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Diet, Exercise is Necessary for Bone Strength in Obese Kids

According to studies, mechanical loading -- running or jumping, as opposed to swimming or biking -- may be the best way to strengthen kids' bones.

The benefits of such exercises are most prominent during skeletal growth and development during childhood and adolescent years.

The reason running and jumping improve bone mass is due to the cellular mechanosensors found within new bone growth, which provide direction to where it is needed most. The only flaw here is that although cellular mechanosensors are efficient, the biological process involved in bone mechanotransduction remains a mystery to scientists.

Obese children and adolescents are apt to have weaker bones than their normal-weight peers, a study confirms. The study also shows that a combined nutritional-behavioral-physical activity intervention can help obese children lose weight and improve their bone strength.

"This is very important, because childhood and adolescence are critical periods for bone mass gain," Dr. Alon Eliakim from the Child Health and Sports Center at Meir General Hospital, Kfar-Saba, Israel told Reuters Health.

Recent studies have suggested that "unlike obese adults, obese children have lower bone mineralization and lower bone strength, probably due to the marked reduced physical activity, and possibly due to reduced calcium intake," Dr. Eliakim said.

In a controlled intervention study involving 24 obese children and adolescents between 6 and 16 years of age, Dr. Eliakim and colleagues found that a three-month dietary and physical activity intervention improved body composition, fitness, and bone strength.

Twelve participants in the intervention group met with a dietitian, with or without their parents depending on their age, six times during the three-month program. These sessions focused largely on reasons for childhood obesity, as well as good and bad food choices, eating habits, and how to read food labels. These sessions also aimed to involve the whole family in the "battle" against obesity.

Intervention subjects also adopted a balanced low calorie diet, participated in supervised twice-weekly exercise sessions and were encouraged to walk on their own for 30 to 45 minutes at least once weekly.

The other 12 obese children, who served as comparisons, were referred for nutritional consultation at least once and were instructed to exercise three times per week on their own.

According to a report in the International Journal of Sports Medicine, the intervention group fared much better than the comparison group in terms of body weight and composition and bone strength.

The nutrition and exercise program led to noteworthy decreases in body mass index and body fat, an increase in physical fitness and improved bone strength based on quantitative ultrasound measurements.

Interestingly, the team notes, bone strength significantly decreased in the obese children and adolescents in the comparison group.

Whether the improved bone strength resulted from decreases in body mass index, the increase in physical fitness due to added weight-bearing activities, or both, needs to be determined in future studies.

The researchers don't think the differences in bone strength were due to increased calcium intake, because calcium intake was similar at the beginning of the study and children in both groups received daily calcium supplements of 600 milligrams.

Consistent with prior studies, calcium intake in most of the obese children studied fell far short of the recommended daily intake of 1000 to 1300 milligrams

Since peak bone mass during childhood and adolescent years is one of the known major contributing factors to osteoperosis, it makes building strong and healthy bones that much more critical during early years of development.

Another concept concerning bone mass that researchers have been attempting to gain ground in is discovering how desensitization of bone cells occurs. They do understand, however, that desensitization plays an important role regarding the mechanosensing apparatus.

One scientist found that in order to create an exercise program to build bone strength meant to incorporate desensitization, age-related effects of exercise and include an exercise "osteogenic index" or OI.