The link between body mass index (BMI) and bone properties, muscle strength, and motor coordination in boys and girls aged 7−9

Background: Obesity affects health parameters that are related to physical activity. The present study examined the relationship between weight and three such parameters in young boys and girls, bone properties, muscle strength, and motor coordination. Material and methods: The study consisted of second-and third-grade 286 students – 144 boys and 142 girls participants. Bone properties were measured at the distal radius and tibia shaft by Speed of Sound technology. Tests were conducted to measure muscle strength and motor coordination. Results: Obese boys were characterized by lower bone properties (p < .01) in the tibia bone than normal-weight boys. They were significantly (p < .05) weaker than normal-weight boys on muscle strength tests. Obese boys scored significantly (p < .05) lower on coordination tests than the normal weight boys. Underweight girls maintained higher bone properties than did the girls in all other BMI categories. Normal-weight girls scored significantly (p < .05) higher than obese girls on muscle strength tests. Obese girls scored significantly (p < .05) lower than normal-weight girls on motor coordination tests. Conclusions: The findings emphasize the need to identify obese children and refer them to special weight loss and exercise programs.