Introduction: A New Perspective on the Epidemiology of Physical Activity; Issues to Be Discussed; References; Contents; Meet the Authors; Chapter 1: Physical Activity and Optimal Health: The Challenge to Epidemiology; 1.1 Introduction; 1.2 Definitions of Physical Activity and Exercise; 1.2.1 Physical Activity; 1.2.2 Exercise; 1.2.3 International Consensus Conference Definitions; 1.2.4 World Health Organisation Definition of Physical Activity; 1.3 Questionnaire Assessments of Intensity, Frequency and Duration of Activity; 1.4 Precautions Needed During Objective Monitoring of Physical Activity

1.4.1 Reactive Response to Activity Measurement1.4.2 Minimum Sampling Period; 1.5 Interpretation of Measurements Obtained from Objective Monitors; 1.5.1 Step Counts; 1.5.1.1 The 10,000 Step/Day Target; 1.5.1.2 Equating Step Counts with Public Health Activity Recommendations; 1.5.1.3 Arbitrary Classification of Activity Patterns; 1.5.2 Estimates of Exercise Intensity; 1.6 Reliability and Validity of Objective Monitoring; 1.6.1 Steady Walking; 1.6.2 Variations in the Speed and Pattern of Walking; 1.6.3 Free-Living Conditions

1.7 Medical Conditions Potentially Modified by Intensity and/or Volume of Habitual Physical Activity1.7.1 Conditions of Interest; 1.7.2 Need for Enhanced Objective Monitors; 1.7.3 New Insights from Objective Monitoring; 1.7.3.1 Relative Value of Activity and Fitness Indices; 1.7.3.2 Thresholds of Benefit; 1.7.3.3 Ceilings of Benefit; 1.7.3.4 Form of Physical Activity/Health Relationship; 1.8 Inference of Causality; 1.8.1 Spurious Associations; 1.8.2 Indirect Associations; 1.8.3 Criteria Suggesting a Causal Association; 1.8.3.1 Strength of the Association

1.8.3.2 Consistency of the Association1.8.3.3 Temporally Correct Association; 1.8.3.4 Specificity of the Association; 1.8.3.5 Biological Gradient; 1.8.3.6 Biological Plausibility; 1.8.3.7 Coherence; 1.8.3.8 Experimental Verification; 1.8.3.9 Analogy; 1.8.4 Critique of the Bradford Hill Criteria; 1.8.4.1 Direct Evidence; 1.8.4.2 Mechanistic Evidence; 1.8.4.3 Parallel Evidence; 1.9 Conclusions; References; Chapter 2: A History of Physical Activity Measurement in Epidemiology; 2.1 Introduction; 2.2 The Cardiac Epidemic; 2.3 The Occupational Epidemiology of Physical Activity and Health

2.3.1 Jeremiah Noah Morris2.3.2 Ralph Paffenbarger; 2.3.3 Henry Longstreet Taylor; 2.3.4 Conclusions from Occupational Comparisons; 2.4 Athletic Status and Health; 2.4.1 Comparisons Between Athletes and the General Population; 2.4.2 University Athletes and Their Academic Peers; 2.4.3 Conclusions from Studies Based on Athletes; 2.5 Exercise Group Assignment in Quasi-experimental Studies of Fitness and Health; 2.5.1 The Trois Rivières Regional Study; 2.5.2 Quasi-experimental Assignment to a Work-Site Fitness Programme; 2.5.3 Conclusions