NASA, Kennedy Space Center (1985–1993)
With my deep desire to translate research findings to operational application and solutions, I decided to move in 1985 from academic research to a position with NASA at the Kennedy Space Center (KSC). As the lead scientist for development of exercise countermeasures, our research focused on management of physiological deconditioning and orthostatic intolerance associated with prolonged exposure to space flight. We used the 6° head-down bed rest model to investigate mechanisms underlying the control of hemodynamics, cardiovascular function, body fluid and electrolyte shifts, renal function, metabolism, muscle, thermoregulation and the role of the autonomic nervous system in the physiological response to microgravity. Because there was no bed rest research facility located at KSC, I had the unique opportunity to collaborate with Dr. Joan Vernikos at NASA’s Ames Research Center, Dr. Robert DeBusk at Stanford University School of Medicine, and Dr. Antonio Guell at the University of Toulouse in France at the invitation of the French Space Agency, CNES, in 1990 and 1991. At least four operationally significant contributions resulted from this work. First, we demonstrated that the salt solution that astronauts were historically asked to drink before reentry in an effort to expand their blood volume was ineffective when individuals remain in microgravity [10]. Second, we showed that to maintain their level of fitness, astronauts would require more exercise during space than less fit counterparts [3]. Third, our seminal studies demonstrated that a single bout of maximal aerobic exercise could prevent for at least 24 h the orthostatic intolerance induced by 2 weeks of bed rest by increasing blood volume, restoring cardiovascular reflex function, cardiac performance and aerobic capacity [11]. This simple yet innovative approach provides a potential countermeasure for reentry and post-flight orthostatic problems that required minimal time and resources (e.g., oxygen, food, water). Finally, we were the first to obtain human muscle biopsies in a 30-day bed rest study that identified the cellular basis for reductions in fast- and slow-twitch muscle fiber size and aerobic enzymes [12]. One important finding from this study was that the tears in muscle fibers and necrotic areas seen in astronauts and believed to have been due to microgravity exposure were not seen during bed rest. This finding was later confirmed in animal flight experiments where such tears were found only after landing. These results spurned NASA to pay greater attention to the post-flight rehabilitation process.
In addition to physiological research on the acute and chronic responses (adaptations) to microgravity, I had the opportunity to collaborate with Don Doerr, the former Chief of Biomedical Engineering at KSC. In this capacity, I participated in the test and development of various operational ensembles and self-contained air breathing apparatuses that enabled development of safety support and guidelines for KSC personnel (e.g., hypergolic fuel handlers, firefighters) who required working in the extreme heat and humidity created by closed impermeable suits (Fig. 3).
Fig. 3 Convertino performing operational tests on an impermeable ensemble during rest (left panel) and physical exercise (right panel) conducted in the summer of 1988 in the Human Physiology Laboratory at NASA’s Kennedy Space Center