Standardized Exercise Tests and Simulated Terrestrial Mission Task Performance

Missions to terrestrial destinations (i.e., asteroids, the Moon, and Mars) will consist of physically challenging mission-critical tasks. These tasks, coupled with the negative physiological effects of prolonged microgravity exposure, create a plausible situation in which physical requirements may exceed an astronaut's physical capacity. Therefore, the objective of the current study was to evaluate the association of aerobic fitness and muscular strength parameters with performance during two field tests designed to simulate upper-body mission-critical activities.

There were 70 subjects who completed a material transport field test requiring the loading, transport, and unloading of geological samples and a device operations field test consisting of tasks associated with equipment set-up and the operations of controls and valves. The relationships between test duration and the following measurements were determined: running Vo(2max), gas exchange threshold (GET), speed at Vo(2max) (s-Vo(2max)), highest sustainable rate of aerobic metabolism [critical speed (CS)], and the finite distance that could be covered above CS (D'); and arm cranking Vo(2peak), GET, critical power (CP), and the finite work that can be performed above CP (W').

CP (r = -0.66), CS (r = -0.56), and arm cranking Vo(2peak) (r = -0.54) were most strongly correlated with the material transport field test and decision tree analysis revealed CP as the best predictor of performance. For the device operations field test, CP (r = -0.70), CS (r = -0.62), and arm cranking peak power output (r = -0.56) were significant predictors.

Arm cranking tests are strongly associated with upper-body dependent tasks, highlighting that the nature of mission tasks needs to be considered when evaluating astronaut physical capacity.