Muscle strength is an important component of physical fitness (Kell et al., 2001; Stodden et al., 2017). Inadequate muscle strength in children and adolescents is recognized as an important marker of poor health (Ortega et al., 2008; Peterson and Krishnan, 2015). Evidence suggests that muscle strength is a strong marker of current and future cardiovascular risk and is negatively associated with all-cause mortality, independent of cardiorespiratory fitness levels (Ortega et al., 2012; Fraser et al., 2016; Ramirez-Velez et al., 2016). Moreover, inadequate muscle strength in children and adolescents is a new risk factor for suicide (Ortega et al., 2012). A meta-analysis showed that the combined risk ratio (HR) for mortality in the weakest and strongest grip groups was 1.67 (Cooper et al., 2010). The number of 1-min sit-ups was negatively associated with mortality (Katzmarzyk and Craig, 2002). Of concern is the long-term trend of decreasing muscle strength levels in young people that has been reported across the globe (Sandercock and Cohen, 2019; Duric et al., 2021; Fuhner et al., 2021). There are also studies that confirm that less than two-fifths of Chinese children and adolescents met the World Health Organization muscle-strengthening exercise recommendations (Xin et al., 2022). Therefore, considering the physical and mental health benefits of muscle strength, further attention needs to be paid to the muscle strength profile of Chinese children and adolescents.

Executive function refers to the top-down control of behavior through the use of its core components, such as inhibit function, refresh memory function (1back, 2back), and cognitive flexibility (Miyake and Friedman, 2012). Normal performance of executive function is associated with physical health, mental health, academic performance and productivity, and career achievement (Diamond, 2013). The development of executive function in children and adolescents is influenced by multiple factors, including the educational environment, dietary behavior, different environmental exposures, and physical activity levels (Zysset et al., 2018; Zeng et al., 2022). Evidence from neurotypical cohorts suggests that high performance on executive function tasks in children and adolescents is associated with high cardiorespiratory fitness and muscle strength (Ludyga et al., 2021). Recent studies have found a strong association between executive function and muscle strength (Liu-Ambrose et al., 2010; Arts et al., 2016), and resistance training has been found to have positive and significant effects on improving functional brain plasticity, executive function, and response inhibition (Yoon et al., 2017). It has also been confirmed that physical exercise enhances cognition and brain function, plays a positive role in preventing neurodegenerative diseases and neurological decline, and is helpful for cognitive brain function (Kramer and Erickson, 2007). This shows that foreign studies on the association between muscle strength and executive function are increasing year by year, but the study population is mostly middle-aged and elderly people or special children and adolescents with diseases, and there are fewer studies on the correlation between muscle strength and executive function in normal children and adolescents (Ludyga et al., 2021).

A further review of previous studies revealed some shortcomings in this area of research. First, fewer studies have been conducted using comprehensive muscle indices. Muscle strength tests are an important part of physical fitness tests in many countries and regions in the world today. The most commonly used simple muscle strength test indices in Chinese children and adolescents’ physical fitness tests are grip strength, pull-ups, standing long jump, and sit-ups. Grip strength and pull-ups are measures of upper limb muscle strength, standing long jump is a common indicator of lower limb body muscle strength, and sit-ups are valid indicators in abdominal strength tests (Yin et al., 2018). However, in many studies, indicators of individual general muscle strength are evaluated with grip strength (Wind et al., 2010), without testing two or more body parts, and a single test cannot fully represent whole-body muscle strength. Therefore, there is a need to investigate the association of whole-body muscle strength aspects on executive function. Second, China is a developing country with highly uneven regional development. There are large disparities between urban and rural children and adolescents in terms of socioeconomic status, educational resources, nutritional status, and physical activity, and fewer previous studies have been conducted on children and adolescents in rural areas. Third, previous studies have found urban-rural differences in muscle strength test results (Liu et al., 2019). In addition, previous analyses of the association between muscle strength and executive function have included limited control for covariates. However, the literature suggests that factors such as parental education, dairy products (Knight et al., 2015), sleep quality (Sewell et al., 2021), and BMI all have an effect on brain executive function, so adjustments need to be given in the analysis to obtain more reliable research evidence (Rollins et al., 2021).

In view of the current status of previous studies, our study tested upper limb, abdominal, and lower limb muscle strength in children and adolescents from rural areas of China and calculated muscle strength indices according to age and gender to provide a comprehensive picture of the muscle strength levels of children and adolescents. Executive function was also tested to analyze the association that exists between muscle strength and executive function. To our knowledge, this is the first study in China to explore the association between muscle strength and executive function in rural children and adolescents. Our study provides a reference and help for the improvement of muscle strength and executive function in Chinese children and adolescents.

We investigated demographic variables, grip strength, sit-ups, pull-ups, standing long jump and executive function in 1,335 (boys 672, 50.3%) children and adolescents aged 13–15 years in rural areas of China with a mean age of (14.15 ± 0.84) years.

Regarding the comparison of muscle strength index among different categories of children and adolescents in rural China, the differences were statistically significant when comparing the detection rates of different muscle strength index classifications in only child and sleep (χ² = 7.638, 54.800, p < 0.05). In terms of BMI and MVPA, the differences were statistically significant when comparing different muscle strength index classifications (F = 69.418, 6.717, p < 0.01) (Table 1).

Our study showed that the inconsistently, congruent, 1back, 2back, conversion, size parity, and cognitive flexibility response times of children and adolescents with different muscle strength indexes in rural China were compared, the differences were statistically significant (F = 46.592, 45.610, 10.809, 32.068, 24.095, 19.260, 11.501, p < 0.001). Overall, children and adolescents with muscle strength index >P80 had shorter reaction times, and those with muscle strength index <P20 had longer reaction times (Table 2).

After adjusting for relevant confounding variables (Model3), the results of multiple linear regression analysis showed that compared to those with muscle strength index <P20, those with muscle strength index >P80 inconsistently, congruent, 1back, 2back, and conversion, size parity, and cognitive flexibility reaction times were reduced by 51.243, 50.653, 100.527, 185.766, 105.641, 39.062, and 66.579 ms, respectively, with statistically significant differences (p < 0.001) (Table 3).

After adjusting for relevant confounding variables (Model3), logistic regression analysis was performed using children and adolescents with muscle strength index >P80 as the control group. The results showed that the risk of 1back dysfunction was higher (OR = 1.764, 95% CI: 1.094, 2.843) in children and adolescents with muscle strength index <P20 (p < 0.05). The risk of 2back dysfunction was higher in children and adolescents with a muscle strength index <P20 (OR = 2.129, 95% CI: 1.329, 3.410) (p < 0.01). Compared with children and adolescents with muscle strength index >P80, the muscle strength index <P20 group had a higher risk of cognitive flexibility dysfunction (OR = 1.820, 95% CI:1.111, 2.982) (p < 0.05) (Table 4).

The purpose of this study was to investigate and analyze the association between muscle strength and executive function in children and adolescents in rural areas of China, in order to better promote the development of muscle strength and executive function. The association between muscle strength and executive function existed in children and adolescents in rural areas of China. Those with higher muscle strength had shorter executive function reaction times and were at lower risk of developing executive dysfunction. Our study included 1,335 children and adolescents aged 13–15 years from four different provinces in rural areas of China. The results of our study showed that the mean BMI (19.98 ± 2.48) kg/m², whole-body muscle strength test results were: grip (29.98 ± 9.06) kg, pull up (2.91 ± 2.93) times, sit ups (29.80 ± 8.57), standing long jump (173.91 ± 31.48) cm.

Further analysis of the results of the muscle strength test revealed that the results of the grip test for rural children and adolescents in China were significantly lower than the average for children and adolescents aged 13–15 years in the United States (60.9 kg) (Ervin et al., 2014). The reason is that there is a correlation between BMI and muscle health, with leaner people tending to have less strength compared to normal weight children and adolescents (Rantanen et al., 2000). Compared to Spanish children and adolescents with similar average age and BMI, the muscle strength test values of children and adolescents in rural China were greater than those of Spanish adolescents with grip 24.71 kg, sit ups 24.90 times and standing long jump 150.99 cm. It may be related to the higher MVPA of children and adolescents in rural areas of China due to different economic levels, lifestyles and transportation modes (Martinez-Lopez et al., 2018). Comparing the results of muscle strength tests with those of Chinese domestic youth, we found that the grip test results were slightly higher than the average of 28.7 kg for 12–15 year olds, the sit ups were higher than the average of 22.53 times, and the standing long jump was lower than the average of 182.43 cm (Xu et al., 2020). This may be related to the data for 12-year-olds in the previous test results, as strength increases significantly with age in both children and adolescents (Martinez-Lopez et al., 2018). Comparison of the test results of our study with relevant national and international data revealed that, as in past studies, muscle mass strength can be used as a marker of nutritional status and physical function (Norman et al., 2011). Body weight and size were negatively correlated with physical performance tests, which were performed against gravity, such as standing long jump, sit ups, and pull up tests (Beunen et al., 1983; Malina et al., 1995). On the other hand, body weight and size are positively correlated with performance against external forces, such as the grip (Watson and O’Donovan, 1977).

One-way ANOVA and multiple linear regression analyses revealed that children and adolescents with high muscle strength had shorter executive function reaction times, i.e., higher levels of executive function. Our results are consistent with the findings of previous studies that muscle strength and executive function are correlated (Bruijn et al., 2018; Oberer et al., 2018; Mora-Gonzalez et al., 2019). Whereas muscle strength is associated with executive ability, the effects on the brain may be to alter the excitability of spinal motor neurons and to induce synaptogenesis in the spinal cord (Adkins et al., 2006). It is also likely that these adaptations in the brain may be mediated by physical activity (Hillman et al., 2008). After all, there is a correlation between increased levels of physical activity and improved muscle strength, and often those with higher physical activity also have higher muscle strength. These changes promote blood flow to the brain, which has a positive effect on the brain’s oxygen supply and nervous system, thus improving executive function (Shao et al., 2022).

Further logistic regression analysis also showed a strong association between poorer muscle strength and a higher prevalence of executive dysfunction. Previous studies have shown that high levels of muscle strength may indirectly improve health through beneficial effects on body composition and aerobic performance (Warburton et al., 2001). Muscle strength has little effect on maximal aerobic capacity, but they may improve submaximal exercise performance and thus reduce the risk of functional decline to indirectly reduce the risk of death (Hirvensalo et al., 2000). A review showed that resistance training particularly benefits cognition by increasing the expression of growth factors (i.e., BDNF, IGF-1) and changes in functional and structural properties of the brain (Herold et al., 2019). Notably, a meta-analysis did not observe a correlation between muscle strength and cognition, but reported that both muscle strength and muscle structure were associated with brain structure (Kilgour et al., 2014). Therefore, our future experimental studies need to verify whether muscle strength results from higher levels of executive function due to higher blood flow to the brain, higher oxygen-carrying capacity, and more excitable brain regions that control executive functions in the brain.

Several strengths exist in our study. On the one hand, our study is the first to investigate and analyze the association between muscle strength and executive function in children and adolescents in rural areas of China, which provides a reference for healthy development of children and adolescents in rural areas. In addition, our study uses a comprehensive muscle index reflecting muscle strength for analysis, which provides a more comprehensive response to the muscle strength level of children and adolescents. However, our study also has some limitations. First, the sample size of our study was relatively low, and the area investigated in the study was only in rural areas of four provinces in China, and the area studied was somewhat limited. Second, the control of covariates in our study was limited, such as the lack of investigation of cardiorespiratory endurance, sugary drinks, and smoking, and these deficiencies are to be remedied in future studies.

There is a close association between muscle strength and executive function in children and adolescents in rural areas of China. Children and adolescents with higher muscle strength in rural areas of China had shorter executive function reaction times and lower risk of executive function disorders. Based on our findings, effective measures should be taken in the future to improve muscle strength and executive function levels of children and adolescents in rural areas of China. Such as securing teaching time for physical education classes, securing time for extracurricular activities, strengthening health education, and conducting executive function training in order to promote the healthy physical and mental development of children and adolescents in rural areas of China. In addition, improving muscle strength and executive function in children and adolescents is a long-term process. It requires concerted efforts and joint efforts of families, schools and children and adolescents themselves to better achieve the improvement results.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved the Human Ethics Committee of Huanghuai University (202105012). Written informed consent to participate in this study was provided by the participants or their legal guardian/next of kin.

QZ, XH, and YW: conceptualization. QZ: data curation, funding acquisition, and visualization. QZ and XH: formal analysis, software, writing—original draft, and writing—review and editing. YW: investigation, methodology, validation, and resources. XH and YW: project administration and supervision. All authors have read and agreed to the published version of the manuscript.