Project Summary/Abstract Neurogenic osteoporosis is a devastating problem that is likely to impact 46,000 Veterans with chronic spinal cord injury (SCI). It is typically associated with low impact fractures of long bones and other medical comorbidities. It is estimated that approximately fifty percent of all individuals with SCI will develop low impact fracture during their lifetime. The management of osteoporosis related fractures can impose substantial economic burden on the health care system, individuals with SCI and their families. Advancement in medical research clearly indicated that neurogenic osteoporosis is linked to reduced loading and Vitamin D (Vit D) deficiency. Our pilot work indicated that a simple rehabilitation paradigm targeting towards evoking skeletal muscle hypertrophy may attenuate deterioration in trabecular bone parameters after SCI. Evoked resistance training (RT) using surface neuromuscular electrical stimulation (NMES) has been shown as a successful and feasible home-based approach to load skeletal muscles after SCI. Our earlier results may imply long term compliance and adherence if successfully applied in conjunction with a telehealth approach. In the present study, we propose a simple home-based approach of using NMES RT in conjunction with oral Vit D supplementation on trabecular bone quality in 20 Veterans with chronic SCI. Data will include measurements of trabecular bone quality as determined by magnetic resonance imaging (MRI) and bone biomarkers associated with the process of bone remodeling. Twenty participants with chronic (> 1-year post-injury) motor complete (AIS A and B) SCI (18 to 65 years of age) will be randomly assigned into either NMES RT plus 2000IU of Vit D (10 participants) or passive movement plus 2000IU Vit D (10 participants) to participate in a repeated measure design trial for 9 months. The NMES RT plus Vit D will undergo 4.5 months of open kinematic chain resistance training followed by 4.5 months of closed kinematic chain using simple rowing approach. This pilot work will have two main specific aims. Aim 1. To determine the impact of home based NMES RT protocol plus oral Vit D supplementation compared to passive movement plus oral Vit D on bone microarchitectural properties. Aim 2. To determine the impact of home based NMES RT protocol plus oral Vit D compared to passive movement and Vit D supplementation on biomarkers of bone formation and bone resorption. Key words: Spinal cord injury, osteoporosis, bone turnover, bone remodeling, bone biomarkers, electrical stimulation, vitamin D.