It's spring and I have to get in shape-why?

[J.C.MacSwell]

I'm wondering from an evolutionary point of view.

 

I can think of a few advantages of the way my body has adapted to a number of sedentary months.

 

I'm fitter in the sense that I can now last longer if I am isolated without food.

 

Some of my muscles have atrophied somewhat. If I'm not going to use them, or don't require them to be that size/strength they might as well be lighter and more portable for the others.

 

But overall, I just don't see myself as being as "fit", certainly not in athletic terms, but in Darwinian terms as well.

 

So, how come I'm not lying on the couch looking more like Superman, ready to fight, flee, attract woman etc. etc.?

 

Keep in mind I'm asking from an evolutionary point of view. If this has happened from my being a lazy slug, then why has this trait been apparently so successful? (I'm not in the minority)

[Psycho]

I'm sure many genes that were advantageous to muscle growth and stamina have been breed out of the gene pool many years ago, that doesn't mean that if you do no exercise you will be able to gain tonnes of muscle as it has only been the last 50 years this trend has occurred within modern society.

 

Other than very recent history food supply has been limited or certain aspects of it have so genes that decrease energy usage so it can stored as fat.

[J.C.MacSwell]

I'm sure many genes that were advantageous to muscle growth and stamina have been breed out of the gene pool many years ago, that doesn't mean that if you do no exercise you will be able to gain tonnes of muscle as it has only been the last 50 years this trend has occurred within modern society.

 

Other than very recent history food supply has been limited or certain aspects of it have so genes that decrease energy usage so it can stored as fat.

 

That's the one really, stamina. I can understand the loss of muscle mass in unused muscles being of some advantage, but what have I possibly gained from having muscles that can do significantly less work before tiring out, and having a respiratory system that won't back them up.

 

I have certainly done my part in eating enough and resting enough to maintain my previous condition. So why has my body chosen to revert to my present condition? What advantage is my present lack of stamina relative to last fall?

Edited April 13, 2009 by J.C.MacSwell

[Sisyphus]

I don't know, but I was under the impression that a "fit" musculature is just expensive to maintain, biologically speaking, so your body doesn't want you to be stronger than you need to be. Yes, muscles are helpful, but everything is a tradeoff, and our ancestor's food supply would have been very inconsistent compared to ours. Hence, your body slowly atrophies your muscles all the time, and builds them up again as they're used, so an equilibrium is maintained that reflects more or less how strong you need to be but not moreso.

[J.C.MacSwell]

I don't know, but I was under the impression that a "fit" musculature is just expensive to maintain, biologically speaking, so your body doesn't want you to be stronger than you need to be. Yes, muscles are helpful, but everything is a tradeoff, and our ancestor's food supply would have been very inconsistent compared to ours. Hence, your body slowly atrophies your muscles all the time, and builds them up again as they're used, so an equilibrium is maintained that reflects more or less how strong you need to be but not moreso.

 

That's probably a pretty reasonable guess, though it is less obvious for stamina "fitness" than strength/size.

 

Anyone have a technical answer as to why stamina and endurance might be expensive to maintain at above average levels?

[lucaspa]

I have certainly done my part in eating enough and resting enough to maintain my previous condition. So why has my body chosen to revert to my present condition? What advantage is my present lack of stamina relative to last fall?

 

Remember, we didn't evolve in a sedentary environment. Our hominid ancestors evolved with a very active lifestyle: foraging for food, avoiding predators, etc. Thus, we didn't really have downtime of resting when they were in Africa.

 

Muscle uses more energy and protein per unit mass than fat. Thus, when muscles are not exercised they do not maintain their mass. That uses less energy to replace the proteins that make up the muscle. In fat, once it's made, it just sits there and doesn't need replacement. But proteins are different. They are constantly being broken down and replaced by newly synthesized proteins. That synthesis takes energy.

 

In our ancestry, high caloric food was not nearly as abundant as it is today. So our ancestors adapted energy saving mechanisms -- and atrophy of muscles not in use was one of them. You have lots of food during the winter, but our H. sapiens ancestors in Europe during winter did not. They had to get by on very little when it was too cold and stormy to go out hunting/gathering. To "maintain" your muscle mass, you need to exercise, not just sit around.