Children are very delicate; injury and accidents happen without warning. While physical play is fun for both you and your child, exercise extreme caution when engaging in it. At 12 months, your child will enjoy mild physical play activities, such as climbing on you when you are lying down or being help in the air. At that age, they are still too young and weak to cope with piggybacks or with strenuous play.
Whatever you do, make sure you don't shake your child or use too-sudden changes in momentum. Children's necks are prone to breaking from rough play and their skulls are still knitting together. Do not throw your child up; the risk of serious injury if you drop your child is not worth the risk.
From the age of 24 to 36 months you can start introducing activities like piggybacking; do so very slowly and over grass or pillows. Even a short fall can hurt you child badly. Avoid swinging your child around by the limbs; they may dislocate the joints and ligaments can be injured. Always support your child's head and neck during rough play. If your child really enjoys being 'thrown' upwards, make it safe by never letting go of your child. The sensation is the same but the danger and risk is much reduced.