サッカーのインステップキックにおけるボール速度と蹴り脚と支持脚の関節運動

The purpose of this study is to investigate the joint movement of the lower legs and the velocity of the ball in an instep kick made as powerful as possible. Subjects were 8 male students who were skilled members of the high school soccer club, including 2 members from Aichi Prefecture. In this study, the velocity of the ball both the kicking leg and the supporting legs the variation of the hip, knee and ankle of angle were analyzed using a high-speed video camera operated at 200 fps during the kicking. The results were as follows. (1) The mean velocity of the ball obtained from these subjects (29.3±1. 1m/s) was significantly higher than that of other high school players. (2) The range of the hip, knee and ankle angle showed little variations in the following phases. In the phase from the foot released until planted, the degree of variation of the hip and knee in the kicking leg and hip in the supporting leg was little. In the phase from the foot landing until the foot impacted the ball, the range of the angle variation of the hip, knee and ankle in the supporting leg was little. In the phase from the foot impacting the ball to when the follow-swing reached the maximum level, the range of the angle variation of the hip and knee in the kicking leg and of the hip in the supporting leg was also small. (3) The hip of the kicking leg started to flex from the foot release until it landed. The hip of the supporting leg started to extend about the same time. In other words, the joint movement of the hip was antithetical, where as the joint movement of the knee and ankle were not. In particular, by keeping the knee of the supporting leg fixed, the knee of the kicking leg started to extend

サッカーのインステップキックにおけるボール速度と支持脚との関係とその基本的役割

The purpose of this study is to investigate the relation between the joint angle and horizontal velocity of the supporting leg and the velocity of the ball by an instep kick as powerful as possible. Subjects were 3 male students who were skilled members of the college soccer club and 3 male non-skilled persons. In this study, the velocity of the ball, foot, greater trochanters and knee and angle of the knee were analyzed three-dimensionally (3-D). The results were as follows : (1) A significant correlation (r=0.903) was found between the velocity of the ball and the velocity of the foot. (2) Skilled persons kicked the ball using good waist rotation. This rotation is a factor which increases the velocity of the ball. (3) Skilled persons fixed the supporting leg, the angle of the knee was about 150 degrees and the velocity of the knee was lower than in non-skilled persons

野球のピッチング動作における踏み出し脚の運動がボール初速度に与える影響

This study deals with how stepping leg and waist motion are related to initial velocity, while practicing baseball pitching. Six pitchers belonging to the university baseball team did the actual pitching for this study and were filmed using the direct linear transformation method of three-dimensional (3D) videography. Several factors determine the initial velocity. Toyoshima^ mentions that the sharp rotation of the waist is one of the big factors. Moreover, the importance of the lower limbs is frequently mentioned on the actual coaching scene. The results of this study are mentioned below. 1. The waist changes its motion from advance to rotating 0.1 sec before the foot lands on the ground, and the right trochanter major speeds up by slowing down the left trochanter major while the waist rotates sharply. 2. It is possible to speed up the waist angular velocity by fixing the joints of the knee and the legs when the foot is landing

Atrial Fibrillation Detection and Ischemic Stroke Recurrence in Cryptogenic Stroke: A Retrospective, Multicenter, Observational Study

Todo K., Okazaki S., Doijiri R., et al. Atrial Fibrillation Detection and Ischemic Stroke Recurrence in Cryptogenic Stroke: A Retrospective, Multicenter, Observational Study. Journal of the American Heart Association 13, e031508 (2024); https://doi.org/10.1161/JAHA.123.031508.BACKGROUND: Atrial fibrillation (AF) is known to be a strong risk factor for stroke. However, the risk of stroke recurrence in patients with cryptogenic stroke with AF detected after stroke by an insertable cardiac monitor (ICM) is not well known. We sought to evaluate the risk of ischemic stroke recurrence in patients with cryptogenic stroke with and without ICM-detected AF. METHODS AND RESULTS: We retrospectively reviewed patients with cryptogenic stroke who underwent ICM implantation at 8 stroke centers in Japan. Cox regression models were developed using landmark analysis and time-dependent analysis. We set the target sample size at 300 patients based on our estimate of the annualized incidence of ischemic stroke recurrence to be 3% in patients without AF detection and 9% in patients with AF detection. Of the 370 patients, 121 were found to have AF, and 110 received anticoagulation therapy after AF detection. The incidence of ischemic stroke recurrence was 4.0% in 249 patients without AF detection and 5.8% in 121 patients with AF detection (P=0.45). In a landmark analysis, the risk of ischemic stroke recurrence was not higher in patients with AF detected ≤90 days than in those without (hazard ratio, 1.47 [95% CI, 0.41–5.28]). In a time-dependent analysis, the risk of ischemic stroke recurrence did not increase after AF detection (hazard ratio, 1.77 [95% CI, 0.70–4.47]). CONCLUSIONS: The risk of ischemic stroke recurrence in patients with cryptogenic stroke with ICM-detected AF, 90% of whom were subsequently anticoagulated, was not higher than in those without ICM-detected AF