This study aimed to examine the effects of college baseball pitching on movement, performance, physical strength, and physiological and psychological functions of pitchers. The participants were 10 right-handed male pitchers from the University baseball team. The number of pitches were 15 per inning and 135 per nine innings. Ball speed and accuracy were measured for each pitching. The grip strength, back muscle strength, and standing long jump were measured before and after all pitches. Blood lactate levels were measured before pitching, at the end of the 5th and 7th innings, and at 3rd, 6th, and 9th minutes after pitching. The participant’s heart rate and subjective exercise intensity were measured at the beginning and end of each inning using the Borg scale measurement. Five high-speed cameras were used to capture the pitching motions. The displacement of the center of gravity, lower and upper limb joint angles, and the speed of each segment were calculated. The baseball speed and accuracy did not change with the increased number of pitches. However, the grip strength decreased. Although blood lactate and heart rate were not altered, subjective exercise intensity was increased. The lower limb kinematics remained unchanged; however, elbow height was reduced in the upper limb. These results suggest that highly competitive pitchers experience subjective fatigue with the increased number of pitches, however, they maintain pitch performance, speed, and accuracy without altering whole-body physiology and lower-body function and form.

Single-tooth sandals under new development have special material and shape characteristics. Exercises with single-tooth sandals can increase pressing stimulus on the soles of the feet, thereby suppressing a decline in medial longitudinal arch and elevating sole surface temperature. This study thus aimed to examine the effects of exercise with single-tooth sandals on medial longitudinal arch and sole surface temperature. Sixteen young adults (23 ± 5 years) participated in 20 min of stepping exercise on the spot. They randomly put on a regular normal sandal (N conditions) or a single-tooth sandal (Z conditions) on each left and right side. Before and after exercise, medial longitudinal arch and sole surface temperature were assessed by digital caliper and straightedge and thermography, respectively. No significant differences in baseline parameters were observed between N and Z conditions. After exercise, arch height and arch height ratio significantly reduced in N conditions, but not in Z conditions. Central sole surface temperature in Z conditions also increased significantly, and the changes in surface temperature were significantly higher in Z conditions than in N conditions. Therefore, these findings suggest that exercise with single-tooth sandals has a positive effect on a suppressing decline in medial longitudinal arch and an elevation in sole surface temperature.

The purpose of this study was to describe the incidence, severity, and burden of injuries in Japanese male collegiate rugby union players. Initially, 170 male collegiate rugby union players from one university club were registered in this epidemiological surveillance study. The occurrence of injuries was recorded by a team medical staff during the 2017–2021 playing seasons. The incidence of injuries was 6.87 injuries/1000 h. This incidence was significantly higher during matches (100.37 injuries/1000 h) than that during training (3.63 injuries/1000 h). The severity of injuries was 31.0 days, and there were no significant differences between matches and training, or forwards and backs. The burden of injuries was 213.1 days/1000 h. This burden was significantly higher during matches (2887.8 days/1000 h) compared to training (120.1 days/1000 h). Matches had higher incidence of ankle sprain/ligament injuries (15.80 injuries/1000 h) and concussion (15.36 injuries/1000 h). The most common injury site was the ankle (1.24 injuries/1000 h). However, the greatest severity and burden were observed for knee injuries (severity: 59.1 days, burden: 48.6 days/1000 h). Furthermore, the greatest burden of injury type was knee sprain/ligament injuries (39.4 days/1000 h). In addition, the incidence of acromioclavicular joint injury was significantly higher in forwards, whereas hamstring strain was significantly higher in backs. The common injury mechanisms identified were being tackled (16.0%) and tackling (14.7%), followed by overuse (12.1%). In order to improve the player welfare of the Japanese collegiate rugby union players, it is necessary to work on the prevention strategy considering the injury profile.

Previous study reported that baseball pitchers had a decreased shoulder internal rotation (IR) range of motion after pitching. However, whether the decreased range of motion associated with pitching is caused by tightness of the posterior shoulder has not been clarified yet. The joint stiffness in the passive torque can be compared with posterior shoulder tightness before and after pitching. Hence, this study aimed to compare shoulder IR stiffness based on passive torque before and after pitching in baseball pitcher. Eleven health male collage baseball pitchers were recruited. Passive torque during IR (max IR, peak torque and stiffness) of dominant and non-dominant arms was measured using an isokinetic dynamometer. Measurements were taken before, after, and post 24 hours after pitching (105 pitches). It was observed that after pitching, max IR and peak torque were significantly decreased compared to those before pitching. However, there was no difference in the stiffness of passive torque among three measurements. In conclusion, healthy college baseball pitchers have a decreased IR range of motion after pitching. However, this result is not due to posterior shoulder tissue tightness, but because of altered stretch tolerance.

The purpose of this study was to determine the developmental pattern of swing speed in youth baseball players between 6 and 14 years old. A total of 1213 baseball players performed toss batting. Swing speed was measured with a specialized accelerometer. In addition, 618 of the 1213 players were measured for total fat free mass by using Inbody770. In study1, Regression analysis was performed on the relationship between chronological age or height and swing speed, and the extreme values were calculated. Then, an allometric equation based on height was also used to estimate the relative growth of swing speed and total fat free mass and to compare the difference of relative growth patterns between swing speed and total fat free mass in study2. Swing speed was strongly related to both chronological age and height, with cubic regression for the relationship with chronological age and linear for the relationship with height. The regression equation obtained for chronological age was solved and found that developmental rate was maximal at approximately 10.25 years old. Allometric analysis showed that the developmental pattern of swing speed differed from that of fat free mass, with a temporary decline in developmental rate from 153.6 cm to 160.9 cm. Based on the results of this study, further research in youth baseball players would be expected to identify the factors causing sluggish development of swing speed as well as to develop an exercise program for improving batting ability.