The Elaysian physique and neural motor cortex was adapted to cope with a low gravity; on their homeworld they were virtually able to "fly". When exposed to Earth-normal gravity environments they needed physical support to function. The type of support varied but included wearing an external skeleton with integrated servomotors which helped by supporting the person's own skeleton, although this only functioned for short periods of time. For longer-term physical support other forms of support were needed, like a wheelchair or an anti-grav unit.
A medical treatment was developed by Doctor Julian Bashir based on earlier neuromuscular adaptation research by Nathaniel Teros. By elevating the neural output to the brain's motor cortex via neural analeptic transmitters, he improved his theory and made this treatment possible. The drawback of this treatment was that if started, no exposure to low gravity environments was advised because this would confuse the person's body and motor cortex. When complete, the person could move naturally in Earth-normal gravity as most typical humanoids. The results of the treatment were irreversible.
Elaysians were introduced along with several other species from the same planet. The Elaysian homeworld was called "Gemworld" as the planet had virtually expired, and was being held together only by the technological feats of it inhabitants. (Gemworld, Book One, Gemworld, Book Two)