Dr. Marc Hamilton, Director and Professor of the Texas Obesity Research Center, will describe the development of the concepts and directions for the emerging field of ‘inactivity physiology’: the science that led to the concept that because of the specific ways skeletal muscle and the rest of the body respond to widely varying doses of muscular contractile activity, then it logically follows that “too much sitting is not the same as too little exercise”. This relatively new research discipline has been rapidly growing since his seminal work introducing this concept a decade ago. There have now been over 1000 research papers by peers investigating this concept because of its profound public health implications. Since he first proposed the inactivity physiology paradigm a decade ago, there has been a global movement of experts taking notice of the time people sit. The effects of sedentary time on health and disease are generally independent of traditional exercise. In contrast to the influence of brief amounts of MVPA (the 2.5 hrs/week recommendation), many aspects of good health appear to be more related to a much greater duration (42 hrs/week is the average time of total upright muscular activity). Therefore, inactivity physiology is about understanding the effects of muscular activity that is generally performed at a lower perceived effort of physical activity distributed throughout dozens of hours each week, and spread over almost the whole waking day. Current studies are probing the association of inactivity with molecular and physiological responses related to risk factors for metabolic syndrome, coronary artery diseases, type 2 diabetes, obesity, some cancers, deep venous thrombosis, and mortality. Our early work identified the most potent known molecular mechanism known to regulate lipoprotein lipase activity in skeletal muscle. In fact, non-fatiguing and intermittent light activity throughout each hour of the day has better effects on lipoprotein lipase and multiple other key processes than does exercise training. Another example is a novel inactivity-responsive gene that potentially may prevent DVT. Experimental and epidemiological studies have recently provided evidence that the healthy effects of low-intensity physical activity are independent of the type of moderate activity historically recommended (but practiced by <10% of the population). This has generated much enthusiasm among public health experts because of the potential for providing more effective behavioral solutions to the millions of people who cannot (or will not) do traditional exercise.