Methods

Study design

This study is based on prospective semi-annual follow-up data over a 3.5-year period on the control group recruited for a randomised controlled trial entitled Screening and counselling for physical activity and mobility in older people (SCAMOB, ISRCTN 07330512)[10]. The study was approved by the Ethical Committee of the Central Finland Central Hospital. Participants were recruited from the population register and selected based on that they were community-dwelling, aged 75–81-years, living in the city centre of Jyväskylä, Finland, were able to walk 500 m without help from another person, were moderately physically active or sedentary, had a Mini-Mental State Examination (MMSE) score> 21 and no medical contraindications for physical activity [10]. The study design has been described in detail elsewhere [10]. Of 632 people included in a randomised controlled trial, 314 (the control group) were followed up at 6-month intervals for the naturally occurring changes in mobility for 3.5 years. Of them, at baseline 100 people had difficulty walking 2 km and were excluded, leaving 214 people for the analysis on incident difficulty in 2-km walking. The corresponding figures for 0.5-km walking were 48 and 266, respectively. Over the 3.5-year follow-up, among those without difficulties in walking 2 km, 28 dropped out and among those without difficulties in walking 0.5 km, 35 dropped out.