In Spanish it is a neologism somewhat forced from another as trainable ("that can or should be trained") with the prefix des- not so much as negation but as "loss of training already obtained by someone". It can have a sporting sense when performance is lowered due to lack of regular exercise, or also medical when a healthy routine is abandoned that causes a recurrence. In other languages it has a very different meaning, so it must be an invention of Spanish, it would not be barbaric. See suffix -ble .
