3% is not a fitness gain; it is a microgravity glitch in the spine's load-bearing code. Weightlessness unweights the vertebral column. The spine behaves like a decompressed data buffer: the intervertebral discs draw in fluid and the spinal curves flatten, so astronauts can measure a few centimeters taller during flight.The body pays for that extra reach. Cerebrospinal fluid shifts headward, while ...More