Soccer; Gymnastics; Swimming; Tennis; Martial arts; Carefully supervised strength training is OK beginning at age 7 or 8 in kids who are motivated. Focus on proper technique and movement. Ages 10 to 12. By this age, children have mature vision and the ability to understand and recall sports strategies. These children are typically ready to take on complex skill sports, such as football, basketball, hockey and volleyball. Keep in mind, however, that growth spurts caused by puberty can temporarily affect a child's coordination and balance.