OPERATING IN ISOLATED CONFINED AND CONTROLLED (ICC) OR EXTREME (ICE) ENVIRONMENTS IMPACTS PHYSICAL STATUS PSYCHOLOGICAL SYMPTOMS AND COGNITIVE FUNCTION ALL SERVING TO DEGRADE CREW PERFORMANCE AND JEOPARDIZE MISSION SUCCESS. COUNTERMEASURES SUCH AS EXERCISE TRAINING HELP TO REDUCE SUCH RISK BUT INDIVIDUALS ARE STILL SUSCEPTIBLE TO PROBLEMS ADAPTING TO AND OPERATING IN ICC/ICE ENVIRONMENTS. PHYSICAL TRAINING HAS BEEN SHOWN TO HAVE POSITIVE BENEFITS ON COGNITIVE AND IMMUNE FUNCTIONS AND PSYCHOLOGICAL STATUS OF INDIVIDUALS. HOWEVER IMPORTANTLY INCREASED STRESS LEVELS HAVE BEEN SHOWN TO SUBSTANTIALLY LIMIT INDIVIDUAL ENGAGEMENT WITH THESE TYPES OF PHYSICAL ACTIVITY. THEREFORE TO ENSURE THE EFFICACY OF A PHYSICAL TRAINING COUNTERMEASURE STRATEGIES NEED TO BE DEVELOPED TO ENSURE CREW MEMBERS MAINTAIN SUFFICIENT LEVELS OF TRAINING STIMULI TO PROVIDE THESE PROTECTIVE EFFECTS WHILE IN THE PRESENCE OF THE INCREASED LEVELS OF STRESS ASSOCIATED WITH OPERATING IN ICC/ICE ENVIRONMENTS. THE OVERARCHING HYPOTHESIS OF THIS PROPOSAL IS THAT STRUCTURED EXERCISE TRAINING PERFORMED IN AN ISOLATED AND CONFINED SPACEFLIGHT ANALOG WILL AMELIORATE STRESS-INDUCED CHANGES IN BEHAVIORAL HEALTH COGNITIVE SENSORIMOTOR AND IMMUNE SYSTEM FUNCTION. WE FURTHER POSIT THAT ADDING A GUIDED IMAGERY (GI) INTERVENTION COMPONENT TO THE EXERCISE TRAINING REGIMEN WILL INCREASE EXERCISE ADHERENCE AND POSITIVE AFFECTIVE RESPONSES AND THAT THE BENEFICIAL EFFECTS OF EXERCISE ON BEHAVIORAL HEALTH COGNITIVE AND IMMUNE SYSTEM FUNCTION WILL BE MEDIATED BY REDUCTIONS IN STRESS AND IMPROVEMENTS/MAINTENANCE OF PHYSICAL HEALTH. THE SPECIFIC AIMS ARE AS FOLLOWS: SA1. DETERMINE THE EFFECTS OF AN IN-FLIGHT VALIDATED EXERCISE REGIMEN ( SPRINT ) ON BEHAVIORAL HEALTH FATIGUE COGNITIVE SENSORIMOTOR AND IMMUNE SYSTEM FUNCTION IN AN ICC SPACEFLIGHT ANALOG SA2. DETERMINE THE IMPACT OF GUIDED IMAGERY ON EXERCISE ADHERENCE AND POSITIVE AFFECTIVE RESPONSES TO EXERCISE IN THE ICC SPACEFLIGHT ANALOG. WE WILL ALSO EXPLORE THE EFFECTS OF ADDING GUIDED IMAGERY TO THE EXERCISE REGIMEN ON BEHAVIORAL HEALTH FATIGUE COGNITIVE SENSORIMOTOR AND IMMUNE SYSTEM FUNCTION. SA3. DETERMINE IF EXERCISE TRAINING WITH OR WITHOUT GUIDED IMAGERY HAS A POSITIVE IMPACT ON BIOMARKERS OF STRESS AND CENTRAL NERVOUS SYSTEM FUNCTION IN THE ICC SPACEFLIGHT ANALOG AND CAN INCREASE RESILIENCE DURING AN ACUTE STRESS MODEL OF SLEEP DEPRIVATION RELATIVE TO THE CONTROL GROUP.