Physical fitness of obese school children in Hat Yai, southern Thailand.

259 primary school children (average age 9.2 years) were randomly selected from three groups of children whose weights-for-height were 90-110% (normal 111), > 110-120% (over weight 25), and > 120% (obesity 123) of reference values for Bangkok children. They underwent physical fitness tests which included measurement of speed (50 meters run), flexibility (sit-reach), abdominal strength and endurance (30 seconds sit-up), vital capacity (spirometer), and indirect maximum oxygen uptake (VO2 max-submaximal bicycle ergometer). The results showed that all physical fitness tests were statistically significantly different (p < 0.05) between groups, except for flexibility in boys. But for the girls, only 50 meters run, sit-up and VO2 max showed statistically significant differences (p < 0.05). In the comparison of physical fitness tests between sexes, normal weight boys did better than girls (p < 0.05) for all tests except flexibility. There were no statistically significant differences between sexes in overweight and obese children. This study demonstrated that physical fitness of obese children was worse than that of normal children in both sexes, especially as measured by 50 meters run, sit-up and VO2 max tests. Thus, promotion of exercise in obese children should be stimulated to develop better physical fitness and weight reduction. In comparison of physical fitness between the sexes, boys had better physical fitness than girls, significant in the normal weight group only. There is no definite explanation as to why increase in weight results in no difference of physical fitness between sexes. Lifestyle, physical skills, and genetic determinants should be considered for interpretation of physical fitness.