A brief measure to predict exercise behavior: the Archer-Garcia Ratio.

Background: Different forms of conscious and planned physical exercise and activity that individuals perform improve not only physical but also psychological health, well-being, and both physical and intellectual performance. Here we put forward and test the predictive validity of the Archer-Garcia Ratio, a brief measure for exercise frequency computed using participants' responses to two questions.

Method: The participants ( = 158) were recruited from a training facility in the south of Sweden. The Archer-Garcia Ratio was constructed by standardizing (i.e., z-scores) and then summarizing individuals' responses to two questions: "How often do you exercise?" (1 = , 5 = ) and "Estimate the level of effort when you exercise" (1 = , 10 = ). Participants responded also to the Godin Leisure-Time Exercise Questionnaire and allowed the collection of electronic data to track the number of times they had trained six months before and both six and twelve months after the survey.

Results: The Archer-Garcia Ratio predicted, moderately, how often individuals had trained during the six months before and both six months and twelve months after the survey.

Conclusion: The Archer-Garcia Ratio is a brief and valid self-report measure that can be used to predict actual retrospective and prospective exercise behavior. It offers a simple and straightforward form to estimate adherence, compliance and propensities of peoples' exercise habits.