Completion of the proposed studies will expand our existing knowledge of ventilatory control in persons with tetraplegia and relate these changes to dyspnea, a common and distressing clinical problem in these individuals. These studies will also provide a better characterization of breathing patterns and their intrasubject variability in persons with tetraplegia. Currently, the only information regarding breathing patterns in tetraplegia are of limited duration (15-30 minutes). If this pilot study reveals significant relationships between motor drive, timing, and dyspnea, compiling "normative" data for breathing patterns from large numbers of individuals with tetraplegia may be useful in evaluating dyspnea in different clinical settings.