Exercise-Related Effects on Executive Functions During a Simulated Underwater Extravehicular Activity

Investigation of cognitive performance during extravehicular activities (EVAs) in a space-analog setting.

EVAs performed by humans in microgravity on the International Space Station (ISS) call for high cognitive performance during upper-body workload. Higher cardiovascular demands interact with cognitive performance, but no knowledge exists about EVA's special requirements. This study simulates EVA-training underwater to investigate its effects on the executive functions inhibition and switching.

In a counterbalanced crossover design, 16 divers (age: 28 ± 2.4 years; eight females) performed two conditions (i.e., EVA vs. Inactivity [INACT]) in 3-5 m submersion (diving gear; not in a space-suit). EVA included 30 min of moderate-, followed by 30 min of high-intensity upper-body exercise intervals, paired with EVA-specific cognitive-motor tasks. INACT included no exercise in submersion and neutral buoyancy. Both conditions included cognitive testing at pre, mid (after the first 30 min), and post (after the second 30 min) on a tablet computer. Reaction times (RTs) and response accuracy (ACC) were calculated for both tasks.

ACC was significantly lower during EVA compared with INACT for inhibition (post: p = .009) and switching (mid: p = .019) at post (p = .005). RTs for inhibition were significantly faster during EVA (p = .022; η_p² = 0.320).

Specific physical exercise, intensity, duration, and tasks performed during the EVA might differently affect the exercise-cognition interaction and need further investigation, especially for future long-term space travel.

Future research might serve to improve mission success and safety for EVAs and long-term space travel.