RESEARCH METHODS

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RESEARCH METHODS Research methods include case studies, epidemiology, and clinical trials. Case studies are usually how research in a medical arena begins. For heart disease, the first case study to support exercise rehabilitation was presented in the 1960s, by Dr. Herman Hellerstein, who sent one of his patients to the YMCA to exercise after a myocardial infarction. The patient made a remarkable recovery. In sharing the course of treatment for this one cardiac patient through a case study presentation, the modern cardiac rehabilitation movement began. More case studies followed which justified bigger population based studies. Epidemiology is the study of the interaction between a disease and the disease causing factors in large populations. In epidemiologic studies, the relationship between the host (patient), agent (cause of disease) and environment are investigated in two different ways. In Incidence Studies, the occurrence of a disease is associated with a prior event, whereas in Prevalence Studies, the number of cases of a disease is measured at a given time. Prevalence studies are more cross-sectional in nature whereas the incidence studies may take years to make the associations with "prior events" (i.e. life-style factors at a younger age). Incidence studies would be found more than prevalence studies in exercise research. In these studies, an attempt would be made to develop a link between physical activity or inactivity (at a prior time) and subsequent disease (current time). Epidemiology research usually has hundreds to thousands of subjects. Risk is usually established in epidemiological studies; although it can be determined from clinical trials too. Risk can be expressed as: Relative Risk (RR) Risk Ratio Odds Ratio Relative risk is the ratio (also called Risk Ratio) of the probability of a disease developing relative to the exposure. That is, the ratio of the disease for non-active vs. active individuals. RR= Probability of non-active individuals         Probability of active individuals Risk Existance of Disease Pesent Absent Physical Inactivity a b Physical Activity c d RR = a/(a+b)          c/(c+d) Odds Ratio is ratio of the outcome in the two groups; the odds of disease in one group vs the odds in the second group. Odds ratio is can also be considered a measure of effect size. OR = ad          bc Epidemiologic studies can help to identify an association between physical inactivity and disease, but it does not necessarily mean that physical inactivity causes the disease. This dilemma with epidemiologic studies is called "Selection vs. Protection". The question becomes, does the exercise truly prevent the disease (i.e. protection) or are the healthy people just healthy enough to do the exercise (i.e. selection)? Clinical trials, then, are the next step in answering these questions. Clinical trials or Intervention Studies are experimental designs, which attempt to isolate cause and effect. Clinical trials would be found in rehabilitation or disease treatment studies whereas interventions studies would found more in prevention studies. Exercise or physical activity "treatment" groups and control groups are an integral part of clinical trials and intervention studies. Randomization into treatment and control groups is essential in clinical trials. In the case of exercise studies, the control group would not exercise and the treatment group would. Then, after a period of time, the incidence of disease would be observed in both groups. If the disease occurred in the control group and not the treatment group, then prevention of the disease could be attributed to exercise. Modern Disease Research Methods Definition of Physical Activity Exercise and All-Cause Mortality The Exercise Dose Comment top

DEFINITION OF PHYSICAL ACTIVITY What is exercise? What is physical activity? Physical activity is any bodily movement produced by skeletal muscle contraction that results in increased energy expenditure. Gardening, house cleaning, occupational activities, and recreational activities are all included within the realm of physical activity. Exercise is planned, structured and repetitive bodily movement done to improve or maintain one or more component of fitness. The components of fitness are cardiorespiratory endurance, flexibility, muscle strength, and muscle endurance. Yes, by these definitions, exercise can be considered to be physical activity. So, when we refer to physical activity, we need to agree that we are defining the low intensity activities that cannot contribute to improved physical fitness. MEASURING PHYSICAL ACTIVITY Defining physical activity and exercise is much simpler than trying to measure them. Exercise is not a simple variable. It is not a dichotomous "yes" or "no" variable like smoking. It is not a continuous variable like cholesterol or blood pressure, where the values range from low to high and any value in between. Exercise is a multidimensional variable that can be described by mode, frequency, duration and intensity. There appears to be as many ways to measure exercise, as there are ways to exercise. LaPorte, RE, et al. Assessment of physical activity in epidemiological research: problems and prospects. Public Health 100:131-146, 1985. ACSM: A collection of physical activity questionnaires fo health-related research. Medicine and Science of Sports and Exercise 29: Supplement 6, 1997. ACSM: Objective monitoring of Physical Activity. Medicine and Science in Sports and Exercise 37: Supplement 11, 2005. Tables 1 & 2 The general categories of assessment tools for the measurement of physical activity include are: Calorimetry Job Classification Survey Physical Markers Behavioral Observation Mechanical/Electrical Monitors Dietary Measures Criteria for good measures of physical activity should demonstrate: Validity Reliability Practicality Non-R

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