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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.
(MDPI, 2019-08-26) Knechtle, Beat; Chlíbková, Daniela; Papadopoulou, Sousana; Mantzorou, Maria; Rosemann, Thomas; Nikolaidis, Pantelis T.
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).
Changes in foot volume, body composition, and hydration status in male and female 24-hour ultra-mountain bikers
(BioMed Central, 2014-03-24) Chlíbková, Daniela
The effects of running and cycling on changes in hydration status and body composition during a 24-hour race have been described previously, but data for 24-hour ultra-mountain bikers are missing. The present study investigated changes in foot volume, body composition, and hydration status in male and female 24-hour ultra-mountain bikers.
The Effect of a 100-km Ultra-Marathon under Freezing Conditions on Selected Immunological and Hematological Parameters
(FRONTIERS MEDIA SA, 2017-09-12) Žákovská, Alena; Knechtle, Beat; Chlíbková, Daniela; Miličková, Marie; Rosemann, Thomas; Nikolaidis, Pantelis T.
Although moderate exercise is beneficial for the human body and its immune system, exhaustive ultra-endurance performance in cold conditions might be harmful. The aim of this study was to examine the effect of a 100-km ultra-marathon under cold conditions (temperatures from -1 degrees C to + 1 degrees C) on selected immunological, biochemical and hematological parameters. Participants were 15 runners (12 men and three women, age 40.3 +/- 9.7 years, body mass 67.3 +/- 9.0 kg and body height 1.74 +/- 0.10 m, mean +/- standard deviation). Leukocytes increased (p < 0.01) and, particularly, the number of leucocytes doubled in seven out of 15 athletes. Immature neutrophils, mature neutrophils and monocytes increased (p < 0.02), whereas lymphocytes and eosinophils did not change. IgG increased (p < 0.02), but IgA and IgM remained unchanged. Platelets increased (p < 0.01), whereas red blood cells, hematocrit and hemoglobin did not change. lactate dehydrogenase (LDH) and creatine kinase (CK) increased (p < 0.01), but alanine aminotransferase (ALT) did not change. There was an association between the markers of the acute inflammation of the organism (i.e., neutrophils, immature neutrophils, platelets, and monocytes) and the markers of muscle damage (i.e., CK, platelets, and LDH). There were no relationships among all the markers in relation to upper respiratory tract infections and liver damage. The highest change was noted in the increase of the number of immature neutrophils (1,019.2%) and CK levels (1,077.6%). In summary, this is the first study investigating immunological, hematological and biochemical parameters and showing that running a 100-km ultra-marathon under cold conditions leads to changes in several immunological, biochemical and hematological parameters indicating a severe stress on the body associated with increasing susceptibility to the development of infections.
Intra- and inter-individual variability in the underwater pull-out technique in 200 m breaststroke turns
(PUBLIC LIBRARY SCIENCE, 2023-03-21) Gonjo, Tomohiro; Olstad, Bjrn H.; Šťastný, Jan; Conceiço, Ana; Seifert, Ludovic
The purpose of the present study was to investigate the intra- and inter-individual variability in arm-leg coordination during the underwater phase of the turn segment in 200 m breaststroke. Thirteen male swimmers were recruited and performed a 200 m breaststroke in a pre-calibrated 25 m pool. Sub-phases during the underwater segment were obtained using a notational analysis, and the mean velocity, displacement and duration during each sub-phase were obtained. A hierarchical cluster analysis (HCA) was performed using the analysed variables in all phases to identify inter-individual variability and random intra-individual variability. In addition, a linear mixed model (LMM: lap as a fixed effect and the participant as a random effect) was conducted to investigate systematic intra-individual variability. HCA identified three coordination patterns that were distinguished by the timing of the dolphin kick relative to the arm pull-out and the duration of the glide with arms at the side. All swimmers except one performed the arm pull-out after the dolphin kick. Nine swimmers maintained one coordination pattern, but other swimmers switched their coordination during the trial, particularly by shortening the duration of the glide with arms at the side. LMM showed a linear decrease (from the first to the last turn) in the time gap between the end of the dolphin kick and the start of the arm pull-out (a glide with the streamlined body position; F = 9.64, p = 0.034) and the glide duration with the arms at the side (F = 11.66, p = 0.015). In conclusion, both inter- and intra-individual variabilities during the underwater phase were evident in 200 m breaststroke turns, which were categorised into three patterns based on the timing of the dolphin kick and the duration of glides.
Training, anthropometric and physiological characteristics in men recreational marathon runners: The role of sport experience
(Frontiers, 2021-03-15) Nikolaidis, Pantelis T.; Chlíbková, Daniela; Clemente-Suárez, Vicente Javier; Knechtle, Beat
The aim of the present study was to examine physiological and training characteristics in marathon runners with different sport experience (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), 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.

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