ABSTRACT
This study investigated the changes in physical inactivity of university students during the COVID-19 pandemic, with reference to their academic calendar. We used the daily step counts recorded by a smartphone application (iPhone Health App) from April 2020 to January 2021 (287 days) for 603 students. The data for 287 days were divided into five periods based on their academic calendar. The median value of daily step counts across each period was calculated. A k-means clustering analysis was performed to classify the 603 participants into subgroups to demonstrate the variability in the physical inactivity responses. The median daily step counts, with a 7-days moving average, dramatically decreased from 5,000 to 2,000 steps/day in early April. It remained at a lower level (less than 2,000 steps/day) during the first semester, then increased to more than 5,000 steps/day at the start of summer vacation. The clustering analysis demonstrated the variability in physical inactivity responses. Independent of the academic calendar, many inactive students did not recover their original daily step counts after its dramatic decrement. Consequently, promoting physical activity is recommended for inactive university students over the course of the whole semester.
ABSTRACT
BackgroundThe COVID-19 pandemic has negatively impacted sporting activities across the world. However, practical training strategies for athletes to reduce the risk of infection during the pandemic has not been definitively studied. ObjectiveThe purpose of this report was to provide an overview of our challenges encountered during the reboot of high-performance sporting activities of the Japanese national handball team during the 3rd wave of the COVID-19 pandemic in Tokyo, Japan. MethodsTwenty-nine Japanese national womens handball players and 24 staff participated in the study. To initiate the reboot of their first training camp after COVID-19 stay-home social policy, we conducted: web-based health-monitoring, SARS-CoV-2 screening with polymerase chain reaction (PCR) test, real-time automated quantitative monitoring of social distancing on-court using video-based artificial intelligence (AI) algorithm, physical intensity evaluation with wearable heart rate (HR) and acceleration sensors, and self-reported online questionnaire. ResultsThe training camp was conducted successfully with no COVID-19 infections. The web-based health monitoring and the frequent PCR testing with short turnaround times contributed remarkably in early detection of athletes health problems and risk screening. During handball, the AI based on-court social-distancing monitoring revealed key time-dependent spatial metrics to define player-to-player proximity. This information facilitated positive team members on and off-game distancing behavior. Athletes regularly achieved around 80% of maximum HR during training, indicating anticipated improvements in achieving their physical intensities. Self-reported questionnaires related to the COVID management in the training camp revealed a sense of security among the athletes allowing them to focus singularly on their training. ConclusionThe current challenge provided us considerable know-how to create and manage a safe environment for high-performing athletes in the COVID-19 pandemic via the Japan Sports-Cyber Physical System (JS-CPS) of SRIP (Japan Sports Agency, Tokyo, Japan). This report is envisioned to provide informed decisions to coaches, trainers, policymakers from the sports federations in creating targeted, infection-free, sporting and training environments.
ABSTRACT
The purpose of this study was to increase knowledge about the landing posture that induces anterior cruciate ligament (ACL) injury. Analysis was done to determine the knee abduction moment during single limb landing using our previously proposed mathematical model. Our model has proven that the criterion of knee abduction occurring is when the acting line of the ground reaction force is directed laterally to the lower leg segment. Based on this, we predicted a medial shift of the knee joint and a lateral leaning of the trunk segment to induce the knee abduction moment. To verify the results of our model prediction, we conducted a motion analysis experiment with a single limb-landing task. Three male and four female subjects participated in the experiment. Subjects were instructed to fall from a 30 cm high box and land on a target which was assigned by PC-controlled laser pointers. Since the landing target was unexpectedly moved during landing, the subjects were perturbed and exhibited various landing postures. The results of the landing experiment showed that trunk leaning laterally towards the landing limb and medially shifted knee alignment induced the knee abduction moment. These results are consistent with the results predicted by our model. In conclusion, appropriate control of both lower limb alignment and trunk motion in the frontal plane in essential for reducing the risk of ACL injury.
ABSTRACT
The aim of this study is to examine the potential of the two-dimensional posture evaluation method as a screening tool for detecting the high-risk population for anterior cruciate ligament injury.Eleven healthy adults participated in this study. They jumped from a 31 cm-high box and landed on their dominant leg. Three-dimensional knee flexion/extension, knee valgus/varus and hip adduction/abduction angle during single-legged landing were calculated. At the same time, the Frontal-plane Knee Displacement index (FKD)-the knee joint position relative to the line between the hip and ankle joint-was measured.FKD reflects the time variation of three-dimensional knee valgus and hip adduction angle very well.Our results suggest that FKD has potential as a screening tool particularly for movement occurring primarily in the frontal-plane.
ABSTRACT
The higher anterior cruciate ligament (ACL) injury rate of females is one of the most sever athletic-related problems today. The purpose of this study is to compare the lower extremity kinematics between male and female during single leg landing.Six male and four female healthy subjects participated in this study. They jumped from a 32 cm high box and landed with the dominant leg. The landing action was filmed with three video cameras. The knee flexion, knee valgus/varus, and hip adduction/abduction angle and angle velocity were calculated.In female subjects, the knee flexion angle and hip adduction angle were greater compared to males. Also, the knee valgus velocity and hip adduction velocity were higher in females.Our results suggest that knee valgus kinematics may be related to hip adduction. It is important to evaluate hip kinematics when considering knee kinematics to prevent knee ligament injuries.