• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Why do we go flabby when we stop exercising?

They'll receive energy... just not the type of energy that builds muscles. :)

LIke running a faucet on very dirty dishes will not really clean them like scrubbing them with a pad will.
 
FireGarden said:
Why can't muscles maintain strength/tone without exercise?
Click to expand...

Muscle cells get bigger to better accomodate the workload exercise presents. When that workload is gone there is no point in them staying larger (waste of energy) so they shrink.
 
HarryKeogh said:
Muscle cells get bigger to better accomodate the workload exercise presents. When that workload is gone there is no point in them staying larger (waste of energy) so they shrink.
Click to expand...

Is that as a result of what Politas said, as in they shrink because the muscle cells die and then are not replaced due to the lack of need?
 
DreadNiK said:
Is that as a result of what Politas said, as in they shrink because the muscle cells die and then are not replaced due to the lack of need?
Click to expand...

This is where my knowledge is lacking. I know muscle cells get bigger as a result of exercise but I don't recall if there's also an increase in the amount of muscle cells as well.

I will defer to someone with better knowledge in this area.
 
Where is El Greco when you need him?? :D

Muscles have 2 types of fibers - red fibers, which develop mitochondria and extensive cappilary networks, and are associated with weak contraction exercises such as swimming and running and increase stamina; and white fibers, which develop filaments of actin and myosin which enlarges the muscle (but does not increase stamina) and are brought on by forceful exercise such as weight lifting.

The muscle enlarges when more filaments of actin and myosin are present, but as soon as the exercise stops these filaments decrease and the muscle can go down to only half its size within just a few months. This is true of both types of fibers, red and white.

So what you are really dealing with here is shrinkage due to not being used, not loss of cells. This is why an atrophied limb can be exercised back to its potential.

The source for this "Hole's Anatomy and Physiology".
 
Last edited:
Amapola said:
The muscle enlarges when more filaments of actin and myosin are present, but as soon as the exercise stops these filaments decrease and the muscle can go down to only half its size within just a few months.
Click to expand...

So what triggers the decrease?

Do the fibres of actin and myosin have a shelf-life or something? Is that the cause of their loss? And you go flabby because without exercise there's no trigger to add new fibres of actin/myosin etc.
 
FireGarden said:
So what triggers the decrease?

Do the fibres of actin and myosin have a shelf-life or something? Is that the cause of their loss? And you go flabby because without exercise there's no trigger to add new fibres of actin/myosin etc.
Click to expand...

I guess you could say it is the lack of need....... the fibers increase due to demand. Once the demand is gone, the fibers decrease. I think consistent exercise only keeps the ones you have. The body is very frugal that way.
 
I should point out (because now that I re-read it, it's not real clear) that this same "bulking up" and decrease, can also happen with the mitochondria and cappilary networks found with red fibers in muscles.

Another way to refer to these two fiber types would be slow-flex (red fibers) and fast-flex (white fibers).
 
HarryKeogh said:
This is where my knowledge is lacking. I know muscle cells get bigger as a result of exercise but I don't recall if there's also an increase in the amount of muscle cells as well.

I will defer to someone with better knowledge in this area.
Click to expand...

First let's define exercise: Exercise is intense physical activity for relatively short periods of time, followed by a period of rest. The rest portion is essential for muscle hypertrophy.

There are two ways that muscles enlarge, well, 3 ways if you count muscle edema and hyperemia.

1. Within the muscle cell, muscle fibers upregulate the production and organization of the acti, myosin and troponin. Muscle mitochondria proliferate. Vessels grow. In addition, myoglobin levels (especially in red muscle), and glycogen deposition increases. In addition, collagen deposition in the intracellular ground substance, fascia, and the muscle tendons increase, increasing the tensile strength of the muscle itself. (hypertrophy)

2. Myoblasts, primordial muscle cells, begin to differentiate into new muscle cells (hyperplasia)

When a person stops resistance-based activities and exercises, the muscle cells down-regulate the production of the substances in item 1. The muscle retains its cellularity (apoptosis occurs only with denervation, trauma, ischemia, or other severe conditions)
 
Amapola said:
I guess you could say it is the lack of need....... the fibers increase due to demand. Once the demand is gone, the fibers decrease. I think consistent exercise only keeps the ones you have. The body is very frugal that way.
Click to expand...

Frugal?
Stingy more like. That budget's way too tight! :)

sickstan said:
2. Myoblasts, primordial muscle cells, begin to differentiate into new muscle cells (hyperplasia)

When a person stops resistance-based activities and exercises, the muscle cells down-regulate the production of the substances in item 1. The muscle retains its cellularity
Click to expand...

Just to clarify..
stopping exercise doesn't undo item 2?

IE: does stopping exercise leads only to muscles in poorer condition rather than less muscle?
 
sickstan said:
First let's define exercise: Exercise is intense physical activity for relatively short periods of time, followed by a period of rest. The rest portion is essential for muscle hypertrophy.

There are two ways that muscles enlarge, well, 3 ways if you count muscle edema and hyperemia.

1. Within the muscle cell, muscle fibers upregulate the production and organization of the acti, myosin and troponin. Muscle mitochondria proliferate. Vessels grow. In addition, myoglobin levels (especially in red muscle), and glycogen deposition increases. In addition, collagen deposition in the intracellular ground substance, fascia, and the muscle tendons increase, increasing the tensile strength of the muscle itself. (hypertrophy)

2. Myoblasts, primordial muscle cells, begin to differentiate into new muscle cells (hyperplasia)

When a person stops resistance-based activities and exercises, the muscle cells down-regulate the production of the substances in item 1. The muscle retains its cellularity (apoptosis occurs only with denervation, trauma, ischemia, or other severe conditions)
Click to expand...
Ok, it sounds like you know what you're talking about. Now can you explain what all that means for us laypeople? That last sentence in particular means almost nothing to me. I understand just enough to get a shadow of meaning, but not enough to be sure where that shadow is coming from. It seems to maybe be referring to item 2, but since it shares no words with the description of item 2, I can't be sure.

Lack of exercise reduces hypertrophy, and I assume that the muscle cells start "eating" that buildup as an easier way to access energy than external sources. What does lack of exercise do to hyperplasia, in words found outside a biology/biochemistry textbook?
 
My understanding is that our bodies have adapted in such a way that efficiency is the name of the game. Our body goes flabby because it is BENEFICIAL as odd as that may seem. Our body is tuned to only do what it needs to do to keep going. So, when we start using our muscles a lot, our body is set up to react by bulking up, triggering a number of reactions as already outlined which make us stronger. The downside to this, at least it was back in the day when food was more scarce, is that doing this requires more energy. So, the moment the muscles stop being used, nature takes it's course and cells die out and are not replaced because there are no triggers to replace them. The muscles are in power saving mode. That way, you don't need to eat as much. The muscles are basically adapted to only bulk up as much as needed to conserve energy.

Unfortunatly, these adaptations had no precedent for food being everywhere at all times. For that matter, neither do our brains, which themselves are tuned to eat eat eat, because in "the day" the next meal was an if, not a when, so stocking up the pounds was a good survival strategy. Our bodies are outdated.

Why do muscle cells die? Same reason the rest do, wear and tear. Why they aren't replaced as much has already been described. Why others aren't replaced and eventually lead to death? Answer that and you are well on your way to ending the disease of aging forever.
 
T'ai Chi said:
They'll receive energy... just not the type of energy that builds muscles. :) LIke running a faucet on very dirty dishes will not really clean them like scrubbing them with a pad will.
Click to expand...
For someone with the handle "Tai Chi" I expect much better koansequeness next time. That was just bad... :gasp:
 
DreadNiK said:
Is that as a result of what Politas said, as in they shrink because the muscle cells die and then are not replaced due to the lack of need?
Click to expand...

Beyond that, I'd bet it's an active evolutionary mechanism to burn off tissue that is now a liability due to it's greater energy useage, even when at rest.

Every other exercise show points out how many supermodels, as skinny as they are, are still flabby because they get very little exercise.
 
politas said:
Ok, it sounds like you know what you're talking about. Now can you explain what all that means for us laypeople?
Click to expand...
I'm also a layperson, but I do know that "apoptosis" means cell death. So if I follow right, muscle can grow by adding bulk to themselves or to surrounding tissue (case 1) or adding cells (case 2) - but the cells don't normally die off when you stop exercising.
 
FireGarden said:
Why can't muscles maintain strength/tone without exercise?
Click to expand...

They do maintain tone. Muscle tone is a nervous system thing.

It is a myth that exercised muscles are more "toned". They are not. They are just bigger.

Organisms, on the whole, react to challenge by increasing their ability to meet that challenge the next time around. Muscle is continuously being made and broken down (anabolism/catabolism). Increased stress on the muscles increases the amount of anabolsm so that it happens at a larger rate than the catabolism. The result is net muscle growth. When that stimulus is removed the catabolism is happening faster and so muscle loss occurs. So you have enough muscle to do your daily tasks and not a lot more.
 
You must log in or register to reply here.

Back
Top Bottom