Biomechanics is fundamental to understanding the work performance capabilities of humans in space. Biomechanics as practiced by NASA has the primary goal of conducting operationally-oriented research focusing on maximizing astronaut on-orbit performance capabilities. One immediate and important objective of this research is to minimize the effects of deconditioning during spaceflight using individualized exercise "prescriptions" and in-flight exercise facilities combined with extensive biomechanical analysis of movement in micro-gravity. Results from experiments on the Gemini, Apollo, and Skylab missions suggest that regular exercise is helpful in minimizing several aspects of spaceflight deconditioning (1,2,3). In fact, exercise is the only countermeasure that can potentially counteract the combined cardiovascular, musculoskeletal and neuromuscular effects of adaptation. One of the ways the human body reacts to the reduced physiological and mechanical demands of micro-gravity is by a deconditioning of the cardiovascular, musculoskeletal, and neuromuscular systems. Deconditioning produces a multitude of physical changes such as loss of muscle mass, decreases in bone density and body calcium. It is also responsible for decreased muscle performance, strength and endurance, orthostatic intolerance, and overall decreases in aerobic and anaerobic fitness. Deconditioning presents operational problems during spaceflight and upon return to I-G. Muscular and cardiovascular deconditioning contributes to decreased work capacity during physically demanding extravehicular activities (EVAs); neuromuscular and perceptual changes precipitate alterations in magnitude estimation, or the so-called "input-offset" phenomenon; and finally, decreased vascular compliance can lead to syncopal episodes upon re-entry and landing. Extravehicular activity is the most physically demanding task that astronauts perform on-orbit. Space Station Freedom and manned Lunar and Mars missions will greatly increase the number, frequency, and complexity of EVA's within the next 10 to 20 years.
The purpose of our biomechanical analysis in space is to
provide a program of exercise countermeasures that will minimize the operational
consequences of microgravity-induced deconditioning by providing individualized exercise
'prescriptions' for each crew member. Task requirements have been defined in terms of the
musculoskeletal and neuromuscular system demands induced by microgravity, and training
protocols developed to address deconditioning in these systems to serve as the basis for
training prescriptions. To achieve these training protocols it was necessary to develop
flight exercise hardware and associated software related to biomechanical measurement
Some of the critical issues that had to be addressed in order to achieve the above goals were:
Next, an exercise dynamometer had to be designed for exercise purposes that could also analyse muscle functions and efficiencies. Some of the requirements of such an in-flight O-G exercise dynamometer were:
Such a system has been developed by the author and its
utilization in a micro-gravity environment shows great promise.