The main results of the present study indicated that there were no significant differences in the mean variability between baseline (pre-pandemic) and follow-up (post-pandemic) in age-adjusted Z scores on the isometric core strength in the Plank Test. This suggests that the performance on the Plank Test remained relatively stable over the 5-year period, even after the impact of the pandemic.
Our findings present different results from what was hypothetically expected regarding the negative effects of the pandemic on children and adolescents. In general, studies suggest that various physical fitness components tend to be reduced in post-pandemic times, but there is a divergence in strength results, with some children increasing and others decreasing it [6, 8, 14, 22–24, 41, 42].
To add further complexity to the research results on the muscular strength of children and adolescents during the transition from pre-to post-pandemic of COVID-19, significant negative effects were observed in the crude values of isometric strength in both groups of girls and boys over the 5 years, indicating a decline in performance on strength tests during this period. In the present sample, the negative effects were not statistically significant for both groups, boys, and girls, when adjusted to age across the time. The divergences in the present studies from other longitudinal data could be due to the fact that other studies did not account for participants' age differences [6, 8, 14, 22–24, 41–43].
This finding suggests that the reduction in isometric strength performance over the 5 years is not only a reflection of the participants' ageing but possibly influenced by other factors. The lack of significant differences in the variability of the Plank Test before and after the pandemic suggests that this component of physical fitness may have remained relatively stable, even in the face of disruptive events like the COVID-19 pandemic, which was also suggested by the literature [43].
From this body of evidence, we understand that lifestyle, social aspects, age, and sex have a higher impact on the strength of children over time is diverse [6, 8, 14, 22–24, 41–43] These include the variability in pandemic impact across different communities and regions, affected by factors such as lockdown measures, access to online education and physical activities, socioeconomic status, and healthcare infrastructure[6, 17, 19, 43, 44]. Psychological effects, such as stress, anxiety, and depression, can impact motivation and participation in physical activities, affecting muscular strength development [41, 45–47]. Lifestyle changes, including increased sedentary behaviors and altered eating habits, also play a role in physical fitness outcomes[6, 19, 48]. Reduced physical activity opportunities due to restrictions on outdoor activities and the closure of schools during the pandemic may have hindered muscular strength development [11, 12, 14]. Additionally, challenges in online learning could have led to decreased structured physical activity sessions and limited guidance on exercise techniques[14].
Several aspects may be related to the present results, but we can affirm that children and adolescents from this population have remote physical education programs for physical fitness improvement focused on the stay-at-home model. This kind of exercise can help the participants of present study to maintain the strength isometric plank test stable[6, 12, 14, 15].
The present results can be used mainly to planning a complex view for multicomponent school physical education interventions based on health promotion. This curricular component plays a crucial role in the physical and cognitive development of students. It may have contributed to the aforementioned aspects, such as stability in Plank Test performance over time and a reduction in negative effects on isometric strength. This is demonstrated in previous research on physical fitness and health conducted in the southern region of Brazil, closely matching the participants of the present study [6, 11, 12, 14, 15, 17, 18, 49].
These perspectives emphasize the crucial role of school physical education in safeguarding bodily health through physical activity, increased strength, and overall fitness, even during the pandemic. The mechanisms supporting physical fitness improvements, including isometric strength measured by the plank test, encompass promoting regular physical activity, developing motor skills, encouraging home-based exercise, focusing on health and a positive mental lifestyle, and adopting a comprehensive approach tailored to individual needs. These factors have contributed to maintaining performance levels and mitigating the negative effects of declining isometric strength, underscoring the importance of school physical education in nurturing students' physical well-being.
Overall, the study highlights the importance of assessing physical fitness and considering age-related factors when interpreting results over time. The Plank Test proved to be a valuable tool for assessing isometric strength, contributing valuable visions into the physical development of children over the course of several years. Further research may delve deeper into understanding the factors influencing these changes and their implications for promoting overall physical well-being in children.
In this sense, the strength of present research is that long-term studies are crucial to understanding the lasting effects of the pandemic on muscular strength, as individual differences in genetics, physiology, and psychology can further influence the outcomes. Overall, the complexity of these factors requires comprehensive and longitudinal research designs to untangle and comprehend their combined effects on children's and adolescents' muscular strength, as made in the present proposal. The study highlights the potential protective role of well-implemented school physical education based on health promotion, which may have contributed to the stability in physical performance [6, 12, 14, 15].
Furthermore, the study may have some limitations, such as the sample size, specific methodology used to assess isometric strength, and other uncontrolled variables that may have influenced the results. Some caution is warranted in interpreting the pandemic's direct impact on physical performance, as the analysis focused on understanding changes over time, with the pandemic period as one of the assessment points. Future research could further explore the pandemic's specific effects on physical performance by incorporating pre-pandemic baseline assessments and controlling for other potential variables. Overall, the study underscores the importance of physical education in supporting students' physical development and well-being during challenging times like the COVID-19 pandemic.