I've been carrying a 25 lb backpack up my local steepest trails for several years as my training for JMT, TMB, etc.
I cycle a lot - 100 - 150 miles a week - so the lower extremities are taken care of, but my issue - and caused an early bailout to Mammoth Lakes on a previous trip - is either sciatica or pinched vertebra nerve in the lumber region. Perhaps I should wear a corset.
Ken.
