Heart Rate Variability (HRV) has been typically used to monitor athletes' physical fitness readiness. The supine position maximizes parasympathetic tone, which is important for monitoring in continuous aerobic sports, however, this is not the case of team sports that rely on anaerobic intermittent bouts, thus increasing sympathetic activation and vagal withdrawal. We hypothesized that HRV during sympathetic activation and vagal withdrawal would be a useful marker to evaluate perceived physical fitness in team sports. HRV was measured in both supine and standing positions during the mornings of 4 match days in 14 professional players. The supine Root Mean Square of the Successive Differences (RMSSD), as well as spectral analysis indices were recorded. Perceived physical fitness was assessed after each match by means of a visual analogue scale (VAS). Supine RMSSD was moderately correlated with perceived physical fitness (rho = 0.416), however, larger correlations were observed for supine and standing spectral indices (rho > 0.5). Correlation between RMSSD and Total Power was very large, thus questioning the usual interpretation of RMSSD (rho > 0.7). Standing Spectral HRV analyses may be a useful method for evaluating perceived physical fitness in the context of team sports. RMSSD may reflect the overall variability of HR and not only the parasympathetic influence, as observed in the current study. © 2020 Guillaume Ravé, Hassane Zouhal, Daniel Boullosa, Patricia K. Doyle-Baker, Ayoub Saeidi, Abderraouf Ben Abderrahman, Jacques-Olivier Fortrat, published by Sciendo.This review aimed to analyse factors that limited performance in ultra-marathons and mountain ultra-marathons. A literature search in one database (PubMed) was conducted in February 2019. Quality of information of the articles was evaluated using the Oxford´s level of evidence and the Physiotherapy Evidence Database (PEDro) scale. The search strategy yielded 111 total citations from which 23 met the inclusion criteria. Twenty one of the 23 included studies had a level of evidence 2b (individual cohort study), while the 2 remaining studies had a level of evidence of 5 (expert opinion).  https://www.selleckchem.com/products/ziritaxestat.html  Also, the mean score in the PEDro scale was 3.65 ± 1.61, with values ranging from 0 to 7. Participants were characterised as experienced or well-trained athletes in all of the studies. The total number of participants was 1002 (893 men, 86 women and 23 unknown). The findings of this review suggest that fatigue in ultra-endurance events is a multifactorial phenomenon that includes physiological, neuromuscular, biomechanical and cognitive factors. Improved exercise performance during ultra-endurance events seems to be related to higher VO2max values and maximal aerobic speed (especially during submaximal efforts sustained over a long time), lower oxygen cost of transport and greater running experience. © 2020 Arkaitz Garbisu-Hualde, Jordan Santos-Concejero, published by Sciendo.Numerous oral ketone supplements are marketed with the claim that they will rapidly induce ketosis and improve exercise performance. The purpose of this study was to assess exercise performance time and related physiological, metabolic and perceptual responses of recreational endurance runners after ingestion of a commercially available oral ketone supplement. Recreational endurance runners (n = 10; age 20.8 ± 1.0 years; body mass 68.9 ± 5.6 kg; height 175.6 ± 4.9 cm) participated in a double-blind, crossover, repeated-measures study where they were randomized to 300 mg.kg-1 body weight of an oral β-hydroxybutyrate-salt + Medium Chain Triglyceride (βHB-salt+MCT) ketone supplement or a flavor matched placebo (PLA) 60 min prior to performing a 5-km running time trial (5KTT) on a treadmill. Time, HR, RPE, affect, RER, VO2, VCO2, and VE were measured during the 5-km run. The Session RPE and affect (Feeling Scale) were obtained post-5KTT. Plasma glucose, lactate and ketones were measured at baseline, 60-min post-supplement, and immediately post-5KTT. Plasma R-βHB (endogenous isomer) was elevated from baseline and throughout the entire protocol under the βHB-salt+MCT condition (p 0.05) were noted in any of the other physiological, metabolic or perceptual measures. © 2020 Philip J. Prins, Andrew P. Koutnik, Dominic P. D’Agostino, Christopher Q. Rogers, Jacob F. Seibert, Jillian A. Breckenridge, Daniel S. Jackson, Edward J. Ryan, Jeffrey D. Buxton, Dana L. Ault, published by Sciendo.Aspirin is a common nonsteroidal anti-inflammatory drug used to reduce fever, pain, and inflammation. However, aspirin's anti-inflammatory properties may also prevent increased levels of blood lactate dehydrogenase, vascular arterial stiffness and oxidative stress induced by high-intensity exercise. The purpose of this study was to investigate the effects of 4 weeks of aspirin supplementation on lactate dehydrogenase activity, lactate, arterial stiffness, and antioxidant capacity during high-intensity exercise in Taekwondo athletes. Participants were randomly divided into two groups aspirin supplementation (n = 10) and placebo-control (n = 10). Blood levels of lactate dehydrogenase (LDH) enzyme activity and lactate were assessed to examine muscle damage and carotid-to-radial pulse wave velocity and the augmentation index were measured to examine arterial stiffness. Blood levels of superoxide dismutase, malondialdehyde, and glutathione peroxidase were assessed to determine antioxidant capacity and levels of ox Sciendo.The aim of this study was to investigate changes in physical and physiological responses to different modes of repeated sprint exercise by measuring speed, total time (sum of sprints), fatigue index, heart rate, local oxygen saturation, total haemoglobin content, and blood lactate. The volume of the physical load (distance, work and rest ratio) was the same in both exercises, but load specifics were different. The first mode consisted of 10 x 30 m sprints (with one change of direction) interspersed with 30 s of passive recovery, while the second mode of 20 x 15 m shuttle sprints interspersed with 15 s of passive recovery. Both exercise modalities were repeated three times with a five-minute rest interval between bouts with 7 days of recovery between each testing condition. Twelve highly trained male basketball players volunteered to participate in this study. Our study showed that different modes of repeated sprint exercises elicited a different physical response and metabolic demand. Longer sprints with directional changes placed a higher demand on the anaerobic glycolytic system compared to straight and more frequent sprint exercises.