Acroyoga (also written Acro-Yoga or Acro Yoga) is a physical practice which combines yoga, acrobaticsand Thai massage. Acroyoga is more vigorous than many traditional yoga practices and may lead to more injuries. Acroyoga has been practiced since the beginning of the century. One of the oldest videos of someone doing Acroyoga is with Sri Tirumalai Krishnamacharya, practicing the role of the base, while a child executed some asanas in 1938. Since then, Acroyoga has gained new movements, and is still changing. There are three primary roles in an Acroyoga practice: base, flyer, and spotter. Base - this is the individual who has the most points of contact with the ground. Often this person is lying on the ground with the entire back torso in full contact. This enables both the arms and legs to be "bone-stacked" for maximum stability and support of the Flyer. Main points of contact with the flyer are the feet (generally placed on the Flyer's hips, groin or lower abdomen) and the hands (which either form handholds or grasp the shoulders). Flyer - this is the individual who is elevated off the ground by the Base. The Flyer can move into a series of dynamic positions, and generally lets gravity do the work for them. A Flyer needs balance, confidence, and core strength. Spotter - this is the individual who has an objective view of the partners, and whose entire focus is on making sure that the Flyer lands safely in case of any slips. The spotter can also make recommendations to the Base and Flyer to improve their form.