Hmmm, not able to reply to your "reply" so I'll post here:
I'm still confused by that 2mph number, the average human walking speed is 5kph (or 3.1 mph), so to walk at a 2mph pace seems suboptimal and potentially more difficult and dangerous than walking at your "normal" pace would be.
"... the average human walking speed is 5kph (or 3.1 mph), so to walk at a 2mph pace seems suboptimal ..."
The forced march (140 cadence) is really is the realm of special forces. Moving over distance is as much about reliability. A function of carry weight X distance travelled. 5km/hr over distance, 30km+/day with 15kg pack, day after day is difficult going. A 100-120 cadence is more reachable. ~ http://www.ibiblio.org/pub/academic/history/marshall/militar...
For your average person a 140 cadence daily over 10km is probably too hard. Just maybe a 3x week might be enough. But is it enough? From the abstract: 'Endurance exercise rescues progeroid aging and induces systemic mitochondrial rejuvenation in mtDNA mutator mice'
"... The systemic mitochondrial rejuvenation through endurance exercise promises to be an effective therapeutic approach to mitigating mitochondrial dysfunction in aging and related comorbidities. ..." ~ http://www.pnas.org/content/early/2011/02/18/1019581108.abst...
You're not taking into account things like carrying a pack and equipment, and difficult varying terrain. I would assume that these would lower the optimal speed.
I'm still confused by that 2mph number, the average human walking speed is 5kph (or 3.1 mph), so to walk at a 2mph pace seems suboptimal and potentially more difficult and dangerous than walking at your "normal" pace would be.