Physical fitness changes in adolescents due to social distancing during the coronavirus disease pandemic in Korea.

Background: At least 60 min of moderate-intensity physical activity per day is recommended for physical and mental health of adolescents. Schools are one of the most suitable places for promoting students' health as it is a place where vigorous physical activity occurs. However, the physical activity of students is threatened because schools are closed worldwide owing to the coronavirus disease (COVID-19) outbreak in 2019. Therefore, this study aimed to analyze the physical fitness changes in 27,782 Korean adolescents during the pandemic and present alternative education and health policies to the school. Methods: We included 29,882 middle school students (age: 13-15 years; males: 14,941, females: 12,841) in Korea from 2019 to 2021 . Participants' physical fitness at school was measured using the physical activity promotion system (PAPS) manual developed to measure students' physical fitness. Physical fitness variables included body mass index (BMI), 20 m shuttle run, handgrip strength, sit-and-reach, and 50 m run. Results: The COVID-19 pandemic has had a negative impact on the BMI and cardiorespiratory endurance of Korean middle school students. Specifically, male students' BMI increased, while body composition, cardiorespiratory endurance, and grip strength decreased significantly. Female students showed significant decreases in BMI and sit-and-reach test scores. It is clear that the physical fitness level of adolescents decreased by a greater degree after the COVID-19 pandemic than before, and the decrease in the physical fitness level of male students was noticeable. Therefore, a lesson strategy should be prepared that considers the contents and methods of physical education classes to improve the physical fitness level of male and female adolescents. Conclusions: Fitness-based classes suitable for online methods should be urgently added as alternative physical education classes to prepare for the second COVID-19 outbreak. In addition, it is necessary to create an environment in which physical activity is a possibility in physical education classes, in any situation using artificial intelligence and virtual reality.

Impact of High-Intensity Circuit Resistance Exercise on Physical Fitness, Inflammation, and Immune Cells in Female Breast Cancer Survivors: A Randomized Control Trial.

Questions remain about whether resistance exercise has a positive effect on immune and inflammatory cells. The purpose of this study was to evaluate the effect of 12 weeks of high-intensity circuit resistance exercise (HCRE) on inflammation and immune cells, and physical fitness, of female breast cancer survivors (FBCSs). Thirty FBCSs were randomly assigned to the HCRE (n = 15) and control (n = 15) groups. HRCE was administered for 50 min a day, 2-3 times a week, for 12 weeks. The control group only performed activities of daily living during the study period. Baseline and post-intervention measures included body composition, muscular strength, muscular endurance, flexibility, reaction time, balance, inflammation, and immune cell measurements. The results showed that HCRE improved body mass index, body fat, muscle mass, grip strength, back muscle strength, sit-up, whole-body reaction, standing on one leg with eyes closed, Y-balance test, and NKCA in FBCSs. The improvement of physical strength and immune cells of FBCSs was achieved using the 12-week HRCE program. Future studies must analyze various exercise intensities and types, and should be conducted on other cancer survivors. In addition, strategies should be developed to allow FBCSs to participate in resistance training.

Impact of Synchronous Online Physical Education Classes Using Tabata Training on Adolescents during COVID-19: A Randomized Controlled Study.

This study aimed to investigate the effects of online physical education classes, using Tabata training, on middle school students' physical fitness. Fifty-four adolescents were randomly assigned to either the asynchronous online class group (AOCG, n = 24, age: 15.8 ± 0.4 years) or the synchronous online class group (SOCG, n = 24 age: 15.9 ± 0.3 years). The online physical education class lasted two days per week for 10 weeks. Recorded video lectures were conducted for the AOCG, and Tabata training for the SOCG, as real-time lecture methods. Baseline and post-online physical education class measures included muscular strength, muscular endurance, flexibility, balance, and cardiorespiratory fitness tests. The results showed that the synchronous online physical education class had a positive effect on the improvement of muscle mass, ankle strength (dorsiflexion), hip strength (abduction, flexion, extension, and external rotation), knee strength (extension and flexion), and balance (Y-balance test) in adolescents. These findings suggest that the physical fitness of adolescents can be sufficiently improved through appropriate online physical education class methods. Further research should focus on developing and evaluating different types of exercises for synchronous online physical education classes as a precautionary measure for the second wave of COVID-19.

Associations between Handgrip Strength with Adverse Cardiometabolic Health among Representative Korean Adults.

Reduced muscle mass and strength are notable features of aging. Loss of muscle mass contributes to cardiometabolic health. Although many studies have focused on skeletal muscle mass, it remains unclear whether muscle strength is beneficial for cardiometabolic health. We aimed to investigate the association between handgrip strength and the risk of adverse cardiometabolic health in middle-aged and older adults in the Korean general population. The study participants included 7602 adults from the Korea National Health and Nutritional Examination Survey (KNHANES). The odds ratio for adverse cardiometabolic health significantly and linearly decreased according to the category of handgrip strength adjusted for potential confounding factors (p-Value < 0.05). In the stratified models by sex we also observed significant associations between handgrip strength and cardiometabolic health in men (p-Value < 0.001), but not in women. Our findings suggest that maintaining higher handgrip strength may contribute to improved cardiometabolic health.

Association of Sarcopenia and Obesity With Multimorbidity in Korean Adults: A Nationwide Cross-Sectional Study.

OBJECTIVES: Age-related muscle loss (sarcopenia) and increased fat mass (obesity) may contribute to chronic disease. Multimorbidity needs more complex health care and is associated with an elevated risk of mortality, disability, and poor quality of life. Sarcopenia and obesity together may be more closely associated with multimorbidity than either sarcopenia or obesity alone. However, a possible multimorbidity link with sarcopenic obesity is unknown. Thus, we aimed to investigate the association of sarcopenic obesity and multimorbidity in Korean adults. DESIGN/SETTING: A nationwide cross-sectional study based on data from Korea National Health and Nutritional Examination Survey, 2008 to 2011. PARTICIPANTS: Study participants included 10,118 adults aged ≥40 years. MEASUREMENTS: Skeletal muscle mass was measured using dual energy x-ray absorptiometry. Sarcopenia was defined as 1 standard deviation below the mean using the skeletal muscle mass index based on a young population reference group. Obesity was defined using the waist circumference sex-specific cutoff point for Asians. RESULTS: When examined individually, there was a significant association of sarcopenia [odds ratio (OR): 1.49, 95% confidence interval (CI): 1.31-1.70] and obesity (OR: 1.63, 95% CI: 1.45-1.84) with the risk of multimorbidity after being adjusted for potential covariates. When examined as sarcopenia and obesity combined, a greater increase in the risk of multimorbidity was found (OR: 3.0, 95% CI: 2.60-3.40) compared with either sarcopenia (OR: 1.50, 95% CI: 1.18-1.77) or obesity (OR: 1.80, 95% CI: 1.39-2.30) alone. CONCLUSIONS: In conclusion, we found that sarcopenia and obesity are independently associated with the risk of multimorbidity, but with these conditions combined, sarcopenic obesity has a greater risk of multimorbidity.

Sedentary Behavior and Sleep Duration Are Associated with Both Stress Symptoms and Suicidal Thoughts in Korean Adults.

Prolonged sedentary time and sleep deprivation are associated with mental health problems such as depression and stress symptoms. Moreover, mental illness is linked with suicidal thoughts and suicide attempts. However, it is not clear whether sedentary time and sleep duration are associated with stress symptoms and suicidal thoughts independent of physical activity. Thus, our study aimed to identify if sedentary time and sleep duration were associated with both stress symptoms and suicidal thoughts. The participants in present cross-sectional study were 4,674 general Korean adults (1,938 male; 2,736 female), aged ≥ 20 years. Prolonged sedentary time (≥ 420 min/day) was significantly associated with the increased risk of stress symptoms (OR, 1.30; 95% CI, 1.04-1.62) compared with sedentary time of < 240 min/day. The OR for stress symptoms was significant for individuals who had ≤ 5 h/day of sleep time (OR, 1.88; 95% CI, 1.48-2.38) compared with sleep duration of ≥ 7 h/day. Moreover, prolonged sedentary time (OR, 1.55; 95% CI, 1.01-2.42 in ≥ 420 min/day vs. < 240 min/day) and short sleep duration (OR, 1.75; 95% CI, 1.17-2.62 in ≤ 5 h/day vs. ≥ 7 h/day) were significantly associated with an increased risk for suicidal thoughts after adjusting for confounding factors including physical activity. Thus, prolonged sedentary time and sleep deprivation are independently associated with both the risk of stress symptoms and suicidal thoughts. From a public health perspective, reducing sedentary time and improvement of sleep deprivation may serve as an effective strategy for preventing mental illness.

Effects of acceleration training 24 weeks after anterior cruciate ligament reconstruction on proprioceptive and dynamic balancing functions.

[Purpose] The present study aimed to investigate whether the effects of rehabilitation exercise performed after anterior cruciate ligament reconstruction on proprioceptive sensory and dynamic balancing functions differ between males and females. [Subjects and Methods] Eighteen subjects aged between 20-30 years enrolled in this study. The ages did not significantly differ between the males and females. The rehabilitation exercise program was performed three times per week for 12 weeks (3 months), and was initiated immediately after anterior cruciate ligament reconstruction. Thereafter, the patients visited the hospital once per week to perform rehabilitation exercise during weeks 12-24 (3-6 months), and education on self-exercise and assessments were conducted during the visits. Self-exercise was performed two times per week according to the determined program. [Results] The extension active joint position sense, extension passive joint position sense, and flexion passive joint position sense of the affected and unaffected knees did not show any interaction effects between the measurement periods or between the groups. In the case of the affected knee, the results of two-way repeated-measures analysis of variance showed no significant difference between the measurement periods or between the groups; moreover, no, interaction effects were observed between the measurement periods or between the groups. In the case of the unaffected knee, although no significant difference was observed between the measurement periods, significant differences were observed between the groups. [Conclusion] In conclusion, this study revealed that most knee rehabilitation exercise training programs can be applied to both genders during the recovery period after ACL reconstruction, except for the knee rotational feedback/feedforward function exercise that may exhibit different effects based on the gender.

Effect of Anticipation on Lower Extremity Biomechanics During Side- and Cross-Cutting Maneuvers in Young Soccer Players.

BACKGROUND: Less mature athletes exhibit biomechanical parameters during cutting maneuvers that may place these athletes at greater risk for injury than their more mature counterparts, especially if the maneuvers are unanticipated. However, most studies on risk factors for anterior cruciate ligament (ACL) injury have focused on neuromuscular and knee kinematic differences between the sexes, not on the biomechanical parameters between specific sporting maneuvers. HYPOTHESES: (1) Anticipation will have a greater effect than the type of cutting maneuver (side- vs cross-cutting) in terms of the biomechanical risk factors for ACL injuries, and (2) the biomechanical risk factors will be different between the 2 types of maneuvers. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-seven young, male middle school soccer players participated in this study. Three-dimensional motion analysis featuring ground-reaction force and electromyography of the right leg was used. Kinematics, kinetics, and electromyography data for each athlete were analyzed during anticipated and unanticipated side- and cross-cutting maneuvers. The differences between anticipated and unanticipated states as well as between side- and cross-cutting maneuvers were calculated and compared. RESULTS: After unanticipated side-cutting, the time to peak ground-reaction force was longer and peak values were smaller compared with anticipated side-cutting. Flexion, valgus, and internal rotations in the knee joint were larger, and greater flexion and valgus moments were observed. The vastus lateralis and vastus medialis showed lower activity, and the lateral gastrocnemius showed higher activity after unanticipated side-cutting maneuvers. With unanticipated cross-cutting, the time to peak ground-reaction force was longer and peak values were smaller compared with anticipated cross-cutting, and the lateral gastrocnemius showed higher activity. Differences in the peak values of the mediolateral and vertical forces were smaller in the cross-cutting maneuver than in side-cutting. Changes in flexion and adduction of the hip joint, flexion of the knee joint, and inversion of the ankle joint were larger during side-cutting. CONCLUSION: Although there were some interactions between direction and anticipation, anticipating a cutting maneuver generally had a greater effect than the type of maneuver when there was no significant interaction. CLINICAL RELEVANCE: Increases in the valgus angle and moment of the knee joint and higher lateral gastrocnemius activity during the late period showed an association with ACL injury risk factors during side-cutting, and higher lateral gastrocnemius activity during the early period showed an association with injury risk factors during cross-cutting.

Serial assessment of knee joint moments in posterior cruciate ligament and posterolateral corner reconstructed patients during a turn running task.

INTRODUCTION: During post-operative rehabilitation for posterior cruciate ligament (PCL) reconstruction, flexion is limited to 90° for the first 6 weeks, and hamstring strengthening is initiated at 3 months because of static stability. The posterolateral corner sling (PLCS) procedure is frequently performed with PCL reconstruction to help alleviate posterolateral rotator instability, and it is possible, during this procedure, to damage the dynamic motion and to over-constrain the knee. MATERIALS AND METHODS: For the patients group, PCL and PLCS reconstructions were performed simultaneously, and all reconstructed patients had stable knees and showed no complications. A motion analysis system was used to measure and calculate kinematic and kinetic data for seven patients after PCL and PLCS reconstruction (patients group) and seven normal subjects (control group) during a turn running task. The study was conducted on two groups at both 3 months (return to daily activity) and 6 months (return to light sports) post-operation. At 6 months after surgery, the dial test was also performed to observe the static rotational stability. RESULTS: Compared to the control group, the patients group showed a decreased extension moment (-1.15 ± 0.46 vs. -3.51 ± 0.69 Nm/kg, p = 0.000), a decreased valgus moment (-1.36 ± 0.72 vs. -2.15 ± 0.54 Nm/kg, p = 0.041) and a decreased external rotational moment (-0.15 ± 0.11 vs. -0.37 ± 0.10 Nm/kg, p = 0.002) 3 months post-operatively. However, these results approximated to the normal control, and the patients group showed an improved extension moment (-2.95 ± 0.67 Nm/kg, p = 0.188), valgus moment (-1.73 ± 0.58 Nm/kg, p = 0.359) and external rotational moment (-0.30 ± 0.09 Nm/kg, p = 0.325) at 6 months post-operatively. A static rotational stability revealed a similar or over-constrained state compared with the contralateral knee, and no patient showed rotational instability. CONCLUSIONS: PCL-PLCS reconstructed patients were reluctant to engage in, or lacked strength for, daily rotational activities. Therefore, we must consider more active and systematic co-contraction exercise of the hamstring and quadriceps and rehabilitation program about rotation that is not adverse to the static stability in PCL-PLCS reconstructed patients for early return to daily activities.

Effects of sports injury prevention training on the biomechanical risk factors of anterior cruciate ligament injury in high school female basketball players.

BACKGROUND: Female athletes have a higher risk of anterior cruciate ligament injury than their male counterparts who play at similar levels in sports involving pivoting and landing. HYPOTHESIS: The competitive female basketball players who participated in a sports injury prevention training program would show better muscle strength and flexibility and improved biomechanical properties associated with anterior cruciate ligament injury than during the pretraining period and than posttraining parameters in a control group. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 22 high school female basketball players were recruited and randomly divided into 2 groups (the experimental group and the control group, 11 participants each). The experimental group was instructed in the 6 parts of the sports injury prevention training program and performed it during the first 20 minutes of team practice for the next 8 weeks, while the control group performed their regular training program. Both groups were tested with a rebound-jump task before and after the 8-week period. A total of 21 reflective markers were placed in preassigned positions. In this controlled laboratory study, a 2-way analysis of variance (2 x 2) experimental design was used for the statistical analysis (P < .05) using the experimental group and a testing session as within and between factors, respectively. Post hoc tests with Sidak correction were used when significant factor effects and/or interactions were observed. RESULTS: A comparison of the experimental group's pretraining and posttraining results identified training effects on all strength parameters (P = .004 to .043) and on knee flexion, which reflects increased flexibility (P = .022). The experimental group showed higher knee flexion angles (P = .024), greater interknee distances (P = .004), lower hamstring-quadriceps ratios (P = .023), and lower maximum knee extension torques (P = .043) after training. In the control group, no statistical differences were observed between pretraining and posttraining findings (P = .084 to .873). At pretraining, no significant differences were observed between the 2 groups for any parameter (P = .067 to .784). However, a comparison of the 2 groups after training revealed that the experimental group had significantly higher knee flexion angles (P = .023), greater knee distances (P = .005), lower hamstring-quadriceps ratios (P = .021), lower maximum knee extension torques (P = .124), and higher maximum knee abduction torques P (= .043) than the control group. CONCLUSION: The sports injury prevention training program improved the strength and flexibility of the competitive female basketball players tested and biomechanical properties associated with anterior cruciate ligament injury as compared with pretraining parameters and with posttraining parameters in the control group. CLINICAL RELEVANCE: This injury prevention program could potentially modify the flexibility, strength, and biomechanical properties associated with ACL injury and lower the athlete's risk for injury.