What are the health impacts of standing / sitting while lecturing?

Question

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.

Answer 1

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!

Answer 2

I don't have hard evidence at hand, but I'd guess

• a bit of everything is probably good

• Walking around is better than standing still or sitting only. One way of doing this could be to walk back and forth between slide changing (keyboard) and a lecturing position somewhere forming a triangle with students and projected slide.

• Some colleagues of mine who have to stand a lot in somewhat similar settings like unstable "rocking chair" shoes.
• AFAIK, people who get swollen feet while standing tend to have the same problem when sitting for a long time. Which is plausible because the swelling has to do with the valves in leg veins and lymphatic vessels not working properly. Walking is better because the calf muscles help getting the blood back up. But for optimal results you need to use all kinds of muscles of the calf and foot, which you normally don't do on flat floors (this would be an argument for the rocking chair shoes, but I have no idea whether they actually help). OTOH, sitting on a table with legs dangling is really bad with resped to swollen feet: the edge compresses the veins in the upper leg. The same can happen with chairs that have the wrong (backward) seat slope and/or height.

• Making good use of breaks could also help without distracting students from the lecture because you do funny gymnastics. I knew a teacher who spent the lunch break doing a power nap with the feet up to prevent/alleviate swollen feet.

• I don't lecture long times, but: my natural idea about lecturing is to do it standing: this way you are better seen by the students, gestures work better and the voice is better as well. Standing still becomes uncomfortable very soon (=> walk). I take this as a (possibly rather late) sign that the body needs to move, so walk. Obviously, you cannot hike or run around the lecture hall, although this would be more healthy than walking a few steps every once in a while: it would make the students crazy.
  Going on with this train of thought, I sit down when standing becomes uncomfortable. Again, I take this as a sign that some (back) muscles get tired from the standing position, so having some other posture for a while is a good idea.
  I call this primarily standing even if you walk a bit back and forth from the observation that I find it much easier to hike a whole day with a substantial (e.g. 25 kg) backback than to keep on my feet in these standing plus a tiny bit of walking postures.