Purpose: When attempting to assess responsiveness to habitual exercise in a health context, there is a wide range of issues that need to be addressed in order to provide science-based recommendations for use in evidence-informed health care delivery. Issues regarding responsiveness include characteristics of the exercise regimen or dose as well as characteristics of the response or effect.
Results: The exercise dose typically has been characterized by its type, intensity, session duration, and session frequency with the concepts of activity profile, activity volume, and accumulation over multiple bouts throughout the day recently added to these discussions. When establishing the dose for a designated outcome, specificity of the response in relation to exercise type needs to be considered. Understanding the role of intensity as a stimulus for change is critical because of the intensity-related biological responses to exercise, its role in exercise-induce medical complications, and the aversion many adults have to vigorous exercise. Receiving considerable attention is whether a higher intensity or greater volume of endurance-type exercise is more important in producing a variety of health-related benefits. To understand the potential role of accumulation of exercise, more information is needed on benefits derived from very short (< or = 5 min) bouts of exercise performed frequently as well as very long bouts (> or = 90 min) performed infrequently.
Conclusions: When considering the response, it is important to establish the priority health outcomes, the relationship of the dose response for individual biological variables to the dose response for clinical outcomes, the basis for substantial interindividual variations in the response to a specific exercise dose, and the health benefit to health risk relationship for various doses of exercise. Scientific resolution of these issues will substantially facilitate the development and dissemination of appropriate guidelines for the use of exercise in promoting health.