Introduction: In Brazil, a person who is sixty years old or more is considered elderly. The incidence of osteoporosis and osteopenia has been increasing, as have fractures resulting from falls. Vitamin D deficiency can cause muscular atrophy in type II fibers (fast contraction and strength), which can increase the risk of falls. The aging process produces reduction in the ability of postural control system to maintain postural balance, which may increase postural instability and consequently increase the elderly risk to falls. Objective: To evaluate if vitamin D supplementation associated with regular exercise in vulnerable older women improves muscle strength and postural balance in 12 weeks. Methods: This will be a randomized prospective clinical trial, double blind, placebo-controlled intervention. Will be part of the study 40 elderly women vulnerable, who meet the inclusion criteria and that will be coming from the community through calls made by radio and social network. The volunteer will undergoing to blood test, body composition and bone mineral density, Mini Mental State Examination, Geriatric Depressive Scale, Falls Efficacy Scale, WHOQOL-OLD and WHOQOL-BREF instruments, functional capacity tests (MiniBEST, Time up and Go, Chair Rising Test, Six-minute walk test), muscular strength assessment (isokinetic dynamometry, handgrip and 1RM test) and postural balance (AccSway force platform for static postural balance and NeuroCom's Balance Master for dynamic postural balance) before and after 12 weeks of intervention with vitamin D supplementation and resistance and postural balance exercise. The intervention that will be perform during the 12 weeks with a progressive resistance training program.

Inclusion Criteria:

1. Age > 60 years;
2. Osteoporosis or osteopenia (bone mineral density lower than -1.5 standard deviations of the T-score);
3. Present hypovitaminosis D (<30 nmol / L);
4. Do not practice regular resistance exercise;
5. Can not have an injury in lower limbs at least on the last three months,;
6. Be able to perform independent gait without climbing for at least 100 meters;
7. Be independent in your daily life activities;
8. Do not present restrictions for the practice of resistance exercises, including having performed a recent exercise test (maximum 6 months);
9. Do not use medications such as estrogen's, diuretics, to improve bone mass;
10. Do not use dietary supplements with vitamin D;
11. Do not present hyperparathyroidism, diabetes, uncontrolled hypertension, hyperprolactinemia, hypercalciuria, renal lithiasis or elevated serum calcium.