We evaluated a range of physical characteristics related to hamstring injuries, as well as the Nordic Hamstring Exercise compliance rate, and whether this influenced the rate hamstring injury. Subjects comprised 259 male soccer players from seven high schools randomly clustered into two groups, a Nordic Hamstring Exercise group and a control group. Training and match time were logged, as well as details of hamstring injury, and subsequent time lost to hamstring injury recorded over a period of 27 weeks. The Nordic Hamstring Exercise compliance rate, injury rate per 10000 playing hours and time-lost-to-sport-injury rate were calculated. The relative risk and hamstring injury severity were also calculated. The hamstring injury rate was 1.04/10 000 h in the control group and 0.88/10 000 h in the intervention group. The relative risk for hamstring injury was 1.14. The time-lost to injury rate was 1116.3/10 000 h in the control group and 113.7/10 000 h in the intervention group; with relative risk 9.81. The Nordic Hamstring Exercise in high school soccer players significantly reduced hamstring injury severity compared to a control intervention. Our results indicate that the time-lost to injury rate should be taken into account when analyzing the severity of hamstring injury.

Background: In recent years, the functional movement screen (FMS) and FMS training have attracted attention as a means of preventing injury, but no studies have examined the effect of such training in high-school baseball players. The aim of this study was to clarify the effect of FMS training on FMS score, physical function and baseball performance in high-school baseball players. Methods: Subjects in this randomized controlled clinical trial were high-school male baseball players assigned to either an FMS training group (intervention group) or a control group. The intervention group performed FMS training 4 times per week for 12 weeks. FMS ability, physical function, and baseball performance were measured prior to the intervention, 8, 12, and 24 weeks after the intervention in the subjects’ school environment. Results: A total of 71 baseball players aged 15 to 17 years were recruited and assigned to either an intervention group (n = 37) or control group (n = 34). There was no significant difference in the characteristics of participants between the 2 groups. Most FMS scores improved to 12 weeks after continued training. In the intervention group compared with the control group, deep squat, hurdle step, inline lunge, active straight leg raise, trunk stability push-up and rotary stability FMS score, total FMS score and eyes closed single leg stance time significantly increased after 8 weeks of training. While hurdle step, inline lunge, active straight leg raise, trunk stability push-up, total FMS score, and eyes closed single leg stance time significantly increased, pitching ball speed significantly decreased at the end of the 12 week training period. Eyes closed single leg stance time and feeling of fatigue significantly improved 12 weeks after training. The number of subjects who scored less than 14 for the total FMS score in the intervention group compared with control group were significantly less after 8 and 12 weeks of FMS training. Conclusion: FMS training for 8 weeks contributes to improving FMS scores for high-school baseball players, but FMS scores go down if FMS training is not continued. Trial registration: University Hospital Medical Information Network Center, Tokyo, Japan: UMIN000027553. Registered on May 30, 2017.

To investigate the factors affecting the knee-flexion range of motion in the early period after total knee arthroplasty. [Participants and Methods] Ninety-nine patients who had undergone total knee arthroplasty at our hospital between 2016 and 2019 were allocated into two groups based on the presence of a 110° knee-flexion range of motion at 14 days post-surgery. From medical records, we extracted data for the participants' basic attributes and preoperative/postoperative physical function (knee-flexion range of motion, Timed Up & Go Test results, resting/walking pain according to a numerical rating scale, and knee-extension muscle strength). Postoperative physical function was measured 14 days post-surgery.[Results] Preoperative knee-flexion range of motion, preoperative femorotibial angle, postoperative knee-extensor strength, and postoperative Timed Up & Go Test value differed significantly as factors related to achieving a 110° knee-flexion range of motion. Through further statistical analyses, we selected the preoperative knee-flexion range of motion, preoperative femorotibial angle, preoperative Timed Up & Go Test result, and postoperative knee-extension strength as factors affecting the knee-flexion range of motion at 14 days post-surgery. [Conclusion] Preoperative knee-flexion range of motion, preoperative femorotibial angle, preoperative Timed Up & Go Test result, and postoperative knee-extension strength influence knee-flexion range of motion at 14 days after total knee arthroplasty, and our findings indicate the effectiveness of active physiotherapy interventions.