NEX4EX - A novel exercise device enabling resistive, plyometric and sensorimotor training during deep-space missions: A case report.

During weightlessness, the human neuro-muscular-skeletal system undergoes maladaptation to the microgravity environment. The European Space Agency (ESA) project NEX4EX, 'Novel Exercise Hardware for Exploration', developed an advanced multipurpose exerciser offering resistive (RES), plyometric (PLYO) and sensorimotor (SENSO) exercises. It is the aim of this case report to assess the functionality of the device. NEX4EX offers RES in terms of squats and heel raises, and PYLO in terms of countermovement jumps and hops. RES and PLYO were compared with standard exercises on ground as reference. SENSO were generated by creating disturbances of the body posture by means of random, rapid pulling on a shoulder harness in four directions and by an oscillating platform. For SENSO, the results showed clear postural reflexes in trunk and leg muscles to stabilise upright posture after perturbation stimuli at the shoulders. RES and PLYO were carried out accurately on NEX4EX by the participants, but with reduced loads compared to reference (up to -37% for RES; up to -24% for PLYO). This resulted in reduced muscle activation for RES, whereas the muscle activation stayed comparable for PLYO. A reduced maximum take-off velocity during PLYO (up to -66%) was shown leading to a reduced jump height (up to -72%). Although some exercises could not be performed with the same intensity with NEX4EX, in general it enabled all intended exercises. The basic functionality of the device was shown, and thus the device showed its potential as an integrative countermeasure device for upcoming deep-space missions.