Respiratory complications are among the leading causes of death in patients with chronic spinal cord injury (SCI). Our previous work showed that pulmonary function can be improved by using our original respiratory training method. However, the effectiveness of this intervention is limited due to the disruption of brain-spinal connections and consequently lowered spinal cord activity below the injury level. Our recent studies showed that electrical stimulation of the spinal cord below the level of injury leads to increased ventilation which indicates activation of the spinal cord structures related to respiration. These findings indicate that spinal cord stimulation can be a promising therapeutic additive to the treatment. The goal of this study is to justify the establishment of a new direction in rehabilitation for patients with SCI by using a non-invasive spinal cord stimulation in combination with respiratory training.

Our aims are: 1) to evaluate the effects of such stimulation applied to the injured spinal cord on pulmonary function and respiratory muscle activity, and 2) to evaluate the effectiveness and therapeutic mechanisms of the spinal cord stimulation combined with respiratory training. Thirty-six individuals with chronic SCI will be recruited and assigned to three groups to receive respiratory training or spinal cord stimulation alone or a combination of them. All participants will be tested before and after cycles of experimental procedures with/or without stimulation. Our hypotheses will be confirmed if the respiratory training combined with spinal cord stimulation results in the most enhanced positive effects.

This is a respiratory rehabilitation-based clinical study consisting of physiologically and functionally relevant mapping of respiratory function that enhances our knowledge of neurophysiological modulation evoked by non-invasive spinal cord Transcutaneous Stimulation (scTS) and contributes to the development of the next generation of rehabilitative approaches. Following the screening process and recruiting, the research subjects will undergo the following procedures: Subjects (total n=36) will be randomly assigned to three groups and will undergo baseline assessments; evaluations before and after 80 sessions of specific intervention (Respiratory Training /RT/ alone, scTS alone, or RT in combination with scTS); and during 16 week-long follow up period.

Inclusion Criteria:

• At least 18 years old;
• stable medical condition;
• no painful musculoskeletal dysfunction, unhealed fracture, contracture, pressure sore or urinary tract infection that might interfere with respiratory training or stimulation;
• no clinically significant depression, psychiatric disorders or ongoing drug abuse;
• non-progressive SCI (no negative change in the neurological level and motor-completeness assessed during screening when compared to the neurological status assessed at 6-mo period after injury or at least 6 months prior to the screening), non-ventilator dependence, motor-complete SCI according to the American Spinal Injury Association Impairment Scale (AIS) grade "A" or "B" above T5 spinal level;
• sustained SCI at least 12 months prior to entering the study;
• compared to the normative values for healthy population, at least 15%-deficit in pulmonary function outcomes (FVC and FEV1) as detected by screening spirometry.

Exclusion Criteria:

Participants will be excluded from the study if there is a presence of

• major pulmonary or cardiovascular disease,
• ventilator dependence,
• endocrine disorders,
• malignancy,
• marked obesity,
• deep vein thrombosis,
• HIV/AIDS-related illness,
• secondary hypotension (anemia, hypervolemia, endocrine and neurological diseases),
• major esophageal/gastrointestinal problem or other major medical illness contraindicated for respiratory training or testing.

During screening, the potential participant will be asked whether she is pregnant or planning to become pregnant during the study period. Pregnant women are excluded from this study, as the risk to the fetus is unknown. No pregnancy test or birth control regimen will be required.

Unidentified data sets will be processed and evaluated by the research staff not directly involved in experimental procedures.