The role of sodium supplements and sex in the occurrence of exercise-associated hyponatremia (EAH) remains controversial. This study investigated hydration status in ultrarunners (19 males and 9 females) who completed seven marathons over seven consecutive days. Due to the limited number of female participants, no statistical comparison between sexes was performed. Plasma sodium concentration ([Na+]) and multiple hydration markers were assessed before, during, and after the race. Reported sodium supplement consumption showed no association with plasma [Na+]. An overall decline in plasma [Na+] was observed in females (regression slope = -1.278, p = 0.02) across the event, whereas no significant change was detected in males (slope = -0.325, p = 0.57). Additionally, no significant associations were found between plasma [Na+] and other monitored variables, including sodium supplement intake, pre-race hydration strategy, body mass, total body water, plasma osmolality, hematocrit, hemoglobin, urine specific gravity, urinary [Na+], thirst rating, or fluid intake reported pre-, during, and post-stage. No cases of symptomatic or asymptomatic hyponatremia were identified, suggesting that total fluid and sodium intake were adequate to maintain fluid-electrolyte balance and prevent EAH in both sexes.

• Klíčová slova
• Marathon, Multistage race, Plasma sodium, Ultrarunners,
• MeSH
• běh * fyziologie   MeSH
• dospělí MeSH
• hyponatremie * krev   etiologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• maratonský běh * fyziologie   MeSH
• sodík * krev   MeSH
• vodní a elektrolytová rovnováha MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• sodík * MeSH

BACKGROUND: Marathon training and running have many beneficial effects on human health and physical fitness; however, they also pose risks. To date, no comprehensive review regarding both the benefits and risks of marathon running on different organ systems has been published. MAIN BODY: The aim of this review was to provide a comprehensive review of the benefits and risks of marathon training and racing on different organ systems. A predefined search strategy including keywords (e.g., marathon, cardiovascular system, etc.) and free text search was used. Articles covering running regardless of sex, age, performance level, and event type (e.g., road races, mountain marathons) were considered, whereas articles examining only cycling, triathlon, stress-tests or other sports were excluded. In total, we found 1021 articles in PubMed, Scopus, and Google Scholar, of which 329 studies were included in this review. Overall, marathon training offers several benefits for different organ systems and reduces all-cause mortality. As such, it improves cardiovascular risk factors, leads to favorable cardiac adaptations, enhances lung function, and improves quality of life in chronic kidney disease patients. It also enhances gastrointestinal mobility and reduces the risk of specific tumors such as colorectal cancer and hepatocellular carcinoma. Marathon training enhances bone health and skeletal muscle metabolism. It further positively affects hematopoiesis and cytotoxic abilities of natural killer cells, and may act neuroprotective on a long-term basis. After a marathon, changes in biomarkers suggesting pathological events in certain organ systems such as cardiovascular, renal, gastrointestinal, liver, hematological, immune, musculoskeletal, central nervous, and endocrine systems can often be observed. Mostly, these changes are limited to 1-3 days post-race and usually normalize within a week. Moreover, marathon running poses the risk of serious adverse events such as sudden cardiac death or acute liver failure. Concerning lung function, a decrease after a marathon race was observed. Acute kidney injury, as well as electrolyte imbalances, are relatively common amongst marathon finishers. Many runners complain of gastrointestinal symptoms during or after long-distance running. Many runners suffer from running-related musculoskeletal injuries often impairing performance. A marathon is often accompanied by an acute inflammatory response with transient immunosuppression, making runners susceptible to infections. Also, hormonal alterations such as increased cortisol levels or decreased testosterone levels immediately after a race are observed. Disturbances in sleep patterns are commonly found in marathon runners leading up to or directly after the race. CONCLUSION: All in all, marathon training is generally safe for human health and individual organ systems. Considering the high popularity of marathon running, these findings supply athletes, coaches, sports scientists, and sports medicine practitioners with practical applications. Further large-scale studies examining long-term effects on the cardiovascular, renal, and other system are needed.

• Klíčová slova
• Athletic injury, Endurance training, Exercise overtraining, Sex differences, sports performance,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

BACKGROUND: Ultra-endurance events are gaining popularity in multiple exercise disciplines, including cycling. With increasing numbers of ultra-cycling events, aspects influencing participation and performance are of interest to the cycling community. MAIN BODY: The aim of this narrative review was, therefore, to assess the types of races offered, the characteristics of the cyclists, the fluid and energy balance during the race, the body mass changes after the race, and the parameters that may enhance performance based on existing literature. A literature search was conducted in PubMed, Scopus, and Google Scholar using the search terms 'ultracycling', 'ultra cycling', 'ultra-cycling', 'ultra-endurance biking', 'ultra-bikers' and 'prolonged cycling'. The search yielded 948 results, of which 111 were relevant for this review. The studies were classified according to their research focus and the results were summarized. The results demonstrated changes in physiological parameters, immunological and oxidative processes, as well as in fluid and energy balance. While the individual race with the most published studies was the Race Across America, most races were conducted in Europe, and a trend for an increase in European participants in international races was observed. Performance seems to be affected by characteristics such as age and sex but not by anthropometric parameters such as skin fold thickness. The optimum age for the top performance was around 40 years. Most participants in ultra-cycling events were male, but the number of female athletes has been increasing over the past years. Female athletes are understudied due to their later entry and less prominent participation in ultra-cycling races. A post-race energy deficit after ultra-cycling events was observed. CONCLUSION: Future studies need to investigate the causes for the observed optimum race age around 40 years of age as well as the optimum nutritional supply to close the observed energy gap under consideration of the individual race lengths and conditions. Another research gap to be filled by future studies is the development of strategies to tackle inflammatory processes during the race that may persist in the post-race period.

• Klíčová slova
• Endurance, Performance, Race across America, ultra-cycling,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Exercise-associated hyponatremia (EAH) was first described as water intoxication by Noakes et al. in 1985 and has become an important topic linked to several pathological conditions. However, despite progressive research, neurological disorders and even deaths due to hyponatremic encephalopathy continue to occur. Therefore, and due to the growing popularity of exercise-associated hyponatremia, this topic is of great importance for marathon runners and all professionals involved in runners' training (e.g., coaches, medical staff, nutritionists, and trainers). The present narrative review sought to evaluate the prevalence of EAH among marathon runners and to identify associated etiological and risk factors. Furthermore, the aim was to derive preventive and therapeutic action plans for marathon runners based on current evidence. The search was conducted on PubMed, Scopus and Google Scholar using a predefined search algorithm by aggregating multiple terms (marathon run; exercise; sport; EAH; electrolyte disorder; fluid balance; dehydration; sodium concentration; hyponatremia). By this criterion, 135 articles were considered for the present study. Our results revealed that a complex interaction of different factors could cause EAH, which can be differentiated into event-related (high temperatures) and person-related (female sex) risk factors. There is variation in the reported prevalence of EAH, and two major studies indicated an incidence ranging from 7 to 15% for symptomatic and asymptomatic EAH. Athletes and coaches must be aware of EAH and its related problems and take appropriate measures for both training and competition. Coaches need to educate their athletes about the early symptoms of EAH to intervene at the earliest possible stage. In addition, individual hydration strategies need to be developed for the daily training routine, ideally in regard to sweat rate and salt losses via sweat. Future studies need to investigate the correlation between the risk factors of EAH and specific subgroups of marathon runners.

• Klíčová slova
• epidemiology, exercise, hyponatremia, marathon, review, risk factors, runners, sports medicine,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The aim of the present study was to examine the physiological and training characteristics in marathon runners with different sport experiences (defined as the number of finishes in marathon races). The anthropometry and physiological characteristics of men recreational endurance runners with three or less finishes in marathon races (novice group, NOV; n = 69, age 43.5 ± 8.0 years) and four or more finishes (experienced group, EXP; n = 66, 45.2 ± 9.4 years) were compared. EXP had faster personal best marathon time (3:44 ± 0:36 vs. 4:20 ± 0:44 h:min, p < 0.001, respectively); lower flexibility (15.9 ± 9.3 vs. 19.3 ± 15.9 cm, p = 0.022), abdominal (20.6 ± 7.9 vs. 23.8 ± 9.0 mm, p = 0.030) and iliac crest skinfold thickness (16.7 ± 6.7 vs. 19.9 ± 7.9 mm, p = 0.013), and body fat assessed by bioimpedance analysis (13.0 ± 4.4 vs. 14.6 ± 4.7%, p = 0.047); more weekly training days (4.6 ± 1.4 vs. 4.1 ± 1.0 days, p = 0.038); and longer weekly running distance (58.8 ± 24.0 vs. 47.2 ± 16.1 km, p = 0.001) than NOV. The findings indicated that long-term marathon training might induce adaptations in endurance performance, body composition, and flexibility.

• Klíčová slova
• body fat, endurance training, maximal oxygen uptake, skinfold thickness, sport history, training volume,
• Publikační typ
• časopisecké články MeSH

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).

• Klíčová slova
• cerebral edema, cold, cycling, heat, prolonged exercise, running, swimming,
• MeSH
• cvičení fyziologie   MeSH
• fyzická vytrvalost fyziologie   MeSH
• hyponatremie etiologie   patofyziologie   MeSH
• lidé MeSH
• prevalence MeSH
• rasové skupiny statistika a číselné údaje   MeSH
• rizikové faktory MeSH
• sexuální faktory * MeSH
• sodík analýza   krev   MeSH
• sporty fyziologie   statistika a číselné údaje   MeSH
• teplota MeSH
• vodní a elektrolytová rovnováha fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• sodík MeSH

Exercise-Associated Hyponatremia in Endurance Performance Abstract. Exercise-associated hyponatremia is defined as a plasma sodium concentration of <135 mmol/l and was first described by Timothy Noakes at the Comrades Marathon in South Africa in the mid-1980s. A decrease in plasma sodium <135 mmol/l occurs with excessive fluid intake. Risk factors include long to very long endurance performance, extreme climatic conditions, female gender and competitions in the USA. Regarding its prevalence by sport, exercise-associated hyponatraemia tends to occur while swimming and running, but rarely when cycling. While mild exercise-associated hyponatremia does not lead to clinical symptoms, severe hyponatremia due to cerebral edema can lead to neurological deficits and even death. The best prevention of exercise-associated hyponatremia is the reduction of fluid intake during exercise.

Zusammenfassung. Die belastungsassoziierte Hyponatriämie ist definiert als eine Plasmakonzentration von <135 mmol/l für Natrium und wurde erstmals Mitte der Achtzigerjahre von Timothy Noakes am Comrades Marathon in Südafrika beschrieben. Ein Absinken des Plasmanatriums unter diesen Grenzwert tritt bei übermässiger Flüssigkeitszufuhr auf. Risikofaktoren sind lange bis sehr lange Ausdauerbelastungen, extreme klimatische Bedingungen, weibliches Geschlecht sowie Wettkämpfe in den USA. Bezüglich Sportarten tritt die Hyponatriämie eher beim Schwimmen und beim Laufen auf, aber ganz selten beim Radfahren. Während eine leichte Hyponatriämie keine klinischen Symptome macht, kann eine ausgeprägte Hyponatriämie aufgrund eines Hirnödems zu neurologischen Ausfällen bis hin zum Tod führen. Die beste Prävention der belastungsassoziierten Hyponatriämie ist die Reduktion der Flüssigkeitszufuhr unter Belastung.

• Klíčová slova
• Gender, Geschlecht, Laufen, Radfahren, Schwimmen, Sexe, Ultramarathon, course à pied, cycling, cyclisme, natation, running, swimming, ultra marathon, ultramarathon,
• MeSH
• běh * MeSH
• fyzická vytrvalost * MeSH
• hyponatremie * MeSH
• lidé MeSH
• nutriční stav MeSH
• plavání MeSH
• sodík MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• sodík MeSH

Background: To date, no study has focused on body composition characteristics and on parameters associated with skeletal muscle damage and renal function in runners participating in a 24-h winter race held under extremely cold environmental conditions (average temperature of -14.3°C). Methods: Anthropometric characteristics, plasma urea (PU), plasma creatinine (Pcr), creatine kinase (CK), plasma volume (PV) and total body water (TBW) were assessed pre- and post-race in 20 finishers (14 men and 6 women). Results: In male runners, body mass (BM) (p = 0.003) and body fat (BF) (p = 0.001) decreased [-1.1 kg (-1.4%) and -1.1 kg (-13.4%), respectively]; skeletal muscle mass (SM) and TBW remained stable (p > 0.05). In female runners, BF decreased (p = 0.036) [-1.3 kg (-7.8%)] while BM, SM and TBW remained stable (p > 0.05). The change (Δ) in BM was not related to Δ BF; however, Δ BM was related to Δ SM [r = 0.58, p = 0.007] and Δ TBW (r = 0.59, p = 0.007). Δ SM correlated with Δ TBW (r = 0.51, p = 0.021). Moreover, Δ BF was negatively associated with Δ SM (r = -0.65, p = 0.002). PV (p < 0.001), CK (p < 0.001), Pcr (p = 0.004) and PU (p < 0.001) increased and creatinine clearance (CrCl) decreased (p = 0.002). The decrease in BM was negatively related to the increase in CK (r = -0.71, p < 0.001). Δ Pcr was positively related to Δ PU (r = 0.64, p = 0.002). The decrease in CrCl was negatively associated with the increase in both PU (r = -0.72, p < 0.001) and CK (r = -0.48, p = 0.032). Conclusion: The 24-h running race under extremely cold conditions led to a significant BF decrease, whereas SM and TBW remained stable in both males and females. Nevertheless, the increase in CK, Pcr and PU was related to the damage of SM with transient impaired renal function.

• Klíčová slova
• 24 h, body composition, extreme weather conditions, ultra-running, winter,
• Publikační typ
• časopisecké články MeSH

Purpose: Excessive or inappropriate non-steroidal anti-inflammatory drug (NSAID) use during ultra-endurance events could cause potential risk to athletes' health. Reports on NSAID consumption in mountain bikers or ultra-mountain bikers are scarce. Therefore, the aim of this study was to investigate the prevalence of NSAID consumption immediately before, during and immediately after a mountain bike (MTB) race and to compare NSAID consumption in two different MTB competitions. Methods: This observational study took place at a three-stage MTB race (SMTB) (n = 63) and at a 24-h MTB race (24MTB) (n = 68), both held in the Czechia in 2017. NSAID consumption was evaluated via self-reported electronic questionnaires. Results: Of all finishers (n = 131), fourteen (10%) consumed NSAID at least once during the competition day (immediately before, during or immediately after the race). The number of NSAID consumers was the same in both competitions. Nevertheless, only three athletes (2%), all of them from the 24MTB, consumed NSAID during the race and 5% of all mountain bikers reported consumption after the race. In contrast to the SMTB, the intake reported by the 24MTB participants was quite homogeneous in terms of the timing of NSAID consumption. The NSAID users were older (p = 0.043) than the non-users. Ibuprofen was most commonly used by 79% of all consumers. Conclusion: The prevalence of NSAID use was higher in the older participants and seems to be lower in comparison with results from studies about runners, ultra-runners and triathletes suggesting that it is determined by the discipline (i.e., cycling). On the other hand, the timing of NSAID consumption was probably affected by the competition character (e.g., MTBS or 24MTB). Future studies should focus on a larger sample size of cyclists from various disciplines.

• Klíčová slova
• anti-inflammatory drug consumption, endurance, ibuprofen, mountain bikers, pain relief,
• Publikační typ
• časopisecké články MeSH

Purpose: Hypohydration and hyperhydration are significant disorders of fluid metabolism in endurance performance; however, little relevant data exist regarding multi-stage endurance activities. The aim of the present study was to examine the effect of running seven marathons in 7 consecutive days on selected anthropometric, hematological and biochemical characteristics with an emphasis on hydration status. Methods: Participants included 6 women and 20 men (age 42.6 ± 6.2 years). Data was collected before day 1 (B1) and after day 1 (A1), 4 (A4), and 7 (A7). Results: The average marathon race time was 4:44 h:min (ranging from 3:09 - 6:19 h:min). Plasma sodium, plasma potassium and urine sodium were maintained during the race. Body mass (p < 0.001, η2 = 0.501), body fat (p < 0.001, η2 = 0.572) and hematocrit (p < 0.001, η2 = 0.358) decreased. Plasma osmolality (Posm) (p < 0.001, η2 = 0.416), urine osmolality (Uosm) (p < 0.001, η2 = 0.465), urine potassium (p < 0.001, η2 = 0.507), urine specific gravity (Usg) (p < 0.001, η2 = 0.540), plasma urea (PUN) (p < 0.001, η2 = 0.586), urine urea (UUN) (p < 0.001, η2 = 0.532) and transtubular potassium gradient (p < 0.001, η2 = 0.560) increased at A1, A4, and A7 vs. B1. Posm correlated with PUN at A1 (r = 0.59, p = 0.001) and A4 (r = 0.58, p = 0.002). The reported post-race fluid intake was 0.5 ± 0.2 L/h and it correlated negatively with plasma [Na+] (r = -0.42, p = 0.007) at A4 and (r = -0.50, p = 0.009) at A7. Uosm was associated with UUN at A1 (r = 0.80, p < 0.001), at A4 (r = 0.81, p < 0.001) and at A7 (r = 0.86, p < 0.001) and with Usg (r = 0.71, p < 0.001) at A1, (r = 0.52, p = 0.006) at A4 and (r = 0.46, p = 0.02) at A7. Conclusions: Despite the decrease in body mass, fluid and electrolyte balance was maintained with no decrease in plasma volume after running seven marathons in seven consecutive days. Current findings support the hypothesis that body mass changes do not reflect changes in the hydration status during prolonged exercise.

• Klíčová slova
• endurance, hydration status, multi-stage marathon, running, sodium,
• Publikační typ
• časopisecké články MeSH