Are Elderly Volunteer Participants in Exercise Trials Fitter than Non-Volunteers?
Introduction: Studies on exercise and functional fitness in the elderly are often subject to biases in selecting the study population: volunteers participants are thought to be in better physical shape than their same-age peers in the general population. The aim of this study was to look into whether volunteers to participate in an exercise controlled trial are fitter than non-volunteers. Methods: A questionnaire about physical activity, functional limitations, state of health, bodily satisfaction, height, weight, and socio-demographic information was sent to 1000 individuals age 60 or over. Subjects were also asked whether or not they would be interested in participating in an exercise intervention study. Results: The questionnaire was answered by 535 individuals. Among them, 233 agreed to participate in the exercise trial and 270 did not. The volunteers were younger than the non-volunteers, but they did not differ in sex. Compared to non-volunteers, volunteers were more educated and
