Yasushi Ikuta

This study aimed to estimate the factors that cause differences in competition level based on the competition performance structure among university student decathletes in Japan. The results of factor analysis using the maximum likelihood method (Oblimin rotation), assuming a five-factor structure estimated from parallel analysis and the information criterion, revealed the following competitive performance structures: "running speed and body projection,” "running endurance,” "rotational throwing power,” "translational throwing power,” and "vertical leaping power.” Some of these were similar to the competitive performance structures of the world’s top athletes, but they were found to have a unique structure: two throwing powers. The analysis results using latent rank theory allowed us to evaluate them on a seven-point scale. The calculated item reference profile, difficulty index, and discrimination index for each rank indicated that shot put and 100 and 400 m performance formed the basis of decathlon performance. In addition, high jump and pole vault, which fall under the category of "vertical leaping power," retained high difficulty and discrimination and were revealed to affect the stage of achievement of overall performance in the decathlon.

The study aims to test three hypotheses: (a) the rotation of the upper trunk consists of roll, pitch and yaw of frequencies harmonic to the stroke frequency of the front crawl stroke, (b) the rotation of the upper trunk generates back-and-forth movements of the shoulders, which enhances the movements of the stroking arms, and (c) the angular velocities of roll, pitch and yaw are associated with hand propulsion (HP). Front crawl strokes performed by twenty male swimmers were measured with a motion capture system. The roll, pitch and yaw angles about the three orthogonal axes embedded in the upper trunk were determined as three sequential Cardan angles and their angular velocities were determined as the three respective components of the angular velocity. HP and the drag and lift components of HP (HPD and HPL) were estimated by the hand positions and the data from twelve pressure sensors attached on hands. The roll, pitch, and yaw angles were altered in frequencies harmonic to the stroke frequency during the front crawl stroke. Shoulders alternately moved back and forth due to the upper trunk rotation. In the pull phase the angular velocity of roll was correlated with HPL (r = -0.62, p = 0.004). Based on the back-and-forth movements of the shoulders and roll motion relative to a hand movement, the arm-stroke technique of the front crawl swimming was discussed in terms of increasing the hand velocity and HP.

高アミロース米の血糖上昇抑制効果に関する報告は複数あるが、日本人を対象とした報告は少ない。そこで、日本人を対象に、高アミロース米「越のかおり」米飯摂取後の血糖応答について検討した。また、加水量を増やし柔らかく炊き上げた高アミロース米飯を用意し、水分量の違いが血糖応答に与える影響についても検証した。試験は健常成人を対象とした二重盲検の無作為化クロスオーバー試験とし、糖質50gを含む3種の米飯(通常加水コシヒカリ、通常加水越のかおり、高加水越のかおり)を用いた。通常加水越のかおりは通常加水コシヒカリと比較し、食後の血糖上昇を有意に抑えた。一方、高加水越のかおりには血糖上昇抑制効果が認められなかった。越のかおりは食後血糖値の急激な上昇を抑えることから糖尿病食事療法等に有用である可能性が示唆されたが、食味と機能性のバランスを両立させた調理方法については更なる検証が必要である。(著者抄録)