levels of physical activity decline with age and gender during adolescence. After the age of 13,girls are significantly less active than boys. In Thailand, 82.2% of boys, 12 to 14 years of age, generally perform more physical activity, compared to 80.9% of girls. Similarly, 78.6% of boys, 15 to 19 years of age, participate in physical activity compared to 59.3% of girls, in Thailand.
At present, the most important health problems in Thailand are non-communicable diseases (NCD) or chronic diseases, such as cardiovascular disease, diabetes mellitus, cancer, and hypertension, which were the major causes of death and disability in 2005. Cardiovascular disease is the major cause of death among women, and the prevalence rapidly increases as women age. Physical inactivity is one of five major risk factors of chronic diseases. Further, the incidence of diabetes in children and adolescence has increased. Recent data suggest that more Thais are overweight, and their sedentary behavior has been increasing, especially among children, with 13 to 18 year olds being the most obese. In grades seven to nine, the percentage of overweight girls (18.6%, 17.6% and 14.8%, respectively) is higher than those of overweight boys (10.1%, 13.0% and 12.7%, respectively). These adolescents reported more sedentary behaviors, i.e. viewing television and playing computer games, than those age six to 12 years. Based on