Tolerability of plyometric exercises on a short-arm centrifuge

Kurzfassung

Artificial Gravity generated by Short Arm Human Centrifuges is a promising multi-system countermeasure for physiological deconditioning during long duration space flights. However, motion sickness symptoms could limit the tolerability of the approach due to cross-coupled forces. Therefore, we determined the feasibility and tolerability, particularly occurrence of motion sickness symptoms, during reactive jumping exercises on a short-arm centrifuge. In a cross-over randomized study, we assessed motion sickness symptoms during reactive jumping exercises on a short-arm centrifuge in 15 healthy men at different +Gz-level (0.5, 0.75, 1.0, 1.25 and 1.5 +Gz referenced to Center of Mass). On the centrifuge, a jumping sledge was attached with low friction bearings that allowed horizontal movements and around pitch axis along the radius. Head movements were not restricted. Vertical jumping in Earth´s Gravity was used as control. The results showed good tolerability of the jumping exercises. Motion sickness ratings (using Motion Sickness Assessment Questionnaire pre/post conditions) were in general low in all conditions, post-hoc analysis only showed higher ratings (z = 2.527, p = 0.034) for condition +1Gz on the Short-arm centrifuge compared to control. Further related effects of motion sickness like mood changes or increased sleepiness recorded with PANAS and Epworth Sleepiness Scale were not significant higher after jumping exercises during centrifugation compared with control. Our study demonstrates that repetitive plyometric exercises are tolerable at different +Gz-levels during short radius centrifugation. The finding is remarkable given the significant head yaw, pitch, and roll velocities being generated in all conditions that are excess of those previously defined as being associated with comfort zones.