What are the health impacts of standing / sitting while lecturing? I often find myself lecturing for 7 hours in one day. This question is not about how to reduce my hours, it is about making healthy choices with my existing constraints.

I am lecturing to different classes during the day (it is not a single group of students for all 7 hours), in case that makes a difference.

I realize that during my lectures, I must choose what to do with my body. Should I sit (blood clots, deep-vein thrombus) or do I stand (I've heard non-lecturers complain about swelling legs when standing too much). 

My questions are:


What impacts are known from standing while lecturing for 7 hours per day, 3 days per week?
Is it better to stand or to walk around?
Is it better to sit for the whole time?
Is it best to do a "little bit of everything?" If so, where is the optimal balance?


I realize that this might be specific to the person but I am hoping to find some experiences or, even better, research, which will indicate the best choices to make when one must lecture for many hours.
The health impacts of standing while doing a job are known to be strongly positive, compared to sitting while performing a similar function. For the seminal paper on this, see Morris et al., 1953 in the Lancet (http://www.sciencedirect.com/science/article/pii/S0140673653914950). Morris examined the incidence of heart disease in bus drivers vs. bus conductors. The former spend the day sat at the wheel while the latter spend the day walking around the bus collecting fares and enforcing the rules. This occupation was chosen because drivers and conductors come from the same socio-economic conditions and were expected to be fairly similar in every respect except for their working activity. Naturally the incidence was sharply reduced in the conductors. A casual Google Scholar search will pick up more recent references, and the health benefits of standing vs. sitting are widespread.

One can imagine that standing for very long periods of time repeatedly might cause problems, particularly on the feet or ankles, but seven hours a day a few times a week is not really anything to be excited about. Many people work in bars or restaurants, on building sites, in hospitals and so on doing much more labour intensive work with shift lengths exceeding twelve hours, six days a week.

All I would say is ensure you wear comfortable shoes!