This Paper Is Concerned With Future Contributions Byresearch to an Evidence-Based Rationale For Exercise Recommendations—Both Tothe Public at Large and to Individuals. It Is Clear That Physically Activepeople Have a Lower Disease Risk Than Sedentary Individuals But the Componentsof Activity Which Determine Particular Health Gains Are Poorly Understood. Thusthe 'Dose-Response' Relationships For Physical Activity Are the Subject Ofcurrent Research Interest. Intuitively, These Will Not Be the Same Fordifferent Health Outcomes and This Is One Reason Why Further Study of Theassociated Mechanisms Is Important. Understanding the Underlying Mechanismswill Clarify the Relative Importance of Intensity, Frequency, Duration and Modeof Exercise For Specified Health Gains. It Will Also Help Us to Distinguish Theeffects of Exercise Per Se from Those of Co-Existing Behaviours and to Identifystages of Life During Which Levels of Particular Types of Activity Are Criticalfor Given Health Outcomes.