Simmonds, B., Fox, K., Davis, M., Ku, P. W., Gray, S., Hillsdon, M., …Trayers, T. (2014). Objectively assessed physical activity and subsequent health service use of UK adults aged 70 and over: A four to five year follow up study. PLoS ONE, 9(5), Article e97676. https://doi.org/10.1371/journal.pone.0097676