Inclusion Criteria:  Traumatic motor-complete SCI C4-L2 (AIS grade A & B); Duration of SCI less than 6 months; Males and females (premenopausal) between the ages of 18 and 50 years old; and a safe range of BMD right above the knee as determined by study staff review;  Exclusion Criteria:  Active and/or history of coronary heart disease or stroke; Bone cancer; Long-bone fracture of the leg within the past year; History of prior bone disease (for example, Paget's hyperparathyroidism, osteoporosis, etc.); Postmenopausal women; Men with known low functioning tests before SCI; Drugs geared toward increasing BMD longer than a six month duration after SCI; As determined by study staff review of my medication history of glucocorticoid administration longer than three months duration within the last year Abnormalities of my endocrine glands such as hyperthyroidism, Cushing's disease or syndrome, etc.; Severe underlying chronic disease (for example chronic obstructive pulmonary disease (COPD), end-stage heart disease, chronic renal failure); Heterotopic ossification (HO) of the distal femur (the knee end of the thigh bone). HO is a condition where bone tissue forms outside of the skeleton. If HO is found in any other area than the distal femur it will not prevent my participation in the study.; History of chronic alcohol abuse; Diagnosis of hypercalcemia (high levels of calcium in the blood); Pregnancy; As determined by study staff review of my medications a bisphosphonate for heterotopic ossification (HO), or other medications to treat osteoporosis other than calcium and vitamin D; Current diagnosis of cancer or history of cancer; As determined by study staff review of my medications, prescribed moderate or high dose corticosteroids (>40 mg/d prednisone or an equivalent dose of other corticosteroid medication) for longer than one week, not including drug administered to preserve neurological function at the time of acute SCI; and Life expectancy less than 5 years.