An apparatus for providing medical treatments is disclosed. In one aspect, an apparatus according the present invention comprises a mattress, a mattress support, cast shoes, a footboard support, a drive for causing the reciprocating movement, and a box frame to contain and support the reciprocating movement platform. In another aspect, an apparatus according to the present invention comprises a sling device connected to a drive causing the reciprocating movement, and a box frame to contain and support the reciprocating movement platform. In yet another aspect, medical treatments by externally applying periodic acceleration according to the present invention include the treatment of inflammatory diseases, the preconditioning or conditioning of vital organs to protect them from the deleterious effects of ischemia, non-invasive ventilation and cardiopulmonary resuscitation, treatment and preconditioning of the organs of animals such as horses, and the treatment of diseases or conditions where oxidative stress plays a role.