We report a high-throughput and label-free computational imaging technique that simultaneously measures in three-dimensional (3D) space the locomotion and angular spin of the freely moving heads of microswimmers and the beating patterns of their flagella over a sample volume more than two orders-of-magnitude larger compared to existing optical modalities. Using this platform, we quantified the 3D locomotion of 2133 bovine sperms and determined the spin axis and the angular velocity of the sperm head, providing the perspective of an observer seated at the moving and spinning sperm head. In this constantly transforming perspective, flagellum-beating patterns are decoupled from both the 3D translation and spin of the head, which provides the opportunity to truly investigate the 3D spatio-temporal kinematics of the flagellum. In addition to providing unprecedented information on the 3D locomotion of microswimmers, this computational imaging technique could also be instrumental for micro-robotics and sensing research, enabling the high-throughput quantification of the impact of various stimuli and chemicals on the 3D swimming patterns of sperms, motile bacteria and other micro-organisms, generating new insights into taxis behaviors and the underlying biophysics.

We aimed to analyze injury profiles and injury severity in Korean youth soccer players. Data on all injuries that occurred in U-15 youth soccer players during the 2019 season were collected from 681 players of 22 teams through a medical questionnaire. The questionnaire was based on injury surveillance procedures of the Federation International de Football Association Medical and Research Centre and International Olympic Committee, and it comprised questions on demographic characteristics, training conditions, and injury information. Among all players, defenders accounted for 33.0%, followed by attackers (30.7%), midfielders (26.8%), and goalkeepers (7.9%). Most players played soccer on artificial grounds (97.4%). Injuries occurred more frequently during training (56.3%) than during matches (43.7%). Recurrent injury rate was 4.4% and average days to return to full activities were 22.58. The ankle (26.6%) and knee joints (14.1%) were the most common injury locations, and ligament sprains (21.0%), contusions (15.6%), and fractures (13.9%) were the most frequent injury types. In conclusion, Korean youth soccer players have a high injury risk. Therefore, researchers and coaching staff need to consider these results as a key to prevent injuries in youth soccer players and injury prevention programs may help decrease injury rate by providing injury management.

Context: Because motions of one segment affect those of an adjacent segment, biomechanical studies must thoroughly investigate the kinematics and kinetics of the proximal joint as well as the ankle joints in patients with chronic ankle instability (CAI). However, there have been few investigations on the altered movement strategies of the lower extremities of patients with CAI compared with lateral ankle sprain (LAS) copers and controls throughout the full gait cycle of walking and jogging. Objective: To investigate biomechanical differences of the lower extremity in those with CAI, LAS copers, and controls during gait. Design: Case-control study. Setting: Controlled laboratory setting. Patients or Other Participants: Eighteen individuals with CAI (age: 24.6 ± 2.8, height: 173.0 ± 8.0, weight: 67.8 ± 14.6), eighteen LAS copers (age: 26.0 ± 4.6, height: 173.4 ± 7.5, weight: 66.9 ± 10.3), and eighteen controls (age: 26.2 ± 2.3, height: 172.2 ± 8.2, weight: 63.3 ± 11.2). Main Outcome Measure(s): Three-dimensional (3D) kinematics and kinetics of the lower extremity during walking and jogging. Results: Individuals with CAI exhibited dorsiflexion deficits and greater inverted ankles, compared with LAS copers and controls, during walking and jogging. In addition, LAS copers generated greater knee internal rotator moments than individuals with CAI. There were no differences in other variables between groups. Conclusions: Given the results from this study, participants with CAI demonstrated altered biomechanics, which needs addressing through intervention programs.

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