The Role and the Function of Japan Institute of Sports Sciences and National Training Center in Japan

Gold Medals in Summer Qlympics Measures A 1) Program to develop junior athletes to top level 2) National Training Center 3) National Coach Academy B 1) Sports medicine and sciences(JISS) 2) Anti-doping 3) To hold international

The Effect of Hamstring Stretching on Muscle Hardness and Isokinetic Muscle Performance

The purpose of this study was to clarify the effects and the time course of moderate hamstring stretching on the hardness and strength of the knee flexor muscles. Thirteen young adults performed static stretching of their hamstrings （2 minx 3 repetitions）. Before and after the static stretching, muscle hardness and concentric isokinetic torque of the knee flexors （180~/s） was determined. The hardness of the long head of the BF （biceps femoris） muscle was measured by using shear wave ultrasound elastography images. To follow the time course of the stretching effects, we determined the above parameters before, immediately after, and every 10 min for torque and every 5 min for muscle hardness until 30 min after stretching. Muscle hardness of the BF significantly decreased when compared with before the stretching （P 〈 0.001）, and remained significantly reduced until 25 min. However, the knee flexion torque did not show any change at any timing. As seen in this experiment, moderate stretching decreased the muscle hardness of the BF without a decline in the knee flexion torque. Thus, these findings suggest that moderate stretching is useful as a warm-up maneuver.

Anthropometric and Physical Performance Profiles of High School Age American Football Players: 11th and 12th Grade Japanese Athletes

Purpose To compare anthropometric and physical performance profiles of Japanese 11th and 12th grade American football players within each positional group.Methods Fifty-two 11th and 12th grade American football players from two Japanese high schools participated in the study during the summer pre-season period.They performed anthropometric(height and body mass)and physical(vertical jump,broad jump,40-yard dash,pro-agility shuttle 4-kg medicine ball chest throw,front throw,and back throw)testing.Vertical jump momentum and 10-yard sprint momentum were also calculated by multiplying the velocity and body mass.Athletes were divided into two groups by playing positions:skill players and linemen.Results Skill players in the 12th grade were better at medicine ball chest throw(d=0.73,P=0.04)and vertical jump momen-tum(d=0.75,P=0.03)than those in the 11th grade.However,there were no differences in any measurements(P>0.05)between linemen from the two grades.Conclusion The current study suggests that upper and lower body absolute power and momentum production can be improved for skill players even over 17 years old.On the other hand,body size and speed,attributes that did not change between 11th and 12th grades,seem to be essential talent identification criteria in the current environment.Further study is needed to monitor longitudinal performance improvements in implementing talent development programs by focusing on the quality of speed,agility and power development at the youth level.

Prolonged Intermittent Running Induces Inspiratory-Muscle Fatigue in Female Runners

Inspiratory-muscle fatigue （IMF） may occur after long-duration or continuous short-duration exercise and may limit exercise performance. Daily athletics training is often intermittent, but it is unclear if intermittent running induces IMF. We investigated IMF after a maximal anaerobic running test （MART） and maximal intermittent graded exercise test. Nine female middle-distance （400 or 800 m） runners performed MART and maximal intermittent graded exercise tests. Maximal inspiratory pressure （MIP） was measured before and after each test using a portable autospirometer. There was no significant difference in mean MIPs before （105 ± 24 cm H2O） and after （104 ± 28 cm H2O） the MART （P = 0.95, effect size [ES] as partial η2 = 0.01）. Mean M IP after the maximal intermittent graded exercise test （97 ± 26 cm H2O） was lower than before exercise （105 ± 27 cm H2O） （P = 0.01, 1]2 = 0.83） Mean IMF was higher for the maximal intermittent graded exercise test （8.5 ± 4.2 cm H2O） than for the MART （0.8 ± 4.1 cm H2O） （P = 0.01, ES as Cohen＇s d = 1.88）. IMF occurs after relatively long-duration intermittent running exercise. Coaches may consider recommending inspiratory-muscle training or warm-up to reduce IMF resulting from relatively long-duration intermittent running exercise.

Mild Decrease in Skin Temperature Reduces the Heart Rate during Moderate Exercise

The purpose of this study was to investigate the effects of a mild decrease in skin temperature on the heart rate, substrate oxidation, and hormonal responses during exercise. Ten young men performed treadmill exercises approximately 65% of their maximal oxygen uptake for 60 min under two trials： （1） mild body cooling trial, and （2） control trial. Rectal and skin temperatures were recorded during and after exercise. Heart rate and oxygen uptake were monitored during exercise. Blood samples for catecholamine, cortisol, free fatty acid, insulin, and glucose concentrations were collected before, immediately after, and 1 h after exercise. In the mild body cooling trial, mean skin temperature decreased by 1.7 ＋ 0.7~C in the last minutes of exercise, compared with before exercise. No differences in rectal temperature were seen between the two trials. Although oxygen uptake during exercise and blood parameters did not differ between the trials, heart rate and subjective fatigue during exercise was lower in the mild body cooling trial than in the control trial. This study suggests that mild body cooling reduces the heart rate and subjective fatigue during moderate exercise, but does not affect substrate oxidation or hormonal responses to exercise.