The NBA has specified basketball sizes not just for official men's, women's, and junior league games, but also unofficial games for children and youth. These size specifications help you choose the right ball for yourself or your children, and it is recommended that they be followed strictly to avoid injury during play.

Basketball is a physically vigorous game, with moves that involve running, jumping, blocking, and shooting. The injuries during the game are categorized into upper body and lower body injuries. While lower body injuries can be prevented by proper shoes, training, and padding, upper body injuries are best prevented by using basketballs of proper size and weight.

According to a survey published by the US Centre for Disease Control and Prevention (CDC), basketball ranks fourth among the major causes of injury in the US. A study quoted on iqHealth.com says that basketball causes 20% of all injuries in children aged 10 to 14. iqHealth.com goes on to suggest that proper basketball weight and size go a long way in preventing such injuries. The NBA recommended basketball size for children in this age group is 27.25 ?, with weight around 12 oz.

Injuries due to improper basketball size are also prevalent among children below the age of 7. NBA recommends that very young children be given foam or rubber basketballs with a 22 ? circumference and weight of 8 oz.

The CDC found that girls are more frequently and acutely injured than boys during basketball games. For adolescents girls between the ages of 14- 16, NBA recommends "junior ? basketballs of circumference 27.75 ? (size 5), with a weight of around 18 oz. Also, the ball for women's official games is 28.5 ? in circumference (size 6) and weigh 20 oz. The men's official basketball, by comparison, is bigger (29.5 ? or size 7), weighing 22 oz.

Even training balls that are not used for official matches have certain size and weight criteria. For shot training, the men's training basketball has 36 ? circumference (size 9). The women's basketball is 33.5 ? or size 8. The men's weighted ball used for muscle building exercises is 29.5 ? in circumference and the women's ball is 28.5 ?, with weight a little more than the official balls.

Choosing the right ball is important for your health and safety, and these guidelines should be adhered to while purchasing basketballs for official or unofficial games.