Hip fracture is a major cause of morbidity in older people, leading to loss of independence, and a huge burden economically in terms of healthcare costs. Osteoporosis, defined as reduction in bone mineral density (BMD) and bone strength, is strongly related to hip fracture risk. Several mechanisms contribute to the age-related decline in BMD and bone strength, including an age-related decline in the intensity and amount of PA, leading to a reduction in the quality and quantity of mechanical strains (defined as deformation of bone per unit length in relation to loading). For example, less than 30% of 65-74 year-olds and 15% of adults aged 75 and over report any moderate intensity PA lasting at least ten minutes in the previous four weeks (Craig R et al, 2009). These low levels of PA have numerous adverse health outcomes, reflecting the importance of physical activity for a range of systems including bone, leading to initiatives to co-ordinate existing activity promotion schemes (http://www.ageuk.org.uk).