Ze Mane - nice to see some scientific analysis applied to this question. Those that have done both a Whitney dayhike and a marathon are really the best source for a subjective determination, but it's always good to get some purely objective comparison.
Out of curiosity, any idea what the change in workload is for a mountain climb when you factor in the added weight of a 10 or 15-pound daypack? Fifteen pounds is probably the upper limit for a summer dayhike for most, with maybe 12 as an average. Would that added weight affect the numbers in any significant way, assuming an average male of 165 pounds?
Thanks. Absolutely the additional weight will have an effect. Now, the exact relationship between added weight and workload I'm not entirely clear on (I've looked up a bunch of papers, but there are some different results) but a good approximation is simply that the % increase in weight (backpack + bodyweight) / bodyweight will lead to a similar increase in workload.
the effects may be nonlinear at higher weights though. it's definitely worth a good research review and discussion on its own. the one thing I will point to is one
paper I posted looking into why Himalayan porters are more efficient hikers than their caucasian counterparts. Basically, with such huge loads on their backs (25 kg +), control of the torso sway probably becomes really important. So if you have a huge load and good control, you are going to have an increase in workload because of more weight, but if you can't control it well, you are going to have an even larger increase in workload.
