Bone-strengthening physical activity done increases bone-mineral content and bone density in youth.

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The answer would be three days a week

Bone-strengthening activity is key to ensuring that bones remain healthy to maintain an individual's lifestyle. The physical activity to strengthen bone may be brisk walking, exercises that include weights, or gymnastics to lift a few. The purpose of these activities are to observed to contribute to an increase in the bone mineral density of adolescents and children. Several studies have established that about 150 minutes a week for adults, or 3 days a week (60 minutes a day) for the youth should be devoted to bone strengthening physical activity to ensure good health of the body.

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