I went to the Exercise and Sport Science Australia conference in April  and I thought I would share one of the more controversial topics for us to discuss!

The ActivityStat Hypothesis comes from the idea of Homeostasis where our bodies have the ability to regulate our internal environments so that we maintain our set level. Things such as Blood Pressure, pH, temperature, and blood glucose levels all fluctuate but are continually brought back to an appropriate level, without us having to think about it. The idea of the ActivityStat runs along similar line. We try to maintain energy homeostasis by three feedback pathways 1 – monitoring and regulating energy intake 2 – energy expenditure 3 – energy surplus. Energy expenditure has been looked at closely. Our overall energy expenditure is made up of three parts 1 – Basal Metabolic Rate 2 – Thermic effect of food 3 – Activity thermogenesis. When thinking about exercise, we are looking at Activity thermogenesis which is again broken into 2 parts 1 – Non Exercise Activity Thermogenesis (NEAT) (such as standing up and walking to the printer) 2 – Exercise. The ActivityStat suggests that if you increase the amount of Exercise you do you will therefore decrease the amount of NEAT you do to maintain your ‘energy expenditure homeostasis.

There have been a number of studies in support of this idea. The ‘Earlybird’ study in British children showed that overall energy expenditure showed less than 1% variance between all children when some children had planned 30min exercise sessions at school and others had none. There is also some evidence that women who are underfed during pregnancy have inactive babies and those women who have high testosterone levels during pregnancy have active babies.

This is just a hypothesis and there could be a number of arguments against, which there have been. However, if it is correct we need to think differently about the type of exercise interventions we use with people if we are trying to increase their overall energy expenditure. Obviously this does not take into consideration the other positive effects exercise does have on the body, but it could be something to consider when working with people who are trying to loose weight.