I have been wondering about something ever since I saw a program about this lady who had not been out of bed in three years. She was incredibly obese, and her legs were absolutely HUGE. Why is it that she had not walked in three years, and her legs were so large, but people who are paralyzed have very thin small legs? What is it that makes the difference in the size, when the legs are not being used at all? I work in a docotr’s office and no one here (even the docs) can explain it to me. Thanks!
Well obviously a lot of it was fat, not muscle. The fact that she hadn’t been out of bed in three years might have been not only due to her weight but to how weak her legs had become.
Also, being bedridden isn’t quite the same as being paralyzed. She presumably still moved her legs some.
Apples and oranges, Kristi.
The lady in question has fat legs because she is obese. As a direct esult of eating too much, a physical disorder, or both, her body has produced much more fat than it burns. The fat is stored all over the body, but in females the thighs are a prime storage area. It becomes a vicious cycle - more fat stored = less activity (less fat burned) = more fat added. She obviously got to the point that her body weight exceeded her muscles ability to lift.
In the case of a paraplegic, the leg muscles no longer get used at all. No electrical stimulation from the brain/nerves, no movement, nothing. This causes the mucles to deteriorate and atrophy. The legs look smaller because there is very little muscle between the bone and skin.
Could a paraplegic develop fat legs? I don’t know for sure but I’ve never seen it. My WAG would be that the body cannot store fat in areas affected by spinal paralysis.
This is a complete guess (aka WAG):
When you move muscles, doesn’t that cause more blood flow to the area? For example when your fingers are cold you flex them to get more blood to the area. I would think that the inability to move the legs in a paralyzed person would cause less blood flow to the area, causing less nutrients for the muscles and thus the muscles deteriorating.
I don’t know if there’s a definite link between the ability to send electrical stimulus to a body part and the blood flow to that area. My guess is that the body assumes it is no longer there, like an amputee, and treats it as such.
I think this is basically what Dr. J (not the basketball player) was saying. Just in more laymans terms.
There’s a very strong trophic effect of neuronal stimulation of muscles. In other words muscles grow or at least maintain size simply because the nerves entering them fire. Once these nerves cease to function the muscle atrophies rapidly. Many people affected by temporary paralysis as well as some paraplegics use artificial electrical stimulation to maintain muscle size. In the case of an obese person the neurons are still functioning and the muscles are still being used if only to turn the body over in bed, so some muscle is being retained. I have seen a paraplegic with fairly fat legs, but because of the way fat is laid down in the human body and the lack of any underlying muscle it’s very hard for someone with severe muscular atrophy in a limb to develop a thick limb from fat deposition.
In the case of a paraplegic, the leg muscles no longer get used at all. No electrical stimulation from the brain/nerves, no movement, nothing. This causes the mucles to deteriorate and atrophy. The legs look smaller because there is very little muscle between the bone and skin.
cannot store fat in areas affected by spinal paralysis. **
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Definitely 100% correct about the thin paraplegic legs. But I wonder about the obese lady…
Kristi said her legs were absolutely HUGE (emphasis mine). Now were they big just b/c of fatness? I dunno. It seems to me that Kristi implies that they were greatly out of proportion with her expectations. Maybe Kristi’s expectations were too low, but I’d wager that edema (swelling due to extra fluid in the tissue) may have contributed to the problem as well.
The way blood circulation works is that arteries carry blood to your tissues. They branch and get smaller until you are eventually at the capillary level. In the capillaries, oxygen and nutrients leave the circulation to enter the tissues. However, a substantial amount of fluid leaves as well. In an individual with normal circulation, the fluid is pulled back in the capillaries (by a shift in the opposing forces of hydrostatic and oncotic pressures) as they unite to form small veins (venules). The veins get larger and larger, terminating at the right atrium of the heart. Most of the fluid in the tissues is removed by the veins, but whatever is left is carted away by other vessels called lymphatics.
Anything that causes excess fluid to leave the capillaries (like an injury or infection) or disrupts the venous (like a clot in a big vein)or lymphatic (think elephantiasis)removal of the fluid can cause swelling. I think that the lady’s obesity is creating a degree of venous and lymphatic compression, inhibiting proper fluid removal from her lower extremity, exacerbating her problems.
There are other reasons for swelling (like heart failure and kidney failure) and she may have such a condition as well.