Background: Extracellular vesicles (EV) released from neurons into the blood can reflect the state of nervous tissue. Measurement of neuron derived EV (NDE) may serve as an indicator of brain injury. Methods: A sandwich immunoassay was established to measure plasma NDE using anti-neuron CD171 and anti-EV CD9 ([CD171 + CD9+]). Plasma samples were obtained from commercial sources, cross-country (n = 9), football (n = 22), soccer (n = 19), and rugby (n = 18) athletes over time. Plasma was also collected from patients undergoing total aortic arch replacement (TAR) with selective cerebral perfusion during cardiopulmonary bypass before and after surgery (n = 36). Results: The specificity, linearity, and reproducibility of NDE assay (measurement of [CD171 + CD9+]) were confirmed. By scanning electron microscopy and nanoparticle tracking, spherical vesicles ranging in size from 150 to 300 nm were confirmed. Plasma levels of NDE were widely spread over 2 to 3 logs in different individuals with a significant age-dependent decrease. However, NDE were very stable in each individual within a ± 50% change over time (cross-country, football, soccer), whereas rugby players were more variable over 4 years. In patients undergoing TAR, NDE increased rapidly in days post-surgery and were significantly ( P = .0004) higher in those developing postoperative delirium (POD) (n = 13) than non-delirium patients (n = 23). Conclusions: The blood test to determine plasma levels of NDE was established by a sandwich immunoassay using 2 antibodies against neuron (CD171) and exosomes (CD9). NDE levels varied widely in different individuals and decreased with age, indicating that NDE levels should be considered as a normalizer of NDE biomarker studies. However, NDE levels were stable over time in each individual, and increased rapidly after TAR with greater increases associated with patients developing POD. This assay may serve as a surrogate for evaluating and monitoring brain injuries.

The purpose of this study was to compare the characteristics of starters and nonstarters with respect to the anthropometric and physical fitness in a Japanese university rugby team. Our sample pool consisted of 54 players of the K University rugby team, who were registered for the official games (all 7 games/year) in 2018 and 2019. The starter group (26 players) comprised of players with more than 3 games/year while the non-starter group (28 players) comprised of players that registered for official games but played less than 3 games. Anthropometric parameters, such as height, body mass, skinfold (8 items), girth (5 items), body composition, muscular strength, intermittent endurance, and sprint time, were assessed. We found that the starter group for forwards had lower skinfold (Biceps, Iliac crest, Supraspinale, Abdominal, Front thigh, and Medial calf) and percentage body fat than in the non-starter group. The starter group for backs had muscle strength of narrow chinning is higher than in the non-starter group. Finally, our study helped to clarify the physical factors that influence the difference in athletic performance between starters and non-starters in university rugby team. The forward starters had lower percentage body fat and better body composition and backs starters had better narrow chinning. The findings provide information to university rugby players who want to become starters, as well as help the coaching staff understand the factors that need to be strengthened in the players.

Ice slurry ingestion enhances exercise performance by lowering the core body temperature. However, an operational issue related to this ingestion is the requirement for a high intake of 7.5 g·kg -1 to produce the desired effects. We investigated the effects of the intake of low amounts of ice slurry at −2°C on the tympanic temperature and exercise performance during repeated high-intensity intermittent exercises in a hot environment. This study was a randomized, crossover study, with a 6-day washout period. Twelve university rugby union players performed two 30-min sessions of high-intensity intermittent exercises separated by a 15-min half-time break on a cycle ergometer in a hot environment (28.8°C ± 0.1°C, 49.5% ± 0.6% relative humidity). The participants ingested 450 g of −2°C-ice slurry (ICE), or a 30°C-beverage (CON) having the same composition as ICE, or 30°C-water (WAT) during the half-time break. The tympanic temperature and skin temperature were measured as the physiological data, and the peak power and mean power as the exercise performance data. The tympanic temperature at the half-time break and beginning of the 2 nd session was significantly lower in the ICE group as compared with the CON and WAT groups. The skin temperature at the half-time break was significantly lower in the ICE group as compared with the WAT group. While the peak power and mean power during the 2 nd session were significantly greater in the ICE group as compared with the CON and WAT groups. Our findings suggest that even the intake of lower amounts, as compared with those used in previous studies, of low-temperature ice slurry can reduce the body temperature and improve the peak power. These results suggest that intake of low-temperature ice slurry as a strategy for internal body cooling is useful for improving endurance exercise performance in hot environments.

The aim of this study was to investigate the effect of ingestion of ice slurry before bedtime on the sleep quality of rugby union players in the summer season. Thirteen healthy male university rugby union players volunteered for this study. The participants ingested either ice slurry or a room-temperature beverage (control) 30 min before bedtime. A wearable activity-based sleep monitor was used to analyze objective sleep parameters, and the subjective sleep scores were assessed using the Oguri–Shirakawa–Azumi Sleep Inventory, middle-aged and aged version (OSA-MA). No differences in the amount or efficiency of sleep were observed between the ice slurry/control beverage conditions. Significant shortening of the sleep latency was observed in the ice slurry condition as compared with the control beverage condition. Moreover, significant improvement of the subjective sleep score for “feeling refreshed” on the OSA-MA was observed in the ice slurry condition. There were no significant differences in the other subjective sleep scores between the two conditions. The results suggest that ice slurry ingestion before bedtime may improve the latency of sleep onset, accelerate recovery from fatigue, and be useful as a sleep improvement strategy in rugby union players engaging in exercises during the summer season.

Delayed recovery of the core body temperature after exercise adversely affects physiological functions, and the effects of ingesting lower-temperature ice slurry on post-exercise recovery remain unclear. We investigated the effects of ingesting −2 °C ice slurry on physiological recovery after field-based rugby union training. Fifteen university rugby union players participated in our randomized controlled study. The players participated in the training for 60 min in a hot outdoor environment (wet-bulb globe temperature, 30.5 °C). Physiological responses were measured during a physical performance test performed after the players ingested either −2 °C-ice slurry (ICE, N = 7) at 5 g/kg body mass or a 30 °C-fluid (CON, N = 8) during the 15 min recovery period after the training. Tympanic temperatures and heart rates were measured as the physiological indices, as well as heat storage. The ICE group showed significantly decreased tympanic temperatures and heart rates (p < 0.05) during the recovery period and increased heat storage (p < 0.05) but did not show improvement of physiological indices during the performance test compared to the CON group. These results suggest that ingestion of −2 °C ice slurry in even lower amounts than those previously reported is useful for physiological recovery after training in hot outdoor environments.