The aim of the study is to investigate the effects of exercise and vitamin D supplementation on reducing falls and injuries in community-dwelling, independent-living women aged 70-79 years of age. The investigators will test the following hypothesis:

1. Exercise including strength, balance and mobility training will improve muscle functioning and body balance, and thus reduce falls by 30% compared with non-exercisers.
2. Vitamin D intake will improve muscle functioning and thus prevent falls by 30% compared with placebo.
3. Together vitamin D and exercise have a stronger influence on fall prevention than either used alone.
4. Training improves mobility functions and bone health.
5. Supervised training twice a week with daily home training will improve physical functioning thus resulting in reduced fear of falling.
6. Reduced fear of falling and improved physical functioning help older people to stay physically active, which further improve their quality of life.

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:

1. exercise with vitamin D
2. exercise with placebo
3. no exercise with vitamin D
4. no exercise with placebo. The rational of this study is to provide important information on how to maintain and improve physical functioning and thus prevent falls and fractures of elderly people. In addition, if fear of falling can be declined with this program, it will further help elderly people to keep physically active and maintain their functional capacity and quality of life.

Inclusion Criteria:

• female
• age 70-80 years old
• lives at home independently
• has fallen at least once during the previous year
• no contraindication to exercise
• understands the procedures of the study
• has been informed of X-ray radiation doses of the DXA and pQCT investigations

Exclusion Criteria:

• moderate-to-vigorous exercise more than 2 hours per week
• regular use of vitamin D, or calcium + vitamin D supplements
• a recent fracture (during preceding 12 months)
• contraindication or inability to participate in the exercise program
• marked decline in the basic activities of daily living (ADL-test)
• cognitive impairments (Mini Mental State Examination, MMSE-test < 18)
• persons with chronic disease conditions, such as Parkinson's disease