The effects of COVID-19 on the Physical Activity and Recreational Screen Time among Chinese children and adolescents.

Background: The lack of Physical Activity (PA) and prolonged Recreational Screen Time (RST) among children and adolescents has been exacerbated during the COVID-19 pandemic, causing this issue to escalate into a crucial public health concern. This study aims to investigate the trends in PA and RST among Chinese children and adolescents from 2019 to 2022, thereby analyzing the short-term and long-term effects of the pandemic on PA and RST among Chinese children and adolescents. Methods: A nationally representative sample of Chinese primary, middle, and high school students was surveyed annually between September and December from 2019 to 2022 using a consistent set of questionnaires. Trends in PA and RST across different school levels, genders, areas (urban/rural), and regions (north/south) were analyzed using Segmented Linear Regression. Results: From 2019 to 2022, the PA and RST of children and adolescents displayed an inverted U-shaped trend, initially increasing and subsequently declining. Specifically, from 2019 to 2021, the PA of children and adolescents significantly increased but dramatically declined from 2021 to 2022. This trend in PA is more pronounced among primary, male, urban, and northern children and adolescent. The RST of children and adolescents increased from 2019 to 2020 but significantly decreased from 2020 to 2022. This trend in RST is more pronounced among primary, urban, and southern children and adolescent. Conclusions: This research unveils the effects of the pandemic on PA and RST in children and adolescents, suggesting short-term beneficial and long-term adverse effects on PA and short-term adverse and long-term beneficial effects on RST. These findings provide a foundation for formulating policies related to children and adolescents' PA and RST during the pandemic.

Trends of physical activity and recreational screen time among Chinese children and adolescents: a national study from 2017 to 2019.

BACKGROUND: The prevalence of physical inactivity and sedentary behavior among children and adolescents is a growing public health concern. This study aims to examine the trends in Physical Activity (PA) and Recreational Screen Time (RST) amongst children and adolescents in China, considering variations in genders, school levels, areas (urban versus rural), and regions (north versus south). The findings provide a foundation to guide policy and strategy making for future health promotion and development. METHODS: An annual national cross-sectional survey was conducted in China from 2017 to 2019 cumulatively involving 52,503 (48% female) children and adolescents from grades 4 to 12 (aged 12.72 ± 2.12). Data on PA and RST were collected through self-administered questionnaires. Weighted least squares regression was used to analyze the trends and differences in PA and RST among the participants' profiles. RESULTS: There was an annual decreased in PA compliance rate of approximately 3.43% (95% CI: 0.79-6.08%) for primary school students, primarily among males residing in rural areas, and in northern regions. Middle school students experienced a yearly decrease of about 5.23% (95% CI: 2.55-7.92%) in PA compliance across all genders, regions, and urban areas. Similarly, the RST compliance rates for primary school students declined by approximately 3.18% (95% CI: 1.57-4.78%) annually for all genders and areas, but only in the northern regions. CONCLUSIONS: This research highlights a downward trend in PA and RST compliance amongst Chinese children and adolescents, with variations based on school level, gender, area, and region. Urgent policies and interventions are imperative to promote PA while mitigating excessive RST within these populations.

Association between physical activity, sedentary time, and physical fitness of female college students in China.

BACKGROUND: Prior research has highlighted the importance of Physical Activity (PA), Sedentary Time (ST), and Physical Fitness (PF) for health. However, there is limited research on the association between PA, ST, and PF in the context of female college students, particularly in Eastern cultures. Therefore, the purpose of this study was to investigate the association between PA, ST, and PF among Eastern female college students to inform policy and practice. METHODS: The study was conducted from February to May 2022 at East China Normal University, Shanghai, China. A total of 512 Chinese female college students participated in this study through snowball sampling. Participants' PA and ST were investigated using the International PA Questionnaire, and PF was measured using the Chinese National Student Physical Fitness Test. Independent samples t-test and binary logistic regression were used to compare the differences in PF between Active Participants (AP) and Inactive Participants (IP), as well as between Low Sedentary Participants (LSP) and High Sedentary Participants (HSP). Multinomial logistic regression was used to compare the differences in PF between Active and Low Sedentary Participants (ALSP), Active and High Sedentary Participants (AHSP), Inactive and Low Sedentary Participants (ILSP), and Inactive and High Sedentary Participants (IHSP). Data analysis was performed using Statistical Package for the Social Sciences version 28. The level of significance was set at 0.05. RESULTS: AP showed significantly higher cardiorespiratory fitness (p < 0.05) and overall fitness (p < 0.01) than IP. Compared to IP, AP was less likely to be classified as unfit in terms of cardiorespiratory fitness [Odds Ratio (OR), 0.57; 95% Confidence Interval (CI), 0.38-0.85; p < 0.05]. Compared to IHSP, ALSP (OR, 0.44; 95% CI 0.25-0.76; p < 0.01) and AHSP (OR, 0.54; 95% CI 0.32-0.93; p < 0.05) were less likely to be classified as unfit in terms of cardiorespiratory fitness. Furthermore, compared to IHSP, AHSP (OR, 1.66; 95% CI 1.02-2.70; p < 0.05) and ILSP (OR, 2.09; 95% CI 1.16-3.77; p < 0.05) were more likely to be classified as unfit in terms of their flexibility. CONCLUSION: There was a positive association between PA, cardiorespiratory fitness, and overall fitness. There was also an association between cardiorespiratory fitness, flexibility, and the combination of PA and ST. These findings suggest that both PA and ST can influence different PF items. Therefore, we recommend that public health policy and practice for college female students should consider PF items when selecting different PA and ST intervention strategies.

Retentive capacity of power output and linear versus non-linear mapping of power loss in the isotonic muscular endurance test.

The limit of dynamic endurance during repetitive contractions has been referred to as the point of muscle fatigue, which can be measured by mechanical and electrophysiological parameters combined with subjective estimates of load tolerance for revealing the human real-world capacity required to work continuously. In this study, an isotonic muscular endurance (IME) testing protocol under a psychophysiological fatigue criterion was developed for measuring the retentive capacity of the power output of lower limb muscles. Additionally, to guide the development of electrophysiological evaluation methods, linear and non-linear techniques for creating surface electromyography (sEMG) models were compared in terms of their ability to estimate muscle fatigue. Forty healthy college-aged males performed three trials of an isometric peak torque test and one trial of an IME test for the plantar flexors and knee and hip extensors. Meanwhile, sEMG activity was recorded from the medial gastrocnemius, lateral gastrocnemius, vastus medialis, rectus femoris, vastus lateralis, gluteus maximus, and biceps femoris of the right leg muscles. Linear techniques (amplitude-based parameters, spectral parameters, and instantaneous frequency parameters) and non-linear techniques (a multi-layer perception neural network) were used to predict the time-dependent power output during dynamic contractions. Two mechanical manifestations of muscle fatigue were observed in the IME tests, including power output reduction between the beginning and end of the test and time-dependent progressive power loss. Compared with linear mapping (linear regression) alone or a combination of sEMG variables, non-linear mapping of power loss during dynamic contractions showed significantly higher signal-to-noise ratios and correlation coefficients between the actual and estimated power output. Muscular endurance required in real-world activities can be measured by considering the amount of work produced or the activity duration via the recommended IME testing protocol under a psychophysiological termination criterion. Non-linear mapping techniques provide more powerful mapping of power loss compared with linear mapping in the IME testing protocol.

Basic Psychological Need Profiles and Correlates in Physical Activity Participation: A Person-Centered Approach.

Guided by Basic Psychological Need Theory, we investigated the combined associations between need satisfaction and need frustration (i.e., need profiles) and their relations with theoretically relevant correlates including mindfulness, physical literacy, physical activity enjoyment, and physical activity. The participants were Singapore-based school students (N = 844, M age = 12.45, SDage = 1.99, boys = 53.1%) who completed a cross-sectional survey. The results of the latent profile analysis identified four distinct need profiles: profile 1-average satisfaction and frustration (n = 364, 44.1%); profile 2-low satisfaction (n = 251, 29.7%), above average frustration; profile 3-very high satisfaction, very low frustration (n = 144, 17.1%); and profile 4-high satisfaction, very high frustration (n = 85, 10.1%). Among these, profile 3 was the most adaptive one; it had the highest levels of mindfulness, physical literacy, physical activity enjoyment, and moderate-to-vigorous physical activity. Experiences of need satisfaction countered the negative effects of need frustration on these correlates. These findings enhance our understanding of students' psychological need experiences and highlight the need for investigating the combined associations between need satisfaction and need frustration.