There is enough information about exercise physiology to support the well-documented public health guidelines promoting at least 150 minutes of moderate-to vigorous physical activity (MVPA)(1). However there is an emergence of inactivity physiology studies. If we divide a day into periods of MVPA, light intensity PA (LIPA), sedentary behavior and sleep we observe a large proportion of the time taken up by time spent sitting, such as TV viewing, car driving and computer use. In fact, evidence exists that excessive time spent in sedentary behavior (SB) is a health risk that is not mitigated by performing half an hour of MVPA per day (2, 3). Life expectancy at birth may increase by ~2y if SB is reduced to <3h/day (4) whereas prospective associations exist between SB with mortality and morbidity (2, 3). Short term experimental studies indicate that physical inactivity affects energy balance and is considered conducive to weight gain (5, 6). A decrease in PA has a considerable ability to decrease total energy expenditure (TEE) without any compensatory changes in energy intake, which generate a positive energy balance. The extent to which reducing and breaking up SB over sustained periods of time considerably increases TEE has never been investigated under free-living conditions.