Fifty years ago, Clark and Euler published a model of the neural control of respiration that stimulated modern studies on the central generator of the rate and depth of breathing. These studies led to new discoveries concerning both anatomical localization and functional characteristics of respiratory central pattern generator (CPG), and as a result our knowledge has greatly changed. This article describes the history of respiratory CPG research and, more specifically, explains how studies concerning the regulation of breathing parameters affect the creation of new hypotheses and theoretical models of the neural control of respiration. Comparing studies on the generators of cyclic movements of respiration and locomotion helps us to show their significance for clinical research, especially in the field of spinal injury. After partial or total paralysis of muscles, techniques of muscle work assistance are especially important. Therefore, different techniques of assisted locomotion and breathing are presented here and an explanation of how locomotion and breathing can influence each other is offered. The ability to reactivate the spinal neuronal network using either pharmacological or electrical stimulation methods is discussed. Research performed with the application of biologically steered servo-respirators allow for a better understanding of respiratory CPG and show the limits of assisted ventilation in clinical practice. This article presents the role of activity-dependent plasticity in the rehabilitation of locomotor and respiratory muscles after spinal injury.