Title: Exploring the Association Between a Novel Index of Volume of Exercise Performed and Health Outcomes
Description: The association between increased participation in physical activity (PA) and improvements in health is so well established that the promotion of regular participation in PA is a key public health priority. However, much remains to be explored about the dose-response relationship between PA and the many health benefits. To address this issue, there is a need to accurately measure PA across all population sub-groups. Finding a valid, reliable and sensitive measure of PA is essential for improving our understanding of PA-related disorders, for more clearly defining the dose-response relationship between the volume, intensity and pattern of PA and the associated health benefits, and to examine the effectiveness of interventions and public health initiatives. We conducted three exercise studies aimed at examining the associations between a novel indexof exercise volume and selected physiological and psychological outcomes. The first and second studies were secondary analyses of studies in which the validity of this index was assessed in two different exercise interventions: 12-weeks of moderate-intensity aerobic exercise and a 6-week high intensity interval training intervention.

The third study was a prospective randomized controlled trial testing the feasibility and practicality of this index as applied to a specific population in an at-home exercise intervention. Taken as a whole, the results from the three studies indicate that the novel method of measuring exercise volume is promising for tracking some of the biological and psychological benefits that are associated with exercise. In these studies, this novel index of exercise volume was significantly associated with specific markers of biological adaptation to exercise training that are clinically meaningful. Further research is needed to replicate these findings in larger, diverse samples, and to broaden our understanding of how applications of this novel index can expand our ability to illuminate mechanisms whereby exercise might improve physical and mental health in research and in practice.