Trancutaneous Abdominal Stimulation on Bowel Function.

Inclusion Criteria: * For spinal cord injury subject group: * Traumatic or non-traumatic spinal cord injury; * Constipation; * Motor-complete or motor-incomplete spinal cord injury; * Quadriplegia or paraplegia; * Post-injury time ≥ 1 year; * Neurogenic Bowel Dysfunction Score ≥ 7. * For able-bodied subject group: * Diagnosis of intestinal constipation according to the Rome IV criteria; * Chronic constipation as defined by \< 3 bowel movements per week for \> 3 months. * For both subject groups: Can read, understand and willingly sign an Institutional Review Board approved informed consent document that describes the study's risks and benefits. Exclusion Criteria: 1. Presence of any organic cause for intestinal constipation; 2. Have chronic fecal incontinence; 3. Have skin infection/lesion in the area of electrode application or systemic skin disease; 4. Have an implanted electronic device (such as heart pacemaker, insulin or baclofen pump, etc); 5. Have symptomatic cardiac disease; 6. Have uncontrolled diabetes; 7. Presence of abdominal hernia; 8. Have a stoma, rectal tear, or untreated hemorrhoids; 9. Have a significant psychiatric disorder; 10. For female subjects, being pregnant, actively planning a pregnancy or breast-feeding a child; 11. Be participating in another clinical study that would confound data analysis; 12. Have a cognitive impairment or exhibits any characteristic that would limit the study candidate's ability to complete study assessments.