Whole Body Periodic Acceleration on Blood Lactate and Recovery

Each visit Subjects will perform a graded treadmill exercise test. They will rest for 10 minutes. At the end of the rest period, resting vital signs (HR and BP) will be recorded as well as resting oxygen consumption (VO2). Resting capillary blood sample will be taken and analyzed by the Accutrend portable lactate analyzer to measure blood lactate levels. The cardiac and metabolic recordings will be measured by PFT GX machine (Medgraphics Ultima; St. Paul, Minnesota) that will record VO2, VCO2, RER (respiratory exchange ratio), Ve. Heart Rate will be monitored by a Polar® HR monitor. This machine is attached to a motorized treadmill with handrails. Each subject will perform a Modified Bruce Protocol which consists of a maximum of five 3-minute stages. The criteria set for peak exercise is one of the following: 1) 90% of THR; 2) a plateau of oxygen uptake is indicated; 3) if the subject is unable to maintain the pace of the treadmill; 4) an RER of over 1.0 and/or 5) a plateau in Ve (3). Additionally, the American College of Sports Medicine (ACSM) guidelines for terminating exercise testing will be followed(American College of Sports Medicine). TIMELINE of PROCEDURES The following recoveries will be tested on 3 separate days: Visit 1 The subject will walk at 30-40 % of V02 max for the next 20 minutes on the treadmill after peak exercise. Blood lactate will be taken at minute 20. Visit 2 The subject will be taken off the treadmill after a 3 minute walk and placed on the WBPA bed. The horizontal displacement will be held constant at 14 mm, and cycles/min will be held constant at 140. There is a footboard where the subjects feet are strapped in while wearing their own shoes. The platform moves in a repetitive motion from head-to- foot imparting mild periodic inertial forces in the subject's spinal axis (pGz). Blood lactate will be taken at minute 20. Visit 3 The subject will be taken off the treadmill after a 3 minute walk and asked to sit in a chair for 20 minutes. Blood lactate will be taken at minute 20.