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Multiple factors result in declining adolescent health

(Chinese Social Sciences Today)

Four girls exercise on a playground. It is suggested that adolescents get approximately an hour or more of physical activity every day, but many teenagers in China and throughout the world at large are not meeting the recommended amount. Photo: FILE

The health of adolescents not only concerns individual growth and happiness, but is also inseparable from sustainable social development and the enhancement of national competitiveness. As socioeconomic levels rise rapidly, the nutritional status of teenagers in both urban and rural China has improved significantly, along with substantial increases to their physiological indicators, such as height. At the same time, however, the bodily functions and athletic abilities of all age groups are weakening, underscoring the particular importance of examining social factors affecting adolescents’ health. 
Social environments
Declining adolescent health is not unique to China. In fact, it seems to be a global phenomenon. Many countries around the world face this common challenge. Through active and extensive exploration of the issue, scholars have reached the basic consensus that social environments are responsible, rather than genetic factors. Changes in lifestyle have a big influence, such as lower levels of physical activity and more time spent playing digital devices. 
Social modernization is partly characterized by the gradual replacement of manual labor with machines. Whether in family life, transportation, or the workplace, this trend is more and more evident. 
According to a survey sponsored by the World Health Organization on approximately 1.6 million students aged between 11 and 17 years old in 146 countries and regions, 77.6% of the boys and 84.7% of the girls failed to meet the recommended one hour of physical activity per day. The proportion of students who were not receiving adequate exercise in China was lower than those in Australia and Canada, and girls were even less physically active than boys. This has negative implications for current and future health of adolescents. A lack of activity multiplies the probabilities of suffering from obesity, high blood pressure, diabetes, and even cancer. 
The development of the internet, the mobile internet in particular, and new media technologies have revolutionized human behaviors of production, consumption, learning, and recreation, drastically reducing opportunities for physical activity and extending screen time. 
From 2002 to 2010, adolescents spent slightly less time in watching TV than previous years, but the decline is far smaller than their rise in screen time. Tablets and cellphones have become part of teenagers’ daily lives. They usually relax themselves with sedentary screen time, instead of going outdoors to play or participate in sports. 
While enjoying high levels of efficiency and convenience brought by technological advances, teenagers who grow up in this era face different health risks from adolescents in the past. 
In China, apart from decreasing physical activity and increasing screen time as a result of social and technological development, teenagers have to shoulder more scholastic burdens due to fierce educational competition and mounting pressure, as widely discussed on social and mass media. Several surveys show notably longer homework and afterschool tutoring time for Chinese students, when compared to their peers in other countries. 
Key social factors
Physical inactivity, excess screen time, and heavy academic workloads are regarded as crucial social risk factors affecting the well-being of adolescents. The former two factors are globally universal, whereas the third factor is related to the unique social culture and social mobility stratum in China.
To grasp social factors influencing adolescent health more comprehensively and accurately, and tailor effective scientific policies which strengthen interventional effects, it is essential to incorporate those three factors into the same framework for comparative analysis. 
If the three factors all have negative impacts on teenagers' health, the absence of any factor will cause bias errors because of the omission of significant variables. More importantly, an isolated analysis will make it impossible to measure the relative effect of each factor and difficult to find key points and directions for the formulation of related social policies. 
A comparative analysis can be unfolded on at least two levels. The first is the macroscopic level, which compares the relative effects of physical activity, screen time, and homework. On the second level, different risk factors are multidimensional in and of themselves. For example, physical activity is not limited to sports, including any energy-consuming movements, such as house chores or taking transportation to go to and from school. Screen time can be used for learning, recreational and social purposes, and would include televisions, computers, or cellphones and tablets via the mobile internet. Study loads could originate either from school or families, and can be divided into school and afterschool work. The comparative analysis of different components of each factor is equally important. 
Physical activity, screen time, and schoolwork will ultimately be embodied in individual daily lives. Theoretically the three factors are in conflict or compromise each other, because everyone’s time is limited. However, some empirical studies have found that this is not the case. 
For example, time spent on extracurricular study and for physical exercises are positively correlated. This raises a few questions. How are physical activity, screen time, and study loads related? Are the connections relevant or irrelevant? Are they positively or negatively correlated? Will the reduction of study loads necessarily lead to the increase of physical activity, and does increasing physical activity mean decreasing screen time? Do the three sides interact with each other? What occupies teenagers’ bodies and lives? To answer these questions, it is necessary to analyze the three factors in the same framework. 
Multilayered measures 
Promoting the health of adolescents is an important component for building a healthy China. However, exclusive empirical studies of the impacts of physical activity, screen time, and schoolwork on teenagers' health are rare, and existing literature mostly investigates one of the three factors, occasionally considering two of them. Few studies have placed all three in one framework, comparing the relative effect of each factor and analyzing their interactivity. 
Based on the China Educational Panel Survey conducted by Renmin University of China and the analysis of the above questions, several conclusions have been reached. First, physical activity, screen time, and homework all have significant impacts on adolescents. The impact of physical activity is positive, whether for exercise or housework, while the use of digital devices and excessive study generally lower teenagers' health levels. Surfing the internet, playing games, long afterschool study hours, and extended homework engagement all have negative impacts on health. 
Moreover, physical activity has the greatest benefits on overall health, and screen time is most harmful to mental health. In other words, although excessive study loads have long been regarded as a critical reason for Chinese adolescents’ decreasing health levels, it is not the biggest risk factor. 
In addition, the three factors are not contradictory, but are positively correlated or irrelevant in most cases. This indicates that the formation and development of the factors have mutually dependent social causes, and any policy measures or efforts related to a single factor will not change the other risk factors. Prevention and control of all factors should be carried out simultaneously with multiple measures. 
Currently, the detriments of insufficient physical activity and heavy academic burdens have been fully recognized throughout China. Intensifying physical exercises and decreasing study loads have become material parts of many national strategies and plans, but the attention to screen time’s impact seems to be inadequate. 
Since physical activity, screen time, and study loads each has independent health impacts, consideration should be given to controlling screen time while emphasizing the need for more physical exercise and lighter study loads. This is vital to teenagers' psychological health. 
At present, digital media has been a major channel and carrier for information acquisition, interpersonal communication, consumption, leisure, and entertainment, imposing requirements on individuals to blend into and adapt to modern social life. Born and growing up in this era, adolescents have a natural attachment to the electronic screen. Protecting their health against harmful social trends poses a great challenge. 
Quan Xiaojuan is from the School of Humanities, Economics and Law at Northwestern Polytechnical University; Lu Chuntian is a professor from the School of Humanities and Social Sciences at Xi’an Jiaotong University.