and would they live longer because of less strain on their organs (from less food processing) ?
Their caloric requirements are lower, yes.
I’ve never heard of them living longer as a result, though.
Also, say someone with no legs running on those springy things, do they have a much lower heart rate and more wind not having to pump blood and oxygen to legs?
And if someone is missing all their limbs, they can save lots of calories just rolling everywhere. (I know, uphill’s a bitch.)
This was an issue when Oscar Pistorius was trying to gain selection for the Olympics - he and his team had to prove that the Blades did not confer an advantage a normal athlete would not have.
As I recall, this involved performance testing of a variety of metrics, including VO[sub]2[/sub]max and stride length/swing time.
A summary is here - eventually, there was an agreement that the blades did not confer an advantage over able-bodied athletes, and Pistorius was allowed by the IAAF to compete in normal competition. However, the compromises in blade length made to allow this means that Pistorius uses blades that are shorter than those allowed by the paralympic running federation - which he felt gave his opponents an unfair advantage in the Paralympic sprints, and he was unable to secure gold in the 200m. Single-legged athletes supported this position, as they are unable to increase blade length in the manner used by some other paralympic competitors.
A physician will be along any minute now. IANAD, but I’ll say that “strain” on one’s organs generally isn’t an issue for people, at least not strain due to physical exertion. Physical exercise puts a strain on your organs, but it tends to result in better health and longer life. I’ll wager that if you lose major limbs, you also have compromised your ability to engage in aerobic exercise, which will be a detriment to your long-term health; a person with no legs and no arms will have substantial difficulty achieving his target heart rate.
A guy at my gym has no legs and a few inches of upper arm. He has no issues achieving his exercise goals with a bit of assistance for setup, and they are pretty impressive. And I wager that he has a higher level of exertion just in his day to day activities than just about any able bodied person.
Where does ones new blood cells come from if one has lost both legs and their blood cell-generating marrow?
Haematopoiesis - Wikipedia occurs in multiple locations within the body, not just in leg bones (and not much in there for adults). We are pretty adaptable, so the body can pick up the slack for missing or damaged parts.
Vertebrae, sternum, ribs, skull, scapulae, pelvis and arms.
While it’s certainly possible and should be encouraged for a person with an amputation to be physically fit, I have more experience with the ones who aren’t. Of course, I would, being as the ones who are fit don’t tend to need a home health nurse! So, major selection bias at work. I see a lot of pretty horrific pressure ulcers (they used to be called “bed sores”), some which are literally decades old and unhealing. I see malnutrition from people who can’t move their bodies well or can’t shop or cook for themselves. These tend to lead to weakness, infection, obesity (yes, obesity can be present at the same time as nutrient deficiency) and heart problems and falls with injuries. Certainly not longer life.
But, again, if there’s a large population of people with amputations who are hale and hearty, I don’t see them professionally. I do see a lot of them outside my front window, which overlooks a wheelchair softball field. Those are some strong, fit men, who, at a distance, don’t appear to have health problems shortening their lives, but I don’t see how they’d be prone to *longer *life than a similarly fit person with all their limbs.
If only we could ask Darth Vader…