I know I’m late in the discussion but I just saw the thread now and, as a physicist, I thought I could provide some insights into this question (but no answer).
One way of seing the problem is to consider only the vertical movement (equivalent to standing in an elevator going up in small steps with stops between them). The stress this puts on the body would be related to the maximum vertical acceleration each time you step up. I did a quick estimate and perhaps that could correspond to a ~15% increase of stress relative to standing still (equivalent to adding 15% mass to the bag and to the person). Another component of the problem is the actual biomechanics of climbing the stairs while maintaining balance. This is the tricky part because it involves "lever problems”. I expect this is the biggest source of stress, especially if your body position is not optimal, because lever problems involve multiplying factors. Therefore, the forces exerted locally by muscles and joints to prevent rotational and torsional imbalances can be much larger than the force required to simply carry the bag (equivalent to multiplying the mass of the bag by a possibly large factor). We normally dont’ hold heavy loads at arm’s length for this reason and we shouldn’t lift loads by bending forward for this reason as well (when lifting by bending forward, I believe the multiplying factor can reach ~20 in the lower back). I guess my message is: in terms of body stress there’s more to stair climbing than vertical lift. Yves On 24 Jun 2017, at 18:33, ann sanfedele <ann...@nyc.rr.com> wrote: > What is the difference in virtual weight of a pack (say, ten lbs) being > carried bys omeone walking on level ground and the same person carrying > the same pack up a flight of stairs? > > I'm sure I'm not using the corrrect terms here, I"m sure but I'm looking for > the as if.... related to the stress it puts on my body. > > Is it like I'm carrying 5 more lbs? 20 more lbs? etc > > answer ON list so ten people don't have to respond :-) > > thanks, guys > > ann > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. > ------------------------------------------------------------------- Yves Caudano, Namur, Belgium Photography website: http://www.yvescaudano.be Physics website: http://directory.unamur.be/staff/ycaudano -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
