p = 0.02), but VAT, fat mass, and lean mass remained unchanged. VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ , MFO, and Fatmax were not affected by the intervention. CONCLUSION: The study found that repeated prolonged exercise reduced LF content, but VAT and VO 2 max $$ {\mathrm{VO}}_{2_{\mathrm{max}}} $$ remained unchanged. Aerobic capacity was aligned with lower LF and VAT in older active men.

Supplementation with food-derived oligopeptides promotes lipid metabolism in young male cyclists: a randomized controlled crossover trial.

BACKGROUND: Accumulation of body fat and dyslipidemia are associated with the development of obesity and cardiometabolic diseases. Moreover, the degree to which lipids can be metabolized has been cited as a determinant of cardiometabolic health and prolonged endurance capacity. In the backdrop of increasing obesity and cardiometabolic diseases, lipid metabolism and its modulation by physical activity, dietary adjustments, and supplementation play a significant role in maintaining health and endurance. Food-derived oligopeptides, such as rice and soybean peptides, have been shown to directly regulate abnormal lipid metabolism or promote hypolipidemia and fat oxidation in cell culture models, animal models, and human studies. However, whether supplementation with oligopeptides derived from multiple food sources can promote lipid degradation and fat oxidation in athletes remains unclear. Therefore, in a randomized controlled crossover trial, we investigated the impact of food-derived oligopeptide supplementation before and during exercise on lipid metabolism in young male cyclists. METHODS: Sixteen young male cyclists (age: 17.0 ± 1.0 years; height: 178.4 ± 6.9 cm; body mass: 68.7 ± 12.7 kg, body mass index: 21.5 ± 3.4 kg/m2; maximum oxygen uptake: 56.3 ± 5.8 mL/min/kg) participated in this randomized controlled crossover trial. Each participant drank two beverages, one containing a blend of three food-derived oligopeptides (treatment, 0.5 g/kg body weight in total) and the other without (control), with a 2-week washout period between two experiments. The cyclists completed a one-day pattern protocol that consisted of intraday fasting, 30 min of sitting still, 85 min of prolonged exercise plus a 5-min sprint (PE), a short recovery period of 60 min, a 20-min time trial (TT), and recovery till next morning. Blood samples were collected for biochemical analyses of serum lipids and other biomarkers. We analyzed plasma triglyceride species (TGs), free amino acids (FAAs), and tricarboxylic acid (TCA) cycle intermediates using omics methods. In addition, exhaled gas was collected to assess the fat oxidation rate. RESULTS: Five of 20 plasma FAAs were elevated pre-exercise (pre-Ex) only 20 min after oligopeptide ingestion, and most FAAs were markedly increased post PE and TT. Serum levels of TG and non-esterified fatty acids were lower in the experimental condition than in the control condition at the post PE and TT assessments, respectively. Further, the omics analysis of plasma TGs for the experimental condition demonstrated that most TGs were lower post PE and at the next fasting when compared with control levels. Simultaneously, the fat oxidation rate began to increase only 20 min after ingestion and during the preceding 85 min of PE. Levels of TCA cycle intermediates did not differ between the conditions. CONCLUSIONS: The study noted that continuous ingestion of food-derived oligopeptides accelerated total body triglyceride breakdown, non-esterified fatty acid uptake, and fat oxidation during both sedentary and exercise states. Elevated circulating and intracellular FAA flux may modulate the selection of substrates for metabolic pathways in conjunction with the release of neuroendocrinological factors that slow down carbohydrate metabolism via acetyl coenzyme A feedback inhibition. This may increase the availability of fatty acids for energy production, with FAAs supplying more substrates for the TCA cycle. The findings of this study provide novel insight into strategies for promoting lipid metabolism in populations with dyslipidemia-related metabolic disorders such as obesity and for improving physiological functioning during endurance training. However, the absence of a non-exercising control group and verification of long-term supplementation effects was a limitation. Future studies will emphasize the impacts of whole protein supplementation as a control and of combined food-derived peptides or oligopeptides with probiotics and healthy food components on lipid metabolism in individuals who exercise.

Medium chain triglycerides with a C8:C10 ratio of 30:70 enhances cognitive performance and mitigates the cognitive decline associated with prolonged exercise in young and healthy adults.

INTRODUCTION: Prolonged exercise has been linked to a decline in cognitive function due to a variety of factors, such as a drop in oxygen in the prefrontal cortex and an increase in stress hormones and neurotransmitters. Medium chain triglycerides (MCTs) may possibly offset this decline as they provide energy for the brain via both direct and indirect pathways, alongside promoting chronic physiological adaptations within the brain. METHODS: Participants were divided into two groups; MCT (n = 9) and Placebo (n = 10). The MCT gels contained 6 g of MCT with a C8:C10 ratio of 30:70, whereas the placebo gels contained carbohydrates of similar calorific value to the MCT gels. Participants visited the laboratory on three occasions (familiarisation/fitness test, pre-supplementation, post-supplementation), during which they performed a battery of cognitive tasks assessing domains such as processing speed, working memory, selective attention, decision making and coordination, before and after a prolonged bout of exercise (60 mins at 90% gas exchange threshold (GET). A 2-week supplementation period between visits 2 and 3 involved the ingestion of 2 gels per day. RESULTS: Exercise resulted in detriments in most cognitive tasks pre-supplementation for both groups, and post-supplementation for the Placebo group (main effect ps< 0.05). Post-supplementation, the effect of exercise was mediated in the MCT group for all cognitive tasks (main effect ps< 0.05), except for the Digit and Spatial Span Backwards test phases (main effect ps> 0.05). Furthermore, MCT supplementation enhanced before-exercise cognitive performance and in some measures, such as working memory, this was maintained after-exercise (interaction effect ps> 0.05). CONCLUSIONS: Chronic MCT supplementation enhanced before-exercise cognitive performance and offset the cognitive decline caused by a prolonged bout of exercise. In some cases, improvements in before-exercise cognitive performance were maintained after-exercise.

Carbohydrate knowledge, beliefs, and intended practices, of endurance athletes who report exercise-associated gastrointestinal symptoms.

This study aimed to explore carbohydrate (CHO) knowledge, beliefs, and intended practices of endurance athletes who experience exercise-associated gastrointestinal symptoms (Ex-GIS) compared to those without Ex-GIS. A validated online questionnaire was completed by endurance athletes (n = 201) participating in >60 min of exercise that present with Ex-GIS (n = 137) or without (n = 64). Descriptive statistics were used for parametric and non-parametric data with appropriate significance tests. Associations between categorical data were assessed by Chi-square analysis, and post-hoc Bonferroni tests were applied when significant. A content analysis of open-ended responses was grouped into themes, and quantitative statistics were applied. Participants included runners (n = 114, 57%), triathletes (n = 43, 21%) and non-running sports (n = 44, 21%) who participate in recreational competitive (n = 74, 37%), recreational non-competitive (n = 64, 32%), or competitive regional, national, or international levels (n = 63, 31%). Athletes correctly categorized CHO (x̄ = 92-95%) and non-CHO (x̄ = 88-90%) food and drink sources. On a Likert scale of 1 (strongly disagree) to 5 (strongly agree) athletes typically agree or strongly agree that consuming CHO around key training sessions and competitions enhances athletic performance [median = 4 (IQR, 4-5)], and they intend to consume more CHO around exercise [median = 3 (IQR, 2-3)]. No differences in beliefs and intentions were found among athletes with or without Ex-GIS. To enhance athletic performance, most endurance athletes intend to consume more CHO around exercise. Adequate knowledge of CHO-containing food sources was apparent; however, specific CHO ingestion practices remain to be verified.

Supplementation with Whey Protein, but Not Pea Protein, Reduces Muscle Damage Following Long-Distance Walking in Older Adults.

Background: Adequate animal-based protein intake can attenuate exercise induced-muscle damage (EIMD) in young adults. We examined the effects of 13 days plant-based (pea) protein supplementation compared to whey protein and placebo on EIMD in active older adults. Methods: 47 Physically active older adults (60+ years) were randomly allocated to the following groups: (I) whey protein (25 g/day), (II) pea protein (25 g/day) or (III) iso-caloric placebo. Blood concentrations of creatine kinase (CK) and lactate dehydrogenase (LDH), and skeletal muscle mass, muscle strength and muscle soreness were measured prior to and 24 h, 48 h and 72 h after a long-distance walking bout (20−30 km). Results: Participants walked 20−30 km and 2 dropped out, leaving n = 15 per subgroup. The whey group showed a significant attenuation of the increase in EIMD at 24 h post-exercise compared to the pea and placebo group (CK concentration: 175 ± 90 versus 300 ± 309 versus 330 ± 165, p = p < 0.001). No differences in LDH levels, muscle strength, skeletal muscle mass and muscle soreness were observed across groups (all p-values > 0.05). Conclusions: Thirteen days of pea protein supplementation (25 g/day) does not attenuate EIMD in older adults following a single bout of prolonged walking exercise, whereas the whey protein supplementation group showed significantly lower post-exercise CK concentrations.

Performance Determinants in Trail-Running Races of Different Distances.

PURPOSE: While the physiological determinants of road running have been widely studied, there is a lack of research in trail-running racing performance. The aim of our study was to determine the physiological predictors of trail-running performance in races of different distances in similar terrain and weather conditions. METHODS: Seventy-five trail runners participating in one of the races of the Ultra-Trail du Mont-Blanc were recruited. Previous to the race, each runner was evaluated with (1) an incremental treadmill test to determine maximal oxygen uptake, ventilatory thresholds, cost of running, and substrate utilization; (2) a power-force-velocity profile on a cycle ergometer; (3) maximal voluntary contractions of the knee extensors and plantar flexors; and (4) anthropometric characteristics. Neuromuscular fatigue was evaluated after the races. Twenty-four runners finished a SHORT (<55 km), 16 finished a MEDIUM (101 km), and 14 finished a LONG (>145 km) race. Correlations and multiple linear regressions were used to find the determinants of performance in each race distance. RESULTS: Performance in SHORT was explained by maximal oxygen uptake and lipid utilization at 10 km/h (r2 = .825, P < .001). Performance in MEDIUM was determined by maximal oxygen uptake, maximal isometric strength, and body fat percentage (r2 = .917, P < .001). A linear model could not be applied in LONG, but performance was correlated to peak velocity during the incremental test. CONCLUSIONS: Performance in trail running is mainly predicted by aerobic capacity, while lipid utilization also influences performance in races <60 km and performance in approximately 100 km is influenced by muscle strength and body composition.

Effects of nasal breathing on partial pressure of carbon dioxide in arterial blood during prolonged exercise in a hot environment / 体力科学

Prolonged exercise in a hot environment increases the minute ventilation (VE) and respiratory rate (RR) with an increase in core temperature. This hyperthermia-induced hyperventilation decreases the partial pressure of arterial blood carbon dioxide (PaCO2). Conversely, nasal breathing during exercise has been reported to produce low VE and RR values and high PaCO2 values; however, no studies have investigated this in hot environments. Therefore, the purpose of this study was to clarify the effect of nasal breathing on estimated partial pressure of carbon dioxide in arterial blood (PaCO2,estimate) during prolonged exercise in a hot environment. Twelve university endurance athletes participated in the study and performed a 40-minutes steady-state cycling exercise at an intensity of 55% of peak oxygen uptake in a hot environment (room temperature 35℃, relative humidity 40%). Using randomized crossover design, two experiments were performed—nasal breathing condition (NB) and mouth breathing condition (MB). Moreover, physiological indices were measured during the exercise. Rectal temperature increased in both conditions, but there was no significant difference between these conditions. PaCO2,estimate values were significantly higher in NB between 10 minutes and 40 minutes of exercise (p < 0.05) compared to MB, and decreased with time in MB. Compared to MB, the VE was significantly lower in NB between 30 minutes and 40 minutes (p < 0.05), while the RR was significantly lower in NB between 25 minutes and 40 minutes of exercise (p < 0.05). Therefore, nasal breathing during a prolonged moderate-intensity exercise in a hot environment prevented the decrease in PaCO2,estimate due to hyperthermia-induced hyperventilation.

Exhaled Breath Reflects Prolonged Exercise and Statin Use during a Field Campaign.

Volatile organic compounds (VOCs) in exhaled breath provide insights into various metabolic processes and can be used to monitor physiological response to exercise and medication. We integrated and validated in situ a sampling and analysis protocol using proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) for exhaled breath research. The approach was demonstrated on a participant cohort comprising users of the cholesterol-lowering drug statins and non-statin users during a field campaign of three days of prolonged and repeated exercise, with no restrictions on food or drink consumption. The effect of prolonged exercise was reflected in the exhaled breath of participants, and relevant VOCs were identified. Most of the VOCs, such as acetone, showed an increase in concentration after the first day of walking and subsequent decrease towards baseline levels prior to walking on the second day. A cluster of short-chain fatty acids including acetic acid, butanoic acid, and propionic acid were identified in exhaled breath as potential indicators of gut microbiota activity relating to exercise and drug use. We have provided novel information regarding the use of breathomics for non-invasive monitoring of changes in human metabolism and especially for the gut microbiome activity in relation to exercise and the use of medication, such as statins.

Physiological Determinants of Ultramarathon Trail-Running Performance.

CONTEXT: The physiological determinants of ultramarathon success have rarely been assessed and likely differ in their contributions to performance as race distance increases. PURPOSE: To examine predictors of performance in athletes who completed either a 50-, 80-, or 160-km trail race over a 20-km loop course on the same day. METHODS: Measures of running history, aerobic fitness, running economy, body mass loss, hematocrit alterations, age, and cardiovascular health were examined in relation to race-day performance. Performance was defined as the percentage difference from the winning time at a given race distance, with 0% representing the fastest possible time. RESULTS: In the 50-km race, training volumes, cardiovascular health, aerobic fitness, and a greater loss of body mass during the race were all related to better performance (all P < .05). Using multiple linear regression, peak velocity achieved in the maximal oxygen uptake test (ß = -11.7, P = .002) and baseline blood pressure (ß = 3.1, P = .007) were the best performance predictors for the men's 50-km race (r = .98, r2 = .96, P < .001), while peak velocity achieved in the maximal oxygen uptake test (ß = -13.6, P = .001) and loss of body mass (ß = 12.8, P = .03) were the best predictors for women (r = .94, r2 = .87, P = .001). In the 80-km race, only peak velocity achieved in the maximal oxygen uptake test predicted performance (ß = -20.3, r = .88, r2 = .78, P < .001). In the 160-km race, there were no significant performance determinants. CONCLUSIONS: While classic determinants of running performance, including cardiovascular health and running fitness, predict 50-km trail-running success, performance in longer-distance races appears to be less influenced by such physiological parameters.

Programmed vs. Thirst-Driven Drinking during Prolonged Cycling in a Warm Environment.

We compared the effect of programmed (PFI) and thirst-driven (TDFI) fluid intake on prolonged cycling performance and exercise associated muscle cramps (EAMC). Eight male endurance athletes (26 ± 6 years) completed two trials consisting of 5 h of cycling at 61% V˙O2peak followed by a 20 km time-trial (TT) in a randomized crossover sequence at 30 °C, 35% relative humidity. EAMC was assessed after the TT with maximal voluntary isometric contractions of the shortened right plantar flexors. Water intake was either programmed to limit body mass loss to 1% (PFI) or consumed based on perceived thirst (TDFI). Body mass loss reached 1.5 ± 1.0% for PFI and 2.5 ± 0.9% for TDFI (p = 0.10). Power output during the 20 km TT was higher (p < 0.05) for PFI (278 ± 41 W) than TDFI (263 ± 39 W), but the total performance time, including the breaks to urinate, was similar (p = 0.48) between conditions. The prevalence of EAMC of the plantar flexors was similar between the drinking conditions. Cyclists competing in the heat for over 5 h may benefit from PFI aiming to limit body mass loss to <2% when a high intensity effort is required in the later phase of the race and when time lost for urination is not a consideration.

Alterations in Cardiac Function Following Endurance Exercise Are Not Duration Dependent.

Cardiac function has been shown to transiently decrease following prolonged exercise, with greater durations related to increased impairment. However, the prospective assessment of exercise duration on cardiac performance is rare, and the influence of relative exercise intensity is typically not assessed in relation to these changes. The aim of this study was to determine whether progressively longer running distances over the same course would elicit greater cardiac impairment. The present investigation examined cardiac alterations in 49 athletes, following trail-running races of 25, 50, 80, and 160 km, performed on the same course on the same day. Echocardiography, including conventional and speckle tracking imaging, was performed with legs-raised to 60° to mitigate alterations in preload both pre- and post-race. Race-intensities were monitored via heart rate (HR). Following the races, mean arterial pressure (Δ-11 ± 7 mmHg, P < 0.0001), and HR (Δ19 ± 14 bpm, P < 0.0001) were altered independent of race distance. Both left and right ventricular (LV and RV) diastolic function were reduced (ΔLV E/A -0.54 ± 0.49, P < 0.0001; ΔRV A' + 0.02 ± 0.04 m/s, P = 0.01) and RV systolic function decreased (ΔTAPSE -0.25 ± 0.9 cm, P = 0.01), independent of race distance. Cardiac impairment was not apparent using speckle tracking analysis with cubic spline interpolation. While race duration was unrelated to cardiac alterations, increased racing HR was related to greater RV base dilation (r = -0.37, P = 0.03). Increased time spent at higher exercise intensities was related to reduced LV ejection fraction following 25 km (r = -0.81, P = 0.03), LV systolic strain rate following 50 km (r = 0.59, P = 0.04), and TAPSE (r = -0.81, P = 0.03) following 80 km races. Increased running duration did not affect the extent of exercise-induced cardiac fatigue, however, intensity may be a greater driver of cardiac alterations.

Multi-Day Prolonged Low- to Moderate-Intensity Endurance Exercise Mimics Training Improvements in Metabolic and Oxidative Profiles Without Concurrent Chromosomal Changes in Healthy Adults.

BACKGROUND: Oxidative stress results in lipid, protein, and DNA oxidation, resulting in telomere erosion, chromosomal damage, and accelerated cellular aging. Training promotes healthy metabolic and oxidative profiles whereas the effects of multi-day, prolonged, and continuous exercise are unknown. This study investigated the effects of multi-day prolonged exercise on metabolic and oxidative stress as well as telomere integrity in healthy adults. METHODS: Fifteen participants performed a 14-day, 260-km, wilderness canoeing expedition (12 males) (EXP) (24 ± 7 years, 72 ± 6 kg, 178 ± 8.0 cm, 18.4 ± 8.4% BF, 47.5 ± 9.3 mlO2 kg-1 min-1), requiring 6-9 h of low- to moderate-intensity exercise daily. Ten controls participated locally (seven males) (CON) (31 ± 11 years, 72 ± 15 kg, 174 ± 10 cm, 22.8 ± 10.0% BF, 47.1 ± 9.0 mlO2 kg-1 min-1). Blood plasma, serum, and mononuclear cells were sampled before and after the expedition to assess hormonal, metabolic, and oxidative changes. RESULTS: Serum cholesterol, high- and low-density lipoprotein, testosterone, insulin, sodium, potassium, urea, and chloride concentrations were not different between groups, whereas triglycerides, glucose, and creatinine levels were lower following the expedition (p < 0.001). Malondialdehyde and relative telomere length (TL) were unaffected (EXP: 4.2 ± 1.3 vs. CON: 4.1 ± 0.7 µM; p > 0.05; EXP: 1.00 ± 0.48 vs. CON: 0.89 ± 0.28 TS ratio; p = 0.77, respectively); however, superoxidase dismutase activity was greater in the expedition group (3.1 ± 0.4 vs. 0.8 ± 0.5 U ml-1; p < 0.001). CONCLUSION: These results indicate a modest improvement in metabolic and oxidative profiles with increased superoxidase dismutase levels, suggesting an antioxidative response to counteract the exercise-associated production of free radicals and reactive oxygen species during prolonged exercise, mimicking the effects from long-term training. Although improved antioxidant activity may lead to increased TL, the present exercise stimulus was insufficient to promote a positive cellular aging profile with concordant chromosomal changes in our healthy and young participants.

The Production of a Rat Model That Inhibits Phosphoenolpyruvate Carboxykinase (PEPCK), a Rate-Limiting Enzyme of Hepatic Gluconeogenesis.

We previously showed that taurine administration contributed to the extension of time to exhaustion through exercise-induced hypoglycemia restraint, and we suggested that the activation of hepatic gluconeogenesis was initiated before the exercise with the taurine administration. We hypothesize that the extension effect of exercise duration with the taurine administration is restrained in the rats which inhibited hepatic gluconeogenesis. In this study, we aimed to produce a rat model that inhibited hepatic gluconeogenesis as a first step in testing our hypothesis.F344 male rats of 8 weeks after birth were purchased. The blood samples were collected via jugular vein catheter to perform the pyruvate tolerance test (PTT) with the intraperitoneal administration, and to determine the optimal time point of blood glucose measurement. 3-mercaptopicolinic acids (3MPA) was used as an inhibitor of PEPCK. The rats were divided into three groups, Non-dosage control (CON) group, 30 mg/kg・BW 3MPA (3MPA 30) group, and 300 mg/kg・BW 3MPA (3MPA 300) group.The blood glucose level showed a significant peak 15 min after pyruvate administration. The change of the blood glucose level after the PTT in 3MPA 300 group was significantly smaller than that of the CON group at this time point. These results show we could prepare the rat model that inhibited hepatic gluconeogenesis.

Exercise-Associated Hyponatremia in Endurance and Ultra-Endurance Performance-Aspects of Sex, Race Location, Ambient Temperature, Sports Discipline, and Length of Performance: A Narrative Review.

Exercise-associated hyponatremia (EAH) is defined as a plasma sodium concentration of <135 mmol/L during or after endurance and ultra-endurance performance and was first described by Timothy Noakes when observed in ultra-marathoners competing in the Comrades Marathon in South Africa in the mid-1980s. It is well-established that a decrease in plasma sodium concentration <135 mmol/L occurs with excessive fluid intake. Clinically, a mild hyponatremia will lead to no or very unspecific symptoms. A pronounced hyponatremia (<120 mmol/L) will lead to central nervous symptoms due to cerebral edema, and respiratory failure can lead to death when plasma sodium concentration reaches values of <110-115 mmol/L. The objective of this narrative review is to present new findings about the aspects of sex, race location, sports discipline, and length of performance. The prevalence of EAH depends on the duration of an endurance performance (i.e., low in marathon running, high to very high in ultra-marathon running), the sports discipline (i.e., rather rare in cycling, more frequent in running and triathlon, and very frequent in swimming), sex (i.e., increased in women with several reported deaths), the ambient temperature (i.e., very high in hot temperatures) and the country where competition takes place (i.e., very common in the USA, very little in Europe, practically never in Africa, Asia, and Oceania). A possible explanation for the increased prevalence of EAH in women could be the so-called Varon-Ayus syndrome with severe hyponatremia, lung and cerebral edema, which was first observed in marathon runners. Regarding the race location, races in Europe seemed to be held under rather moderate conditions whereas races held in the USA were often performed under thermally stressing conditions (i.e., greater heat or greater cold).

Impact of Physical and Cognitive Exertion on Cognitive Control.

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

Impact of acute versus repetitive moderate intensity endurance exercise on kidney injury markers.

Exercise may lead to kidney injury through several mechanisms. Urinary Kidney Injury Molecule-1 (uKIM1) and Neutrophil Gelatinase-Associated Lipocalin (uNGAL) are known biomarkers for acute kidney injury, but their response to repetitive exercise remains unknown. We examined the effects of a single versus repetitive bouts of exercise on markers for kidney injury in a middle-aged population. Sixty subjects (aged 29-78 years, 50% male) were included and walked 30, 40 or 50 km for three consecutive days. At baseline and after exercise day 1 and 3, a urine sample was collected to determine uNGAL and uKIM1. Furthermore, urinary cystatin C, creatinine, and osmolality were used to correct for dehydration-related changes in urinary concentration. Baseline uNGAL was 9.2 (5.2-14.7) ng/mL and increased to 20.7 (11.0-37.2) ng/mL and 14.2(8.0-26.3) ng/mL after day 1 and day 3, respectively, (P ≤ 0.001). Baseline uKIM1 concentration was 2.6 (1.4-6.0) ng/mL and increased to 5.2 (2.4-9.1) ng/mL (P = 0.002) after day 1, whereas uKIM1 was not different from baseline at day 3 (2.9 [1.4-6.4] ng/mL (P = 0.52)). Furthermore, both uNGAL and uKIM1 levels were higher after day 1 compared to day 3 (P < 0.01). When corrected for urinary cystatin C, creatinine, and osmolality, uNGAL demonstrated a similar response compared to the uncorrected data, whereas differences in uKIM1 between baseline, day 1 and day 3 (Ptime = 0.63) were no longer observed for cystatin C and creatinine corrected data. A single bout of prolonged exercise significantly increased uNGAL concentration, whereas no changes in uKIM1 were found. Repetitive bouts of exercise show that there is no cumulative effect of kidney injury markers.

Fluid replacement modulates oxidative stress- but not nitric oxide-mediated cutaneous vasodilation and sweating during prolonged exercise in the heat.

The roles of nitric oxide synthase (NOS), reactive oxygen species (ROS), and angiotensin II type 1 receptor (AT1R) activation in regulating cutaneous vasodilation and sweating during prolonged (≥60 min) exercise are currently unclear. Moreover, it remains to be determined whether fluid replacement (FR) modulates the above thermoeffector responses. To investigate, 11 young men completed 90 min of continuous moderate intensity (46% V̇o2peak) cycling performed at a fixed rate of metabolic heat production of 600 W (No FR condition). On a separate day, participants completed a second session of the same protocol while receiving FR to offset sweat losses (FR condition). Cutaneous vascular conductance (CVC) and local sweat rate (LSR) were measured at four intradermal microdialysis forearm sites perfused with: 1) lactated Ringer (Control); 2) 10 mM NG-nitro-l-arginine methyl ester (l-NAME, NOS inhibition); 3) 10 mM ascorbate (nonselective antioxidant); or 4) 4.34 nM losartan (AT1R inhibition). Relative to Control (71% CVCmax at both time points), CVC with ascorbate (80% and 83% CVCmax) was elevated at 60 and 90 min of exercise during FR (both P < 0.02) but not at any time during No FR (all P > 0.31). In both conditions, CVC was reduced at end exercise with l-NAME (60% CVCmax; both P < 0.02) but was not different relative to Control at the losartan site (76% CVCmax; both P > 0.19). LSR did not differ between sites in either condition (all P > 0.10). We conclude that NOS regulates cutaneous vasodilation, but not sweating, irrespective of FR, and that ROS influence cutaneous vasodilation during prolonged exercise with FR.

Effects of prolonged exercise versus multiple short exercise sessions on risk for metabolic syndrome and the atherogenic index in middle-aged obese women: a randomised controlled trial.

BACKGROUND: Many people, although they may recognise the positive effects of exercise, do not exercise regularly owing to lack of time. This study aimed to investigate the effects of prolonged single-session exercise and multiple short sessions of exercise on the risk of metabolic syndrome and the atherogenic index in middle-aged obese women. METHODS: Thirty-six participants were divided into the single-session group, multiple-session group, and control group. The single-session group engaged in one session of treadmill exercise for 30 min a day; the multiple-session group had three sessions of 10 min a day. Both groups exercised 3 days/week for 12 weeks. The control group did not perform any exercise. RESULTS: The single-session group showed decreases in weight (0.97 kg [95% C.I. = 0.09-1.83], p < .05), body mass index (0.43 kg/m2 [95% C.I. = 0.03-0.81], p < .05), and fat mass (1.65 kg, [95% C.I. = 0.78-2.51], p < .01). Systolic blood pressure dropped in the single-session group (6.66 mmHg, [95% C.I. = 1.44-11.88], p < .05), and diastolic blood pressure dropped in the multiple-session group (3.38 mmHg, [95% C.I. = 1.44-5.88], p < .01). High-density lipoprotein cholesterol rose in the single-session group (4.08 mg/dL, [95% C.I. = -8.08-(-)0.07], p < .05) and dropped in the control group (10.75 mg/dL [95% C.I. = 1.95-19.54], p < .01). According to post hoc analysis, high-density lipoprotein cholesterol increased more in the single-session group than the control group (95% C.I. = 0.61-21.88, p < .05). Glucose levels decreased in both the single-session group (16 mg/dL [95% C.I. = 5.64-26.35], p < .01) and the multiple-session group (12.16 mg/dL, [95% C.I. = 2.18-22.14], p < .05). Waist circumference decreased in the single-session group (2.65 cm [95% C.I. = 1.46-3.83], p < .001) and multiple-session group (2.04 cm, [95% C.I. = 1.51-2.73], p < .001). Low-density lipoprotein cholesterol levels rose in both the multiple-session group (-15.79 mg/dL [95% C.I. = -34.24-(-)3.78], p < .05) and the control group (-22.94 mg/dL [95% C.I. = -44.63-(-)1.24], p < .05). The atherogenic index increased in the control group (-1.06 [95% C.I. = -1.69-(-)0.41], p < .01). CONCLUSIONS: The findings indicate that prolonged exercise is superior to multiple short sessions for improving the risk of metabolic syndrome and the atherogenic index in middle-aged obese women. However, multiple short sessions can be recommended as an alternative to prolonged exercise when the goal is to decrease blood glucose or waist circumference.