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• Ice slurry ingestion improves physical performance during high-intensity intermittent exercise in a hot environment

  Morito A., Inami T., Hirata A., Yamada S., Shimomasuda M., Haramoto M., Kato K., Tahara S., Oguma Y., Ishida H., Kohtake N.

  PLoS ONE （PLoS ONE)  17 （ 9 September ）  2022年09月

  　概要を見る

  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 gkg-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?Cbeverage (CON) having the same composition as ICE, or 30?C-water (WAT) during the halftime 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 2nd 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 2nd 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.

  • Access to Document (DOI)

• A comparison of physical characteristics in starters and non-starters in a Japanese university rugby football players

  Hirata A., Nakajima T., Iwamoto S., Oguma Y., Kotake N.

  Japanese Journal of Physical Fitness and Sports Medicine （Japanese Journal of Physical Fitness and Sports Medicine)  71 （ 6 ） 523 - 530 2022年

  ISSN  0039906X

  　概要を見る

  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.

  • Access to Document (DOI)

• Monitoring of Post-Brain Injuries By Measuring Plasma Levels of Neuron-Derived Extracellular Vesicles

  Hotta N., Tadokoro T., Henry J., Koga D., Kawata K., Ishida H., Oguma Y., Hirata A., Mitsuhashi M., Yoshitani K.

  Biomarker Insights （Biomarker Insights)  17 2022年

  　概要を見る

  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.

  • Access to Document (DOI)