Why do we get fitter when we exercise and is their different types of fitness?

This is one of my most favorite subjects!!! :)

I could go on for days but I'll try to make it short and sweet.

Exercise doesn't really do much to the lungs. Our lungs already deliver oxygen faster than we can use it. Our problem is our blood can't deliver it to our muscles fast enough. Which is why I always laugh when I see football players sucking down oxygen anywhere other than Denver. Anywhere else their blood is already 98-99% saturated with oxygen as it leaves the lungs.

The easiest way our bodies can fix this is to increase oxygen binding capability. So that's one way exercise effects our fitness. The iron in the heme groups of hemoglobin in the red blood cells (RBCs) bind oxygen, the more RBCs we have the more oxygen our blood can carry. There are also heme groups in myoglobin which is found in our skeletal muscle (yes our muscles can store oxygen!). However, myoglobin is not very abundant in humans... (Compared to seals and other marine mammals which can go a very long time in between breaths because their muscles can store a lot of oxygen) So... any slight improvement in our myoglobin concentration in the muscle actually helps a ton!

That is how exercise affects our oxygen capacity...

So now that we have more oxygen available to the muscles we can see how it is used.

Muscle is categorized by the myosin isoforms that constitutes it. To avoid getting to technical just understand that each type here is just a different form of the protein that makes up muscle.

Humans have 2 main types of skeletal muscle.

Type 1: slow twitch, oxidative muscle. This type has the most blood flow, the most mitochondria and the most bound myoglobin, so it has the most potential for using oxygen.

Type 2: fast twitch, less oxidative and comes in a few more isoforms:

type 2a - slowest of the fast twitch, has a decent blood supply and mitochondria and myoglobin concentration.

type 2x - faster than 2a, even less myoglobin and mitochondria. We use this for short bursts of speed/power because it uses energy very quickly, but inefficiently (doesn't use oxygen much).

There is also a type 2b but humans do not have it. It is even faster than type 2x and looks pure white. Which is why some animals look very pale when they are shaved and you're able to see this very white muscle through their skin.

Anyway, each of your skeletal muscles contain a mixture of these types. When you do sprints you're using the fast twitch fibers of your muscles. Your body can maintain this glycolytic activity for 10-15 seconds before the muscles are fatigued and don't work. Sprints train the fast twitch fibers to increase in mass, so the next time you will be able to go even faster. If you watched the Olympics last year you probably noticed the sheer size of the sprinters' legs. That's just pure, unadulterated, unoxygenated power.

When you train aerobically, you might get a small increase in muscle mass but the majority of your exercise will go into inducing the fast twitch fibers to convert to slow twitch! You're actually losing power, but your muscles are becoming much more efficient, and able to withstand long periods of activity. So as this change in your fiber types is happening there's also going to be a better blood supply, more myoglobin, more mitochondria, you're going to able to use more of that oxygen your lungs have no problem saturating your blood with. And now, with more efficient muscles and blood you're going to push your lungs to their capacity until you reach a point where no matter how much more training you do, you couldn't possibly become more fit.

Lance Armstrong is the only human being I know of that has reached this point. (I know there's more but I don't know their names) If you took a sample of his muscles they would be nearly entirely type 1 and the slowest of type 2, 2a! His muscles use oxygen so fast that his lungs can't keep up. Now a lot of this is genetic, Lance, after his battle with cancer, no training for months, was still in better shape than the average trained man. But with training Lance becomes an incredible specimen of human fitness.

If you want to know more about this subject you should research VO2 max, which is a measurement of how fast one can consume oxygen per body mass (ml/kg/min). To put it in perspective:

An average untrained male will have a VO2 max around 40 ml/kg/min

Average trained man can reach 60 maybe 70

Untrained Lance Armstrong had 68

Navy SEALs score around the lower to mid 70s

World class athletes typically score in the upper 70s

Trained Lance Armstrong reached 90!

Trained Sled dogs approach 250!

The reason is quite simple. The more you use your heart, the more productive it becomes. When you have more blood coursing though to your brain and the rest of your body it gives you a sense of felling better. For different types of fitness like long running your body usually keeps between 120-160bpm (beats per minute) and the more bpm the faster the blood in your body will be going instead of sitting here on the computer answering this question =)

you have three different kinds of muscle cells (skeletal, smooth, and cardiac)...and when you exercise you engage skeletal muscle, which comes in different subtypes that are resistance to fatigue in varying degrees and that you would engage during a long run or short quick run (depending on what type of exercise you activate different muscle types)...also like during lifting...there is something called recruitment and you engage your first muscle type, if it is not enough, you engage another, and another until it is enough to do whatever activity it is that you are doing.

Exercise also activates your brain to release these chemicals called endorphins (which help with pain during exercise, but there effects last after exercise is done for about 30min to an hour "runner's high" leaving you feeling pleasant)...just like your skeletal muscles, when you work your lungs hard during exercise during a long period the muscles get bigger and can expand bigger, giving you a greater lung capacity (lance armstrong's for example is huge)

Their are 4 basic types of exercise in the game- Yoga Strength Training Arobics and Ballance Games.

Would like to find out more about this as well

I do not think that is accurate