The impact of long-term confinement and exercise on central and peripheral stress markers.

Long-term isolation has been reported to have impact on psycho-physiological performance in humans. As part of the 520 days isolation study (MARS500, n=6) from June 3rd 2010 to November 4th 2011, this study aimed to show that stress caused by isolation and confinement is mirrored in cortical activity and cortisol levels and that exercise is a valid countermeasure. Cortical activity was measured by electroencephalography (EEG) pre- and post-moderate exercise every two weeks, salivary cortisol was taken every 60 days. Data show a decrease of global cortical activity, in both alpha- and beta-activity (p<.05-p<.001), and an increase of salivary cortisol (p<.05-p<.001), during the isolation, indicating that isolation acts as a chronic stressor with impact on cortical activity and cortisol levels. Moderate exercise leads to an increase (p<.01) in cortical activity. Therefore, during long-term space missions the factor isolation must be kept in mind as the reduction of cortical activity and the heightened stress level could impair performance. However moderate exercise might be able to counteract this impairment.