Falls account for over 80% of all injury-related admissions to hospital among older people. Although there is evidence that both exercise and vitamin D improve neuromuscular and cognitive function, and may thus reduce the risk of falls and fractures, these two factors have never been evaluated together in a clinical trial. This study is a randomized 24-month intervention in elderly women. The investigators hypothesize that exercise and vitamin D supplementation reduce falls and injuries including fractures in community-dwelling, independent-living women 70-79 years of age. The eligible participants will be randomly assigned into one of four groups: