Functional Performance Evaluation

The Extended Duration Orbiter Medical Project (EDOMP) was established to address specific issues associated with optimizing the ability of crews to complete mission tasks deemed essential to entry, landing, and egress for spaceflights lasting up to 16 days. The main objectives of this functional performance evaluation were to investigate the physiological effects of long-duration spaceflight on skeletal muscle strength and endurance, as well as aerobic capacity and orthostatic function. Long-duration exposure to a microgravity environment may produce physiological alterations that affect crew ability to complete critical tasks such as extravehicular activity (EVA), intravehicular activity (IVA), and nominal or emergency egress. Ultimately, this information will be used to develop and verify countermeasures. The answers to three specific functional performance questions were sought: (1) What are the performance decrements resulting from missions of varying durations? (2) What are the physical requirements for successful entry, landing, and emergency egress from the Shuttle? and (3) What combination of preflight fitness training and in-flight countermeasures will minimize in-flight muscle performance decrements? To answer these questions, the Exercise Countermeasures Project looked at physiological changes associated with muscle degradation as well as orthostatic intolerance. A means of ensuring motor coordination was necessary to maintain proficiency in piloting skills, EVA, and IVA tasks. In addition, it was necessary to maintain musculoskeletal strength and function to meet the rigors associated with moderate altitude bailout and with nominal or emergency egress from the landed Orbiter. Eight investigations, referred to as Detailed Supplementary Objectives (DSOs) 475, 476, 477, 606, 608, 617, 618, and 624, were conducted to study muscle degradation and the effects of exercise on exercise capacity and orthostatic function (Table 3-1). This chapter is divided into three parts. Part 1 describes specific findings from studies of muscle strength, endurance, fiber size, and volume. Part 2 describes results from studies of how in-flight exercise affects postflight exercise capacity and orthostatic function. Part 3 focuses on the development of new noninvasive methods for assessing body composition in astronauts and how those methods can be used to correlate measures of exercise performance and changes in body composition.